src/streamlit_app.py

import streamlit as st
import pandas as pd
import plotly.express as px
from datetime import date, timedelta

# Import ObsPy for live data fetching
import obspy
from obspy.clients.fdsn import Client
from obspy import UTCDateTime

# --- Page Configuration ---
st.set_page_config(
    page_title="Live Earthquake Explorer (ObsPy)",
    page_icon="🛰️",
    layout="wide",
    initial_sidebar_state="expanded"
)

# --- Live Data Fetching Function using ObsPy ---
@st.cache_data(ttl=900)  # Cache the data for 15 minutes
def fetch_live_data(start_date, end_date, min_mag):
    """
    Fetches live earthquake data from the IRIS FDSN web service using ObsPy.
    """
    client = Client("IRIS")
    start_time = UTCDateTime(start_date)
    end_time = UTCDateTime(end_date) + timedelta(days=1)

    try:
        catalog = client.get_events(
            starttime=start_time,
            endtime=end_time,
            minmagnitude=min_mag
        )
    except Exception as e:
        st.error(f"Could not retrieve data from IRIS FDSN service: {e}")
        return pd.DataFrame()

    event_list = []
    for event in catalog:
        if not (event.preferred_origin() and event.preferred_magnitude()):
            continue

        origin = event.preferred_origin()
        magnitude = event.preferred_magnitude()

        # Get location description safely.
        description = "N/A"
        if hasattr(event, 'descriptions'):
            if event.descriptions and event.descriptions[0].text:
                description = event.descriptions[0].text

        event_list.append({
            "latitude": origin.latitude,
            "longitude": origin.longitude,
            "depth": origin.depth / 1000,
            "magnitude": magnitude.mag,
            "time": origin.time.datetime,
            "place": description,
        })

    if not event_list:
        return pd.DataFrame()

    return pd.DataFrame(event_list)

# --- UI Design ---
st.title("🛰️ Live Earthquake Explorer with ObsPy")
st.markdown("Data is fetched in real-time from the **IRIS FDSN** web service.")

with st.sidebar:
    st.header("🔍 Search Parameters")
    today = date.today()
    thirty_days_ago = today - timedelta(days=30)
    start_date = st.date_input("Start Date", value=thirty_days_ago)
    end_date = st.date_input("End Date", value=today)
    min_magnitude = st.slider("Minimum Magnitude", 0.0, 10.0, 5.0, 0.1)
    search_button = st.button("Search Earthquakes", type="primary", use_container_width=True)

# --- Main Content Area ---
if search_button:
    if start_date > end_date:
        st.error("Error: Start date cannot be after end date.")
    else:
        with st.spinner(f"Fetching earthquakes from {start_date} to {end_date}..."):
            df = fetch_live_data(start_date, end_date, min_magnitude)

        if not df.empty:
            st.success(f"Found {len(df)} earthquakes matching your criteria.")

            st.subheader("📊 Summary Statistics")
            col1, col2, col3 = st.columns(3)
            col1.metric("Total Earthquakes", f"{len(df):,}")
            col2.metric("Largest Magnitude", f"{df['magnitude'].max():.1f}")
            col3.metric("Deepest Event (km)", f"{df['depth'].max():.1f}")

            st.markdown("---")
            st.subheader("🌍 Interactive Earthquake Map")
            st.markdown("Hover over points for details. Circle size represents magnitude.")

            fig = px.scatter_geo(
                df,
                lat='latitude',
                lon='longitude',
                size='magnitude',
                color='depth',
                hover_name='place',
                hover_data={'latitude': ':.2f', 'longitude': ':.2f', 'time': '|%Y-%m-%d %H:%M', 'magnitude': ':.1f', 'depth': ':.1f km'},
                projection="natural earth",
                title=f"Live Earthquakes from {start_date} to {end_date} (Magnitude > {min_magnitude})",
                color_continuous_scale=px.colors.sequential.Plasma_r
            )
            fig.update_layout(margin={"r":0,"t":40,"l":0,"b":0}, coloraxis_colorbar_title_text='Depth (km)')
            st.plotly_chart(fig, use_container_width=True)

            # --- Show Earthquakes in a Table ---
            st.subheader("📋 Detailed Earthquake Data")
            
            # This line is changed to show latitude and longitude instead of place.
            display_df = df[['time', 'latitude', 'longitude', 'magnitude', 'depth']].copy()
            
            st.dataframe(
                display_df.sort_values(by='time', ascending=False),
                use_container_width=True,
                height=400,
                column_config={"time": st.column_config.DatetimeColumn("Time (UTC)", format="YYYY-MM-DD HH:mm")}
            )
        else:
            st.warning("No earthquakes were found for the specified criteria. Try expanding the date range or lowering the magnitude.")
else:
    st.info("Set your desired parameters in the sidebar and click 'Search Earthquakes' to begin.")