import crypto from 'node:crypto';

const PUBLIC_PAGE_LIMIT_KEY = 'public_page_limit';
const ANALYTICS_ENABLED_KEY = 'analytics_enabled';
const ANALYTICS_WEBSITE_ID_KEY = 'analytics_website_id';
const ANALYTICS_URL_KEY = 'analytics_url';
const ANALYTICS_DOMAINS_KEY = 'analytics_domains';
const ANALYTICS_ID_SECRET_KEY = 'analytics_id_secret';

function secretKey(env = process.env) {
  return crypto.createHash('sha256').update(String(env.TKMIND_SERVER__SECRET_KEY ?? 'local-dev-secret')).digest();
}

function encryptSecret(value, env = process.env) {
  const iv = crypto.randomBytes(12);
  const cipher = crypto.createCipheriv('aes-256-gcm', secretKey(env), iv);
  const ciphertext = Buffer.concat([cipher.update(String(value), 'utf8'), cipher.final()]);
  return JSON.stringify({ v: 1, iv: iv.toString('base64'), tag: cipher.getAuthTag().toString('base64'), data: ciphertext.toString('base64') });
}

function decryptSecret(value, env = process.env) {
  try {
    const payload = JSON.parse(String(value));
    const decipher = crypto.createDecipheriv('aes-256-gcm', secretKey(env), Buffer.from(payload.iv, 'base64'));
    decipher.setAuthTag(Buffer.from(payload.tag, 'base64'));
    return Buffer.concat([decipher.update(Buffer.from(payload.data, 'base64')), decipher.final()]).toString('utf8');
  } catch {
    return '';
  }
}

function asPositiveInteger(value, fallback) {
  const parsed = Number(value);
  if (!Number.isFinite(parsed) || parsed < 1) return fallback;
  return Math.floor(parsed);
}

async function ensureConfigTable(pool) {
  await pool.query(`
    CREATE TABLE IF NOT EXISTS mindspace_config (
      \`key\` VARCHAR(64) PRIMARY KEY,
      value TEXT NOT NULL,
      description VARCHAR(255) NULL,
      updated_at BIGINT NOT NULL
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
  `);
}

export function defaultMindSpaceConfig(env = process.env) {
  return {
    publicPageLimit: asPositiveInteger(env.MINDSPACE_FREE_PUBLIC_PAGE_LIMIT ?? 5, 5),
    analytics: {
      enabled: String(env.MEMIND_ANALYTICS_ENABLED ?? '').toLowerCase() === 'true',
      websiteId: String(env.MEMIND_ANALYTICS_WEBSITE_ID ?? '').trim(),
      analyticsUrl: String(env.MEMIND_ANALYTICS_URL ?? 'http://127.0.0.1:3100').trim(),
      domains: String(env.MEMIND_ANALYTICS_DOMAINS ?? '127.0.0.1,localhost').trim(),
      idSecretConfigured: Boolean(String(env.MEMIND_ANALYTICS_ID_SECRET ?? '').trim()),
    },
  };
}

async function readConfigRows(pool) {
  const [rows] = await pool.query(
    'SELECT `key`, value FROM mindspace_config',
  );
  return rows;
}

export async function ensureMindSpaceConfig(pool, { env = process.env, seedDefault = true } = {}) {
  await ensureConfigTable(pool);
  if (!seedDefault) return;
  const [rows] = await pool.query('SELECT COUNT(*) AS count FROM mindspace_config');
  if (Number(rows[0]?.count ?? 0) > 0) return;

  const now = Date.now();
  const defaults = defaultMindSpaceConfig(env);
  await pool.query(
    `INSERT INTO mindspace_config (\`key\`, value, description, updated_at)
     VALUES (?, ?, ?, ?)`,
    [PUBLIC_PAGE_LIMIT_KEY, String(defaults.publicPageLimit), '公开页面数量上限', now],
  );
}

export async function loadMindSpaceConfig(pool, { env = process.env, includeAnalyticsSecret = false } = {}) {
  const config = defaultMindSpaceConfig(env);
  try {
    const rows = await readConfigRows(pool);
    for (const row of rows) {
      if (row.key === PUBLIC_PAGE_LIMIT_KEY) {
        config.publicPageLimit = asPositiveInteger(row.value, config.publicPageLimit);
      }
      if (row.key === ANALYTICS_ENABLED_KEY) config.analytics.enabled = row.value === 'true';
      if (row.key === ANALYTICS_WEBSITE_ID_KEY) config.analytics.websiteId = String(row.value ?? '');
      if (row.key === ANALYTICS_URL_KEY) config.analytics.analyticsUrl = String(row.value ?? '');
      if (row.key === ANALYTICS_DOMAINS_KEY) config.analytics.domains = String(row.value ?? '');
      if (row.key === ANALYTICS_ID_SECRET_KEY) {
        const secret = decryptSecret(row.value, env);
        config.analytics.idSecretConfigured = Boolean(secret);
        if (includeAnalyticsSecret) config.analytics.idSecret = secret;
      }
    }
  } catch (error) {
    if (error?.code === 'ER_NO_SUCH_TABLE') return config;
    throw error;
  }
  return config;
}

export async function updateMindSpaceConfig(pool, patch, { env = process.env } = {}) {
  await ensureConfigTable(pool);
  const updates = [];
  if (patch?.publicPageLimit !== undefined) {
    const publicPageLimit = asPositiveInteger(patch.publicPageLimit, null);
    if (!publicPageLimit) {
      throw Object.assign(new Error('公开页面数量上限必须是大于 0 的整数'), {
        code: 'invalid_mindspace_config',
      });
    }
    updates.push([PUBLIC_PAGE_LIMIT_KEY, String(publicPageLimit), '公开页面数量上限']);
  }
  if (patch?.analytics) {
    const analytics = patch.analytics;
    if (analytics.enabled !== undefined) updates.push([ANALYTICS_ENABLED_KEY, String(Boolean(analytics.enabled)), '本地 Umami 分析开关']);
    if (analytics.websiteId !== undefined) updates.push([ANALYTICS_WEBSITE_ID_KEY, String(analytics.websiteId ?? '').trim(), '本地 Umami Website ID']);
    if (analytics.analyticsUrl !== undefined) updates.push([ANALYTICS_URL_KEY, String(analytics.analyticsUrl || 'http://127.0.0.1:3100').trim(), '本地 Umami 地址']);
    if (analytics.domains !== undefined) updates.push([ANALYTICS_DOMAINS_KEY, String(analytics.domains ?? '').trim(), '本地统计域名']);
    if (analytics.idSecret !== undefined && String(analytics.idSecret).trim()) updates.push([ANALYTICS_ID_SECRET_KEY, encryptSecret(String(analytics.idSecret).trim(), env), '本地分析匿名化密钥']);
  }

  if (updates.length === 0) return loadMindSpaceConfig(pool, { env });

  const now = Date.now();
  for (const [key, value, description] of updates) {
    await pool.query(
      `INSERT INTO mindspace_config (\`key\`, value, description, updated_at)
       VALUES (?, ?, ?, ?)
       ON DUPLICATE KEY UPDATE
         value = VALUES(value),
         description = VALUES(description),
         updated_at = VALUES(updated_at)`,
      [key, value, description, now],
    );
  }
  return loadMindSpaceConfig(pool, { env });
}

export const mindspaceConfigInternals = {
  PUBLIC_PAGE_LIMIT_KEY,
  ANALYTICS_ENABLED_KEY,
  ANALYTICS_WEBSITE_ID_KEY,
  ANALYTICS_URL_KEY,
  ANALYTICS_DOMAINS_KEY,
  ANALYTICS_ID_SECRET_KEY,
};