<?php

declare(strict_types=1);

namespace OCA\NgBackup\Tests\Unit\Repository;

use OCA\NgBackup\Backend\BackendException;
use OCA\NgBackup\Backend\IBackend;
use OCA\NgBackup\Backend\LocalBackend;
use OCA\NgBackup\Crypto\KeyRing;
use OCA\NgBackup\Repository\Repository;
use OCA\NgBackup\Tests\Unit\TempDirTrait;
use PHPUnit\Framework\TestCase;

class VerifyTest extends TestCase {
	use TempDirTrait;

	private LocalBackend $backend;
	private KeyRing $keys;
	private string $root;
	private string $src;

	protected function setUp(): void {
		$this->root = $this->tempDir();
		$this->backend = new LocalBackend($this->root);
		$this->keys = KeyRing::generate();
		$this->src = $this->tempDir();
		file_put_contents("$this->src/a", random_bytes(100000));
		file_put_contents("$this->src/b", random_bytes(100000));
	}

	private function open(): Repository {
		return Repository::openWithKey($this->backend, $this->keys, null, null);
	}

	public function testShallowVerifyPassesOnAHealthyRepository(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);

		$result = $this->open()->verify($s['snapshot']);

		$this->assertSame(2, $result['filesChecked']);
		$this->assertGreaterThanOrEqual(1, $result['blobsChecked']);
		$this->assertSame(0, $result['bytesChecked']); // not downloaded without --deep
		$this->assertSame([], $result['missing']);
		$this->assertSame([], $result['failed']);
	}

	public function testDeepVerifyDownloadsAndCountsBytes(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);

		$result = $this->open()->verify($s['snapshot'], deep: true);

		$this->assertSame(200000, $result['bytesChecked']);
		$this->assertSame([], $result['missing']);
		$this->assertSame([], $result['failed']);
	}

	public function testShallowVerifyDetectsAMissingPack(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		foreach ($this->backend->list('packs') as $pack) {
			$this->backend->delete($pack);
		}

		$result = $this->open()->verify($s['snapshot']);

		$this->assertNotSame([], $result['missing']);
	}

	public function testVerifyFailsOnAMissingDatabaseManifest(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$repo->writeSnapshot('snap-no-db', ['time' => gmdate('c'), 'db' => 'db/does-not-exist'], []);

		$result = $this->open()->verify('snap-no-db');

		$this->assertSame(['db/does-not-exist'], $result['missing']);
	}

	public function testVerifyReportsHowFarItIs(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		$seen = [];

		$this->open()->verify($s['snapshot'], heartbeat: function (array $p) use (&$seen): void {
			$seen[] = $p;
		});

		$phases = array_values(array_unique(array_column($seen, 'phase')));
		$this->assertSame(['index', 'packs', 'files'], $phases);
		$this->assertSame(['phase' => 'packs', 'done' => 256, 'total' => 256], $seen[array_key_last(array_filter($seen, fn ($p) => $p['phase'] === 'packs'))]);
		$last = end($seen);
		$this->assertSame(2, $last['done']);
		$this->assertNull($last['total'], 'this snapshot has no file count in its metadata (a backup run records one)');
	}

	public function testVerifyListsPackFoldersInsteadOfCheckingEveryPack(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		$counting = new ListingBackend($this->backend);

		$result = Repository::openWithKey($counting, $this->keys, null, null)->verify($s['snapshot']);

		$this->assertSame([], $result['missing']);
		$this->assertSame(0, $counting->packExists);
	}

	public function testAPackFolderThatCannotBeListedIsCheckedPackByPack(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		$counting = new ListingBackend($this->backend, unlistable: true);

		$result = Repository::openWithKey($counting, $this->keys, null, null)->verify($s['snapshot']);

		$this->assertSame([], $result['missing']);
		$this->assertGreaterThan(0, $counting->packExists);
	}

	public function testAnEmptyFolderListingIsNoProofThatItsPacksAreGone(): void {
		// A storage also reports an empty folder when it could not look (is_dir() false).
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		$counting = new ListingBackend($this->backend, emptyListings: true);

		$result = Repository::openWithKey($counting, $this->keys, null, null)->verify($s['snapshot']);

		$this->assertSame([], $result['missing']);
		$this->assertGreaterThan(0, $counting->packExists);
	}

	public function testAPackMissingFromAFolderThatIsNotEmptyIsReportedWithoutAskingForIt(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		$packs = $this->backend->list('packs');
		// Another file in the same folder keeps its listing non-empty.
		$this->backend->put(dirname($packs[0]) . '/0000other', fopen('data://text/plain,x', 'r'));
		foreach ($packs as $pack) {
			$this->backend->delete($pack);
		}
		$counting = new ListingBackend($this->backend);

		$result = Repository::openWithKey($counting, $this->keys, null, null)->verify($s['snapshot']);

		$this->assertNotSame([], $result['missing']);
		$this->assertSame(0, $counting->packExists);
	}

	public function testAPackMissingFromAnEmptyFolderIsReportedToo(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		foreach ($this->backend->list('packs') as $pack) {
			$this->backend->delete($pack);
		}

		$result = Repository::openWithKey(new ListingBackend($this->backend), $this->keys, null, null)->verify($s['snapshot']);

		$this->assertNotSame([], $result['missing']);
	}

	public function testDeepVerifyDetectsATamperedPack(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		$packs = $this->backend->list('packs');
		$this->assertNotEmpty($packs);
		$path = $this->root . '/' . $packs[0];
		$bytes = file_get_contents($path);
		// Flip a byte well inside the file, away from any header, so decryption's own
		// authentication tag catches it (this must fail loudly, not just "do nothing").
		$bytes[(int)(strlen($bytes) / 2)] = chr(~ord($bytes[(int)(strlen($bytes) / 2)]) & 0xFF);
		file_put_contents($path, $bytes);

		$result = $this->open()->verify($s['snapshot'], deep: true);

		$this->assertNotSame([], $result['failed']);
	}

	public function testDeepVerifyRetriesAReadThatFailsOnce(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		$flaky = new FlakyRangeBackend($this->backend, failures: 1);

		$result = Repository::openWithKey($flaky, $this->keys, null, null)->verify($s['snapshot'], deep: true);

		$this->assertSame(200000, $result['bytesChecked']);
		$this->assertSame([], $result['failed']);
		$this->assertSame([], $result['unreadable']);
	}

	public function testDeepVerifyReportsAPersistentReadErrorAsUnreadableNotCorrupted(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		$broken = new FlakyRangeBackend($this->backend, failures: PHP_INT_MAX);

		$result = Repository::openWithKey($broken, $this->keys, null, null)->verify($s['snapshot'], deep: true);

		$this->assertSame([], $result['failed']);
		$this->assertNotSame([], $result['unreadable']);
		$this->assertSame('connection reset', $result['readError']);
	}

	public function testDeepVerifyDoesNotHideAProgrammingError(): void {
		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
		$s = $repo->backupDirectory($this->src);
		$buggy = new FlakyRangeBackend($this->backend, failures: PHP_INT_MAX, error: new \TypeError('bug'));

		$this->expectException(\TypeError::class);
		Repository::openWithKey($buggy, $this->keys, null, null)->verify($s['snapshot'], deep: true);
	}
}

/** Delegates to a real backend, but reading a pack throws for the first $failures reads. */
final class FlakyRangeBackend implements IBackend {
	use \OCA\NgBackup\Backend\GetsOneByOne;

	public function __construct(
		private IBackend $inner,
		private int $failures,
		private ?\Throwable $error = null,
	) {
	}

	public function put(string $path, $stream): void {
		$this->inner->put($path, $stream);
	}

	public function get(string $path) {
		if (str_starts_with($path, 'packs/')) {
			$this->fail();
		}
		return $this->inner->get($path);
	}

	public function getRange(string $path, int $offset, int $length): string {
		$this->fail();
		return $this->inner->getRange($path, $offset, $length);
	}

	private function fail(): void {
		if ($this->failures > 0) {
			$this->failures--;
			throw $this->error ?? new BackendException('connection reset');
		}
	}

	public function exists(string $path): bool {
		return $this->inner->exists($path);
	}

	public function move(string $from, string $to): void {
		$this->inner->move($from, $to);
	}

	public function list(string $prefix): array {
		return $this->inner->list($prefix);
	}

	public function listFiles(string $dir): array {
		return $this->inner->listFiles($dir);
	}

	public function delete(string $path): void {
		$this->inner->delete($path);
	}
}

/** Delegates to a real backend; counts exists() on packs, and can refuse to list pack folders. */
final class ListingBackend implements IBackend {
	use \OCA\NgBackup\Backend\GetsOneByOne;

	public int $packExists = 0;

	public function __construct(
		private IBackend $inner,
		private bool $unlistable = false,
		private bool $emptyListings = false,
	) {
	}

	public function put(string $path, $stream): void {
		$this->inner->put($path, $stream);
	}

	public function get(string $path) {
		return $this->inner->get($path);
	}

	public function getRange(string $path, int $offset, int $length): string {
		return $this->inner->getRange($path, $offset, $length);
	}

	public function exists(string $path): bool {
		if (str_starts_with($path, 'packs/')) {
			$this->packExists++;
		}
		return $this->inner->exists($path);
	}

	public function move(string $from, string $to): void {
		$this->inner->move($from, $to);
	}

	public function list(string $prefix): array {
		return $this->inner->list($prefix);
	}

	public function listFiles(string $dir): array {
		if ($this->unlistable && str_starts_with($dir, 'packs/')) {
			throw new BackendException('Cannot list ' . $dir);
		}
		if ($this->emptyListings && str_starts_with($dir, 'packs/')) {
			return [];
		}
		return $this->inner->listFiles($dir);
	}

	public function delete(string $path): void {
		$this->inner->delete($path);
	}
}