/**
 * The contract of the backup sidecar's `status.json` (ADR 0015, issue #83):
 * the sidecar writes it after every run, the api reads it for the readyz
 * backup-freshness check (issue #85) and the admin panel's backup card
 * (issue #86). Keep the shape additive — bump `schemaVersion` on breaking
 * changes.
 */

export const BACKUP_STATUS_FILE = 'status.json';

/**
 * Freshness bound for readiness (operations.md §Health): the nightly cadence
 * plus a two-hour grace window. An older (or missing) last success degrades
 * readyz — it never hard-fails it.
 */
export const BACKUP_FRESH_MAX_AGE_HOURS = 26;

/**
 * Freshness bound of the off-host copy (issue #103) when the upload
 * schedule is `weekly`: seven nightly cadences plus the same grace window.
 * `daily` uploads share {@link BACKUP_FRESH_MAX_AGE_HOURS}.
 */
export const BACKUP_REMOTE_WEEKLY_MAX_AGE_HOURS = 7 * 24 + 2;

export interface BackupSizes {
  dumpBytes: number;
  archiveBytes: number;
}

export interface BackupRun {
  backupId: string;
  startedAt: string;
  finishedAt: string;
  durationMs: number;
  outcome: 'succeeded' | 'failed';
  /** Present on failure: the first error the run hit, as a plain string. */
  error?: string;
  /** Present on success. */
  sizes?: BackupSizes;
}

export interface BackupStatus {
  schemaVersion: 1;
  updatedAt: string;
  retentionDays: number;
  lastRun: BackupRun;
  /** Carried across failed runs so freshness checks see the real gap. */
  lastSuccess: { backupId: string; finishedAt: string; sizes: BackupSizes } | null;
  /**
   * Off-host upload state (issue #103). Absent until a Nextcloud target was
   * configured and the sidecar attempted its first upload; carried across
   * runs like `lastSuccess` so a broken target keeps its last good copy
   * visible.
   */
  remote?: BackupRemoteStatus;
  /** rsync mirror state (issue #84); absent until a target is configured. */
  mirror?: BackupMirrorStatus;
}

/** One WebDAV upload attempt of a complete restore set (issue #103). */
export interface BackupRemoteUpload {
  backupId: string;
  finishedAt: string;
  outcome: 'succeeded' | 'failed';
  /** Present on failure: the first error the upload hit, as a plain string. */
  error?: string;
  /** Present on success: size of the uploaded bundle. */
  sizeBytes?: number;
}

export interface BackupRemoteStatus {
  lastUpload: BackupRemoteUpload;
  /** Carried across failed uploads — the newest copy known to exist remotely. */
  lastSuccessfulUpload: { backupId: string; finishedAt: string; sizeBytes: number } | null;
}

/**
 * The rsync mirror to a private host (issue #84, ADR 0015) — an
 * operator-level extra beside the admin-configured Nextcloud target
 * (#103). Present once a mirror target is configured; carried across
 * failed runs like the other blocks.
 */
export interface BackupMirrorStatus {
  lastRun: {
    finishedAt: string;
    outcome: 'succeeded' | 'failed';
    /** Present on failure: the first error the mirror hit. */
    error?: string;
    /** Present on success: files rsync actually transferred (0 = idempotent re-run). */
    transferredFiles?: number;
  };
  /** Carried across failed runs — when the mirror last matched the local sets. */
  lastSuccessAt: string | null;
}

/**
 * The remote bundle naming scheme (issue #103): one self-contained archive
 * per restore set, everything needed to rebuild an instance after total
 * loss (`db-<id>.dump`, `files-<id>.tar.gz`, `manifest.json`).
 */
export function remoteBundleName(backupId: string): string {
  return `dorfteich-backup-${backupId}.tar.gz`;
}

const REMOTE_BUNDLE_PATTERN = /^dorfteich-backup-(\d{8}-\d{6})\.tar\.gz$/;

/** The backup id encoded in a remote bundle name, or null for foreign files. */
export function remoteBundleId(name: string): string | null {
  return REMOTE_BUNDLE_PATTERN.exec(name)?.[1] ?? null;
}

/**
 * The in-app restore contract (issue #103): the sidecar orchestrates a
 * restore and mirrors its progress into `restore-status.json` next to
 * `status.json`. The api's maintenance gate answers 503 while `state` is
 * `running`, and restarts itself once it flips to `succeeded`.
 */
export const RESTORE_STATUS_FILE = 'restore-status.json';

/**
 * Safety valve: a `running` restore older than this is treated as crashed
 * (sidecar died before writing a final state), so the api leaves maintenance
 * mode instead of serving 503 forever.
 */
export const RESTORE_STALE_MAX_AGE_MINUTES = 30;

export interface RestoreStatus {
  schemaVersion: 1;
  state: 'running' | 'succeeded' | 'failed';
  backupId: string;
  source: 'local' | 'remote';
  /** Username of the requesting Site Admin (display only). */
  requestedBy: string | null;
  startedAt: string;
  finishedAt: string | null;
  /** Present when `state` is `failed`. */
  error?: string;
}

/**
 * PostgreSQL `NOTIFY` channel over which the api sends commands to the
 * backup sidecar (issue #103) — the same primitive as the api↔collab bus
 * (collab-token.ts). Payload is a JSON {@link BackupCommand}.
 */
export const BACKUP_COMMAND_CHANNEL = 'backup_command';

export type BackupCommand =
  | { kind: 'run'; requestedBy: string | null }
  | { kind: 'restore'; source: 'local' | 'remote'; backupId: string; requestedBy: string | null };

/**
 * PostgreSQL `NOTIFY` channel over which the backup sidecar announces
 * maintenance-mode transitions during an in-app restore (issue #103). The
 * collab server listens and closes/refuses live sessions so no in-memory
 * document persists pre-restore content back over the restored database.
 * Payload is a JSON {@link MaintenanceEvent}.
 */
export const BACKUP_MAINTENANCE_CHANNEL = 'backup_maintenance';

export interface MaintenanceEvent {
  phase: 'enter' | 'exit';
}