from fastapi import FastAPI, HTTPException, Request
from fastapi.exceptions import RequestValidationError
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse

from app.config import settings
from app.routers import api_router


def create_app() -> FastAPI:
    app = FastAPI(title=settings.app_name, debug=settings.app_debug)

    app.add_middleware(
        CORSMiddleware,
        allow_origins=["*"],
        allow_credentials=True,
        allow_methods=["*"],
        allow_headers=["*"],
    )

    @app.get("/health", tags=["health"])
    async def health_check() -> dict[str, str]:
        return {"status": "ok"}

    @app.exception_handler(HTTPException)
    async def http_exception_handler(request: Request, exc: HTTPException) -> JSONResponse:
        _ = request
        code_map = {
            400: 1005,
            401: 1001,
            403: 1002,
            404: 1003,
        }
        return JSONResponse(
            status_code=exc.status_code,
            content={
                "code": code_map.get(exc.status_code, 1005),
                "message": exc.detail,
                "data": None,
            },
        )

    @app.exception_handler(RequestValidationError)
    async def validation_exception_handler(
        request: Request, exc: RequestValidationError
    ) -> JSONResponse:
        _ = request
        field_errors = []
        for error in exc.errors():
            location = error.get("loc", [])
            field_name = location[-1] if location else "unknown"
            field_errors.append(
                {
                    "field": field_name,
                    "message": error.get("msg", "参数校验失败"),
                    "type": error.get("type"),
                }
            )

        return JSONResponse(
            status_code=422,
            content={
                "code": 1004,
                "message": "参数校验失败",
                "data": {"field_errors": field_errors},
            },
        )

    @app.exception_handler(Exception)
    async def generic_exception_handler(request: Request, exc: Exception) -> JSONResponse:
        _ = request
        return JSONResponse(
            status_code=500,
            content={
                "code": 1005,
                "message": str(exc) if settings.app_debug else "服务器内部错误",
                "data": None,
            },
        )

    app.include_router(api_router, prefix=settings.api_v1_prefix)
    return app


app = create_app()