webapp/app/main.py

from contextlib import asynccontextmanager
from fastapi import FastAPI, Depends, Request
from fastapi.responses import JSONResponse
from fastapi.middleware.cors import CORSMiddleware
from fastapi.openapi.utils import get_openapi
from fastapi.exceptions import RequestValidationError
from starlette.exceptions import HTTPException as StarletteHTTPException

from app.api import router
from app.core.database import AsyncSessionLocal
from app.core.auth import RoleLevel, require_min_role
from app.core.config import settings
from app.core.payment import init_stripe
from app.core.biz_exception import BizException
from app.core.logger import logger


@asynccontextmanager
async def lifespan(app: FastAPI):
    init_stripe()
    logger.info("🟢 Stripe config done")

    yield


app = FastAPI(title=settings.app_name, lifespan=lifespan)


# -----------------------
# Exception Handlers
# -----------------------
@app.exception_handler(BizException)
async def biz_exception_handler(request: Request, exc: BizException):
    return JSONResponse(
        status_code=exc.http_status,
        content={
            "code": exc.code,
            "message": exc.message,
            "data": exc.extra,
        },
    )


@app.exception_handler(Exception)
async def unhandled_exception_handler(request: Request, exc: Exception):
    logger.error("Unhandled exception", exc_info=exc)

    return JSONResponse(
        status_code=500,
        content={
            "code": 50000,
            "message": "Internal Server Error",
            "data": None,
        },
    )

@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request: Request, exc: RequestValidationError):
    """
    接管 FastAPI 默认的 422 数据校验错误
    """
    # 1. 获取所有的错误详情
    errors = exc.errors()
    
    # 2. 提取第一个错误作为主要提示信息（通常用户只关心第一个报错）
    if errors:
        first_error = errors[0]
        # 处理路径：去掉 'body', 'query' 等前缀，只保留字段名，用点连接
        # 例如: ['body', 'user', 'age'] -> 'user.age'
        # 如果路径只有 ['body'] (比如传了空JSON)，则通过 [1:] 过滤可能为空，要做个保护
        raw_path = first_error.get("loc", [])
        path_parts = [str(p) for p in raw_path if p not in ('body', 'query', 'path')]
        field_path = ".".join(path_parts) if path_parts else "request_body"
        
        err_msg = first_error.get("msg")
        
        # 优化提示文案
        message = f"Invalid parameter [{field_path}]: {err_msg}"
    else:
        message = "Invalid request parameters"

    # 3. 返回标准格式
    return JSONResponse(
        status_code=422,
        content={
            "code": 42200,            # 或者是你们约定的参数错误码
            "message": message,       # 转换后的人类可读提示
            "data": errors            # 保留原始错误详情，方便前端开发排查
        },
    )
    
@app.exception_handler(StarletteHTTPException)
async def http_exception_handler(request: Request, exc: StarletteHTTPException):
    """
    接管所有 HTTP 错误，包括 404 Not Found 和 405 Method Not Allowed
    """
    return JSONResponse(
        status_code=exc.status_code,
        content={
            # 这里你可以根据 status_code 生成你的业务 code，比如 404 -> 40400
            "code": exc.status_code*100, 
            "message": exc.detail,  # 这里通常是 "Not Found"
            "data": None,
        },
    )

# -----------------------
# CORS
# -----------------------
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)


# -----------------------
# Routers
# -----------------------
app.include_router(
    router.public_router,
    prefix="/api"
)

app.include_router(
    router.protected_router,
    prefix="/api",
    dependencies=[Depends(require_min_role(RoleLevel.user))]
)

app.include_router(
    router.admin_required_router,
    prefix="/api",
    dependencies=[Depends(require_min_role(RoleLevel.admin))]
)


# -----------------------
# Swagger Bearer Token
# -----------------------
def custom_openapi():
    if app.openapi_schema:
        return app.openapi_schema

    openapi_schema = get_openapi(
        title=app.title,
        version="1.0.0",
        description="API documentation",
        routes=app.routes,
    )

    openapi_schema.setdefault("components", {})
    openapi_schema["components"]["securitySchemes"] = {
        "BearerAuth": {
            "type": "http",
            "scheme": "bearer",
            "bearerFormat": "JWT",
        }
    }

    for path in openapi_schema["paths"].values():
        for method in path.values():
            method.setdefault("security", [])
            method["security"].append({"BearerAuth": []})

    app.openapi_schema = openapi_schema
    return app.openapi_schema


app.openapi = custom_openapi