import Taro from '@tarojs/taro';
import { fetchClientConfig } from './pay-wechat';

/** 与 package.json version 同步，供服务端 minClientVersion 比对 */
export const APP_VERSION = '3.5.4';

export const APP_VERSION_LABEL = `v${APP_VERSION}`;

function parseSemver(v: string): number[] {
  return v.split('.').map((n) => parseInt(n, 10) || 0);
}

export function compareSemver(a: string, b: string): number {
  const pa = parseSemver(a);
  const pb = parseSemver(b);
  const len = Math.max(pa.length, pb.length);
  for (let i = 0; i < len; i += 1) {
    const da = pa[i] ?? 0;
    const db = pb[i] ?? 0;
    if (da !== db) return da - db;
  }
  return 0;
}

function exitMiniProgramIfSupported() {
  if (process.env.TARO_ENV !== 'weapp') return;
  if (typeof Taro.exitMiniProgram !== 'function') return;
  void Taro.exitMiniProgram({});
}

/** 微信 CDN 有新包时引导 applyUpdate；返回是否已触发更新流程 */
function tryWeappForceUpdate(min: string): Promise<boolean> {
  if (process.env.TARO_ENV !== 'weapp' || typeof Taro.getUpdateManager !== 'function') {
    return Promise.resolve(false);
  }

  return new Promise((resolve) => {
    const manager = Taro.getUpdateManager();
    let settled = false;
    const finish = (updated: boolean) => {
      if (settled) return;
      settled = true;
      resolve(updated);
    };

    manager.onCheckForUpdate((res) => {
      if (!res.hasUpdate) {
        finish(false);
        return;
      }
      manager.onUpdateReady(() => {
        void Taro.showModal({
          title: '版本过低',
          content: `当前 ${APP_VERSION_LABEL} 低于要求版本 v${min}，已检测到新版本，请立即更新后继续使用。`,
          showCancel: false,
          confirmText: '立即更新',
          success: (r) => {
            if (r.confirm) {
              manager.applyUpdate();
              finish(true);
            } else {
              finish(false);
            }
          },
          fail: () => finish(false),
        });
      });
      manager.onUpdateFailed(() => finish(false));
    });

    setTimeout(() => finish(false), 4000);
  });
}

async function enforceMinClientVersion(min: string) {
  const updated = await tryWeappForceUpdate(min);
  if (updated) return;

  await Taro.showModal({
    title: '版本过低',
    content: `当前 ${APP_VERSION_LABEL} 低于要求版本 v${min}，请更新至最新版本后继续使用。`,
    showCancel: false,
    confirmText: '我知道了',
  });

  exitMiniProgramIfSupported();
}

export async function checkClientVersionGate() {
  try {
    const config = await fetchClientConfig();
    const min = config.minClientVersion?.trim();
    if (min && compareSemver(APP_VERSION, min) < 0) {
      await enforceMinClientVersion(min);
    }
  } catch {
    /* 配置拉取失败不阻塞启动 */
  }
}

export function setupWeappUpdateManager() {
  if (process.env.TARO_ENV !== 'weapp') return;
  if (typeof Taro.getUpdateManager !== 'function') return;

  const manager = Taro.getUpdateManager();
  manager.onCheckForUpdate((res) => {
    if (!res.hasUpdate) return;
    manager.onUpdateReady(() => {
      void Taro.showModal({
        title: '更新提示',
        content: '新版本已准备好，是否重启应用？',
        confirmText: '立即更新',
        success: (r) => {
          if (r.confirm) manager.applyUpdate();
        },
      });
    });
    manager.onUpdateFailed(() => {
      void Taro.showModal({
        title: '更新失败',
        content: '新版本下载失败，请删除小程序后重新搜索打开。',
        showCancel: false,
      });
    });
  });
}

export function initClientVersionChecks() {
  setupWeappUpdateManager();
  void checkClientVersionGate();
}