import { Client } from 'pg';
import { z } from 'zod';

/**
 * The sidecar's read-only view of the backup-related instance settings
 * (issue #103). The api owns the `instance_settings` registry; the sidecar
 * reads the raw rows with the same defaults, so admin changes apply on the
 * next run without a restart or a config channel. A row that is missing or
 * fails validation falls back to its default — never to a crash.
 */

export const NEXTCLOUD_PASSWORD_SECRET_KEY = 'BACKUP_NEXTCLOUD_PASSWORD';

const SETTING_SCHEMAS = {
  // Local retention: `null` means "no admin override" — the env value
  // (BACKUP_RETENTION_DAYS, stage-specific) stays authoritative until a
  // Site Admin saves the setting once.
  'backup.localRetentionDays': z.number().int().min(1).nullable().default(null),
  'backup.remoteRetentionDays': z.number().int().min(1).default(30),
  'backup.nextcloud.enabled': z.boolean().default(false),
  'backup.nextcloud.baseUrl': z.string().default(''),
  'backup.nextcloud.username': z.string().default(''),
  'backup.nextcloud.folder': z.string().default('dorfteich-backups'),
  'backup.nextcloud.uploadSchedule': z.enum(['off', 'daily', 'weekly']).default('daily'),
} as const;

export interface BackupDbSettings {
  localRetentionDays: number | null;
  remoteRetentionDays: number;
  nextcloud: {
    enabled: boolean;
    baseUrl: string;
    username: string;
    folder: string;
    uploadSchedule: 'off' | 'daily' | 'weekly';
  };
}

export function parseBackupSettings(rows: { key: string; value: unknown }[]): BackupDbSettings {
  const byKey = new Map(rows.map((row) => [row.key, row.value]));
  const get = <K extends keyof typeof SETTING_SCHEMAS>(
    key: K,
  ): z.infer<(typeof SETTING_SCHEMAS)[K]> => {
    const parsed = SETTING_SCHEMAS[key].safeParse(byKey.get(key));
    return parsed.success ? parsed.data : SETTING_SCHEMAS[key].parse(undefined);
  };
  return {
    localRetentionDays: get('backup.localRetentionDays'),
    remoteRetentionDays: get('backup.remoteRetentionDays'),
    nextcloud: {
      enabled: get('backup.nextcloud.enabled'),
      baseUrl: get('backup.nextcloud.baseUrl'),
      username: get('backup.nextcloud.username'),
      folder: get('backup.nextcloud.folder'),
      uploadSchedule: get('backup.nextcloud.uploadSchedule'),
    },
  };
}

/**
 * Reads the settings rows with a short-lived connection. A database that is
 * unreachable or predates the settings keys yields plain defaults — the
 * local backup must still run when the instance is at its most broken.
 */
export async function readBackupDbSettings(databaseUrl: string): Promise<BackupDbSettings> {
  const client = new Client({ connectionString: databaseUrl });
  try {
    await client.connect();
    const result = await client.query<{ key: string; value: unknown }>(
      `SELECT key, value FROM instance_settings WHERE key LIKE 'backup.%'`,
    );
    return parseBackupSettings(result.rows);
  } catch {
    return parseBackupSettings([]);
  } finally {
    await client.end().catch(() => undefined);
  }
}