import os
from fastapi import FastAPI
from fastapi.templating import Jinja2Templates
from fastapi.middleware.cors import CORSMiddleware
from app.core.config import settings
from app.api.routes import register_routes
from app.services.qa_service import QAService
from app.core.logger import logger

def create_app() -> FastAPI:
    """创建并配置FastAPI应用实例"""
    logger.info("Starting application initialization...")
    
    app = FastAPI(
        title=settings.APP_NAME,
        description=settings.APP_DESCRIPTION,
        version=settings.APP_VERSION,
        docs_url="/docs",
        redoc_url="/redoc"
    )
    
    logger.info("Configuring CORS middleware...")
    # 配置CORS
    app.add_middleware(
        CORSMiddleware,
        allow_origins=settings.CORS_ORIGINS,
        allow_credentials=settings.CORS_CREDENTIALS,
        allow_methods=settings.CORS_METHODS,
        allow_headers=settings.CORS_HEADERS,
    )
    
    logger.info("Setting up templates...")
    # 配置模板
    templates = Jinja2Templates(directory=os.path.join(os.path.dirname(__file__), 'templates'))
    app.state.templates = templates
    
    logger.info(f"Initializing QA service with model: {settings.DEFAULT_MODEL}")
    # 初始化服务
    qa_service = QAService(
        model_name=settings.DEFAULT_MODEL,
        temperature=settings.TEMPERATURE
    )
    
    logger.info("Registering routes...")
    # 注册路由
    register_routes(app, qa_service)
    
    logger.info("Application initialization completed successfully!")
    return app