const DEFAULT_TIMEOUT_MS = 10000;

function trimEnv(name) {
  const value = process.env[name];
  return typeof value === 'string' ? value.trim() : '';
}

function parseTimeout(value) {
  const n = Number(value);
  return Number.isFinite(n) && n > 0 ? n : DEFAULT_TIMEOUT_MS;
}

async function safeJson(response) {
  const text = await response.text();
  if (!text) return null;
  try {
    return JSON.parse(text);
  } catch {
    return text;
  }
}

function responseMessage(payload, fallback) {
  if (payload && typeof payload === 'object' && typeof payload.message === 'string' && payload.message.trim()) {
    return payload.message.trim();
  }
  if (typeof payload === 'string' && payload.trim()) return payload.trim();
  return fallback;
}

export function createPlanSyncService(logger = console) {
  const baseUrl = trimEnv('PLAN_SYNC_TARGET_BASE_URL').replace(/\/$/, '');
  const username = trimEnv('PLAN_SYNC_USERNAME');
  const password = trimEnv('PLAN_SYNC_PASSWORD');
  const timeoutMs = parseTimeout(trimEnv('PLAN_SYNC_TIMEOUT_MS'));

  if (!baseUrl || !username || !password) {
    return {
      enabled: false,
      reason: '未配置生产套餐同步环境变量',
      async syncPlanUpsert() {
        return { enabled: false, ok: false, message: '未配置生产套餐同步环境变量' };
      },
      async syncPlanDelete() {
        return { enabled: false, ok: false, message: '未配置生产套餐同步环境变量' };
      },
      async syncAllPlans() {
        return { enabled: false, ok: false, message: '未配置生产套餐同步环境变量', synced: 0, total: 0 };
      },
    };
  }

  async function request(path, init = {}) {
    const controller = new AbortController();
    const timer = setTimeout(() => controller.abort(), timeoutMs);
    try {
      return await fetch(`${baseUrl}${path}`, { ...init, signal: controller.signal });
    } finally {
      clearTimeout(timer);
    }
  }

  async function loginAndGetCookie() {
    const response = await request('/auth/login', {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify({ username, password }),
    });
    const payload = await safeJson(response);
    if (!response.ok) {
      throw new Error(`生产后台登录失败：${responseMessage(payload, `${response.status} ${response.statusText}`)}`);
    }
    const cookie = response.headers.get('set-cookie');
    if (!cookie) throw new Error('生产后台登录成功，但未返回会话 Cookie');
    return cookie.split(';', 1)[0];
  }

  async function syncRequest(path, init = {}) {
    const cookie = await loginAndGetCookie();
    const response = await request(path, {
      ...init,
      headers: {
        'content-type': 'application/json',
        'x-plan-sync-hop': '1',
        ...(init.headers ?? {}),
        cookie,
      },
    });
    const payload = await safeJson(response);
    if (!response.ok) {
      throw new Error(responseMessage(payload, `${response.status} ${response.statusText}`));
    }
    return payload;
  }

  async function syncPlanUpsert(planType, plan) {
    try {
      await syncRequest(`/admin-api/subscriptions/plans/${encodeURIComponent(planType)}`, {
        method: 'PUT',
        body: JSON.stringify(plan),
      });
      return {
        enabled: true,
        ok: true,
        message: `已同步到生产后台 ${baseUrl}`,
      };
    } catch (error) {
      logger.warn?.('[plan-sync] upsert failed', { planType, error: String(error) });
      return {
        enabled: true,
        ok: false,
        message: error instanceof Error ? error.message : '同步生产后台失败',
      };
    }
  }

  async function syncPlanDelete(planType) {
    try {
      await syncRequest(`/admin-api/subscriptions/plans/${encodeURIComponent(planType)}`, {
        method: 'DELETE',
      });
      return {
        enabled: true,
        ok: true,
        message: `已同步删除生产后台套餐 ${planType}`,
      };
    } catch (error) {
      logger.warn?.('[plan-sync] delete failed', { planType, error: String(error) });
      return {
        enabled: true,
        ok: false,
        message: error instanceof Error ? error.message : '同步生产后台失败',
      };
    }
  }

  async function syncAllPlans(plans) {
    let synced = 0;
    const failures = [];
    for (const plan of plans) {
      const result = await syncPlanUpsert(plan.planType, plan);
      if (result.ok) synced += 1;
      else failures.push(`${plan.planType}: ${result.message}`);
    }
    return {
      enabled: true,
      ok: failures.length === 0,
      message: failures.length === 0
        ? `已同步 ${synced}/${plans.length} 个套餐到生产后台`
        : `已同步 ${synced}/${plans.length} 个套餐，失败：${failures.join('；')}`,
      synced,
      total: plans.length,
      failures,
    };
  }

  return {
    enabled: true,
    reason: '',
    syncPlanUpsert,
    syncPlanDelete,
    syncAllPlans,
  };
}