const CONFIG_TABLE = 'h5_wechat_admin_config';
const CONFIG_KEY = 'intent_router';

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 normalizeString(value) {
  if (value == null) return '';
  return String(value).trim();
}

function normalizeNumber(value, fallback) {
  if (value == null || value === '') return fallback;
  const parsed = Number(value);
  return Number.isFinite(parsed) ? parsed : fallback;
}

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

function normalizeOpenidList(value) {
  return [...new Set(String(value ?? '')
    .split(/[\s,]+/u)
    .map((item) => item.trim())
    .filter(Boolean))].slice(0, 1000);
}

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
  `);
}

export function defaultsFromEnv(env = process.env) {
  return {
    enabled: normalizeBoolean(env.MEMIND_WECHAT_INTENT_LLM_ENABLED, false),
    shadowMode: normalizeBoolean(env.MEMIND_WECHAT_INTENT_LLM_SHADOW, true),
    modelProviderKeyId: normalizeString(env.MEMIND_WECHAT_INTENT_MODEL_PROVIDER_KEY_ID),
    model: normalizeString(env.MEMIND_WECHAT_INTENT_MODEL),
    minConfidence: normalizeNumber(env.MEMIND_WECHAT_INTENT_MIN_CONFIDENCE, 0.65),
    timeoutMs: normalizeNumber(env.MEMIND_WECHAT_INTENT_TIMEOUT_MS, 4000),
    canaryOpenids: normalizeOpenidList(env.MEMIND_WECHAT_INTENT_CANARY_OPENIDS),
  };
}

export function createWechatIntentRouterConfigService(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 {
      enabled: normalizeBoolean(stored.enabled, defaults.enabled),
      shadowMode: normalizeBoolean(stored.shadowMode, defaults.shadowMode),
      modelProviderKeyId: normalizeString(stored.modelProviderKeyId) || defaults.modelProviderKeyId || null,
      model: normalizeString(stored.model) || defaults.model || null,
      minConfidence: normalizeNumber(stored.minConfidence, defaults.minConfidence),
      timeoutMs: normalizeNumber(stored.timeoutMs, defaults.timeoutMs),
      canaryOpenids: stored.canaryOpenids != null
        ? normalizeOpenidList(stored.canaryOpenids)
        : defaults.canaryOpenids,
    };
  }

  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 getRuntimeState() {
      const config = await this.getConfig();
      const overrides = {
        MEMIND_WECHAT_INTENT_LLM_ENABLED: config.enabled ? '1' : '0',
        MEMIND_WECHAT_INTENT_LLM_SHADOW: config.shadowMode ? '1' : '0',
        MEMIND_WECHAT_INTENT_MODEL_PROVIDER_KEY_ID: config.modelProviderKeyId ?? '',
        MEMIND_WECHAT_INTENT_MODEL: config.model ?? '',
        MEMIND_WECHAT_INTENT_MIN_CONFIDENCE: String(config.minConfidence),
        MEMIND_WECHAT_INTENT_TIMEOUT_MS: String(config.timeoutMs),
        MEMIND_WECHAT_INTENT_CANARY_OPENIDS: config.canaryOpenids.join(','),
      };
      return {
        source: 'admin-db',
        updatedAt: config.updatedAt,
        updatedBy: config.updatedBy,
        fingerprint: JSON.stringify(config),
        overrides,
        config,
      };
    },

    async updateConfig(payload = {}, { updatedBy = null } = {}) {
      const current = await this.getConfig();
      const next = {
        enabled: payload.enabled === undefined
          ? current.enabled
          : normalizeBoolean(payload.enabled, current.enabled),
        shadowMode: payload.shadowMode === undefined
          ? current.shadowMode
          : normalizeBoolean(payload.shadowMode, current.shadowMode),
        modelProviderKeyId: payload.modelProviderKeyId === undefined
          ? (current.modelProviderKeyId ?? '')
          : normalizeString(payload.modelProviderKeyId),
        model: payload.model === undefined
          ? (current.model ?? '')
          : normalizeString(payload.model),
        minConfidence: payload.minConfidence === undefined
          ? current.minConfidence
          : normalizeNumber(payload.minConfidence, current.minConfidence),
        timeoutMs: payload.timeoutMs === undefined
          ? current.timeoutMs
          : normalizeNumber(payload.timeoutMs, current.timeoutMs),
        canaryOpenids: payload.canaryOpenids === undefined
          ? current.canaryOpenids
          : normalizeOpenidList(payload.canaryOpenids),
      };
      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 wechatIntentRouterConfigInternals = {
  normalizeBoolean,
  normalizeOpenidList,
  defaultsFromEnv,
};