const { PERMISSIONS, normalizePermissionKeys } = require('../rbac');

function parseCsvIds(value) {
  return String(value || '')
    .split(',')
    .map(function (item) {
      return Number(item);
    })
    .filter(function (item) {
      return Number.isInteger(item) && item > 0;
    });
}

async function fetchPermissions(pool) {
  const [rows] = await pool.query('SELECT id, permission_key, name, section_name, description FROM permissions ORDER BY section_name ASC, name ASC');
  return rows || [];
}

async function fetchRoles(pool) {
  const [rows] = await pool.query(
    `SELECT r.id, r.role_key, r.name, r.description, r.created_at, r.modified_at,
            (SELECT COUNT(*) FROM user_roles ur WHERE ur.role_id = r.id) AS user_count,
            (SELECT COUNT(*) FROM role_permissions rp WHERE rp.role_id = r.id) AS permission_count
     FROM roles r
     ORDER BY r.name ASC`
  );
  return rows || [];
}

async function fetchRoleById(pool, roleId) {
  const [rows] = await pool.query(
    `SELECT r.id, r.role_key, r.name, r.description, r.created_at, r.modified_at,
            (SELECT COUNT(*) FROM user_roles ur WHERE ur.role_id = r.id) AS user_count,
            (SELECT COUNT(*) FROM role_permissions rp WHERE rp.role_id = r.id) AS permission_count
     FROM roles r
     WHERE r.id = ?
     LIMIT 1`,
    [roleId]
  );
  return rows[0] || null;
}

async function fetchRolePermissionKeys(pool, roleId) {
  const [rows] = await pool.query(
    `SELECT p.permission_key
     FROM role_permissions rp
     JOIN permissions p ON p.id = rp.permission_id
     WHERE rp.role_id = ?
     ORDER BY p.section_name ASC, p.name ASC`,
    [roleId]
  );
  return (rows || []).map(function (row) {
    return String(row.permission_key || '').trim();
  }).filter(Boolean);
}

async function fetchRoleUserIds(pool, roleId) {
  const [rows] = await pool.query(
    `SELECT ur.user_id
     FROM user_roles ur
     WHERE ur.role_id = ?
     ORDER BY ur.user_id ASC`,
    [roleId]
  );
  return (rows || []).map(function (row) {
    return Number(row.user_id);
  }).filter(function (userId) {
    return Number.isInteger(userId) && userId > 0;
  });
}

async function fetchRolesForUser(pool, userId) {
  const [rows] = await pool.query(
    `SELECT r.id, r.role_key, r.name, r.description
     FROM user_roles ur
     JOIN roles r ON r.id = ur.role_id
     WHERE ur.user_id = ?
     ORDER BY r.name ASC`,
    [userId]
  );
  return rows || [];
}

async function fetchUsersWithRoles(pool) {
  const [rows] = await pool.query(
    `SELECT u.id, u.name, u.username, u.created_at, u.modified_at,
            COALESCE(role_data.role_names, '') AS role_names,
            COALESCE(role_data.role_ids_csv, '') AS role_ids_csv
     FROM users u
     LEFT JOIN (
       SELECT ur.user_id,
              GROUP_CONCAT(DISTINCT r.name ORDER BY r.name SEPARATOR ', ') AS role_names,
              GROUP_CONCAT(DISTINCT r.id ORDER BY r.name SEPARATOR ',') AS role_ids_csv
       FROM user_roles ur
       JOIN roles r ON r.id = ur.role_id
       GROUP BY ur.user_id
     ) role_data ON role_data.user_id = u.id
     ORDER BY u.id ASC`
  );

  return (rows || []).map(function (row) {
    return Object.assign({}, row, {
      roleIds: parseCsvIds(row.role_ids_csv),
      roleNames: String(row.role_names || '').trim()
    });
  });
}

async function fetchUserWithRoles(pool, userId) {
  const [rows] = await pool.query(
    `SELECT u.id, u.name, u.username, u.created_at, u.modified_at,
            COALESCE(role_data.role_names, '') AS role_names,
            COALESCE(role_data.role_ids_csv, '') AS role_ids_csv
     FROM users u
     LEFT JOIN (
       SELECT ur.user_id,
              GROUP_CONCAT(DISTINCT r.name ORDER BY r.name SEPARATOR ', ') AS role_names,
              GROUP_CONCAT(DISTINCT r.id ORDER BY r.name SEPARATOR ',') AS role_ids_csv
       FROM user_roles ur
       JOIN roles r ON r.id = ur.role_id
       GROUP BY ur.user_id
     ) role_data ON role_data.user_id = u.id
     WHERE u.id = ?
     LIMIT 1`,
    [userId]
  );

  if (!rows.length) {
    return null;
  }

  return Object.assign({}, rows[0], {
    roleIds: parseCsvIds(rows[0].role_ids_csv),
    roleNames: String(rows[0].role_names || '').trim()
  });
}

async function syncUserRoles(pool, userId, roleIds) {
  const uniqueRoleIds = Array.from(new Set((Array.isArray(roleIds) ? roleIds : []).map(function (roleId) {
    return Number(roleId);
  }).filter(function (roleId) {
    return Number.isInteger(roleId) && roleId > 0;
  })));

  await pool.query('DELETE FROM user_roles WHERE user_id = ?', [userId]);
  for (const roleId of uniqueRoleIds) {
    await pool.query('INSERT IGNORE INTO user_roles (user_id, role_id, created_by, modified_by) VALUES (?, ?, ?, ?)', [userId, roleId, null, null]);
  }
}

async function syncRoleUsers(pool, roleId, userIds) {
  const uniqueUserIds = Array.from(new Set((Array.isArray(userIds) ? userIds : []).map(function (userId) {
    return Number(userId);
  }).filter(function (userId) {
    return Number.isInteger(userId) && userId > 0;
  })));

  await pool.query('DELETE FROM user_roles WHERE role_id = ?', [roleId]);
  for (const userId of uniqueUserIds) {
    await pool.query('INSERT IGNORE INTO user_roles (user_id, role_id, created_by, modified_by) VALUES (?, ?, ?, ?)', [userId, roleId, null, null]);
  }
}

async function syncRolePermissions(pool, roleId, permissionKeys) {
  const uniquePermissionKeys = normalizePermissionKeys(permissionKeys);

  if (!uniquePermissionKeys.length) {
    await pool.query('DELETE FROM role_permissions WHERE role_id = ?', [roleId]);
    return;
  }

  const [permissionRows] = await pool.query('SELECT id, permission_key FROM permissions WHERE permission_key IN (?)', [uniquePermissionKeys]);
  if (permissionRows.length !== uniquePermissionKeys.length) {
    throw new Error('One or more selected permissions are invalid.');
  }

  await pool.query('DELETE FROM role_permissions WHERE role_id = ?', [roleId]);
  for (const permissionRow of permissionRows) {
    await pool.query('INSERT IGNORE INTO role_permissions (role_id, permission_id, created_by, modified_by) VALUES (?, ?, ?, ?)', [roleId, Number(permissionRow.id), null, null]);
  }
}

module.exports = {
  PERMISSIONS,
  fetchPermissions,
  fetchRoles,
  fetchRoleById,
  fetchRolePermissionKeys,
  fetchRoleUserIds,
  fetchRolesForUser,
  fetchUsersWithRoles,
  fetchUserWithRoles,
  syncUserRoles,
  syncRoleUsers,
  syncRolePermissions
};