"""
Cooling Load Calculator Page

This module implements the cooling load calculator interface for the HVAC Load Calculator web application.
It provides a step-by-step form for inputting building information and calculates cooling loads
using the ASHRAE method.
"""

import streamlit as st
import pandas as pd
import numpy as np
import plotly.express as px
import plotly.graph_objects as go
import json
import os
import sys
from pathlib import Path
from datetime import datetime

# Add the parent directory to sys.path to import modules
sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

# Import custom modules
from cooling_load import CoolingLoadCalculator
from reference_data import ReferenceData
from utils.validation import validate_input, ValidationWarning
from utils.export import export_data


def load_session_state():
    """Initialize or load session state variables."""
    # Initialize session state for form data
    if 'cooling_form_data' not in st.session_state:
        st.session_state.cooling_form_data = {
            'building_info': {},
            'building_envelope': {},
            'windows': {},
            'internal_loads': {},
            'ventilation': {},
            'results': {}
        }
    
    # Initialize session state for validation warnings
    if 'cooling_warnings' not in st.session_state:
        st.session_state.cooling_warnings = {
            'building_info': [],
            'building_envelope': [],
            'windows': [],
            'internal_loads': [],
            'ventilation': []
        }
    
    # Initialize session state for form completion status
    if 'cooling_completed' not in st.session_state:
        st.session_state.cooling_completed = {
            'building_info': False,
            'building_envelope': False,
            'windows': False,
            'internal_loads': False,
            'ventilation': False
        }
    
    # Initialize session state for calculation results
    if 'cooling_results' not in st.session_state:
        st.session_state.cooling_results = None


def building_info_form(ref_data):
    """
    Form for building information.
    
    Args:
        ref_data: Reference data object
    """
    st.subheader("Building Information")
    st.write("Enter general building information, location, and design temperatures.")
    
    # Get location options from reference data
    location_options = {loc_id: loc_data['name'] for loc_id, loc_data in ref_data.locations.items()}
    
    col1, col2 = st.columns(2)
    
    with col1:
        # Building name
        building_name = st.text_input(
            "Building Name",
            value=st.session_state.cooling_form_data['building_info'].get('building_name', ''),
            help="Enter a name for this building or project"
        )
        
        # Location selection
        location = st.selectbox(
            "Location",
            options=list(location_options.keys()),
            format_func=lambda x: location_options[x],
            index=list(location_options.keys()).index(st.session_state.cooling_form_data['building_info'].get('location', 'sydney')) if st.session_state.cooling_form_data['building_info'].get('location') in location_options else 0,
            help="Select the location of the building"
        )
        
        # Get climate data for selected location
        location_data = ref_data.get_location_data(location)
        
        # Indoor design temperature
        indoor_temp = st.number_input(
            "Indoor Design Temperature (°C)",
            value=float(st.session_state.cooling_form_data['building_info'].get('indoor_temp', 24.0)),
            min_value=18.0,
            max_value=30.0,
            step=0.5,
            help="Recommended indoor design temperature for cooling is 24°C"
        )
    
    with col2:
        # Building type
        building_type = st.selectbox(
            "Building Type",
            options=["Residential", "Small Office", "Educational", "Other"],
            index=["Residential", "Small Office", "Educational", "Other"].index(st.session_state.cooling_form_data['building_info'].get('building_type', 'Residential')),
            help="Select the type of building"
        )
        
        # Outdoor design temperature (with default from location data)
        outdoor_temp = st.number_input(
            "Outdoor Design Temperature (°C)",
            value=float(st.session_state.cooling_form_data['building_info'].get('outdoor_temp', location_data['summer_design_temp'])),
            min_value=25.0,
            max_value=45.0,
            step=0.5,
            help=f"Default value is based on selected location ({location_data['name']})"
        )
        
        # Daily temperature range
        daily_range_options = {
            "low": "Low (< 8.5°C)",
            "medium": "Medium (8.5-14°C)",
            "high": "High (> 14°C)"
        }
        daily_range = st.selectbox(
            "Daily Temperature Range",
            options=list(daily_range_options.keys()),
            format_func=lambda x: daily_range_options[x],
            index=list(daily_range_options.keys()).index(st.session_state.cooling_form_data['building_info'].get('daily_range', location_data['daily_temp_range'])),
            help="Daily temperature range affects solar heat gain calculations"
        )
    
    # Building dimensions
    st.subheader("Building Dimensions")
    
    col1, col2, col3 = st.columns(3)
    
    with col1:
        length = st.number_input(
            "Length (m)",
            value=float(st.session_state.cooling_form_data['building_info'].get('length', 10.0)),
            min_value=1.0,
            step=0.1,
            help="Building length in meters"
        )
    
    with col2:
        width = st.number_input(
            "Width (m)",
            value=float(st.session_state.cooling_form_data['building_info'].get('width', 8.0)),
            min_value=1.0,
            step=0.1,
            help="Building width in meters"
        )
    
    with col3:
        height = st.number_input(
            "Height (m)",
            value=float(st.session_state.cooling_form_data['building_info'].get('height', 2.7)),
            min_value=1.0,
            step=0.1,
            help="Floor-to-ceiling height in meters"
        )
    
    # Calculate floor area and volume
    floor_area = length * width
    volume = floor_area * height
    
    st.info(f"Floor Area: {floor_area:.2f} m² | Volume: {volume:.2f} m³")
    
    # Save form data to session state
    form_data = {
        'building_name': building_name,
        'building_type': building_type,
        'location': location,
        'location_name': location_data['name'],
        'indoor_temp': indoor_temp,
        'outdoor_temp': outdoor_temp,
        'daily_range': daily_range,
        'length': length,
        'width': width,
        'height': height,
        'floor_area': floor_area,
        'volume': volume,
        'temp_diff': outdoor_temp - indoor_temp
    }
    
    # Validate inputs
    warnings = []
    
    # Check if building name is provided
    if not building_name:
        warnings.append(ValidationWarning("Building name is empty", "Consider adding a building name for reference"))
    
    # Check if temperature difference is reasonable
    if form_data['temp_diff'] <= 0:
        warnings.append(ValidationWarning(
            "Invalid temperature difference",
            "Outdoor temperature should be higher than indoor temperature for cooling load calculation",
            is_critical=False  # Changed to non-critical to allow proceeding with warnings
        ))
    
    # Check if dimensions are reasonable
    if floor_area > 500:
        warnings.append(ValidationWarning(
            "Large floor area",
            "Floor area exceeds 500 m², verify if this is correct for a residential building"
        ))
    
    if height < 2.4 or height > 3.5:
        warnings.append(ValidationWarning(
            "Unusual ceiling height",
            "Typical residential ceiling heights are between 2.4m and 3.5m"
        ))
    
    # Save warnings to session state
    st.session_state.cooling_warnings['building_info'] = warnings
    
    # Display warnings if any
    if warnings:
        st.warning("Please review the following warnings:")
        for warning in warnings:
            st.write(f"- {warning.message}" + (" (Critical)" if warning.is_critical else ""))
            st.write(f"  Suggestion: {warning.suggestion}")
    
    # Save form data regardless of warnings
    st.session_state.cooling_form_data['building_info'] = form_data
    
    # Mark this step as completed if there are no critical warnings
    st.session_state.cooling_completed['building_info'] = not any(w.is_critical for w in warnings)
    
    # Navigation buttons
    col1, col2 = st.columns([1, 1])
    
    with col2:
        next_button = st.button("Next: Building Envelope →", key="building_info_next")
        if next_button:
            st.session_state.cooling_active_tab = "building_envelope"
            st.experimental_rerun()


def building_envelope_form(ref_data):
    """
    Form for building envelope information.
    
    Args:
        ref_data: Reference data object
    """
    st.subheader("Building Envelope")
    st.write("Enter information about walls, roof, and floor construction.")
    
    # Get building dimensions from previous step
    building_info = st.session_state.cooling_form_data['building_info']
    length = building_info.get('length', 10.0)
    width = building_info.get('width', 8.0)
    height = building_info.get('height', 2.7)
    temp_diff = building_info.get('temp_diff', 11.0)
    
    # Calculate default areas
    default_wall_area = 2 * (length + width) * height
    default_roof_area = length * width
    default_floor_area = length * width
    
    # Initialize envelope data if not already in session state
    if 'walls' not in st.session_state.cooling_form_data['building_envelope']:
        st.session_state.cooling_form_data['building_envelope']['walls'] = []
    
    if 'roof' not in st.session_state.cooling_form_data['building_envelope']:
        st.session_state.cooling_form_data['building_envelope']['roof'] = {}
    
    if 'floor' not in st.session_state.cooling_form_data['building_envelope']:
        st.session_state.cooling_form_data['building_envelope']['floor'] = {}
    
    # Walls section
    st.write("### Walls")
    
    # Get wall material options from reference data
    wall_material_options = {mat_id: mat_data['name'] for mat_id, mat_data in ref_data.materials['walls'].items()}
    # Add custom option
    wall_material_options["custom_walls"] = "Custom Wall (User-defined)"
    
    # Display existing wall entries
    if st.session_state.cooling_form_data['building_envelope']['walls']:
        st.write("Current walls:")
        walls_df = pd.DataFrame(st.session_state.cooling_form_data['building_envelope']['walls'])
        walls_df['Material'] = walls_df['material_id'].map(lambda x: wall_material_options.get(x, "Unknown"))
        # Add orientation column with default value if not present
        walls_df['orientation'] = walls_df['orientation'].fillna('not specified')
        walls_df = walls_df[['name', 'Material', 'area', 'u_value', 'orientation']]
        walls_df.columns = ['Name', 'Material', 'Area (m²)', 'U-Value (W/m²°C)', 'Orientation']
        st.dataframe(walls_df)
    
    # Add new wall form
    st.write("Add a new wall:")
    
    col1, col2 = st.columns(2)
    
    with col1:
        wall_name = st.text_input("Wall Name", value="", key="new_wall_name")
        wall_material = st.selectbox(
            "Wall Material",
            options=list(wall_material_options.keys()),
            format_func=lambda x: wall_material_options[x],
            key="new_wall_material"
        )
        
        # Add wall orientation selection
        wall_orientation = st.selectbox(
            "Wall Orientation",
            options=["north", "east", "south", "west"],
            key="new_wall_orientation"
        )
        
        # Get material properties
        material_data = ref_data.get_material_by_type("walls", wall_material)
        u_value = material_data['u_value']
        
        # Add custom U-value input if custom material is selected
        if wall_material == "custom_walls":
            u_value = st.number_input(
                "Custom U-Value (W/m²°C)",
                value=1.0,
                min_value=0.1,
                max_value=5.0,
                step=0.1,
                key="custom_wall_u_value"
            )
            
            # Store custom material in session state
            if "custom_materials" not in st.session_state:
                st.session_state.custom_materials = {}
            
            st.session_state.custom_materials["walls"] = {
                "name": "Custom Wall",
                "u_value": u_value,
                "r_value": 1.0 / u_value if u_value > 0 else 1.0,
                "description": "Custom wall with user-defined properties"
            }
        
    with col2:
        wall_area = st.number_input(
            "Wall Area (m²)",
            value=default_wall_area / 4,  # Default to 1/4 of total wall area as a starting point
            min_value=0.1,
            step=0.1,
            key="new_wall_area"
        )
        
        st.write(f"Material U-Value: {u_value} W/m²°C")
        st.write(f"Heat Transfer: {u_value * wall_area * temp_diff:.2f} W")
    
    # Add wall button
    if st.button("Add Wall"):
        new_wall = {
            'name': wall_name if wall_name else f"Wall {len(st.session_state.cooling_form_data['building_envelope']['walls']) + 1}",
            'material_id': wall_material,
            'area': wall_area,
            'u_value': u_value,
            'temp_diff': temp_diff,
            'orientation': wall_orientation  # Add orientation to wall data
        }
        st.session_state.cooling_form_data['building_envelope']['walls'].append(new_wall)
        st.experimental_rerun()
    
    # Roof section
    st.write("### Roof")
    
    # Get roof material options from reference data
    roof_material_options = {mat_id: mat_data['name'] for mat_id, mat_data in ref_data.materials['roofs'].items()}
    # Add custom option
    roof_material_options["custom_roofs"] = "Custom Roof (User-defined)"
    
    col1, col2 = st.columns(2)
    
    with col1:
        roof_material = st.selectbox(
            "Roof Material",
            options=list(roof_material_options.keys()),
            format_func=lambda x: roof_material_options[x],
            index=list(roof_material_options.keys()).index(st.session_state.cooling_form_data['building_envelope'].get('roof', {}).get('material_id', 'metal_deck_insulated')) if st.session_state.cooling_form_data['building_envelope'].get('roof', {}).get('material_id') in roof_material_options else 0
        )
        
        # Get material properties
        material_data = ref_data.get_material_by_type("roofs", roof_material)
        roof_u_value = material_data['u_value']
        
        # Add custom U-value input if custom material is selected
        if roof_material == "custom_roofs":
            roof_u_value = st.number_input(
                "Custom Roof U-Value (W/m²°C)",
                value=1.0,
                min_value=0.1,
                max_value=5.0,
                step=0.1,
                key="custom_roof_u_value"
            )
            
            # Store custom material in session state
            if "custom_materials" not in st.session_state:
                st.session_state.custom_materials = {}
            
            st.session_state.custom_materials["roofs"] = {
                "name": "Custom Roof",
                "u_value": roof_u_value,
                "r_value": 1.0 / roof_u_value if roof_u_value > 0 else 1.0,
                "description": "Custom roof with user-defined properties"
            }
        
    with col2:
        roof_area = st.number_input(
            "Roof Area (m²)",
            value=float(st.session_state.cooling_form_data['building_envelope'].get('roof', {}).get('area', default_roof_area)),
            min_value=0.1,
            step=0.1
        )
        
        st.write(f"Material U-Value: {roof_u_value} W/m²°C")
        st.write(f"Heat Transfer: {roof_u_value * roof_area * temp_diff:.2f} W")
    
    # Save roof data
    st.session_state.cooling_form_data['building_envelope']['roof'] = {
        'material_id': roof_material,
        'area': roof_area,
        'u_value': roof_u_value,
        'temp_diff': temp_diff
    }
    
    # Floor section
    st.write("### Floor")
    
    # Get floor material options from reference data
    floor_material_options = {mat_id: mat_data['name'] for mat_id, mat_data in ref_data.materials['floors'].items()}
    # Add custom option
    floor_material_options["custom_floors"] = "Custom Floor (User-defined)"
    
    col1, col2 = st.columns(2)
    
    with col1:
        floor_material = st.selectbox(
            "Floor Material",
            options=list(floor_material_options.keys()),
            format_func=lambda x: floor_material_options[x],
            index=list(floor_material_options.keys()).index(st.session_state.cooling_form_data['building_envelope'].get('floor', {}).get('material_id', 'concrete_slab_ground')) if st.session_state.cooling_form_data['building_envelope'].get('floor', {}).get('material_id') in floor_material_options else 0
        )
        
        # Get material properties
        material_data = ref_data.get_material_by_type("floors", floor_material)
        floor_u_value = material_data['u_value']
        
        # Add custom U-value input if custom material is selected
        if floor_material == "custom_floors":
            floor_u_value = st.number_input(
                "Custom Floor U-Value (W/m²°C)",
                value=1.0,
                min_value=0.1,
                max_value=5.0,
                step=0.1,
                key="custom_floor_u_value"
            )
            
            # Store custom material in session state
            if "custom_materials" not in st.session_state:
                st.session_state.custom_materials = {}
            
            st.session_state.custom_materials["floors"] = {
                "name": "Custom Floor",
                "u_value": floor_u_value,
                "r_value": 1.0 / floor_u_value if floor_u_value > 0 else 1.0,
                "description": "Custom floor with user-defined properties"
            }
        
    with col2:
        floor_area = st.number_input(
            "Floor Area (m²)",
            value=float(st.session_state.cooling_form_data['building_envelope'].get('floor', {}).get('area', default_floor_area)),
            min_value=0.1,
            step=0.1
        )
        
        st.write(f"Material U-Value: {floor_u_value} W/m²°C")
        st.write(f"Heat Transfer: {floor_u_value * floor_area * temp_diff:.2f} W")
    
    # Save floor data
    st.session_state.cooling_form_data['building_envelope']['floor'] = {
        'material_id': floor_material,
        'area': floor_area,
        'u_value': floor_u_value,
        'temp_diff': temp_diff
    }
    
    # Validate inputs
    warnings = []
    
    # Check if walls are defined
    if not st.session_state.cooling_form_data['building_envelope']['walls']:
        warnings.append(ValidationWarning(
            "No walls defined",
            "Add at least one wall to continue",
            is_critical=False  # Changed to non-critical to allow proceeding with warnings
        ))
    
    # Check if total wall area is reasonable
    total_wall_area = sum(wall['area'] for wall in st.session_state.cooling_form_data['building_envelope']['walls'])
    expected_wall_area = 2 * (length + width) * height
    
    if total_wall_area < expected_wall_area * 0.8 or total_wall_area > expected_wall_area * 1.2:
        warnings.append(ValidationWarning(
            "Unusual wall area",
            f"Total wall area ({total_wall_area:.2f} m²) differs significantly from the expected area ({expected_wall_area:.2f} m²) based on building dimensions"
        ))
    
    # Check if roof area matches floor area
    if abs(roof_area - floor_area) > 1.0:
        warnings.append(ValidationWarning(
            "Roof area doesn't match floor area",
            "For a simple building, roof area should approximately match floor area"
        ))
    
    # Save warnings to session state
    st.session_state.cooling_warnings['building_envelope'] = warnings
    
    # Display warnings if any
    if warnings:
        st.warning("Please review the following warnings:")
        for warning in warnings:
            st.write(f"- {warning.message}" + (" (Critical)" if warning.is_critical else ""))
            st.write(f"  Suggestion: {warning.suggestion}")
    
    # Mark this step as completed if there are no critical warnings
    st.session_state.cooling_completed['building_envelope'] = not any(w.is_critical for w in warnings)
    
    # Navigation buttons
    col1, col2 = st.columns([1, 1])
    
    with col1:
        prev_button = st.button("← Back: Building Information", key="building_envelope_prev")
        if prev_button:
            st.session_state.cooling_active_tab = "building_info"
            st.experimental_rerun()
    
    with col2:
        next_button = st.button("Next: Windows & Doors →", key="building_envelope_next")
        if next_button:
            st.session_state.cooling_active_tab = "windows"
            st.experimental_rerun()


def windows_form(ref_data):
    """
    Form for windows and doors information.
    
    Args:
        ref_data: Reference data object
    """
    st.subheader("Windows & Doors")
    st.write("Enter information about windows and doors.")
    
    # Get temperature difference from building info
    temp_diff = st.session_state.cooling_form_data['building_info'].get('temp_diff', 11.0)
    daily_range = st.session_state.cooling_form_data['building_info'].get('daily_range', 'medium')
    
    # Initialize windows data if not already in session state
    if 'windows' not in st.session_state.cooling_form_data['windows']:
        st.session_state.cooling_form_data['windows']['windows'] = []
    
    if 'doors' not in st.session_state.cooling_form_data['windows']:
        st.session_state.cooling_form_data['windows']['doors'] = []
    
    # Windows section
    st.write("### Windows")
    
    # Get glass type options from reference data
    glass_type_options = {glass_id: glass_data['name'] for glass_id, glass_data in ref_data.glass_types.items()}
    
    # Get shading options from reference data
    shading_options = {shade_id: shade_data['name'] for shade_id, shade_data in ref_data.shading_factors.items()}
    
    # Display existing window entries
    if st.session_state.cooling_form_data['windows']['windows']:
        st.write("Current windows:")
        windows_df = pd.DataFrame(st.session_state.cooling_form_data['windows']['windows'])
        windows_df['Glass Type'] = windows_df['glass_type'].map(lambda x: glass_type_options.get(x, "Unknown"))
        windows_df['Shading'] = windows_df['shading'].map(lambda x: shading_options.get(x, "Unknown"))
        windows_df = windows_df[['name', 'orientation', 'Glass Type', 'Shading', 'area', 'u_value']]
        windows_df.columns = ['Name', 'Orientation', 'Glass Type', 'Shading', 'Area (m²)', 'U-Value (W/m²°C)']
        st.dataframe(windows_df)
    
    # Add new window form
    st.write("Add a new window:")
    
    col1, col2 = st.columns(2)
    
    with col1:
        window_name = st.text_input("Window Name", value="", key="new_window_name")
        
        orientation = st.selectbox(
            "Orientation",
            options=["north", "east", "south", "west", "horizontal"],
            key="new_window_orientation"
        )
        
        glass_type = st.selectbox(
            "Glass Type",
            options=list(glass_type_options.keys()),
            format_func=lambda x: glass_type_options[x],
            key="new_window_glass_type"
        )
        
        # Get glass properties
        glass_data = ref_data.get_glass_type(glass_type)
        window_u_value = glass_data['u_value']
        
    with col2:
        window_area = st.number_input(
            "Window Area (m²)",
            value=2.0,
            min_value=0.1,
            step=0.1,
            key="new_window_area"
        )
        
        shading = st.selectbox(
            "Shading",
            options=list(shading_options.keys()),
            format_func=lambda x: shading_options[x],
            key="new_window_shading"
        )
        
        # Get shading factor
        shading_data = ref_data.get_shading_factor(shading)
        shade_factor = shading_data['factor']
        
        st.write(f"Glass U-Value: {window_u_value} W/m²°C")
        st.write(f"Conduction Heat Transfer: {window_u_value * window_area * temp_diff:.2f} W")
    
    # Add window button
    if st.button("Add Window"):
        # Calculate solar heat gain factor
        calculator = CoolingLoadCalculator()
        shgf = calculator.get_solar_heat_gain_factor(
            orientation=orientation,
            glass_type=glass_type,
            daily_range=daily_range
        )
        
        new_window = {
            'name': window_name if window_name else f"Window {len(st.session_state.cooling_form_data['windows']['windows']) + 1}",
            'orientation': orientation,
            'glass_type': glass_type,
            'shading': shading,
            'area': window_area,
            'u_value': window_u_value,
            'shgf': shgf,
            'shade_factor': shade_factor,
            'temp_diff': temp_diff
        }
        st.session_state.cooling_form_data['windows']['windows'].append(new_window)
        st.experimental_rerun()
    
    # Doors section
    st.write("### Doors")
    
    # Display existing door entries
    if st.session_state.cooling_form_data['windows']['doors']:
        st.write("Current doors:")
        doors_df = pd.DataFrame(st.session_state.cooling_form_data['windows']['doors'])
        doors_df = doors_df[['name', 'type', 'area', 'u_value']]
        doors_df.columns = ['Name', 'Type', 'Area (m²)', 'U-Value (W/m²°C)']
        st.dataframe(doors_df)
    
    # Add new door form
    st.write("Add a new door:")
    
    col1, col2 = st.columns(2)
    
    with col1:
        door_name = st.text_input("Door Name", value="", key="new_door_name")
        
        door_type = st.selectbox(
            "Door Type",
            options=["Solid wood", "Hollow core", "Glass", "Insulated"],
            key="new_door_type"
        )
        
        # Set U-value based on door type
        door_u_values = {
            "Solid wood": 2.0,
            "Hollow core": 2.5,
            "Glass": 5.0,
            "Insulated": 1.2
        }
        door_u_value = door_u_values[door_type]
        
    with col2:
        door_area = st.number_input(
            "Door Area (m²)",
            value=2.0,
            min_value=0.1,
            step=0.1,
            key="new_door_area"
        )
        
        st.write(f"Door U-Value: {door_u_value} W/m²°C")
        st.write(f"Heat Transfer: {door_u_value * door_area * temp_diff:.2f} W")
    
    # Add door button
    if st.button("Add Door"):
        new_door = {
            'name': door_name if door_name else f"Door {len(st.session_state.cooling_form_data['windows']['doors']) + 1}",
            'type': door_type,
            'area': door_area,
            'u_value': door_u_value,
            'temp_diff': temp_diff
        }
        st.session_state.cooling_form_data['windows']['doors'].append(new_door)
        st.experimental_rerun()
    
    # Validate inputs
    warnings = []
    
    # Check if windows are defined
    if not st.session_state.cooling_form_data['windows']['windows']:
        warnings.append(ValidationWarning(
            "No windows defined",
            "Add at least one window to continue"
        ))
    
    # Check window-to-wall ratio
    if st.session_state.cooling_form_data['windows']['windows']:
        total_window_area = sum(window['area'] for window in st.session_state.cooling_form_data['windows']['windows'])
        total_wall_area = sum(wall['area'] for wall in st.session_state.cooling_form_data['building_envelope']['walls'])
        window_wall_ratio = total_window_area / total_wall_area if total_wall_area > 0 else 0
        
        if window_wall_ratio > 0.6:
            warnings.append(ValidationWarning(
                "High window-to-wall ratio",
                f"Window-to-wall ratio is {window_wall_ratio:.2f}, which is unusually high. Typical ratios are 0.2-0.4."
            ))
    
    # Save warnings to session state
    st.session_state.cooling_warnings['windows'] = warnings
    
    # Display warnings if any
    if warnings:
        st.warning("Please review the following warnings:")
        for warning in warnings:
            st.write(f"- {warning.message}" + (" (Critical)" if warning.is_critical else ""))
            st.write(f"  Suggestion: {warning.suggestion}")
    
    # Mark this step as completed if there are no critical warnings
    st.session_state.cooling_completed['windows'] = not any(w.is_critical for w in warnings)
    
    # Navigation buttons
    col1, col2 = st.columns([1, 1])
    
    with col1:
        prev_button = st.button("← Back: Building Envelope", key="windows_prev")
        if prev_button:
            st.session_state.cooling_active_tab = "building_envelope"
            st.experimental_rerun()
    
    with col2:
        next_button = st.button("Next: Internal Loads →", key="windows_next")
        if next_button:
            st.session_state.cooling_active_tab = "internal_loads"
            st.experimental_rerun()


def internal_loads_form(ref_data):
    """
    Form for internal loads information.
    
    Args:
        ref_data: Reference data object
    """
    st.subheader("Internal Loads")
    st.write("Enter information about occupants, lighting, and equipment.")
    
    # Initialize internal loads data if not already in session state
    if 'occupants' not in st.session_state.cooling_form_data['internal_loads']:
        st.session_state.cooling_form_data['internal_loads']['occupants'] = {
            'count': 4,
            'activity_level': 'seated_resting'
        }
    
    if 'lighting' not in st.session_state.cooling_form_data['internal_loads']:
        st.session_state.cooling_form_data['internal_loads']['lighting'] = {
            'type': 'led',
            'power_density': 5.0  # W/m²
        }
    
    if 'appliances' not in st.session_state.cooling_form_data['internal_loads']:
        st.session_state.cooling_form_data['internal_loads']['appliances'] = {
            'kitchen': True,
            'living_room': True,
            'bedroom': True,
            'office': False
        }
    
    # Occupants section
    st.write("### Occupants")
    
    col1, col2 = st.columns(2)
    
    with col1:
        occupant_count = st.number_input(
            "Number of Occupants",
            value=int(st.session_state.cooling_form_data['internal_loads']['occupants'].get('count', 4)),
            min_value=1,
            step=1
        )
    
    with col2:
        # Get activity level options from reference data
        activity_options = {act_id: act_data['name'] for act_id, act_data in ref_data.internal_loads['people'].items()}
        
        activity_level = st.selectbox(
            "Activity Level",
            options=list(activity_options.keys()),
            format_func=lambda x: activity_options[x],
            index=list(activity_options.keys()).index(st.session_state.cooling_form_data['internal_loads']['occupants'].get('activity_level', 'seated_resting')) if st.session_state.cooling_form_data['internal_loads']['occupants'].get('activity_level') in activity_options else 0
        )
    
    # Get heat gain per person
    activity_data = ref_data.get_internal_load('people', activity_level)
    sensible_heat_pp = activity_data['sensible_heat']
    latent_heat_pp = activity_data['latent_heat']
    total_heat_pp = sensible_heat_pp + latent_heat_pp
    
    st.write(f"Heat gain per person: {total_heat_pp} W ({sensible_heat_pp} W sensible + {latent_heat_pp} W latent)")
    st.write(f"Total occupant heat gain: {total_heat_pp * occupant_count} W")
    
    # Save occupants data
    st.session_state.cooling_form_data['internal_loads']['occupants'] = {
        'count': occupant_count,
        'activity_level': activity_level,
        'sensible_heat_pp': sensible_heat_pp,
        'latent_heat_pp': latent_heat_pp,
        'total_heat_gain': total_heat_pp * occupant_count
    }
    
    # Lighting section
    st.write("### Lighting")
    
    col1, col2 = st.columns(2)
    
    with col1:
        # Get lighting type options from reference data
        lighting_options = {light_id: light_data['name'] for light_id, light_data in ref_data.internal_loads['lighting'].items()}
        
        lighting_type = st.selectbox(
            "Lighting Type",
            options=list(lighting_options.keys()),
            format_func=lambda x: lighting_options[x],
            index=list(lighting_options.keys()).index(st.session_state.cooling_form_data['internal_loads']['lighting'].get('type', 'led')) if st.session_state.cooling_form_data['internal_loads']['lighting'].get('type') in lighting_options else 0
        )
    
    with col2:
        lighting_power_density = st.number_input(
            "Lighting Power Density (W/m²)",
            value=float(st.session_state.cooling_form_data['internal_loads']['lighting'].get('power_density', 5.0)),
            min_value=1.0,
            max_value=20.0,
            step=0.5,
            help="Typical values: Residential 5-10 W/m², Office 10-15 W/m²"
        )
    
    # Get lighting heat factor
    lighting_data = ref_data.get_internal_load('lighting', lighting_type)
    lighting_heat_factor = lighting_data['heat_factor']
    
    # Calculate lighting heat gain
    floor_area = st.session_state.cooling_form_data['building_info'].get('floor_area', 80.0)
    lighting_heat_gain = lighting_power_density * floor_area * lighting_heat_factor
    
    st.write(f"Lighting heat factor: {lighting_heat_factor}")
    st.write(f"Total lighting heat gain: {lighting_heat_gain:.2f} W")
    
    # Save lighting data
    st.session_state.cooling_form_data['internal_loads']['lighting'] = {
        'type': lighting_type,
        'power_density': lighting_power_density,
        'heat_factor': lighting_heat_factor,
        'total_heat_gain': lighting_heat_gain
    }
    
    # Appliances section
    st.write("### Appliances")
    
    # Get appliance options from reference data
    appliance_options = {app_id: app_data for app_id, app_data in ref_data.internal_loads['appliances'].items()}
    
    col1, col2 = st.columns(2)
    
    with col1:
        has_kitchen = st.checkbox(
            "Kitchen Appliances",
            value=st.session_state.cooling_form_data['internal_loads']['appliances'].get('kitchen', True),
            help=f"Heat gain: {appliance_options['kitchen']['heat_gain']} W"
        )
        
        has_living_room = st.checkbox(
            "Living Room Appliances",
            value=st.session_state.cooling_form_data['internal_loads']['appliances'].get('living_room', True),
            help=f"Heat gain: {appliance_options['living_room']['heat_gain']} W"
        )
    
    with col2:
        has_bedroom = st.checkbox(
            "Bedroom Appliances",
            value=st.session_state.cooling_form_data['internal_loads']['appliances'].get('bedroom', True),
            help=f"Heat gain: {appliance_options['bedroom']['heat_gain']} W"
        )
        
        has_office = st.checkbox(
            "Home Office Equipment",
            value=st.session_state.cooling_form_data['internal_loads']['appliances'].get('office', False),
            help=f"Heat gain: {appliance_options['office']['heat_gain']} W"
        )
    
    # Calculate appliance heat gain
    appliance_heat_gain = 0
    if has_kitchen:
        appliance_heat_gain += appliance_options['kitchen']['heat_gain']
    if has_living_room:
        appliance_heat_gain += appliance_options['living_room']['heat_gain']
    if has_bedroom:
        appliance_heat_gain += appliance_options['bedroom']['heat_gain']
    if has_office:
        appliance_heat_gain += appliance_options['office']['heat_gain']
    
    st.write(f"Total appliance heat gain: {appliance_heat_gain} W")
    
    # Save appliances data
    st.session_state.cooling_form_data['internal_loads']['appliances'] = {
        'kitchen': has_kitchen,
        'living_room': has_living_room,
        'bedroom': has_bedroom,
        'office': has_office,
        'total_heat_gain': appliance_heat_gain
    }
    
    # Calculate total internal heat gain
    total_internal_gain = (
        st.session_state.cooling_form_data['internal_loads']['occupants']['total_heat_gain'] +
        st.session_state.cooling_form_data['internal_loads']['lighting']['total_heat_gain'] +
        st.session_state.cooling_form_data['internal_loads']['appliances']['total_heat_gain']
    )
    
    st.info(f"Total Internal Heat Gain: {total_internal_gain:.2f} W")
    
    # Save total internal gain
    st.session_state.cooling_form_data['internal_loads']['total_internal_gain'] = total_internal_gain
    
    # Validate inputs
    warnings = []
    
    # Check if occupant count is reasonable for the floor area
    floor_area = st.session_state.cooling_form_data['building_info'].get('floor_area', 80.0)
    area_per_person = floor_area / occupant_count if occupant_count > 0 else float('inf')
    
    if area_per_person < 10:
        warnings.append(ValidationWarning(
            "High occupant density",
            f"Area per person ({area_per_person:.2f} m²) is low. Typical residential values are 20-30 m² per person."
        ))
    
    # Check if lighting power density is reasonable
    if lighting_power_density > 15:
        warnings.append(ValidationWarning(
            "High lighting power density",
            "Lighting power density exceeds 15 W/m², which is high for residential buildings."
        ))
    
    # Save warnings to session state
    st.session_state.cooling_warnings['internal_loads'] = warnings
    
    # Display warnings if any
    if warnings:
        st.warning("Please review the following warnings:")
        for warning in warnings:
            st.write(f"- {warning.message}" + (" (Critical)" if warning.is_critical else ""))
            st.write(f"  Suggestion: {warning.suggestion}")
    
    # Mark this step as completed if there are no critical warnings
    st.session_state.cooling_completed['internal_loads'] = not any(w.is_critical for w in warnings)
    
    # Navigation buttons
    col1, col2 = st.columns([1, 1])
    
    with col1:
        prev_button = st.button("← Back: Windows & Doors", key="internal_loads_prev")
        if prev_button:
            st.session_state.cooling_active_tab = "windows"
            st.experimental_rerun()
    
    with col2:
        next_button = st.button("Next: Ventilation →", key="internal_loads_next")
        if next_button:
            st.session_state.cooling_active_tab = "ventilation"
            st.experimental_rerun()


def ventilation_form(ref_data):
    """
    Form for ventilation and infiltration information.
    
    Args:
        ref_data: Reference data object
    """
    st.subheader("Ventilation & Infiltration")
    st.write("Enter information about ventilation and infiltration rates.")
    
    # Get building info
    building_info = st.session_state.cooling_form_data['building_info']
    volume = building_info.get('volume', 216.0)
    temp_diff = building_info.get('temp_diff', 11.0)
    
    # Initialize ventilation data if not already in session state
    if 'infiltration' not in st.session_state.cooling_form_data['ventilation']:
        st.session_state.cooling_form_data['ventilation']['infiltration'] = {
            'air_changes': 0.5
        }
    
    if 'ventilation' not in st.session_state.cooling_form_data['ventilation']:
        st.session_state.cooling_form_data['ventilation']['ventilation'] = {
            'type': 'natural',
            'air_changes': 0.0
        }
    
    # Infiltration section
    st.write("### Infiltration")
    st.write("Infiltration is the unintended air leakage through the building envelope.")
    
    infiltration_ach = st.slider(
        "Infiltration Rate (air changes per hour)",
        value=float(st.session_state.cooling_form_data['ventilation']['infiltration'].get('air_changes', 0.5)),
        min_value=0.1,
        max_value=2.0,
        step=0.1,
        help="Typical values: 0.5 ACH for modern construction, 1.0 ACH for average construction, 1.5+ ACH for older buildings"
    )
    
    # Calculate infiltration heat gain
    infiltration_heat_gain = 0.33 * volume * infiltration_ach * temp_diff
    
    st.write(f"Infiltration heat gain: {infiltration_heat_gain:.2f} W")
    
    # Save infiltration data
    st.session_state.cooling_form_data['ventilation']['infiltration'] = {
        'air_changes': infiltration_ach,
        'volume': volume,
        'temp_diff': temp_diff,
        'heat_gain': infiltration_heat_gain
    }
    
    # Ventilation section
    st.write("### Ventilation")
    st.write("Ventilation is the intentional introduction of outside air into the building.")
    
    col1, col2 = st.columns(2)
    
    with col1:
        ventilation_type = st.selectbox(
            "Ventilation Type",
            options=["natural", "mechanical", "mixed"],
            format_func=lambda x: x.capitalize(),
            index=["natural", "mechanical", "mixed"].index(st.session_state.cooling_form_data['ventilation']['ventilation'].get('type', 'natural'))
        )
    
    with col2:
        ventilation_ach = st.number_input(
            "Ventilation Rate (air changes per hour)",
            value=float(st.session_state.cooling_form_data['ventilation']['ventilation'].get('air_changes', 0.0)),
            min_value=0.0,
            max_value=5.0,
            step=0.1,
            help="Typical values: 0.35-1.0 ACH for residential buildings"
        )
    
    # Calculate ventilation heat gain
    ventilation_heat_gain = 0.33 * volume * ventilation_ach * temp_diff
    
    st.write(f"Ventilation heat gain: {ventilation_heat_gain:.2f} W")
    
    # Save ventilation data
    st.session_state.cooling_form_data['ventilation']['ventilation'] = {
        'type': ventilation_type,
        'air_changes': ventilation_ach,
        'volume': volume,
        'temp_diff': temp_diff,
        'heat_gain': ventilation_heat_gain
    }
    
    # Calculate total ventilation and infiltration heat gain
    total_ventilation_gain = infiltration_heat_gain + ventilation_heat_gain
    
    st.info(f"Total Ventilation & Infiltration Heat Gain: {total_ventilation_gain:.2f} W")
    
    # Save total ventilation gain
    st.session_state.cooling_form_data['ventilation']['total_gain'] = total_ventilation_gain
    
    # Validate inputs
    warnings = []
    
    # Check if infiltration rate is reasonable
    if infiltration_ach < 0.3:
        warnings.append(ValidationWarning(
            "Low infiltration rate",
            "Infiltration rate below 0.3 ACH is unusually low for most buildings."
        ))
    elif infiltration_ach > 1.5:
        warnings.append(ValidationWarning(
            "High infiltration rate",
            "Infiltration rate above 1.5 ACH indicates a leaky building envelope."
        ))
    
    # Check if ventilation rate is reasonable
    if ventilation_ach > 0 and ventilation_ach < 0.35:
        warnings.append(ValidationWarning(
            "Low ventilation rate",
            "Ventilation rate below 0.35 ACH may not provide adequate fresh air."
        ))
    elif ventilation_ach > 2.0:
        warnings.append(ValidationWarning(
            "High ventilation rate",
            "Ventilation rate above 2.0 ACH is unusually high for residential buildings."
        ))
    
    # Save warnings to session state
    st.session_state.cooling_warnings['ventilation'] = warnings
    
    # Display warnings if any
    if warnings:
        st.warning("Please review the following warnings:")
        for warning in warnings:
            st.write(f"- {warning.message}" + (" (Critical)" if warning.is_critical else ""))
            st.write(f"  Suggestion: {warning.suggestion}")
    
    # Mark this step as completed if there are no critical warnings
    st.session_state.cooling_completed['ventilation'] = not any(w.is_critical for w in warnings)
    
    # Navigation buttons
    col1, col2 = st.columns([1, 1])
    
    with col1:
        prev_button = st.button("← Back: Internal Loads", key="ventilation_prev")
        if prev_button:
            st.session_state.cooling_active_tab = "internal_loads"
            st.experimental_rerun()
    
    with col2:
        calculate_button = st.button("Calculate Results →", key="ventilation_calculate")
        if calculate_button:
            # Calculate cooling load
            calculate_cooling_load()
            st.session_state.cooling_active_tab = "results"
            st.experimental_rerun()


def calculate_cooling_load():
    """Calculate cooling load based on input data."""
    # Create calculator instance
    calculator = CoolingLoadCalculator()
    
    # Get form data
    form_data = st.session_state.cooling_form_data
    
    # Prepare building components for calculation
    building_components = []
    
    # Add walls
    for wall in form_data['building_envelope'].get('walls', []):
        building_components.append({
            'name': wall['name'],
            'area': wall['area'],
            'u_value': wall['u_value'],
            'temp_diff': wall['temp_diff']
        })
    
    # Add roof
    roof = form_data['building_envelope'].get('roof', {})
    if roof:
        building_components.append({
            'name': 'Roof',
            'area': roof['area'],
            'u_value': roof['u_value'],
            'temp_diff': roof['temp_diff']
        })
    
    # Add floor
    floor = form_data['building_envelope'].get('floor', {})
    if floor:
        building_components.append({
            'name': 'Floor',
            'area': floor['area'],
            'u_value': floor['u_value'],
            'temp_diff': floor['temp_diff']
        })
    
    # Prepare windows for calculation
    windows = []
    for window in form_data['windows'].get('windows', []):
        windows.append({
            'name': window['name'],
            'area': window['area'],
            'u_value': window['u_value'],
            'orientation': window['orientation'],
            'glass_type': window['glass_type'],
            'shading': window['shading'],
            'shgf': window['shgf'],
            'shade_factor': 1.0 - window['shade_factor'],
            'temp_diff': window['temp_diff']
        })
    
    # Add doors to building components
    for door in form_data['windows'].get('doors', []):
        building_components.append({
            'name': door['name'],
            'area': door['area'],
            'u_value': door['u_value'],
            'temp_diff': door['temp_diff']
        })
    
    # Prepare infiltration data
    infiltration = form_data['ventilation'].get('infiltration', {})
    ventilation = form_data['ventilation'].get('ventilation', {})
    
    infiltration_data = {
        'volume': infiltration.get('volume', 0),
        'air_changes': infiltration.get('air_changes', 0) + ventilation.get('air_changes', 0),
        'temp_diff': infiltration.get('temp_diff', 0)
    }
    
    # Prepare internal gains data
    internal_gains = {
        'num_people': form_data['internal_loads'].get('occupants', {}).get('count', 0),
        'has_kitchen': form_data['internal_loads'].get('appliances', {}).get('kitchen', False),
        'equipment_watts': (
            form_data['internal_loads'].get('lighting', {}).get('total_heat_gain', 0) +
            form_data['internal_loads'].get('appliances', {}).get('total_heat_gain', 0) -
            (1000 if form_data['internal_loads'].get('appliances', {}).get('kitchen', False) else 0)  # Subtract kitchen heat gain if included
        )
    }
    
    # Calculate cooling load
    results = calculator.calculate_total_cooling_load(
        building_components=building_components,
        windows=windows,
        infiltration=infiltration_data,
        internal_gains=internal_gains
    )
    
    # Save results to session state
    st.session_state.cooling_results = results
    
    # Add timestamp
    st.session_state.cooling_results['timestamp'] = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
    
    # Add building info
    st.session_state.cooling_results['building_info'] = form_data['building_info']
    
    return results


def results_page():
    """Display calculation results."""
    st.subheader("Cooling Load Calculation Results")
    
    # Check if results are available
    if not st.session_state.cooling_results:
        st.warning("No calculation results available. Please complete the input forms and calculate results.")
        return
    
    # Get results
    results = st.session_state.cooling_results
    
    # Display summary
    st.write("### Summary")
    
    col1, col2 = st.columns(2)
    
    with col1:
        st.metric("Sensible Cooling Load", f"{results['sensible_load']:.2f} W")
        st.metric("Total Cooling Load", f"{results['total_load']:.2f} W")
        
        # Convert to kW
        total_load_kw = results['total_load'] / 1000
        st.metric("Total Cooling Load", f"{total_load_kw:.2f} kW")
    
    with col2:
        st.metric("Latent Cooling Load", f"{results['latent_load']:.2f} W")
        
        # Calculate cooling load per area
        floor_area = results['building_info'].get('floor_area', 80.0)
        cooling_load_per_area = results['total_load'] / floor_area
        st.metric("Cooling Load per Area", f"{cooling_load_per_area:.2f} W/m²")
        
        # Equipment sizing recommendation
        # Add 10% safety factor
        recommended_size = total_load_kw * 1.1
        st.metric("Recommended Equipment Size", f"{recommended_size:.2f} kW")
    
    # Display load breakdown
    st.write("### Load Breakdown")
    
    # Prepare data for pie chart
    load_components = {
        'Conduction (Opaque Surfaces)': results['conduction_gain'],
        'Conduction (Windows)': results['window_conduction_gain'],
        'Solar Radiation (Windows)': results['window_solar_gain'],
        'Infiltration & Ventilation': results['infiltration_gain'],
        'Internal Gains': results['internal_gain']
    }
    
    # Create pie chart
    fig = px.pie(
        values=list(load_components.values()),
        names=list(load_components.keys()),
        title="Cooling Load Components",
        color_discrete_sequence=px.colors.sequential.Turbo,
        hole=0.4,  # Create a donut chart for better readability
        labels={'label': 'Component', 'value': 'Heat Gain (W)'}
    )
    
    # Improve layout and formatting
    fig.update_traces(
        textposition='inside',
        textinfo='percent+label',
        hoverinfo='label+percent+value',
        marker=dict(line=dict(color='#FFFFFF', width=2))
    )
    
    # Improve layout
    fig.update_layout(
        legend_title_text='Load Components',
        font=dict(size=14),
        title_font=dict(size=18),
        title_x=0.5,  # Center the title
        margin=dict(t=50, b=50, l=50, r=50)
    )
    
    st.plotly_chart(fig)
    
    # Display load components in a table
    load_df = pd.DataFrame({
        'Component': list(load_components.keys()),
        'Load (W)': list(load_components.values()),
        'Percentage (%)': [value / results['sensible_load'] * 100 for value in load_components.values()]
    })
    
    # Sort by load value for better readability
    load_df = load_df.sort_values(by='Load (W)', ascending=False).reset_index(drop=True)
    
    st.dataframe(load_df.style.format({
        'Load (W)': '{:.2f}',
        'Percentage (%)': '{:.2f}'
    }).background_gradient(cmap='Blues', subset=['Percentage (%)']))
    
    # Display detailed results
    st.write("### Detailed Results")
    
    # Create tabs for different result sections
    tabs = st.tabs([
        "Building Envelope", 
        "Windows & Doors", 
        "Internal Loads", 
        "Ventilation"
    ])
    
    with tabs[0]:
        st.subheader("Building Envelope Heat Gains")
        
        # Get building components
        building_components = []
        
        # Add walls
        for wall in st.session_state.cooling_form_data['building_envelope'].get('walls', []):
            building_components.append({
                'Component': wall['name'],
                'Area (m²)': wall['area'],
                'U-Value (W/m²°C)': wall['u_value'],
                'Temperature Difference (°C)': wall['temp_diff'],
                'Heat Gain (W)': wall['area'] * wall['u_value'] * wall['temp_diff']
            })
        
        # Add roof
        roof = st.session_state.cooling_form_data['building_envelope'].get('roof', {})
        if roof:
            building_components.append({
                'Component': 'Roof',
                'Area (m²)': roof['area'],
                'U-Value (W/m²°C)': roof['u_value'],
                'Temperature Difference (°C)': roof['temp_diff'],
                'Heat Gain (W)': roof['area'] * roof['u_value'] * roof['temp_diff']
            })
        
        # Add floor
        floor = st.session_state.cooling_form_data['building_envelope'].get('floor', {})
        if floor:
            building_components.append({
                'Component': 'Floor',
                'Area (m²)': floor['area'],
                'U-Value (W/m²°C)': floor['u_value'],
                'Temperature Difference (°C)': floor['temp_diff'],
                'Heat Gain (W)': floor['area'] * floor['u_value'] * floor['temp_diff']
            })
        
        # Create dataframe
        envelope_df = pd.DataFrame(building_components)
        
        # Display table
        st.dataframe(envelope_df.style.format({
            'Area (m²)': '{:.2f}',
            'U-Value (W/m²°C)': '{:.2f}',
            'Temperature Difference (°C)': '{:.2f}',
            'Heat Gain (W)': '{:.2f}'
        }))
        
        # Create bar chart
        fig = px.bar(
            envelope_df,
            x='Component',
            y='Heat Gain (W)',
            title="Heat Gain by Building Component",
            color='Component',
            color_discrete_sequence=px.colors.qualitative.Set3
        )
        
        st.plotly_chart(fig)
    
    with tabs[1]:
        st.subheader("Windows & Doors Heat Gains")
        
        # Windows section
        st.write("#### Windows")
        
        # Get windows
        windows_data = []
        for window in st.session_state.cooling_form_data['windows'].get('windows', []):
            windows_data.append({
                'Component': window['name'],
                'Orientation': window['orientation'].capitalize(),
                'Area (m²)': window['area'],
                'U-Value (W/m²°C)': window['u_value'],
                'Temperature Difference (°C)': window['temp_diff'],
                'Conduction Heat Gain (W)': window['area'] * window['u_value'] * window['temp_diff'],
                'Solar Heat Gain Factor (W/m²)': window['shgf'],
                'Shading Factor': 1.0 - window['shade_factor'],
                'Solar Heat Gain (W)': window['area'] * window['shgf'] * (1.0 - window['shade_factor']),
                'Total Heat Gain (W)': (window['area'] * window['u_value'] * window['temp_diff']) + 
                                      (window['area'] * window['shgf'] * (1.0 - window['shade_factor']))
            })
        
        if windows_data:
            # Create dataframe
            windows_df = pd.DataFrame(windows_data)
            
            # Display table
            st.dataframe(windows_df.style.format({
                'Area (m²)': '{:.2f}',
                'U-Value (W/m²°C)': '{:.2f}',
                'Temperature Difference (°C)': '{:.2f}',
                'Conduction Heat Gain (W)': '{:.2f}',
                'Solar Heat Gain Factor (W/m²)': '{:.2f}',
                'Shading Factor': '{:.2f}',
                'Solar Heat Gain (W)': '{:.2f}',
                'Total Heat Gain (W)': '{:.2f}'
            }))
            
            # Create grouped bar chart
            fig = go.Figure()
            
            fig.add_trace(go.Bar(
                x=windows_df['Component'],
                y=windows_df['Conduction Heat Gain (W)'],
                name='Conduction Heat Gain',
                marker_color='#1f77b4',
                text=windows_df['Conduction Heat Gain (W)'].round(1),
                textposition='auto',
                hovertemplate='<b>%{x}</b><br>Conduction Heat Gain: %{y:.1f} W<extra></extra>'
            ))
            
            fig.add_trace(go.Bar(
                x=windows_df['Component'],
                y=windows_df['Solar Heat Gain (W)'],
                name='Solar Heat Gain',
                marker_color='#ff7f0e',
                text=windows_df['Solar Heat Gain (W)'].round(1),
                textposition='auto',
                hovertemplate='<b>%{x}</b><br>Solar Heat Gain: %{y:.1f} W<extra></extra>'
            ))
            
            fig.update_layout(
                title="Window Heat Gains",
                xaxis_title="Window",
                yaxis_title="Heat Gain (W)",
                barmode='stack',
                font=dict(size=14),
                title_font=dict(size=18),
                title_x=0.5,  # Center the title
                margin=dict(t=50, b=50, l=50, r=50),
                legend=dict(
                    orientation="h",
                    yanchor="bottom",
                    y=1.02,
                    xanchor="right",
                    x=1
                )
            )
            
            st.plotly_chart(fig)
        else:
            st.write("No windows defined.")
        
        # Doors section
        st.write("#### Doors")
        
        # Get doors
        doors_data = []
        for door in st.session_state.cooling_form_data['windows'].get('doors', []):
            doors_data.append({
                'Component': door['name'],
                'Type': door['type'],
                'Area (m²)': door['area'],
                'U-Value (W/m²°C)': door['u_value'],
                'Temperature Difference (°C)': door['temp_diff'],
                'Heat Gain (W)': door['area'] * door['u_value'] * door['temp_diff']
            })
        
        if doors_data:
            # Create dataframe
            doors_df = pd.DataFrame(doors_data)
            
            # Display table
            st.dataframe(doors_df.style.format({
                'Area (m²)': '{:.2f}',
                'U-Value (W/m²°C)': '{:.2f}',
                'Temperature Difference (°C)': '{:.2f}',
                'Heat Gain (W)': '{:.2f}'
            }))
            
            # Create bar chart
            fig = px.bar(
                doors_df,
                x='Component',
                y='Heat Gain (W)',
                title="Door Heat Gains",
                color='Type',
                color_discrete_sequence=px.colors.qualitative.Pastel
            )
            
            st.plotly_chart(fig)
        else:
            st.write("No doors defined.")
    
    with tabs[2]:
        st.subheader("Internal Heat Gains")
        
        # Get internal loads data
        internal_loads = st.session_state.cooling_form_data['internal_loads']
        
        # Create dataframe
        internal_loads_data = [
            {
                'Source': 'Occupants',
                'Details': f"{internal_loads['occupants']['count']} people",
                'Heat Gain (W)': internal_loads['occupants']['total_heat_gain']
            },
            {
                'Source': 'Lighting',
                'Details': f"{internal_loads['lighting']['type']} lighting",
                'Heat Gain (W)': internal_loads['lighting']['total_heat_gain']
            },
            {
                'Source': 'Appliances',
                'Details': ', '.join([k for k, v in internal_loads['appliances'].items() if v and k != 'total_heat_gain']),
                'Heat Gain (W)': internal_loads['appliances']['total_heat_gain']
            }
        ]
        
        internal_loads_df = pd.DataFrame(internal_loads_data)
        
        # Display table
        st.dataframe(internal_loads_df.style.format({
            'Heat Gain (W)': '{:.2f}'
        }))
        
        # Create bar chart
        fig = px.bar(
            internal_loads_df,
            x='Source',
            y='Heat Gain (W)',
            title="Internal Heat Gains",
            color='Source',
            color_discrete_sequence=px.colors.qualitative.Pastel1
        )
        
        st.plotly_chart(fig)
    
    with tabs[3]:
        st.subheader("Ventilation & Infiltration Heat Gains")
        
        # Get ventilation data
        ventilation_data = st.session_state.cooling_form_data['ventilation']
        
        # Create dataframe
        ventilation_df = pd.DataFrame([
            {
                'Source': 'Infiltration',
                'Air Changes per Hour': ventilation_data['infiltration']['air_changes'],
                'Volume (m³)': ventilation_data['infiltration']['volume'],
                'Temperature Difference (°C)': ventilation_data['infiltration']['temp_diff'],
                'Heat Gain (W)': ventilation_data['infiltration']['heat_gain']
            },
            {
                'Source': 'Ventilation',
                'Air Changes per Hour': ventilation_data['ventilation']['air_changes'],
                'Volume (m³)': ventilation_data['ventilation']['volume'],
                'Temperature Difference (°C)': ventilation_data['ventilation']['temp_diff'],
                'Heat Gain (W)': ventilation_data['ventilation']['heat_gain']
            }
        ])
        
        # Display table
        st.dataframe(ventilation_df.style.format({
            'Air Changes per Hour': '{:.2f}',
            'Volume (m³)': '{:.2f}',
            'Temperature Difference (°C)': '{:.2f}',
            'Heat Gain (W)': '{:.2f}'
        }))
        
        # Create bar chart
        fig = px.bar(
            ventilation_df,
            x='Source',
            y='Heat Gain (W)',
            title="Ventilation & Infiltration Heat Gains",
            color='Source',
            color_discrete_sequence=px.colors.qualitative.Pastel2
        )
        
        st.plotly_chart(fig)
    
    # Export options
    st.write("### Export Options")
    
    col1, col2 = st.columns(2)
    
    with col1:
        if st.button("Export Results as CSV"):
            # Create a CSV file with results
            csv_data = export_data(st.session_state.cooling_form_data, st.session_state.cooling_results, format='csv')
            
            # Provide download link
            st.download_button(
                label="Download CSV",
                data=csv_data,
                file_name=f"cooling_load_results_{datetime.now().strftime('%Y%m%d_%H%M%S')}.csv",
                mime="text/csv"
            )
    
    with col2:
        if st.button("Export Results as JSON"):
            # Create a JSON file with results
            json_data = export_data(st.session_state.cooling_form_data, st.session_state.cooling_results, format='json')
            
            # Provide download link
            st.download_button(
                label="Download JSON",
                data=json_data,
                file_name=f"cooling_load_results_{datetime.now().strftime('%Y%m%d_%H%M%S')}.json",
                mime="application/json"
            )
    
    # Navigation buttons
    col1, col2 = st.columns([1, 1])
    
    with col1:
        prev_button = st.button("← Back: Ventilation", key="results_prev")
        if prev_button:
            st.session_state.cooling_active_tab = "ventilation"
            st.experimental_rerun()
    
    with col2:
        recalculate_button = st.button("Recalculate", key="results_recalculate")
        if recalculate_button:
            # Recalculate cooling load
            calculate_cooling_load()
            st.experimental_rerun()


def cooling_calculator():
    """Main function for the cooling load calculator page."""
    st.title("Cooling Load Calculator")
    
    # Initialize reference data
    ref_data = ReferenceData()
    
    # Initialize session state
    load_session_state()
    
    # Initialize active tab if not already set
    if 'cooling_active_tab' not in st.session_state:
        st.session_state.cooling_active_tab = "building_info"
    
    # Create tabs for different steps
    tabs = st.tabs([
        "1. Building Information", 
        "2. Building Envelope", 
        "3. Windows & Doors", 
        "4. Internal Loads", 
        "5. Ventilation", 
        "6. Results"
    ])
    
    # Add direct navigation buttons at the top
    st.write("### Navigation")
    st.write("Click on any button below to navigate directly to that section:")
    
    col1, col2, col3 = st.columns(3)
    with col1:
        if st.button("1. Building Information", key="direct_nav_building_info"):
            st.session_state.cooling_active_tab = "building_info"
            st.experimental_rerun()
        
        if st.button("2. Building Envelope", key="direct_nav_building_envelope"):
            st.session_state.cooling_active_tab = "building_envelope"
            st.experimental_rerun()
    
    with col2:
        if st.button("3. Windows & Doors", key="direct_nav_windows"):
            st.session_state.cooling_active_tab = "windows"
            st.experimental_rerun()
        
        if st.button("4. Internal Loads", key="direct_nav_internal_loads"):
            st.session_state.cooling_active_tab = "internal_loads"
            st.experimental_rerun()
    
    with col3:
        if st.button("5. Ventilation", key="direct_nav_ventilation"):
            st.session_state.cooling_active_tab = "ventilation"
            st.experimental_rerun()
        
        if st.button("6. Results", key="direct_nav_results"):
            # Only enable if all previous steps are completed
            if all(st.session_state.cooling_completed.values()):
                st.session_state.cooling_active_tab = "results"
                st.experimental_rerun()
            else:
                st.warning("Please complete all previous steps before viewing results.")
    
    # Display the active tab
    with tabs[0]:
        if st.session_state.cooling_active_tab == "building_info":
            building_info_form(ref_data)
    
    with tabs[1]:
        if st.session_state.cooling_active_tab == "building_envelope":
            building_envelope_form(ref_data)
    
    with tabs[2]:
        if st.session_state.cooling_active_tab == "windows":
            windows_form(ref_data)
    
    with tabs[3]:
        if st.session_state.cooling_active_tab == "internal_loads":
            internal_loads_form(ref_data)
    
    with tabs[4]:
        if st.session_state.cooling_active_tab == "ventilation":
            ventilation_form(ref_data)
    
    with tabs[5]:
        if st.session_state.cooling_active_tab == "results":
            results_page()


if __name__ == "__main__":
    cooling_calculator()