import json
from decimal import Decimal, ROUND_HALF_UP
from uuid import uuid4

from fastapi import APIRouter, HTTPException, Request, status

from app.config import wechat_pay_settings
from app.database import Database
from app.schemas import WeChatJSAPIPayRequest, WeChatJSAPIPayResponse
from app.temple_scope import TempleId, ensure_temple_exists
from app.wechat_pay import (
    build_jsapi_pay_params,
    decrypt_notify_resource,
    post_wechat_json,
    verify_notify_signature,
)


router = APIRouter(prefix="/payments", tags=["payments"])


def yuan_to_fen(amount: float) -> int:
    return int((Decimal(str(amount)) * Decimal("100")).quantize(Decimal("1"), rounding=ROUND_HALF_UP))


def get_order_row(db: Database, temple_id: int, order_id: int):
    row = db.execute(
        """
        SELECT id, temple_id, item_name, amount, status
        FROM orders
        WHERE id = ? AND temple_id = ?
        """,
        (order_id, temple_id),
    ).fetchone()
    if row is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="订单不存在")
    return row


@router.post("/wechat/jsapi", response_model=WeChatJSAPIPayResponse)
def create_wechat_jsapi_payment(payload: WeChatJSAPIPayRequest, db: Database, temple_id: TempleId) -> WeChatJSAPIPayResponse:
    ensure_temple_exists(db, temple_id)
    order = get_order_row(db, temple_id, payload.order_id)
    if order["status"] == "paid":
        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="订单已支付，无需重复发起支付")

    amount = yuan_to_fen(float(order["amount"]))
    if amount <= 0:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="订单金额必须大于 0")

    out_trade_no = f"T{temple_id}O{order['id']}{uuid4().hex[:16]}"
    description = (payload.description or order["item_name"])[:127]
    wechat_payload = {
        "appid": wechat_pay_settings.appid,
        "mchid": wechat_pay_settings.mch_id,
        "description": description,
        "out_trade_no": out_trade_no,
        "notify_url": wechat_pay_settings.notify_url,
        "amount": {
            "total": amount,
            "currency": "CNY",
        },
        "payer": {
            "openid": payload.openid,
        },
    }
    result = post_wechat_json("/v3/pay/transactions/jsapi", wechat_payload)
    prepay_id = result.get("prepay_id")
    if not prepay_id:
        raise HTTPException(status_code=status.HTTP_502_BAD_GATEWAY, detail="微信支付未返回 prepay_id")

    db.execute(
        """
        INSERT INTO payment_transactions
            (temple_id, order_id, out_trade_no, amount, status, prepay_id)
        VALUES (?, ?, ?, ?, ?, ?)
        """,
        (temple_id, order["id"], out_trade_no, amount, "prepay", prepay_id),
    )
    db.commit()

    return WeChatJSAPIPayResponse(
        **build_jsapi_pay_params(prepay_id),
        out_trade_no=out_trade_no,
        prepay_id=prepay_id,
    )


@router.post("/wechat/notify")
async def handle_wechat_pay_notify(request: Request, db: Database) -> dict[str, str]:
    body = (await request.body()).decode("utf-8")
    headers = {key.lower(): value for key, value in request.headers.items()}
    if not verify_notify_signature(headers, body):
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="微信支付通知验签失败")

    notify_payload = json.loads(body)
    resource = notify_payload.get("resource")
    if not isinstance(resource, dict):
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="微信支付通知缺少 resource")

    trade = decrypt_notify_resource(resource)
    out_trade_no = trade.get("out_trade_no")
    trade_state = trade.get("trade_state")
    transaction_id = trade.get("transaction_id")
    if not out_trade_no:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="微信支付通知缺少商户订单号")

    payment = db.execute(
        """
        SELECT id, order_id
        FROM payment_transactions
        WHERE out_trade_no = ?
        """,
        (out_trade_no,),
    ).fetchone()
    if payment is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="支付流水不存在")

    status_value = "paid" if trade_state == "SUCCESS" else str(trade_state or "unknown").lower()
    db.execute(
        """
        UPDATE payment_transactions
        SET status = ?, transaction_id = ?, raw_notify_json = ?, updated_at = CURRENT_TIMESTAMP
        WHERE id = ?
        """,
        (status_value, transaction_id, json.dumps(trade, ensure_ascii=False), payment["id"]),
    )
    if trade_state == "SUCCESS":
        db.execute("UPDATE orders SET status = 'paid' WHERE id = ?", (payment["order_id"],))
    db.commit()

    return {"code": "SUCCESS", "message": "成功"}