use module_auth::{WechatAuthScene, WechatIdentityProfile};
use reqwest::Client;
use serde::Deserialize;
use tracing::warn;
use url::Url;

use crate::{config::AppConfig, http_error::AppError};
use axum::http::StatusCode;

#[derive(Clone, Debug)]
pub enum WechatProvider {
    Disabled,
    Mock(MockWechatProvider),
    Real(RealWechatProvider),
}

#[derive(Clone, Debug)]
pub struct MockWechatProvider {
    mock_user_id: String,
    mock_union_id: Option<String>,
    mock_display_name: String,
    mock_avatar_url: Option<String>,
}

#[derive(Clone, Debug)]
pub struct RealWechatProvider {
    client: Client,
    app_id: String,
    app_secret: String,
    authorize_endpoint: String,
    access_token_endpoint: String,
    user_info_endpoint: String,
}

#[derive(Debug, Deserialize)]
struct WechatAccessTokenResponse {
    access_token: Option<String>,
    openid: Option<String>,
    unionid: Option<String>,
    errmsg: Option<String>,
}

#[derive(Debug, Deserialize)]
struct WechatUserInfoResponse {
    openid: Option<String>,
    unionid: Option<String>,
    nickname: Option<String>,
    headimgurl: Option<String>,
    errmsg: Option<String>,
}

pub fn build_wechat_provider(config: &AppConfig) -> WechatProvider {
    if !config.wechat_auth_enabled {
        return WechatProvider::Disabled;
    }

    if config
        .wechat_auth_provider
        .trim()
        .eq_ignore_ascii_case("mock")
    {
        return WechatProvider::Mock(MockWechatProvider {
            mock_user_id: config.wechat_mock_user_id.clone(),
            mock_union_id: config.wechat_mock_union_id.clone(),
            mock_display_name: config.wechat_mock_display_name.clone(),
            mock_avatar_url: config.wechat_mock_avatar_url.clone(),
        });
    }

    let Some(app_id) = config.wechat_app_id.clone() else {
        return WechatProvider::Disabled;
    };
    let Some(app_secret) = config.wechat_app_secret.clone() else {
        return WechatProvider::Disabled;
    };

    WechatProvider::Real(RealWechatProvider {
        client: Client::new(),
        app_id,
        app_secret,
        authorize_endpoint: config.wechat_authorize_endpoint.clone(),
        access_token_endpoint: config.wechat_access_token_endpoint.clone(),
        user_info_endpoint: config.wechat_user_info_endpoint.clone(),
    })
}

impl WechatProvider {
    pub fn build_authorization_url(
        &self,
        callback_url: &str,
        state: &str,
        scene: &WechatAuthScene,
    ) -> Result<String, AppError> {
        match self {
            Self::Disabled => {
                Err(AppError::from_status(StatusCode::BAD_REQUEST).with_message("微信登录暂未启用"))
            }
            Self::Mock(_) => {
                let mut callback = Url::parse(callback_url).map_err(|error| {
                    AppError::from_status(StatusCode::INTERNAL_SERVER_ERROR)
                        .with_message(format!("微信回调地址非法：{error}"))
                })?;
                callback
                    .query_pairs_mut()
                    .append_pair("mock_code", "wx-mock-code")
                    .append_pair("state", state);
                Ok(callback.to_string())
            }
            Self::Real(provider) => provider.build_authorization_url(callback_url, state, scene),
        }
    }

    pub async fn resolve_callback_profile(
        &self,
        code: Option<&str>,
        mock_code: Option<&str>,
    ) -> Result<WechatIdentityProfile, AppError> {
        match self {
            Self::Disabled => {
                Err(AppError::from_status(StatusCode::BAD_REQUEST).with_message("微信登录暂未启用"))
            }
            Self::Mock(provider) => Ok(provider.resolve_callback_profile(mock_code)),
            Self::Real(provider) => provider.resolve_callback_profile(code).await,
        }
    }
}

impl MockWechatProvider {
    fn resolve_callback_profile(&self, mock_code: Option<&str>) -> WechatIdentityProfile {
        let provider_uid = mock_code
            .map(str::trim)
            .filter(|value| !value.is_empty())
            .unwrap_or(self.mock_user_id.as_str())
            .to_string();
        WechatIdentityProfile {
            provider_uid,
            provider_union_id: self.mock_union_id.clone(),
            display_name: Some(self.mock_display_name.clone()),
            avatar_url: self.mock_avatar_url.clone(),
        }
    }
}

impl RealWechatProvider {
    fn build_authorization_url(
        &self,
        callback_url: &str,
        state: &str,
        scene: &WechatAuthScene,
    ) -> Result<String, AppError> {
        let mut url = Url::parse(match scene {
            WechatAuthScene::Desktop => &self.authorize_endpoint,
            WechatAuthScene::WechatInApp => "https://open.weixin.qq.com/connect/oauth2/authorize",
        })
        .map_err(|error| {
            AppError::from_status(StatusCode::INTERNAL_SERVER_ERROR)
                .with_message(format!("微信授权地址非法：{error}"))
        })?;
        url.query_pairs_mut()
            .append_pair("appid", &self.app_id)
            .append_pair("redirect_uri", callback_url)
            .append_pair("response_type", "code")
            .append_pair(
                "scope",
                match scene {
                    WechatAuthScene::Desktop => "snsapi_login",
                    WechatAuthScene::WechatInApp => "snsapi_userinfo",
                },
            )
            .append_pair("state", state);
        Ok(format!("{url}#wechat_redirect"))
    }

    async fn resolve_callback_profile(
        &self,
        code: Option<&str>,
    ) -> Result<WechatIdentityProfile, AppError> {
        let code = code
            .map(str::trim)
            .filter(|value| !value.is_empty())
            .ok_or_else(|| {
                AppError::from_status(StatusCode::BAD_REQUEST).with_message("缺少微信授权 code")
            })?;

        let mut access_token_url = Url::parse(&self.access_token_endpoint).map_err(|error| {
            AppError::from_status(StatusCode::INTERNAL_SERVER_ERROR)
                .with_message(format!("微信 access_token 地址非法：{error}"))
        })?;
        access_token_url
            .query_pairs_mut()
            .append_pair("appid", &self.app_id)
            .append_pair("secret", &self.app_secret)
            .append_pair("code", code)
            .append_pair("grant_type", "authorization_code");

        let access_token_payload = self
            .client
            .get(access_token_url.as_str())
            .send()
            .await
            .map_err(|error| {
                warn!(error = %error, "微信 access_token 请求失败");
                AppError::from_status(StatusCode::BAD_GATEWAY)
                    .with_message("微信登录失败：access_token 请求失败")
            })?
            .json::<WechatAccessTokenResponse>()
            .await
            .map_err(|error| {
                warn!(error = %error, "微信 access_token 响应解析失败");
                AppError::from_status(StatusCode::BAD_GATEWAY)
                    .with_message("微信登录失败：access_token 响应非法")
            })?;

        let access_token = access_token_payload
            .access_token
            .filter(|value| !value.trim().is_empty())
            .ok_or_else(|| {
                AppError::from_status(StatusCode::BAD_GATEWAY).with_message(format!(
                    "微信登录失败：{}",
                    access_token_payload
                        .errmsg
                        .unwrap_or_else(|| "缺少 access_token".to_string())
                ))
            })?;
        let openid = access_token_payload
            .openid
            .filter(|value| !value.trim().is_empty())
            .ok_or_else(|| {
                AppError::from_status(StatusCode::BAD_GATEWAY)
                    .with_message("微信登录失败：缺少 openid")
            })?;

        let mut user_info_url = Url::parse(&self.user_info_endpoint).map_err(|error| {
            AppError::from_status(StatusCode::INTERNAL_SERVER_ERROR)
                .with_message(format!("微信用户信息地址非法：{error}"))
        })?;
        user_info_url
            .query_pairs_mut()
            .append_pair("access_token", &access_token)
            .append_pair("openid", &openid)
            .append_pair("lang", "zh_CN");

        let user_info_payload = self
            .client
            .get(user_info_url.as_str())
            .send()
            .await
            .map_err(|error| {
                warn!(error = %error, "微信用户信息请求失败");
                AppError::from_status(StatusCode::BAD_GATEWAY)
                    .with_message("微信登录失败：用户信息请求失败")
            })?
            .json::<WechatUserInfoResponse>()
            .await
            .map_err(|error| {
                warn!(error = %error, "微信用户信息响应解析失败");
                AppError::from_status(StatusCode::BAD_GATEWAY)
                    .with_message("微信登录失败：用户信息响应非法")
            })?;

        let provider_uid = user_info_payload
            .openid
            .filter(|value| !value.trim().is_empty())
            .ok_or_else(|| {
                AppError::from_status(StatusCode::BAD_GATEWAY).with_message(format!(
                    "微信登录失败：{}",
                    user_info_payload
                        .errmsg
                        .unwrap_or_else(|| "缺少 openid".to_string())
                ))
            })?;

        Ok(WechatIdentityProfile {
            provider_uid,
            provider_union_id: user_info_payload.unionid.or(access_token_payload.unionid),
            display_name: user_info_payload.nickname,
            avatar_url: user_info_payload.headimgurl,
        })
    }
}