from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles
import logging
import os

from app.core.config import settings
from app.core.database import create_tables, SessionLocal
from app.models.document import Document, ChatMessage
import shutil
from app.api.endpoints import documents, chat
from app.services.vector_store import VectorStore

# Configure logging
logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s - %(name)s - %(levelname)s - %(message)s"
)

# Create FastAPI app
app = FastAPI(
    title=settings.PROJECT_NAME,
    description="A comprehensive PDF-based Q&A chatbot system",
    version="1.0.0",
    docs_url="/docs",
    redoc_url="/redoc"
)

# Add CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.BACKEND_CORS_ORIGINS,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Include API routes
app.include_router(
    documents.router,
    prefix=f"{settings.API_V1_STR}/documents",
    tags=["documents"]
)

app.include_router(
    chat.router,
    prefix=f"{settings.API_V1_STR}/chat",
    tags=["chat"]
)

# Serve static frontend (exported Next.js) at root
frontend_path = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "frontend_out"))
if os.path.isdir(frontend_path):
    app.mount("/", StaticFiles(directory=frontend_path, html=True), name="frontend")

# Health check endpoint
@app.get("/health")
def health_check():
    """Health check endpoint"""
    return {
        "status": "healthy",
        "service": settings.PROJECT_NAME,
        "version": "1.0.0"
    }

# Root endpoint
@app.get("/")
def root():
    """Root endpoint with API information"""
    return {
        "message": "PDF Q&A Chatbot API",
        "version": "1.0.0",
        "docs": "/docs",
        "health": "/health"
    }

# Startup event
@app.on_event("startup")
async def startup_event():
    """Initialize application on startup"""
    # Create database tables
    create_tables()
    
    # Ensure directories exist
    os.makedirs(settings.UPLOAD_DIR, exist_ok=True)
    os.makedirs(settings.CHROMA_PERSIST_DIRECTORY, exist_ok=True)

    # --- ERASE ALL DOCUMENTS, CHAT MESSAGES, AND VECTORS ON STARTUP ---
    # 1. Delete all rows from documents and chat_messages tables
    db = SessionLocal()
    try:
        db.query(Document).delete()
        db.query(ChatMessage).delete()
        db.commit()
    finally:
        db.close()
    # 2. Remove all files in chroma_db directory (but keep the directory)
    chroma_dir = settings.CHROMA_PERSIST_DIRECTORY
    for filename in os.listdir(chroma_dir):
        file_path = os.path.join(chroma_dir, filename)
        try:
            if os.path.isfile(file_path) or os.path.islink(file_path):
                os.unlink(file_path)
            elif os.path.isdir(file_path):
                shutil.rmtree(file_path)
        except Exception as e:
            logging.warning(f"Failed to delete {file_path}: {e}")
    # 3. Explicitly clear ChromaDB vector store
    vector_store = VectorStore()
    vector_store.clear_all()
    logging.info("All documents, chat messages, and vector store erased on startup.")
    # --- END ERASE ---

    logging.info("Application started successfully")

# Shutdown event
@app.on_event("shutdown")
async def shutdown_event():
    """Cleanup on application shutdown"""
    logging.info("Application shutting down")

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(
        "main:app",
        host="0.0.0.0",
        port=8000,
        reload=True,
        log_level="info"
    )