import { mkdtemp, readdir, rm, writeFile } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { join } from 'node:path';

import { afterEach, beforeEach, describe, expect, it } from 'vitest';

import { archiveFileName, dumpFileName } from './backup-set.js';
import { runBackup, type RunnerDeps } from './runner.js';
import { readStatus } from './status.js';

/**
 * Time-accelerated nightly runs (issue #83 acceptance criteria): the clock
 * is injected, so "a month of nights" is a loop, with real files in a temp
 * backups directory and dump/archive doubles standing in for pg_dump/tar
 * (their real counterparts are covered by pg.ts/archive.ts on the stage).
 */

const DAY = 24 * 60 * 60 * 1000;
const START = new Date('2026-07-01T03:00:00Z').getTime();

let dir: string;
let clock: Date;
let failures: Array<{ backupId: string; error: string; lastSuccessAt: string | null }>;

function makeDeps(overrides: Partial<RunnerDeps> = {}): RunnerDeps {
  return {
    backupsDir: dir,
    retentionDays: 7,
    now: () => new Date(clock),
    dump: (outFile) => writeFile(outFile, 'dump-bytes'),
    archive: (outFile) => writeFile(outFile, 'archive-bytes!'),
    onFailure: async (run) => {
      failures.push(run);
    },
    log: { info: () => {}, error: () => {} },
    ...overrides,
  };
}

beforeEach(async () => {
  dir = await mkdtemp(join(tmpdir(), 'dorfteich-backup-'));
  clock = new Date(START);
  failures = [];
});

afterEach(async () => {
  await rm(dir, { recursive: true, force: true });
});

describe('runBackup', () => {
  it('produces a dump, a matching archive, and status.json', async () => {
    const status = await runBackup(makeDeps());

    const names = await readdir(dir);
    expect(names).toContain(dumpFileName('20260701-030000'));
    expect(names).toContain(archiveFileName('20260701-030000'));
    expect(status.lastRun.outcome).toBe('succeeded');
    expect(status.lastRun.sizes).toEqual({ dumpBytes: 10, archiveBytes: 14 });
    expect(status.lastSuccess?.backupId).toBe('20260701-030000');
    expect(readStatus(dir)).toEqual(status);
  });

  it('keeps exactly the retention window across simulated nights', async () => {
    for (let night = 0; night < 30; night += 1) {
      clock = new Date(START + night * DAY);
      await runBackup(makeDeps());
    }

    const names = (await readdir(dir)).filter((name) => name.startsWith('db-'));
    // Retention 7 days: the last 7 nights survive plus the current night's set.
    expect(names.length).toBe(8);
    expect(names).toContain(dumpFileName('20260730-030000'));
    expect(names).not.toContain(dumpFileName('20260722-030000'));
    expect(names).toContain(dumpFileName('20260723-030000'));
  });

  it('records a failed run, keeps lastSuccess, alerts, and cleans partials', async () => {
    await runBackup(makeDeps());

    clock = new Date(START + DAY);
    const status = await runBackup(
      makeDeps({
        dump: async () => {
          throw new Error('connection refused');
        },
      }),
    );

    expect(status.lastRun.outcome).toBe('failed');
    expect(status.lastRun.error).toContain('connection refused');
    expect(status.lastSuccess?.backupId).toBe('20260701-030000');
    expect(failures).toHaveLength(1);
    expect(failures[0]?.lastSuccessAt).toBe(new Date(START).toISOString());

    const names = await readdir(dir);
    expect(names.filter((name) => name.endsWith('.partial'))).toHaveLength(0);
    // The last good set survives a failed night.
    expect(names).toContain(dumpFileName('20260701-030000'));
  });

  it('a failure alert that itself fails never breaks the run', async () => {
    const status = await runBackup(
      makeDeps({
        dump: async () => {
          throw new Error('disk full');
        },
        onFailure: async () => {
          throw new Error('smtp down');
        },
      }),
    );
    expect(status.lastRun.outcome).toBe('failed');
    expect(readStatus(dir)?.lastRun.error).toContain('disk full');
  });

  it('after long downtime the newest complete set survives pruning', async () => {
    await runBackup(makeDeps());

    // 60 days later (retention 7): the old set is expired but must survive
    // as the newest complete one until a new success replaces it.
    clock = new Date(START + 60 * DAY);
    const status = await runBackup(
      makeDeps({
        dump: async () => {
          throw new Error('db gone');
        },
      }),
    );
    expect(status.lastRun.outcome).toBe('failed');
    expect(await readdir(dir)).toContain(dumpFileName('20260701-030000'));

    // The next success prunes it.
    clock = new Date(START + 61 * DAY);
    await runBackup(makeDeps());
    const names = await readdir(dir);
    expect(names).not.toContain(dumpFileName('20260701-030000'));
    expect(names).toContain(dumpFileName('20260831-030000'));
  });
});