app.py

from fastapi import FastAPI, WebSocket, WebSocketDisconnect, HTTPException
from fastapi.staticfiles import StaticFiles
from fastapi.responses import HTMLResponse
from fastapi.templating import Jinja2Templates
import json
import asyncio
from datetime import datetime
from typing import Dict, List, Set
import base64
import mimetypes
import os
import uvicorn
app = FastAPI(title="Tri-Chat API", description="Real-time chat with WebSocket support")

# Setup templates
templates = Jinja2Templates(directory="templates")

# Connection Manager to handle WebSocket connections
class ConnectionManager:
    def __init__(self):
        # Store active connections by room
        self.active_connections: Dict[str, List[Dict]] = {}
        # Store message history by room (in-memory for demo)
        self.message_history: Dict[str, List[Dict]] = {}
        
    async def connect(self, websocket: WebSocket, room: str, username: str):
        await websocket.accept()
        
        # Initialize room if it doesn't exist
        if room not in self.active_connections:
            self.active_connections[room] = []
            self.message_history[room] = []
            
        # Add connection to room
        connection_info = {
            "websocket": websocket,
            "username": username,
            "joined_at": datetime.now().isoformat()
        }
        self.active_connections[room].append(connection_info)
        
        # Send join notification
        join_message = {
            "type": "system",
            "message": f"{username} joined the room",
            "timestamp": datetime.now().isoformat(),
            "room": room
        }
        await self.broadcast_to_room(room, join_message)
        
        # Send message history to new user
        for message in self.message_history[room]:
            await websocket.send_text(json.dumps(message))
    
    def disconnect(self, websocket: WebSocket, room: str):
        if room in self.active_connections:
            # Find and remove the connection
            for conn in self.active_connections[room]:
                if conn["websocket"] == websocket:
                    self.active_connections[room].remove(conn)
                    return conn["username"]
        return None
    
    async def broadcast_to_room(self, room: str, message: dict):
        if room not in self.active_connections:
            return
            
        # Store message in history
        self.message_history[room].append(message)
        
        # Keep only last 100 messages per room
        if len(self.message_history[room]) > 100:
            self.message_history[room] = self.message_history[room][-100:]
        
        # Send to all connections in room
        disconnected = []
        for connection_info in self.active_connections[room]:
            try:
                await connection_info["websocket"].send_text(json.dumps(message))
            except:
                disconnected.append(connection_info)
        
        # Remove disconnected clients
        for conn in disconnected:
            self.active_connections[room].remove(conn)
    
    def get_room_users(self, room: str) -> List[str]:
        if room not in self.active_connections:
            return []
        return [conn["username"] for conn in self.active_connections[room]]

# Global connection manager instance
manager = ConnectionManager()

@app.get("/", response_class=HTMLResponse)
async def get_chat_page():
    """Serve the chat HTML page"""
    try:
        with open("templates/index.html", "r", encoding="utf-8") as f:
            html_content = f.read()
        return HTMLResponse(content=html_content)
    except FileNotFoundError:
        return HTMLResponse(
            content="<h1>Error: templates/index.html not found</h1><p>Please make sure the templates directory exists with index.html</p>",
            status_code=404
        )

@app.websocket("/ws/{room}")
async def websocket_endpoint(websocket: WebSocket, room: str, username: str):
    """WebSocket endpoint for real-time chat"""
    
    # Validate inputs
    if not username or len(username.strip()) == 0:
        await websocket.close(code=1008, reason="Username is required")
        return
        
    if not room or len(room.strip()) == 0:
        room = "global"
    
    # Sanitize inputs
    username = username.strip()[:20]  # Limit username length
    room = room.strip()[:30]  # Limit room name length
    
    await manager.connect(websocket, room, username)
    
    try:
        while True:
            # Receive message from client
            data = await websocket.receive_text()
            message_data = json.loads(data)
            
            # Validate message type
            if message_data.get("type") not in ["text", "file"]:
                continue
                
            # Process text message
            if message_data["type"] == "text":
                text_content = message_data.get("text", "").strip()
                if len(text_content) == 0:
                    continue
                    
                # Sanitize and limit text length
                text_content = text_content[:500]
                
                message = {
                    "type": "text",
                    "username": username,
                    "text": text_content,
                    "timestamp": datetime.now().isoformat(),
                    "room": room
                }
                
                await manager.broadcast_to_room(room, message)
            
            # Process file message
            elif message_data["type"] == "file":
                file_name = message_data.get("fileName", "unknown")[:100]
                file_type = message_data.get("fileType", "application/octet-stream")
                file_size = message_data.get("fileSize", 0)
                file_data = message_data.get("fileData", "")
                
                # Validate file size (5MB limit)
                if file_size > 5 * 1024 * 1024:
                    await websocket.send_text(json.dumps({
                        "type": "error",
                        "message": "File size exceeds 5MB limit"
                    }))
                    continue
                
                # Validate base64 data
                try:
                    base64.b64decode(file_data)
                except Exception:
                    await websocket.send_text(json.dumps({
                        "type": "error", 
                        "message": "Invalid file data"
                    }))
                    continue
                
                message = {
                    "type": "file",
                    "username": username,
                    "fileName": file_name,
                    "fileType": file_type,
                    "fileSize": file_size,
                    "fileData": file_data,
                    "timestamp": datetime.now().isoformat(),
                    "room": room
                }
                
                await manager.broadcast_to_room(room, message)
                
    except WebSocketDisconnect:
        disconnected_username = manager.disconnect(websocket, room)
        if disconnected_username:
            leave_message = {
                "type": "system",
                "message": f"{disconnected_username} left the room",
                "timestamp": datetime.now().isoformat(),
                "room": room
            }
            await manager.broadcast_to_room(room, leave_message)

@app.get("/api/rooms")
async def get_active_rooms():
    """Get list of active chat rooms"""
    rooms = []
    for room_name, connections in manager.active_connections.items():
        if connections:  # Only include rooms with active connections
            rooms.append({
                "name": room_name,
                "user_count": len(connections),
                "users": [conn["username"] for conn in connections]
            })
    return {"rooms": rooms}

@app.get("/api/rooms/{room}/users")
async def get_room_users(room: str):
    """Get list of users in a specific room"""
    users = manager.get_room_users(room)
    return {
        "room": room,
        "users": users,
        "user_count": len(users)
    }



if __name__ == "__main__":
    port = int(os.getenv("PORT", 7860))  # Hugging Face expects 7860
    uvicorn.run(app, host="0.0.0.0", port=port)