/**
 * Admin-configurable backup destinations — service layer.
 * See docs/superpowers/specs/2026-06-04-backup-destinations-design.md.
 *
 * Responsibilities:
 *  - CRUD over `backup_destinations` with secret encryption at rest + masking on
 *    read (mirrors the send-from-accounts pattern: API returns only `*IsSet`).
 *  - test / manual-push / prune to a destination.
 *  - scheduled push to all enabled destinations, with failure alerting.
 *
 * Every push transports the exact SHA-verified tar from `createFullBackupTar()`
 * — the same bundle admins download — optionally AES-256 encrypted first.
 */

import { unlink } from 'node:fs/promises';

import { and, eq, isNull } from 'drizzle-orm';

import { createAuditLog } from '@/lib/audit';
import { db } from '@/lib/db';
import {
  backupDestinations,
  backupJobs,
  systemSettings,
  type BackupDestination,
} from '@/lib/db/schema/system';
import { userPortRoles, userProfiles } from '@/lib/db/schema/users';
import { logger } from '@/lib/logger';
import { createNotification } from '@/lib/services/notifications.service';
import { createFullBackupTar } from '@/lib/services/backup-export.service';
import { decrypt, encrypt } from '@/lib/utils/encryption';

import {
  buildTransport,
  type BackupDestinationType,
  type BackupTransport,
} from './backup-destinations';
import { encryptFileToFile } from './backup-destinations/bundle-encryption';

// ─── secret config handling ─────────────────────────────────────────────────

const SECRET_FIELDS: Record<BackupDestinationType, string[]> = {
  sftp: ['password', 'privateKey', 'passphrase'],
  s3: ['secretKey'],
  filesystem: [],
};

type Cfg = Record<string, unknown>;

/**
 * Prepare an incoming config for storage: encrypt every secret field that
 * carries a new non-empty value; for blank/absent secret fields, carry over the
 * already-encrypted value from `existing` (so "leave unchanged" works on edit).
 * Non-secret fields are taken from `incoming` (falling back to `existing`).
 */
export function serializeConfig(type: BackupDestinationType, incoming: Cfg, existing?: Cfg): Cfg {
  const secrets = new Set(SECRET_FIELDS[type] ?? []);
  const out: Cfg = {};
  // Non-secret fields from incoming (or carry existing if omitted).
  for (const [k, v] of Object.entries(incoming)) {
    if (!secrets.has(k)) out[k] = v;
  }
  for (const field of secrets) {
    const incomingVal = incoming[field];
    if (typeof incomingVal === 'string' && incomingVal.length > 0) {
      out[field] = encrypt(incomingVal);
    } else if (existing && typeof existing[field] === 'string') {
      out[field] = existing[field];
    }
  }
  return out;
}

/** Decrypt the secret fields of a stored config back to plaintext for transport use. */
export function decryptConfig(type: BackupDestinationType, stored: Cfg): Cfg {
  const secrets = new Set(SECRET_FIELDS[type] ?? []);
  const out: Cfg = { ...stored };
  for (const field of secrets) {
    const v = stored[field];
    if (typeof v === 'string' && v.length > 0) {
      try {
        out[field] = decrypt(v);
      } catch (err) {
        logger.error({ err, field }, 'Failed to decrypt backup destination secret');
        delete out[field];
      }
    }
  }
  return out;
}

/** Strip secret fields from a stored config and expose `<field>IsSet` markers. */
export function maskConfig(type: BackupDestinationType, stored: Cfg): Cfg {
  const secrets = new Set(SECRET_FIELDS[type] ?? []);
  const out: Cfg = {};
  for (const [k, v] of Object.entries(stored)) {
    if (!secrets.has(k)) out[k] = v;
  }
  for (const field of secrets) {
    out[`${field}IsSet`] =
      typeof stored[field] === 'string' && (stored[field] as string).length > 0;
  }
  return out;
}

export interface MaskedDestination {
  id: string;
  name: string;
  type: BackupDestinationType;
  enabled: boolean;
  config: Cfg;
  retentionCount: number | null;
  encryptBundle: boolean;
  encryptionKeyIsSet: boolean;
  lastRunAt: Date | null;
  lastStatus: string | null;
  lastError: string | null;
  lastBackupBytes: number | null;
  createdAt: Date;
  updatedAt: Date;
}

function mask(row: BackupDestination): MaskedDestination {
  const type = row.type as BackupDestinationType;
  return {
    id: row.id,
    name: row.name,
    type,
    enabled: row.enabled,
    config: maskConfig(type, (row.config ?? {}) as Cfg),
    retentionCount: row.retentionCount,
    encryptBundle: row.encryptBundle,
    encryptionKeyIsSet: Boolean(row.encryptionKeyEncrypted),
    lastRunAt: row.lastRunAt,
    lastStatus: row.lastStatus,
    lastError: row.lastError,
    lastBackupBytes: row.lastBackupBytes,
    createdAt: row.createdAt,
    updatedAt: row.updatedAt,
  };
}

// ─── schedule ────────────────────────────────────────────────────────────────

export type BackupSchedule = 'off' | 'daily' | 'weekly';

/** Whether a scheduled push should run for `date` under `schedule`. */
export function isScheduleDue(schedule: BackupSchedule, date: Date): boolean {
  if (schedule === 'off') return false;
  if (schedule === 'daily') return true;
  return date.getUTCDay() === 0; // weekly → Sundays
}

export async function getSchedule(): Promise<BackupSchedule> {
  const [row] = await db
    .select()
    .from(systemSettings)
    .where(and(eq(systemSettings.key, 'backup_schedule'), isNull(systemSettings.portId)));
  const v = row?.value;
  return v === 'daily' || v === 'weekly' ? v : 'off';
}

export async function setSchedule(value: BackupSchedule, userId: string): Promise<void> {
  const existing = await db.query.systemSettings.findFirst({
    where: and(eq(systemSettings.key, 'backup_schedule'), isNull(systemSettings.portId)),
  });
  if (existing) {
    await db
      .update(systemSettings)
      .set({ value, updatedBy: userId, updatedAt: new Date() })
      .where(and(eq(systemSettings.key, 'backup_schedule'), isNull(systemSettings.portId)));
  } else {
    await db
      .insert(systemSettings)
      .values({ key: 'backup_schedule', value, portId: null, updatedBy: userId });
  }
}

// ─── CRUD ──────────────────────────────────────────────────────────────────

export async function listDestinations(): Promise<MaskedDestination[]> {
  const rows = await db.query.backupDestinations.findMany({
    orderBy: (d, { asc }) => [asc(d.createdAt)],
  });
  return rows.map(mask);
}

export interface DestinationInput {
  name: string;
  type: BackupDestinationType;
  enabled?: boolean;
  config: Cfg;
  retentionCount?: number | null;
  encryptBundle?: boolean;
  /** Plaintext bundle passphrase; encrypted at rest. Blank = leave unchanged. */
  encryptionKey?: string;
}

export async function createDestination(input: DestinationInput): Promise<MaskedDestination> {
  const [row] = await db
    .insert(backupDestinations)
    .values({
      name: input.name,
      type: input.type,
      enabled: input.enabled ?? false,
      config: serializeConfig(input.type, input.config),
      retentionCount: input.retentionCount ?? null,
      encryptBundle: input.encryptBundle ?? false,
      encryptionKeyEncrypted:
        input.encryptionKey && input.encryptionKey.length > 0 ? encrypt(input.encryptionKey) : null,
    })
    .returning();
  if (!row) throw new Error('Failed to create backup destination');
  return mask(row);
}

export async function updateDestination(
  id: string,
  input: DestinationInput,
): Promise<MaskedDestination> {
  const existing = await db.query.backupDestinations.findFirst({
    where: eq(backupDestinations.id, id),
  });
  if (!existing) throw new Error('Backup destination not found');

  const [row] = await db
    .update(backupDestinations)
    .set({
      name: input.name,
      type: input.type,
      enabled: input.enabled ?? existing.enabled,
      config: serializeConfig(input.type, input.config, (existing.config ?? {}) as Cfg),
      retentionCount: input.retentionCount ?? null,
      encryptBundle: input.encryptBundle ?? false,
      encryptionKeyEncrypted:
        input.encryptionKey && input.encryptionKey.length > 0
          ? encrypt(input.encryptionKey)
          : existing.encryptionKeyEncrypted,
      updatedAt: new Date(),
    })
    .where(eq(backupDestinations.id, id))
    .returning();
  if (!row) throw new Error('Failed to update backup destination');
  return mask(row);
}

export async function deleteDestination(id: string): Promise<void> {
  await db.delete(backupDestinations).where(eq(backupDestinations.id, id));
}

// ─── transport helpers ────────────────────────────────────────────────────

function transportFor(row: BackupDestination): BackupTransport {
  const type = row.type as BackupDestinationType;
  return buildTransport(type, decryptConfig(type, (row.config ?? {}) as Cfg));
}

export async function testDestination(id: string): Promise<void> {
  const row = await db.query.backupDestinations.findFirst({
    where: eq(backupDestinations.id, id),
  });
  if (!row) throw new Error('Backup destination not found');
  await transportFor(row).test();
}

// ─── push ─────────────────────────────────────────────────────────────────

interface PushOpts {
  /** Reuse an already-assembled tar (scheduled push assembles once for all). */
  tarPath?: string;
  filename?: string;
  trigger: 'manual' | 'cron';
  triggeredBy?: string | null;
}

export async function pushBackupToDestination(
  id: string,
  opts: PushOpts,
): Promise<{
  bytes: number;
  remoteRef: string;
}> {
  const row = await db.query.backupDestinations.findFirst({
    where: eq(backupDestinations.id, id),
  });
  if (!row) throw new Error('Backup destination not found');

  const transport = transportFor(row);
  let tarPath = opts.tarPath;
  let filename = opts.filename;
  let ownTar: (() => Promise<void>) | null = null;
  let encPath: string | null = null;

  try {
    if (!tarPath || !filename) {
      const made = await createFullBackupTar();
      tarPath = made.tarPath;
      filename = made.filename;
      ownTar = made.cleanup;
    }

    // Optional client-side encryption before the bytes leave this server.
    let uploadPath = tarPath;
    let remoteName = filename;
    if (row.encryptBundle) {
      if (!row.encryptionKeyEncrypted) {
        throw new Error('Destination has encryption enabled but no passphrase configured');
      }
      const passphrase = decrypt(row.encryptionKeyEncrypted);
      encPath = `${tarPath}.enc`;
      await encryptFileToFile(tarPath, encPath, passphrase);
      uploadPath = encPath;
      remoteName = `${filename}.enc`;
    }

    const { bytes, remoteRef } = await transport.push(uploadPath, remoteName);
    await transport.prune(row.retentionCount).catch((err) => {
      logger.warn({ err, destinationId: id }, 'Backup prune failed (push succeeded)');
    });

    await db
      .update(backupDestinations)
      .set({
        lastRunAt: new Date(),
        lastStatus: 'ok',
        lastError: null,
        lastBackupBytes: bytes,
      })
      .where(eq(backupDestinations.id, id));

    await db.insert(backupJobs).values({
      status: 'completed',
      trigger: opts.trigger,
      triggeredBy: opts.triggeredBy ?? null,
      sizeBytes: bytes,
      storagePath: remoteRef,
      completedAt: new Date(),
    });

    logger.info({ destinationId: id, bytes, remoteRef }, 'Backup pushed to destination');
    return { bytes, remoteRef };
  } catch (err) {
    const message = err instanceof Error ? err.message : 'unknown';
    await db
      .update(backupDestinations)
      .set({ lastRunAt: new Date(), lastStatus: 'failed', lastError: message })
      .where(eq(backupDestinations.id, id));
    await db
      .insert(backupJobs)
      .values({
        status: 'failed',
        trigger: opts.trigger,
        triggeredBy: opts.triggeredBy ?? null,
        errorMessage: `[${row.name}] ${message}`,
        completedAt: new Date(),
      })
      .catch(() => {});
    await notifyBackupFailure(row.name, message, opts.trigger);
    throw err;
  } finally {
    if (encPath) await unlink(encPath).catch(() => {});
    if (ownTar) await ownTar();
  }
}

/**
 * Scheduled push: assemble the bundle ONCE and fan it out to every enabled
 * destination. Per-destination failures are isolated (one bad server doesn't
 * skip the others) and alerted.
 */
export async function runScheduledBackupPush(now = new Date()): Promise<{
  ran: boolean;
  pushed: number;
  failed: number;
}> {
  const schedule = await getSchedule();
  if (!isScheduleDue(schedule, now)) {
    logger.info({ schedule }, 'Scheduled backup not due');
    return { ran: false, pushed: 0, failed: 0 };
  }

  const enabled = await db.query.backupDestinations.findMany({
    where: eq(backupDestinations.enabled, true),
  });
  if (enabled.length === 0) {
    logger.warn('Backup schedule is on but no destinations are enabled');
    return { ran: false, pushed: 0, failed: 0 };
  }

  const bundle = await createFullBackupTar();
  let pushed = 0;
  let failed = 0;
  try {
    for (const dest of enabled) {
      try {
        await pushBackupToDestination(dest.id, {
          tarPath: bundle.tarPath,
          filename: bundle.filename,
          trigger: 'cron',
        });
        pushed += 1;
      } catch (err) {
        failed += 1;
        logger.error({ err, destinationId: dest.id }, 'Scheduled push to destination failed');
      }
    }
  } finally {
    await bundle.cleanup();
  }
  logger.info({ pushed, failed, total: enabled.length }, 'Scheduled backup push complete');
  return { ran: true, pushed, failed };
}

// ─── failure alerting ────────────────────────────────────────────────────

async function notifyBackupFailure(
  destinationName: string,
  message: string,
  trigger: 'manual' | 'cron',
): Promise<void> {
  // Guaranteed signal: an error-severity audit row (visible in /admin/audit).
  await createAuditLog({
    userId: null,
    portId: null,
    action: 'job_failed',
    entityType: 'backup_destination',
    entityId: destinationName,
    severity: 'error',
    source: trigger === 'cron' ? 'cron' : 'job',
    metadata: { destination: destinationName, error: message },
  });

  // Best-effort: in-app system alert to every super-admin (per their port).
  try {
    const admins = await db
      .select({ userId: userProfiles.userId, portId: userPortRoles.portId })
      .from(userProfiles)
      .innerJoin(userPortRoles, eq(userPortRoles.userId, userProfiles.userId))
      .where(eq(userProfiles.isSuperAdmin, true));
    const seen = new Set<string>();
    for (const a of admins) {
      const key = `${a.userId}:${a.portId}`;
      if (seen.has(key)) continue;
      seen.add(key);
      await createNotification({
        portId: a.portId,
        userId: a.userId,
        type: 'system_alert',
        title: 'Backup push failed',
        description: `Backup to "${destinationName}" failed: ${message}`,
        dedupeKey: `backup-fail:${destinationName}`,
        cooldownMs: 60 * 60 * 1000,
      });
    }
  } catch (err) {
    logger.error({ err }, 'Failed to notify super-admins of backup failure');
  }
}