"""
Flask backend for the chat assistance website.

This application provides API endpoints for processing chat screenshots,
manual text input, and generating response suggestions.
"""
import os
import base64
import json
from flask import Flask, request, jsonify, send_file
from flask_cors import CORS
from dotenv import load_dotenv
from img2chat import img2chat
from chat_analysis import get_suggestion

# Load environment variables
load_dotenv()

# Initialize Flask app
app = Flask(__name__)
CORS(app)  # Enable CORS for all routes

# Configure max content length
app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024  # 16MB max upload size

ALLOWED_EXTENSIONS = {'png', 'jpg', 'jpeg', 'gif'}

def allowed_file(filename):
    """Check if the file extension is allowed"""
    return '.' in filename and \
           filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS

def generate_response(chat_text):
    """
    Generate response suggestions based on chat text.
    
    Uses the get_suggestion function from chat_analysis.py to generate
    response suggestions based on the provided chat text.
    
    Args:
        chat_text (str): The chat text to analyze
        
    Returns:
        dict: Analysis and response suggestions
    """
    # Get suggestion from chat_analysis module
    suggestion_text = get_suggestion(chat_text)
    
    # Parse the XML response to extract suggestion and example
    # The response format is expected to be:
    # <suggestion>Suggestion text</suggestion><example>Example text</example>
    
    analysis = "分析中..."
    suggestion = suggestion_text
    
    # Simple parsing of XML tags (could be improved with proper XML parsing)
    if "<suggestion>" in suggestion_text and "</suggestion>" in suggestion_text:
        start_idx = suggestion_text.find("<suggestion>") + len("<suggestion>")
        end_idx = suggestion_text.find("</suggestion>")
        analysis = suggestion_text[start_idx:end_idx].strip()
    
    if "<example>" in suggestion_text and "</example>" in suggestion_text:
        start_idx = suggestion_text.find("<example>") + len("<example>")
        end_idx = suggestion_text.find("</example>")
        suggestion = suggestion_text[start_idx:end_idx].strip()
    
    return {
        "analysis": analysis,
        "suggestion": suggestion
    }

@app.route('/', methods=['GET'])
def index():
    """Serve the main HTML page"""
    return send_file('index.html')

@app.route('/api/health', methods=['GET'])
def health_check():
    """Health check endpoint"""
    return jsonify({"status": "ok"})

@app.route('/api/process-image', methods=['POST'])
def process_image():
    """
    Process a chat screenshot and return analysis and suggestions.
    
    Accepts an image file or a base64 encoded image string.
    """
    try:
        # Check if the post request has the file part
        if 'file' in request.files:
            file = request.files['file']
            if file.filename == '':
                return jsonify({"error": "No selected file"}), 400
                
            if file and allowed_file(file.filename):
                # Read file data directly and convert to base64
                file_data = file.read()
                base64_image = base64.b64encode(file_data).decode('utf-8')
                
                # Get file extension
                file_ext = file.filename.rsplit('.', 1)[1].lower()
                image_url = f"data:image/{file_ext};base64,{base64_image}"
                
                # Process the image
                chat_text = img2chat(image_url)
                
                # Generate response suggestions
                response_data = generate_response(chat_text)
                
                # Return the results
                return jsonify({
                    "chat_text": chat_text,
                    "analysis": response_data["analysis"],
                    "suggestion": response_data["suggestion"]
                })
            else:
                return jsonify({"error": "File type not allowed"}), 400
                
        # Check if base64 image was provided
        elif 'image_data' in request.json:
            image_data = request.json['image_data']
            
            # Process the image
            chat_text = img2chat(image_data)
            
            # Generate response suggestions
            response_data = generate_response(chat_text)
            
            # Return the results
            return jsonify({
                "chat_text": chat_text,
                "analysis": response_data["analysis"],
                "suggestion": response_data["suggestion"]
            })
            
        else:
            return jsonify({"error": "No image provided"}), 400
            
    except Exception as e:
        return jsonify({"error": str(e)}), 500

@app.route('/api/process-text', methods=['POST'])
def process_text():
    """
    Process manually entered chat text and return analysis and suggestions.
    """
    try:
        data = request.json
        
        if not data or 'chat_text' not in data:
            return jsonify({"error": "No chat text provided"}), 400
            
        chat_text = data['chat_text']
        
        # Generate response suggestions
        response_data = generate_response(chat_text)
        
        # Return the results
        return jsonify({
            "analysis": response_data["analysis"],
            "suggestion": response_data["suggestion"]
        })
        
    except Exception as e:
        return jsonify({"error": str(e)}), 500

if __name__ == '__main__':
    port = int(os.environ.get('PORT', 8080))
    app.run(host='0.0.0.0', port=port, debug=True)