import os
import logging
import sys
import torch
import tempfile
from fastapi import FastAPI, HTTPException, Request
from fastapi.responses import JSONResponse
from pydantic import BaseModel
from typing import List, Optional
import uvicorn
import random

# Configure logging
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s',
    handlers=[logging.StreamHandler(sys.stdout)]
)
logger = logging.getLogger(__name__)

app = FastAPI(title="Chat API", description="Simple chat API for Hugging Face Space")

# Use the system's temporary directory which should be writable
temp_dir = tempfile.mkdtemp()
os.environ["TRANSFORMERS_CACHE"] = temp_dir
os.environ["HF_HOME"] = temp_dir

logger.info(f"Using temporary directory: {temp_dir}")

# Pydantic models for request/response
class ChatTurn(BaseModel):
    user: Optional[str] = None
    assistant: Optional[str] = None

class ChatRequest(BaseModel):
    message: str
    history: Optional[List[ChatTurn]] = []

class ChatResponse(BaseModel):
    response: str

# Fallback responses
FALLBACK_RESPONSES = [
    "I apologize, but I'm currently having trouble processing your request.",
    "Sorry, I'm experiencing technical difficulties at the moment.",
    "I'm unable to generate a proper response right now. Please try again later.",
    "My language model is temporarily unavailable. Please check back soon.",
    "I would like to help, but I'm having some technical issues. Please try again shortly."
]

# Error handler
@app.exception_handler(Exception)
async def generic_exception_handler(request: Request, exc: Exception):
    logger.error(f"Unhandled exception: {str(exc)}", exc_info=True)
    return JSONResponse(
        status_code=500,
        content={"detail": f"Internal server error: {str(exc)}"}
    )

# Simple text-only route
@app.get("/")
async def root():
    return {"message": "Chat API is running. Use /api/chat for chat functionality."}

# Chat endpoint - just use fallback responses for now
@app.post("/api/chat", response_model=ChatResponse)
async def chat(request: ChatRequest):
    logger.info(f"Received chat request: {request.message[:50]}...")
    
    # Select a random fallback response
    fallback = random.choice(FALLBACK_RESPONSES)
    
    # Add a bit of personalization
    if "hello" in request.message.lower() or "hi" in request.message.lower():
        fallback = "Hello! " + fallback
    elif "help" in request.message.lower():
        fallback = "I'd like to help you with that, but " + fallback.lower()
    
    logger.info(f"Returning fallback response")
    return ChatResponse(response=fallback)

@app.get("/health")
async def health_check():
    return {
        "status": "ok",
        "system_info": {
            "device": "cpu",  # No GPU for now
            "temp_dir": temp_dir,
            "pwd": os.getcwd(),
            "user": os.getenv("USER", "unknown"),
            "writable_temp": os.access(temp_dir, os.W_OK),
            "writable_cwd": os.access(os.getcwd(), os.W_OK)
        }
    }

if __name__ == "__main__":
    port = int(os.environ.get("PORT", 7860))
    uvicorn.run("app:app", host="0.0.0.0", port=port, reload=False)