"""
FastAPI 应用入口。

严格遵守全局架构，本文件只负责：
1. 创建 FastAPI 实例
2. 注册路由（router）
3. 统一全局异常返回格式（{success, data, message}）
"""

from fastapi import FastAPI, Request
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse
from starlette.exceptions import HTTPException as StarletteHTTPException

from .routers import api_router
from .schemas import UnifiedResponse

# 创建 FastAPI 实例
app = FastAPI(
    title="MyBlog API",
    description="个人博客系统后端 API（FastAPI + SQLite + JWT）",
    version="0.1.0",
)


def _unified_error(status_code: int, message: str) -> JSONResponse:
    """构造符合全局统一格式的错误响应。"""
    return JSONResponse(
        status_code=status_code,
        content=UnifiedResponse(success=False, data=None, message=message).model_dump(),
    )


@app.exception_handler(StarletteHTTPException)
async def http_exception_handler(request: Request, exc: StarletteHTTPException) -> JSONResponse:
    """统一 HTTP 异常（业务错误）的返回格式。"""
    return _unified_error(exc.status_code, str(exc.detail))


@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request: Request, exc: RequestValidationError) -> JSONResponse:
    """统一请求参数校验错误的返回格式。"""
    return _unified_error(422, "请求参数校验失败")


# 注册路由：后续任务在 routers 包中实现各业务路由后统一挂载
app.include_router(api_router)