"""
第三方 OAuth2 登录（微信开放平台扫码、QQ、GitHub、Gitee）。

各平台需在开放平台登记「授权回调域 / redirect_uri」为：
  {API}/system/auth/oauth/{provider}/callback
例如：https://your-domain.com/api/v1/system/auth/oauth/github/callback

环境变量见 Settings 中 OAUTH_* 字段。
"""

import json
import secrets
from typing import Any, Literal
from urllib.parse import quote, urlencode

import httpx
from fastapi import Request
from redis.asyncio.client import Redis
from sqlalchemy.ext.asyncio import AsyncSession

from app.api.v1.module_system.user.crud import UserCRUD
from app.api.v1.module_system.user.model import UserModel
from app.api.v1.module_system.user.schema import UserRegisterSchema
from app.api.v1.module_system.user.service import UserService
from app.config.setting import settings
from app.core.base_schema import AuthSchema, JWTOutSchema
from app.core.exceptions import CustomException
from app.core.logger import logger
from app.core.redis_crud import RedisCURD

from .service import LoginService

OAuthProvider = Literal["wechat", "qq", "github", "gitee"]

STATE_PREFIX = "oauth_state:"
STATE_TTL_SECONDS = 600


def _callback_url(request: Request, provider: OAuthProvider) -> str:
    root = str(request.base_url).rstrip("/")
    return f"{root}/system/auth/oauth/{provider}/callback"


def _frontend_error_redirect(frontend_base: str, message: str) -> str:
    sep = "&" if "?" in frontend_base else "?"
    return f"{frontend_base}{sep}oauth_error={quote(message, safe='')}"


def _frontend_success_redirect(frontend_base: str, access_token: str, refresh_token: str, token_type: str) -> str:
    q = urlencode(
        {
            "access_token": access_token,
            "refresh_token": refresh_token,
            "token_type": token_type,
        }
    )
    sep = "&" if "?" in frontend_base else "?"
    return f"{frontend_base}{sep}{q}"


def _require_credentials(provider: OAuthProvider) -> tuple[str, str]:
    if provider == "github":
        cid, sec = settings.OAUTH_GITHUB_CLIENT_ID, settings.OAUTH_GITHUB_CLIENT_SECRET
    elif provider == "gitee":
        cid, sec = settings.OAUTH_GITEE_CLIENT_ID, settings.OAUTH_GITEE_CLIENT_SECRET
    elif provider == "wechat":
        cid, sec = settings.OAUTH_WECHAT_OPEN_APP_ID, settings.OAUTH_WECHAT_OPEN_APP_SECRET
    elif provider == "qq":
        cid, sec = settings.OAUTH_QQ_APP_ID, settings.OAUTH_QQ_APP_SECRET
    else:
        raise CustomException(msg="不支持的 OAuth 渠道")
    if not cid or not sec:
        raise CustomException(msg=f"{provider} OAuth 未配置（客户端密钥为空）")
    return cid, sec


def build_authorize_url(
    *,
    provider: OAuthProvider,
    callback_url: str,
    state: str,
) -> str:
    """构造跳转至第三方授权页的 URL。"""
    cid, _ = _require_credentials(provider)

    if provider == "github":
        params = {
            "client_id": cid,
            "redirect_uri": callback_url,
            "scope": "user:email",
            "state": state,
        }
        return "https://github.com/login/oauth/authorize?" + urlencode(params)

    if provider == "gitee":
        params = {
            "client_id": cid,
            "redirect_uri": callback_url,
            "response_type": "code",
            "state": state,
        }
        return "https://gitee.com/oauth/authorize?" + urlencode(params)

    if provider == "wechat":
        params = {
            "appid": cid,
            "redirect_uri": callback_url,
            "response_type": "code",
            "scope": "snsapi_login",
            "state": state,
        }
        return "https://open.weixin.qq.com/connect/qrconnect?" + urlencode(params) + "#wechat_redirect"

    if provider == "qq":
        params = {
            "response_type": "code",
            "client_id": cid,
            "redirect_uri": callback_url,
            "state": state,
            "scope": "get_user_info",
        }
        return "https://graph.qq.com/oauth2.0/authorize?" + urlencode(params)

    raise CustomException(msg="不支持的 OAuth 渠道")


async def _http_json(method: str, url: str, **kwargs: Any) -> Any:
    timeout = getattr(settings, "HTTPX_DEFAULT_TIMEOUT", 15.0)
    async with httpx.AsyncClient(timeout=timeout) as client:
        r = await client.request(method, url, **kwargs)
        r.raise_for_status()
        try:
            return r.json()
        except json.JSONDecodeError:
            text = r.text
            logger.error(f"OAuth 非 JSON 响应: {text[:500]}")
            raise CustomException(msg="OAuth 接口返回异常")


async def _http_text(method: str, url: str, **kwargs: Any) -> str:
    timeout = getattr(settings, "HTTPX_DEFAULT_TIMEOUT", 15.0)
    async with httpx.AsyncClient(timeout=timeout) as client:
        r = await client.request(method, url, **kwargs)
        r.raise_for_status()
        return r.text


async def exchange_github_token(client_id: str, client_secret: str, code: str, redirect_uri: str) -> str:
    data = await _http_json(
        "POST",
        "https://github.com/login/oauth/access_token",
        headers={"Accept": "application/json"},
        data={
            "client_id": client_id,
            "client_secret": client_secret,
            "code": code,
            "redirect_uri": redirect_uri,
        },
    )
    if not isinstance(data, dict):
        raise CustomException(msg="GitHub token 响应格式错误")
    token = data.get("access_token")
    if not token:
        raise CustomException(msg=data.get("error_description") or "GitHub 换取令牌失败")
    return str(token)


async def exchange_gitee_token(client_id: str, client_secret: str, code: str, redirect_uri: str) -> str:
    qs = urlencode(
        {
            "grant_type": "authorization_code",
            "code": code,
            "client_id": client_id,
            "client_secret": client_secret,
            "redirect_uri": redirect_uri,
        }
    )
    data = await _http_json("GET", f"https://gitee.com/oauth/token?{qs}")
    if not isinstance(data, dict):
        raise CustomException(msg="Gitee token 响应格式错误")
    token = data.get("access_token")
    if not token:
        raise CustomException(msg=data.get("error_description") or "Gitee 换取令牌失败")
    return str(token)


async def exchange_wechat_token(app_id: str, secret: str, code: str) -> tuple[str, str]:
    qs = urlencode(
        {
            "appid": app_id,
            "secret": secret,
            "code": code,
            "grant_type": "authorization_code",
        }
    )
    data = await _http_json("GET", f"https://api.weixin.qq.com/sns/oauth2/access_token?{qs}")
    if not isinstance(data, dict):
        raise CustomException(msg="微信 token 响应格式错误")
    token = data.get("access_token")
    openid = data.get("openid")
    if not token or not openid:
        raise CustomException(msg=data.get("errmsg") or "微信换取令牌失败")
    return str(token), str(openid)


async def exchange_qq_token(client_id: str, client_secret: str, code: str, redirect_uri: str) -> tuple[str, str]:
    qs = urlencode(
        {
            "grant_type": "authorization_code",
            "client_id": client_id,
            "client_secret": client_secret,
            "code": code,
            "redirect_uri": redirect_uri,
        }
    )
    text = await _http_text("GET", f"https://graph.qq.com/oauth2.0/token?{qs}")
    parts = dict(p.split("=", 1) for p in text.split("&") if "=" in p)
    token = parts.get("access_token")
    if not token:
        raise CustomException(msg="QQ 换取 access_token 失败")
    me = await _http_json(
        "GET",
        "https://graph.qq.com/oauth2.0/me",
        params={"access_token": token, "fmt": "json"},
    )
    if not isinstance(me, dict):
        raise CustomException(msg="QQ openid 响应格式错误")
    openid = me.get("openid")
    if not openid:
        raise CustomException(msg="QQ 获取 openid 失败")
    return str(token), str(openid)


async def fetch_github_profile(access_token: str) -> tuple[str, str, str | None]:
    headers = {"Authorization": f"Bearer {access_token}", "Accept": "application/json"}
    user = await _http_json("GET", "https://api.github.com/user", headers=headers)
    if not isinstance(user, dict):
        raise CustomException(msg="GitHub 用户信息格式错误")
    login = str(user.get("login") or "")
    name = str(user.get("name") or login or "github")
    email = user.get("email")
    if not email:
        emails = await _http_json("GET", "https://api.github.com/user/emails", headers=headers)
        if isinstance(emails, list):
            primary = next((e for e in emails if isinstance(e, dict) and e.get("primary")), None)
            if primary:
                email = primary.get("email")
    return login, name, email


async def fetch_gitee_profile(access_token: str) -> tuple[str, str, str | None]:
    user = await _http_json(
        "GET",
        "https://gitee.com/api/v5/user",
        params={"access_token": access_token},
    )
    if not isinstance(user, dict):
        raise CustomException(msg="Gitee 用户信息格式错误")
    login = str(user.get("login") or "")
    name = str(user.get("name") or login)
    email = user.get("email")
    return login, name, email


async def fetch_wechat_profile(access_token: str, openid: str) -> tuple[str, str]:
    qs = urlencode({"access_token": access_token, "openid": openid, "lang": "zh_CN"})
    user = await _http_json("GET", f"https://api.weixin.qq.com/sns/userinfo?{qs}")
    if not isinstance(user, dict):
        raise CustomException(msg="微信用户信息格式错误")
    nickname = str(user.get("nickname") or "wechat")
    unionid = user.get("unionid")
    oid = unionid or openid
    return str(oid), nickname


async def fetch_qq_profile(access_token: str, app_id: str, openid: str) -> tuple[str, str]:
    qs = urlencode(
        {
            "access_token": access_token,
            "oauth_consumer_key": app_id,
            "openid": openid,
        }
    )
    user = await _http_json("GET", f"https://graph.qq.com/user/get_user_info?{qs}")
    if not isinstance(user, dict):
        raise CustomException(msg="QQ 用户信息格式错误")
    if user.get("ret") not in (0, "0", None):
        raise CustomException(msg=user.get("msg") or "QQ 用户信息失败")
    nickname = str(user.get("nickname") or "qq")
    return openid, nickname


def _username_for_oauth(provider: OAuthProvider, unique_id: str) -> str:
    """生成符合注册规则的登录名：oauth_{provider}_{id}。"""
    raw = f"oauth_{provider}_{unique_id}"
    raw = "".join(c if c.isalnum() or c in "_-." else "_" for c in raw)[:32]
    if len(raw) < 3:
        raw = (raw + "usr")[:32]
    if not raw[0].isalpha():
        raw = "o" + raw[:31]
    return raw


async def ensure_oauth_user(
    *,
    db: AsyncSession,
    provider: OAuthProvider,
    unique_id: str,
    display_name: str,
) -> UserModel:
    auth = AuthSchema(db=db, user=None, tenant_id=1, check_data_scope=False)
    username = _username_for_oauth(provider, unique_id)
    existing = await UserCRUD(auth).get(username=username)
    if existing:
        return existing

    reg = UserRegisterSchema(
        username=username,
        password=secrets.token_urlsafe(24),
        name=(display_name or username)[:32],
        role_ids=list(settings.OAUTH_DEFAULT_ROLE_IDS),
    )
    try:
        await UserService(auth).register(data=reg)
    except Exception:
        # 并发创建可能触发唯一约束冲突，回退到再次查询
        existing = await UserCRUD(auth).get(username=username)
        if existing:
            return existing
        raise CustomException(msg="OAuth 注册失败")
    user = await UserCRUD(auth).get(username=username)
    if not user:
        raise CustomException(msg="OAuth 注册失败")
    logger.info(f"OAuth 自动注册用户: {username} ({provider})")
    return user


async def complete_oauth_login(
    *,
    request: Request,
    redis: Redis,
    db: AsyncSession,
    provider: OAuthProvider,
    code: str,
    state: str,
) -> tuple[JWTOutSchema, str]:
    rc = RedisCURD(redis)
    raw = await rc.get(f"{STATE_PREFIX}{state}")
    if not raw:
        raise CustomException(msg="登录状态已失效，请重试")
    if isinstance(raw, bytes):
        raw = raw.decode("utf-8")
    payload = json.loads(raw)
    if payload.get("provider") != provider:
        raise CustomException(msg="OAuth 状态不匹配")

    frontend = str(payload.get("frontend_redirect") or "").strip()
    if not frontend:
        raise CustomException(msg="缺少前端回调地址")

    callback_url = _callback_url(request, provider)
    cid, csec = _require_credentials(provider)

    if provider == "github":
        access = await exchange_github_token(cid, csec, code, callback_url)
        login_k, name, _email = await fetch_github_profile(access)
        uid = login_k
    elif provider == "gitee":
        access = await exchange_gitee_token(cid, csec, code, callback_url)
        login_k, name, _email = await fetch_gitee_profile(access)
        uid = login_k
    elif provider == "wechat":
        access, openid = await exchange_wechat_token(cid, csec, code)
        uid, name = await fetch_wechat_profile(access, openid)
    elif provider == "qq":
        access, openid = await exchange_qq_token(cid, csec, code, callback_url)
        uid, name = await fetch_qq_profile(access, cid, openid)
    else:
        raise CustomException(msg="不支持的 OAuth 渠道")

    user = await ensure_oauth_user(db=db, provider=provider, unique_id=uid, display_name=name)
    if user.status == 1:
        raise CustomException(msg="用户已被停用")

    user = await UserCRUD(AuthSchema(db=db, user=None, tenant_id=1, check_data_scope=False)).update_last_login_crud(id=user.id)
    if not user:
        raise CustomException(msg="用户不存在")

    login_type = f"oauth_{provider}"
    token = await LoginService.create_token(request=request, redis=redis, user=user, login_type=login_type)
    await rc.delete(f"{STATE_PREFIX}{state}")
    return token, frontend


async def save_oauth_state(
    *,
    redis: Redis,
    state: str,
    provider: OAuthProvider,
    frontend_redirect: str,
) -> None:
    rc = RedisCURD(redis)
    ok = await rc.set(
        f"{STATE_PREFIX}{state}",
        json.dumps({"provider": provider, "frontend_redirect": frontend_redirect}),
        expire=STATE_TTL_SECONDS,
    )
    if not ok:
        raise CustomException(msg="缓存 OAuth 状态失败")


def oauth_service_frontend_redirect_from_token(frontend_base: str, token: JWTOutSchema) -> str:
    return _frontend_success_redirect(
        frontend_base,
        token.access_token,
        token.refresh_token,
        token.token_type,
    )


def oauth_service_error_redirect(frontend_base: str, message: str) -> str:
    return _frontend_error_redirect(frontend_base, message)


__all__ = [
    "OAuthProvider",
    "STATE_PREFIX",
    "build_authorize_url",
    "complete_oauth_login",
    "save_oauth_state",
    "_callback_url",
    "oauth_service_frontend_redirect_from_token",
    "oauth_service_error_redirect",
]