import streamlit as st
import torch
import copy
import os
from PIL import Image
from transformers import AutoModelForCausalLM, AutoTokenizer, BitsAndBytesConfig
from typing import Tuple, Optional
from my_model.utilities.gen_utilities import free_gpu_resources
from my_model.captioner.image_captioning import ImageCaptioningModel
from my_model.detector.object_detection import ObjectDetector
import my_model.config.kbvqa_config as config



class KBVQA:
    """
    The KBVQA class encapsulates the functionality for the Knowledge-Based Visual Question Answering (KBVQA) model. 
    It integrates various components such as an image captioning model, object detection model, and a fine-tuned 
    language model (LLAMA2) on OK-VQA dataset for generating answers to visual questions.

    Attributes:
        kbvqa_model_name (str): Name of the fine-tuned language model used for KBVQA.
        quantization (str): The quantization setting for the model (e.g., '4bit', '8bit').
        max_context_window (int): The maximum number of tokens allowed in the model's context window.
        add_eos_token (bool): Flag to indicate whether to add an end-of-sentence token to the tokenizer.
        trust_remote (bool): Flag to indicate whether to trust remote code when using the tokenizer.
        use_fast (bool): Flag to indicate whether to use the fast version of the tokenizer.
        low_cpu_mem_usage (bool): Flag to optimize model loading for low CPU memory usage.
        kbvqa_tokenizer (Optional[AutoTokenizer]): The tokenizer for the KBVQA model.
        captioner (Optional[ImageCaptioningModel]): The model used for generating image captions.
        detector (Optional[ObjectDetector]): The object detection model.
        detection_model (Optional[str]): The name of the object detection model.
        detection_confidence (Optional[float]): The confidence threshold for object detection.
        kbvqa_model (Optional[AutoModelForCausalLM]): The fine-tuned language model for KBVQA.
        bnb_config (BitsAndBytesConfig): Configuration for BitsAndBytes optimized model.
        access_token (str): Access token for Hugging Face API.
        current_prompt_length (int): Prompt length.

    Methods:
        create_bnb_config: Creates a BitsAndBytes configuration based on the quantization setting.
        load_caption_model: Loads the image captioning model.
        get_caption: Generates a caption for a given image.
        load_detector: Loads the object detection model.
        detect_objects: Detects objects in a given image.
        load_fine_tuned_model: Loads the fine-tuned KBVQA model along with its tokenizer.
        all_models_loaded: Checks if all the required models are loaded.
        force_reload_model: Forces a reload of all models, freeing up GPU resources.
        format_prompt: Formats the prompt for the KBVQA model.
        generate_answer: Generates an answer to a given question using the KBVQA model.
    """

    def __init__(self):

        if st.session_state["method"] == "7b-Fine-Tuned Model":
            self.kbvqa_model_name: str = config.KBVQA_MODEL_NAME_7b
        elif st.session_state["method"] == "13b-Fine-Tuned Model":
            self.kbvqa_model_name: str = config.KBVQA_MODEL_NAME_13b
        self.quantization: str = config.QUANTIZATION
        self.max_context_window: int = config.MAX_CONTEXT_WINDOW
        self.add_eos_token: bool = config.ADD_EOS_TOKEN
        self.trust_remote: bool = config.TRUST_REMOTE
        self.use_fast: bool = config.USE_FAST
        self.low_cpu_mem_usage: bool = config.LOW_CPU_MEM_USAGE
        self.kbvqa_tokenizer: Optional[AutoTokenizer] = None
        self.captioner: Optional[ImageCaptioningModel] = None
        self.detector: Optional[ObjectDetector] = None
        self.detection_model: Optional[str] = None
        self.detection_confidence: Optional[float] = None
        self.kbvqa_model: Optional[AutoModelForCausalLM] = None
        self.bnb_config: BitsAndBytesConfig = self.create_bnb_config()
        self.access_token: str = config.HUGGINGFACE_TOKEN
        self.current_prompt_length = None
        
 
    def create_bnb_config(self) -> BitsAndBytesConfig:
        """
        Creates a BitsAndBytes configuration based on the quantization setting.
        Returns:
            BitsAndBytesConfig: Configuration for BitsAndBytes optimized model.
        """
        if self.quantization == '4bit':
            return BitsAndBytesConfig(
                load_in_4bit=True,
                bnb_4bit_use_double_quant=True,
                bnb_4bit_quant_type="nf4",
                bnb_4bit_compute_dtype=torch.bfloat16
            )
        elif self.quantization == '8bit':
            return BitsAndBytesConfig(
                load_in_8bit=True,
                bnb_8bit_use_double_quant=True,
                bnb_8bit_quant_type="nf4",
                bnb_8bit_compute_dtype=torch.bfloat16
            )


    def load_caption_model(self) -> None:
        """
        Loads the image captioning model into the KBVQA instance.
        """
        
        self.captioner = ImageCaptioningModel()
        self.captioner.load_model()
        free_gpu_resources()

    def get_caption(self, img: Image.Image) -> str:
        """
        Generates a caption for a given image using the image captioning model.

        Args:
            img (PIL.Image.Image): The image for which to generate a caption.

        Returns:
            str: The generated caption for the image.
        """
        caption = self.captioner.generate_caption(img)
        free_gpu_resources()
        return caption

    def load_detector(self, model: str) -> None:
        """
        Loads the object detection model.

        Args:
            model (str): The name of the object detection model to load.
        """

        self.detector = ObjectDetector()
        self.detector.load_model(model)
        free_gpu_resources()

    def detect_objects(self, img: Image.Image) -> Tuple[Image.Image, str]:
        """
        Detects objects in a given image using the loaded object detection model.

        Args:
            img (PIL.Image.Image): The image in which to detect objects.

        Returns:
            tuple: A tuple containing the image with detected objects drawn and a string representation of detected objects.
        """
      
        image = self.detector.process_image(img)
        free_gpu_resources()
        detected_objects_string, detected_objects_list = self.detector.detect_objects(image, threshold=st.session_state['confidence_level'])
        free_gpu_resources()
        image_with_boxes = self.detector.draw_boxes(img, detected_objects_list)
        free_gpu_resources()
        return image_with_boxes, detected_objects_string

    def load_fine_tuned_model(self) -> None:
        """
        Loads the fine-tuned KBVQA model along with its tokenizer.
        """
        
        self.kbvqa_model = AutoModelForCausalLM.from_pretrained(self.kbvqa_model_name, 
                                                                device_map="auto", 
                                                                low_cpu_mem_usage=True, 
                                                                quantization_config=self.bnb_config,
                                                                token=self.access_token)

        free_gpu_resources()
        
        self.kbvqa_tokenizer = AutoTokenizer.from_pretrained(self.kbvqa_model_name, 
                                                             use_fast=self.use_fast, 
                                                             low_cpu_mem_usage=True, 
                                                             trust_remote_code=self.trust_remote, 
                                                             add_eos_token=self.add_eos_token,
                                                             token=self.access_token)
        free_gpu_resources()

    @property
    def all_models_loaded(self):
        """
        Checks if all the required models (KBVQA, captioner, detector) are loaded.

        Returns:
            bool: True if all models are loaded, False otherwise.
        """
        
        return self.kbvqa_model is not None and self.captioner is not None and self.detector is not None
        


    def format_prompt(self, current_query: str, history: Optional[str] = None, sys_prompt: Optional[str] = None, caption: str = None, objects: Optional[str] = None) -> str:
        """
        Formats the prompt for the KBVQA model based on the provided parameters.

        Args:
            current_query (str): The current question to be answered.
            history (str, optional): The history of previous interactions.
            sys_prompt (str, optional): The system prompt or instructions for the model.
            caption (str, optional): The caption of the image.
            objects (str, optional): The detected objects in the image.

        Returns:
            str: The formatted prompt for the KBVQA model.
        """
    
        B_SENT = '<s>'
        E_SENT = '</s>'
        B_INST = '[INST]'
        E_INST = '[/INST]'
        B_SYS = '<<SYS>>\n'
        E_SYS = '\n<</SYS>>\n\n'
        B_CAP = '[CAP]'
        E_CAP = '[/CAP]'
        B_QES = '[QES]'
        E_QES = '[/QES]'
        B_OBJ = '[OBJ]'
        E_OBJ = '[/OBJ]'
        current_query = current_query.strip()
        if sys_prompt is None:
            sys_prompt = config.SYSTEM_PROMPT.strip()
        if history is None:
            if objects is None:
                p = f"""{B_SENT}{B_INST} {B_SYS}{sys_prompt}{E_SYS}{B_CAP}{caption}{E_CAP}{B_QES}{current_query}{E_QES}{E_INST}"""
            else:
              p = f"""{B_SENT}{B_INST} {B_SYS}{sys_prompt}{E_SYS}{B_CAP}{caption}{E_CAP}{B_OBJ}{objects}{E_OBJ}{B_QES}taking into consideration the objects with high certainty, {current_query}{E_QES}{E_INST}"""
        else:
            p = f"""{history}\n{B_SENT}{B_INST} {B_QES}{current_query}{E_QES}{E_INST}"""
        
        return p

    @staticmethod
    def trim_objects(detected_objects_str):
        """
        Trim the last object from the detected objects string.
    
        Args:
        - detected_objects_str (str): String containing detected objects.
    
        Returns:
        - (str): The string with the last object removed.
        """
        objects = detected_objects_str.strip().split("\n")
        if len(objects) >= 1:
            return "\n".join(objects[:-1])
        return ""

    def generate_answer(self, question: str, caption: str, detected_objects_str: str) -> str:
        """
        Generates an answer to a given question using the KBVQA model.

        Args:
            question (str): The question to be answered.
            caption (str): The caption of the image related to the question.
            detected_objects_str (str): The string representation of detected objects in the image.

        Returns:
            str: The generated answer to the question.
        """
    
        
        free_gpu_resources()
        prompt = self.format_prompt(question, caption=caption, objects=detected_objects_str)
        num_tokens = len(self.kbvqa_tokenizer.tokenize(prompt))
        self.current_prompt_length = num_tokens
        trim = False
        if self.current_prompt_length > self.max_context_window:
            trim = True
            st.warning(f"Prompt length is {self.current_prompt_length} which is larger than the maximum context window of LLaMA-2, objects detected with low confidence will be removed one at a time until the prompt length is within the maximum context window ...")
        while self.current_prompt_length > self.max_context_window:
            detected_objects_str = self.trim_objects(detected_objects_str)
            prompt = self.format_prompt(question, caption=caption, objects=detected_objects_str)
            self.current_prompt_length = len(self.kbvqa_tokenizer.tokenize(prompt))
    
            if detected_objects_str == "":
                break  # Break if no objects are left
        if trim:
            st.warning(f"New prompt length is: {self.current_prompt_length}")
            trim = False

        model_inputs = self.kbvqa_tokenizer(prompt, add_special_tokens=False, return_tensors="pt").to('cuda')
        free_gpu_resources()
        input_ids = model_inputs["input_ids"]
        output_ids = self.kbvqa_model.generate(input_ids)
        free_gpu_resources()
        index = input_ids.shape[1] # needed to avoid printing the input prompt
        history = self.kbvqa_tokenizer.decode(output_ids[0], skip_special_tokens=False)
        output_text = self.kbvqa_tokenizer.decode(output_ids[0][index:], skip_special_tokens=True)

        return output_text.capitalize()

def prepare_kbvqa_model(only_reload_detection_model: bool = False, force_reload: bool = False) -> KBVQA:
    """
    Prepares the KBVQA model for use, including loading necessary sub-models.

    Args:
        only_reload_detection_model (bool): If True, only the object detection model is reloaded.

    Returns:
        KBVQA: An instance of the KBVQA model ready for inference.
    """
  
    if force_reload:
        loading_message = 'Force Reloading model.. this should take no more than a few minutes!'
        try:
            del kbvqa
        except:
            free_gpu_resources()
            pass
        free_gpu_resources()
        
    else: loading_message = 'Looading model.. this should take no more than 2 or 3 minutes!'

    free_gpu_resources()
    kbvqa = KBVQA()
    kbvqa.detection_model = st.session_state.detection_model
    # Progress bar for model loading
    
    with st.spinner(loading_message):
        if not only_reload_detection_model:
            progress_bar = st.progress(0)
            kbvqa.load_detector(kbvqa.detection_model)
            progress_bar.progress(33)
            kbvqa.load_caption_model()
            free_gpu_resources()
            progress_bar.progress(75)
            st.text('Almost there :)')
            kbvqa.load_fine_tuned_model()
            free_gpu_resources()
            progress_bar.progress(100)
        else:
            free_gpu_resources()
            progress_bar = st.progress(0)
            kbvqa.load_detector(kbvqa.detection_model)
            progress_bar.progress(100)
            
    if kbvqa.all_models_loaded:
        st.success('Model loaded successfully and ready for inferecne!')
        kbvqa.kbvqa_model.eval()
        free_gpu_resources()
        return kbvqa