<?php

declare(strict_types=1);

namespace KTXT\Mail\Tests\Unit;

use JsonException;
use KTXM\Mail\Stores\CompositionStore;
use PHPUnit\Framework\TestCase;

final class CompositionStoreTest extends TestCase {

    private const TENANT_ID = 'tenant-1';
    private const USER_ID = 'user-1';
    private const COMPOSITION_ID = 'draft-1';

    private string $rootDir;
    private CompositionStore $store;

    protected function setUp(): void {
        $this->rootDir = sys_get_temp_dir() . '/ktrix-mail-store-test-' . uniqid('', true);
        mkdir($this->rootDir, 0755, true);
        $this->store = new CompositionStore($this->rootDir);
    }

    protected function tearDown(): void {
        $this->deleteDir($this->rootDir);
    }

    public function testFailedReplacementPreservesPreviousSnapshot(): void {
        $initial = ['identifier' => self::COMPOSITION_ID, 'revision' => 1];
        $this->saveSnapshot($initial);

        $resource = fopen('php://memory', 'r');
        try {
            $saveInvalidSnapshot = static fn(): array => [
                'identifier' => self::COMPOSITION_ID,
                'invalid' => $resource,
            ];
            $this->store->compositionSave(
                self::TENANT_ID,
                self::USER_ID,
                self::COMPOSITION_ID,
                $saveInvalidSnapshot,
            );
            $this->fail('Saving a value that cannot be encoded as JSON should fail');
        } catch (JsonException) {
            $this->assertSame(
                $initial,
                $this->store->compositionFetch(self::TENANT_ID, self::USER_ID, self::COMPOSITION_ID),
            );
        } finally {
            fclose($resource);
        }
    }

    public function testUpdateCanLeaveSnapshotUnchanged(): void {
        $initial = ['identifier' => self::COMPOSITION_ID, 'revision' => 1];
        $this->saveSnapshot($initial);

        $leaveUnchanged = static fn(?array $snapshot): ?array => null;
        $updated = $this->store->compositionSave(
            self::TENANT_ID,
            self::USER_ID,
            self::COMPOSITION_ID,
            $leaveUnchanged,
        );

        $this->assertNull($updated);
        $this->assertSame(
            $initial,
            $this->store->compositionFetch(self::TENANT_ID, self::USER_ID, self::COMPOSITION_ID),
        );
    }

    public function testConcurrentUpdatesDoNotLoseChanges(): void {
        if (!function_exists('pcntl_fork')) {
            $this->markTestSkipped('The pcntl extension is required for the concurrency test');
        }

        $this->saveSnapshot([
            'identifier' => self::COMPOSITION_ID,
            'updates' => 0,
        ]);

        $childPid = pcntl_fork();
        if ($childPid === -1) {
            $this->fail('Unable to fork the concurrency test process');
        }

        if ($childPid === 0) {
            $this->incrementAfterDelay();
            exit(0);
        }

        $this->incrementAfterDelay();
        pcntl_waitpid($childPid, $status);

        $this->assertTrue(pcntl_wifexited($status));
        $this->assertSame(0, pcntl_wexitstatus($status));
        $this->assertSame(
            2,
            $this->store->compositionFetch(self::TENANT_ID, self::USER_ID, self::COMPOSITION_ID)['updates'],
        );
    }

    private function incrementAfterDelay(): void {
        $incrementSnapshot = static function (?array $snapshot): array {
            usleep(200_000);
            $snapshot['updates']++;
            return $snapshot;
        };

        $this->store->compositionSave(
            self::TENANT_ID,
            self::USER_ID,
            self::COMPOSITION_ID,
            $incrementSnapshot,
        );
    }

    private function saveSnapshot(array $snapshot): void {
        $saveSnapshot = static fn(): array => $snapshot;
        $this->store->compositionSave(
            self::TENANT_ID,
            self::USER_ID,
            self::COMPOSITION_ID,
            $saveSnapshot,
        );
    }

    private function deleteDir(string $path): void {
        if (!is_dir($path)) {
            return;
        }

        foreach (scandir($path) ?: [] as $entry) {
            if ($entry === '.' || $entry === '..') {
                continue;
            }

            $child = $path . '/' . $entry;
            if (is_dir($child)) {
                $this->deleteDir($child);
                continue;
            }

            unlink($child);
        }

        rmdir($path);
    }
}