const CONFIG_TABLE = 'h5_wechat_admin_config';
const CONFIG_KEY = 'schedule_llm';

function normalizeBoolean(value, fallback = false) {
  if (value == null || value === '') return fallback;
  if (typeof value === 'boolean') return value;
  const normalized = String(value).trim().toLowerCase();
  if (['1', 'true', 'yes', 'on'].includes(normalized)) return true;
  if (['0', 'false', 'no', 'off'].includes(normalized)) return false;
  return fallback;
}

function parseConfigJson(value) {
  if (!value) return {};
  if (typeof value === 'object') return value;
  try {
    return JSON.parse(String(value));
  } catch {
    return {};
  }
}

async function ensureConfigTable(pool) {
  await pool.query(`
    CREATE TABLE IF NOT EXISTS ${CONFIG_TABLE} (
      config_key VARCHAR(64) PRIMARY KEY,
      config_json JSON NOT NULL,
      updated_by CHAR(36) NULL,
      updated_at BIGINT NOT NULL
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
  `);
}

function defaultsFromEnv(env = process.env) {
  return {
    scheduleLlmEnabled: normalizeBoolean(env.H5_WECHAT_SCHEDULE_LLM_ENABLED, false),
  };
}

export function createWechatScheduleLlmConfigService(pool, { env = process.env } = {}) {
  let ensurePromise = null;

  async function ensureReady() {
    if (!ensurePromise) ensurePromise = ensureConfigTable(pool);
    await ensurePromise;
  }

  async function readRow() {
    await ensureReady();
    const [rows] = await pool.query(
      `SELECT config_json, updated_by, updated_at
         FROM ${CONFIG_TABLE}
        WHERE config_key = ?
        LIMIT 1`,
      [CONFIG_KEY],
    );
    return rows[0] ?? null;
  }

  function mergeConfig(row) {
    const defaults = defaultsFromEnv(env);
    const stored = parseConfigJson(row?.config_json);
    return {
      scheduleLlmEnabled: normalizeBoolean(
        stored.scheduleLlmEnabled,
        defaults.scheduleLlmEnabled,
      ),
    };
  }

  return {
    async getConfig() {
      const row = await readRow();
      return {
        ...mergeConfig(row),
        updatedAt: row?.updated_at ? Number(row.updated_at) : null,
        updatedBy: row?.updated_by ?? null,
      };
    },

    async isScheduleLlmEnabled() {
      const config = await this.getConfig();
      return config.scheduleLlmEnabled;
    },

    async updateConfig(payload = {}, { updatedBy = null } = {}) {
      const current = await this.getConfig();
      const next = {
        scheduleLlmEnabled:
          payload.scheduleLlmEnabled === undefined
            ? current.scheduleLlmEnabled
            : normalizeBoolean(payload.scheduleLlmEnabled, current.scheduleLlmEnabled),
      };
      const now = Date.now();
      await pool.query(
        `INSERT INTO ${CONFIG_TABLE} (config_key, config_json, updated_by, updated_at)
         VALUES (?, ?, ?, ?)
         ON DUPLICATE KEY UPDATE
           config_json = VALUES(config_json),
           updated_by = VALUES(updated_by),
           updated_at = VALUES(updated_at)`,
        [CONFIG_KEY, JSON.stringify(next), updatedBy, now],
      );
      return this.getConfig();
    },
  };
}

export const wechatScheduleLlmConfigInternals = {
  normalizeBoolean,
  defaultsFromEnv,
};