"""多渠道网关公开 Webhook 路由。"""

from __future__ import annotations

from fastapi import APIRouter, Depends, HTTPException, Request, status

channel_webhook = APIRouter(prefix="/channels", tags=["channels"])

# Webhook 公开入口最大允许请求体大小（字节）。
_MAX_WEBHOOK_PAYLOAD_SIZE = 10 * 1024 * 1024


def _get_gateway(request: Request):
    gateway = getattr(request.app.state, "channel_gateway", None)
    if gateway is None:
        raise HTTPException(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            detail="Channel gateway not initialized",
        )
    return gateway


async def _check_webhook_payload_size(request: Request):
    """依据 Content-Length 头限制公开 Webhook 请求体大小。"""
    content_length = request.headers.get("content-length")
    if content_length is not None:
        try:
            size = int(content_length)
        except ValueError:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Invalid Content-Length header",
            ) from None
        if size > _MAX_WEBHOOK_PAYLOAD_SIZE:
            raise HTTPException(
                status_code=status.HTTP_413_REQUEST_ENTITY_TOO_LARGE,
                detail="Webhook payload too large",
            )


@channel_webhook.post(
    "/{channel_type}/webhook",
    dependencies=[Depends(_check_webhook_payload_size)],
)
async def channel_webhook_entry(
    channel_type: str,
    request: Request,
):
    """多渠道网关公开 Webhook 入口。"""
    gateway = _get_gateway(request)
    return await gateway.handle_webhook(channel_type, request)