import { Logger } from '@nestjs/common';
import * as path from 'node:path';
import { JobRun } from '../../generated/prisma';
import { PrismaService } from '../prisma/prisma.service';
import { JobRunService } from '../system/job-run.service';
import {
  APP_BACKUP_LOCK_TIMEOUT_MS,
  BackupSchedulerService,
} from './backup-scheduler.service';
import { BackupService } from './backup.service';
import { BackupSettingsService } from './backup-settings.service';

jest.mock('node:fs/promises', () => ({
  mkdir: jest.fn(),
  writeFile: jest.fn(),
  readdir: jest.fn(),
  stat: jest.fn(),
  unlink: jest.fn(),
}));

import * as fs from 'node:fs/promises';

type RawCall = [readonly string[], ...unknown[]];

const SEALED = {
  format: 'apicore-backup',
  exportedAt: '2026-10-13T01:05:00.000Z',
  ciphertext: 'x'.repeat(2000),
};

describe('BackupSchedulerService', () => {
  const originalEnv = { ...process.env };
  const directory = path.resolve('/data/backups');
  let service: BackupSchedulerService;
  let backupService: { exportSealed: jest.Mock };
  let settings: { get: jest.Mock };
  let tx: {
    $executeRaw: jest.Mock<Promise<number>, RawCall>;
    $queryRaw: jest.Mock<Promise<{ now: Date }[]>, RawCall>;
  };
  let prisma: { $transaction: jest.Mock };
  let jobRuns: { recent: jest.Mock };
  let error: jest.SpyInstance;
  let warn: jest.SpyInstance;

  const sqlText = (call: RawCall): string => call[0].join('?');

  beforeEach(() => {
    jest.clearAllMocks();
    process.env.BACKUP_STORAGE_PATH = directory;
    delete process.env.BACKUP_MAX_IMPORT_BYTES;
    delete process.env.BACKUP_RETENTION_COUNT;
    delete process.env.BACKUP_CRON_SCHEDULE;
    error = jest.spyOn(Logger.prototype, 'error').mockImplementation(() => {});
    warn = jest.spyOn(Logger.prototype, 'warn').mockImplementation(() => {});

    backupService = { exportSealed: jest.fn().mockResolvedValue(SEALED) };
    settings = {
      get: jest.fn().mockResolvedValue({
        storagePath: null,
        cronSchedule: null,
        retentionCount: null,
      }),
    };
    tx = {
      $executeRaw: jest.fn<Promise<number>, RawCall>().mockResolvedValue(1),
      $queryRaw: jest
        .fn<Promise<{ now: Date }[]>, RawCall>()
        .mockResolvedValue([{ now: new Date('2026-10-13T01:05:00Z') }]),
    };
    prisma = {
      $transaction: jest.fn((work: (client: typeof tx) => Promise<unknown>) =>
        work(tx),
      ),
    };
    jobRuns = { recent: jest.fn().mockResolvedValue([]) };
    service = new BackupSchedulerService(
      backupService as unknown as BackupService,
      settings as unknown as BackupSettingsService,
      prisma as unknown as PrismaService,
      jobRuns as unknown as JobRunService,
    );
    (fs.mkdir as jest.Mock).mockResolvedValue(undefined);
    (fs.writeFile as jest.Mock).mockResolvedValue(undefined);
    (fs.readdir as jest.Mock).mockResolvedValue([]);
    (fs.unlink as jest.Mock).mockResolvedValue(undefined);
  });

  afterEach(() => {
    error.mockRestore();
    warn.mockRestore();
    process.env = { ...originalEnv };
  });

  function onDisk(files: { name: string; size: number; mtime: string }[]) {
    (fs.readdir as jest.Mock).mockResolvedValue(files.map((f) => f.name));
    (fs.stat as jest.Mock).mockImplementation((filePath: string) => {
      const file = files.find((f) => filePath.endsWith(f.name));
      return Promise.resolve({
        size: file?.size,
        mtime: new Date(file!.mtime),
      });
    });
  }

  function jobRun(overrides: Partial<JobRun> = {}): JobRun {
    return {
      id: 'run-1',
      job: 'app-backup',
      status: 'SUCCEEDED',
      startedAt: new Date('2026-10-13T01:00:02.000Z'),
      finishedAt: new Date('2026-10-13T01:00:09.000Z'),
      result: { written: true },
      error: null,
      ...overrides,
    };
  }

  describe('getStatus', () => {
    it('reports the import limit and the size of the newest backup', async () => {
      process.env.BACKUP_MAX_IMPORT_BYTES = '1000';
      onDisk([
        {
          name: 'apicore-backup-old.json',
          size: 5000,
          mtime: '2026-10-10T03:00:00.000Z',
        },
        {
          name: 'apicore-backup-new.json',
          size: 900,
          mtime: '2026-10-11T03:00:00.000Z',
        },
      ]);

      const status = await service.getStatus();

      expect(status).toEqual(
        expect.objectContaining({
          importLimitBytes: 1000,
          lastBackupSizeBytes: 900,
          lastBackupExceedsImportLimit: false,
        }),
      );
    });

    it('warns when the newest backup could no longer be imported', async () => {
      process.env.BACKUP_MAX_IMPORT_BYTES = '1000';
      onDisk([
        {
          name: 'apicore-backup-new.json',
          size: 1001,
          mtime: '2026-10-11T03:00:00.000Z',
        },
      ]);

      const status = await service.getStatus();

      expect(status.lastBackupSizeBytes).toBe(1001);
      expect(status.lastBackupExceedsImportLimit).toBe(true);
    });

    it('still reports the import limit while no schedule is configured', async () => {
      delete process.env.BACKUP_STORAGE_PATH;

      const status = await service.getStatus();

      expect(status).toEqual(
        expect.objectContaining({
          enabled: false,
          importLimitBytes: 50 * 1024 * 1024,
          lastBackupSizeBytes: null,
          lastBackupExceedsImportLimit: false,
        }),
      );
    });

    it('reports the newest app-backup job run', async () => {
      jobRuns.recent.mockResolvedValue([
        jobRun({
          status: 'FAILED',
          finishedAt: new Date('2026-10-13T01:00:05.000Z'),
          result: null,
          error: 'EACCES: permission denied',
        }),
      ]);

      const status = await service.getStatus();

      expect(jobRuns.recent).toHaveBeenCalledWith(1, 'app-backup');
      expect(status.lastJobRun).toEqual({
        status: 'FAILED',
        startedAt: '2026-10-13T01:00:02.000Z',
        finishedAt: '2026-10-13T01:00:05.000Z',
        error: 'EACCES: permission denied',
      });
    });

    it('reports a running job run without an end and the run also without a path', async () => {
      delete process.env.BACKUP_STORAGE_PATH;
      jobRuns.recent.mockResolvedValue([
        jobRun({ status: 'RUNNING', finishedAt: null, result: null }),
      ]);

      const status = await service.getStatus();

      expect(status.lastJobRun).toEqual({
        status: 'RUNNING',
        startedAt: '2026-10-13T01:00:02.000Z',
        finishedAt: null,
        error: null,
      });
    });

    it('reports no job run before the first one', async () => {
      const status = await service.getStatus();

      expect(status.lastJobRun).toBeNull();
    });
  });

  describe('runNow', () => {
    it('keeps a backup larger than the import limit but logs an error', async () => {
      process.env.BACKUP_MAX_IMPORT_BYTES = '1000';

      const result = await service.runNow();

      expect(fs.writeFile).toHaveBeenCalledTimes(1);
      expect(result.fileName).toMatch(/^apicore-backup-.*\.json$/);
      expect(error).toHaveBeenCalledTimes(1);
      expect(error).toHaveBeenCalledWith(
        expect.stringContaining('Import-Limit'),
      );
    });

    it('logs nothing for a backup within the import limit', async () => {
      await service.runNow();

      expect(fs.writeFile).toHaveBeenCalledTimes(1);
      expect(error).not.toHaveBeenCalled();
    });

    // A human asked for it: no due check, no wait for the schedule lock.
    it('always writes, without the schedule lock', async () => {
      onDisk([
        {
          name: 'apicore-backup-new.json',
          size: 900,
          mtime: new Date().toISOString(),
        },
      ]);

      await service.runNow();

      expect(fs.writeFile).toHaveBeenCalledTimes(1);
      expect(prisma.$transaction).not.toHaveBeenCalled();
    });
  });

  describe('runIfDue', () => {
    const lastNight = '2026-10-12T01:00:00.000Z';

    it('writes nothing without a path', async () => {
      delete process.env.BACKUP_STORAGE_PATH;

      const result = await service.runIfDue(new Date('2026-10-13T01:05:00Z'));

      expect(result).toEqual({ written: false, reason: 'no-path' });
      expect(backupService.exportSealed).not.toHaveBeenCalled();
      expect(fs.writeFile).not.toHaveBeenCalled();
    });

    it('writes nothing while the newest backup covers the last scheduled time', async () => {
      onDisk([{ name: 'apicore-backup-a.json', size: 900, mtime: lastNight }]);

      const result = await service.runIfDue(new Date('2026-10-13T00:30:00Z'));

      expect(result).toEqual({ written: false, reason: 'not-due' });
      expect(backupService.exportSealed).not.toHaveBeenCalled();
      expect(fs.writeFile).not.toHaveBeenCalled();
      expect(fs.unlink).not.toHaveBeenCalled();
    });

    it('writes and prunes once the next scheduled time has passed', async () => {
      process.env.BACKUP_RETENTION_COUNT = '1';
      onDisk([
        { name: 'apicore-backup-a.json', size: 900, mtime: lastNight },
        {
          name: 'apicore-backup-b.json',
          size: 800,
          mtime: '2026-10-11T01:00:00.000Z',
        },
      ]);

      const result = await service.runIfDue(new Date('2026-10-13T01:05:00Z'));

      expect(fs.writeFile).toHaveBeenCalledTimes(1);
      expect(result).toEqual({
        written: true,
        fileName: 'apicore-backup-2026-10-13T01-05-00-000Z.json',
        sizeBytes: Buffer.byteLength(JSON.stringify(SEALED)),
        pruned: 1,
      });
      expect(fs.unlink).toHaveBeenCalledWith(
        path.join(directory, 'apicore-backup-b.json'),
      );
    });

    it('writes the first backup into an empty directory', async () => {
      const result = await service.runIfDue(new Date('2026-10-13T00:30:00Z'));

      expect(result).toEqual(expect.objectContaining({ written: true }));
      expect(fs.writeFile).toHaveBeenCalledTimes(1);
    });

    it('reads the schedule in Europe/Berlin', async () => {
      process.env.BACKUP_CRON_SCHEDULE = '0 3 * * *';
      onDisk([
        {
          name: 'apicore-backup-a.json',
          size: 900,
          mtime: '2026-10-12T03:00:00.000Z',
        },
      ]);

      // 03:00 Berlin = 01:00Z has passed, 03:00 UTC has not.
      const result = await service.runIfDue(new Date('2026-10-13T02:00:00Z'));

      expect(result.written).toBe(true);
    });

    it('does not count a file it could not delete as pruned', async () => {
      process.env.BACKUP_RETENTION_COUNT = '1';
      onDisk([
        { name: 'apicore-backup-a.json', size: 900, mtime: lastNight },
        {
          name: 'apicore-backup-b.json',
          size: 800,
          mtime: '2026-10-11T01:00:00.000Z',
        },
        {
          name: 'apicore-backup-c.json',
          size: 700,
          mtime: '2026-10-10T01:00:00.000Z',
        },
      ]);
      (fs.unlink as jest.Mock)
        .mockResolvedValueOnce(undefined)
        .mockRejectedValueOnce(new Error('EBUSY'));

      const result = await service.runIfDue(new Date('2026-10-13T01:05:00Z'));

      expect(result).toEqual(expect.objectContaining({ pruned: 1 }));
      expect(warn).toHaveBeenCalledTimes(1);
    });

    // Two job pods (a CronJob run and a manual `kubectl create job`) must
    // not both find the backup due: the check and the write happen under
    // one database lock, so the second one sees the first one's file.
    it('checks and writes only while holding the schedule lock', async () => {
      await service.runIfDue(new Date('2026-10-13T01:05:00Z'));

      expect(prisma.$transaction).toHaveBeenCalledWith(expect.any(Function), {
        timeout: APP_BACKUP_LOCK_TIMEOUT_MS,
        maxWait: expect.any(Number) as number,
      });
      expect(tx.$executeRaw).toHaveBeenCalledTimes(1);
      const [lockCall] = tx.$executeRaw.mock.calls;
      expect(sqlText(lockCall)).toContain('pg_advisory_xact_lock');
      expect(lockCall.slice(1)).toEqual(['app-backup:schedule']);
      const lockedAt = tx.$executeRaw.mock.invocationCallOrder[0];
      expect(
        (fs.readdir as jest.Mock).mock.invocationCallOrder[0],
      ).toBeGreaterThan(lockedAt);
      expect(
        (fs.writeFile as jest.Mock).mock.invocationCallOrder[0],
      ).toBeGreaterThan(lockedAt);
    });

    it('takes the time from the database clock when none is given', async () => {
      onDisk([{ name: 'apicore-backup-a.json', size: 900, mtime: lastNight }]);
      tx.$queryRaw.mockResolvedValue([
        { now: new Date('2026-10-13T00:30:00Z') },
      ]);

      // The pod's own clock (2026-10-14) would say due; the database's says no.
      jest.useFakeTimers({ now: new Date('2026-10-14T12:00:00Z') });
      try {
        await expect(service.runIfDue()).resolves.toEqual({
          written: false,
          reason: 'not-due',
        });
      } finally {
        jest.useRealTimers();
      }
      expect(sqlText(tx.$queryRaw.mock.calls[0])).toContain('now()');
    });

    it('gives up the lock as soon as the backup is not due', async () => {
      onDisk([{ name: 'apicore-backup-a.json', size: 900, mtime: lastNight }]);

      await service.runIfDue(new Date('2026-10-13T00:30:00Z'));

      expect(prisma.$transaction).toHaveBeenCalledTimes(1);
      expect(fs.mkdir).not.toHaveBeenCalled();
    });

    it('fails the run when the export fails', async () => {
      backupService.exportSealed.mockRejectedValue(new Error('export broke'));

      await expect(
        service.runIfDue(new Date('2026-10-13T01:05:00Z')),
      ).rejects.toThrow('export broke');
      expect(fs.writeFile).not.toHaveBeenCalled();
    });

    it('fails the run on an invalid schedule instead of skipping silently', async () => {
      process.env.BACKUP_CRON_SCHEDULE = 'every night';

      await expect(
        service.runIfDue(new Date('2026-10-13T01:05:00Z')),
      ).rejects.toThrow();
      expect(fs.writeFile).not.toHaveBeenCalled();
    });
  });
});