<?php

namespace App\Tests\MyEp\Cache;

use App\MyEp\Cache\StaleWhileErrorCache;
use PHPUnit\Framework\TestCase;
use Psr\Log\NullLogger;
use Symfony\Component\Cache\Adapter\ArrayAdapter;

class StaleWhileErrorCacheTest extends TestCase
{
    public function testTheProducedValueIsReturnedAndCached(): void
    {
        $pool = new ArrayAdapter();
        $cache = new StaleWhileErrorCache($pool, new NullLogger());

        $value = $cache->get('myep.hotels.v1', 3600, fn () => ['a' => 1]);

        $this->assertEquals(['a' => 1], $value);
        $this->assertTrue($pool->getItem('myep.hotels.v1')->isHit());
        $this->assertTrue($pool->getItem('myep.hotels.v1.last_good')->isHit());
    }

    public function testACachedValueIsServedWithoutProducingAgain(): void
    {
        $pool = new ArrayAdapter();
        $cache = new StaleWhileErrorCache($pool, new NullLogger());
        $calls = 0;

        $producer = function () use (&$calls) {
            ++$calls;

            return ['a' => 1];
        };

        $cache->get('myep.hotels.v1', 3600, $producer);
        $value = $cache->get('myep.hotels.v1', 3600, $producer);

        $this->assertEquals(['a' => 1], $value);
        $this->assertEquals(1, $calls);
    }

    public function testTheLastKnownValueIsServedWhenProducingFails(): void
    {
        $pool = new ArrayAdapter();
        $cache = new StaleWhileErrorCache($pool, new NullLogger());

        $cache->get('myep.hotels.v1', 3600, fn () => ['a' => 1]);
        $pool->deleteItem('myep.hotels.v1');

        $value = $cache->get('myep.hotels.v1', 3600, fn () => throw new \RuntimeException('upstream is down'));

        $this->assertEquals(['a' => 1], $value);
    }

    public function testAServedStaleValueSuppressesFurtherAttempts(): void
    {
        $pool = new ArrayAdapter();
        $cache = new StaleWhileErrorCache($pool, new NullLogger());
        $calls = 0;

        $failing = function () use (&$calls) {
            ++$calls;

            throw new \RuntimeException('upstream is down');
        };

        $cache->get('myep.hotels.v1', 3600, fn () => ['a' => 1]);
        $pool->deleteItem('myep.hotels.v1');

        $cache->get('myep.hotels.v1', 3600, $failing);
        $cache->get('myep.hotels.v1', 3600, $failing);

        $this->assertEquals(1, $calls);
    }

    public function testAFailureWithoutAnyCachedValueIsEmpty(): void
    {
        $cache = new StaleWhileErrorCache(new ArrayAdapter(), new NullLogger());

        $value = $cache->get('myep.hotels.v1', 3600, fn () => throw new \RuntimeException('upstream is down'));

        $this->assertEquals([], $value);
    }

    public function testEachKeyKeepsItsOwnValue(): void
    {
        $pool = new ArrayAdapter();
        $cache = new StaleWhileErrorCache($pool, new NullLogger());

        $cache->get('myep.hotels.v1', 3600, fn () => ['hotel']);
        $cache->get('myep.pickups.v1', 3600, fn () => ['pickup']);

        $this->assertEquals(['hotel'], $cache->get('myep.hotels.v1', 3600, fn () => ['other']));
        $this->assertEquals(['pickup'], $cache->get('myep.pickups.v1', 3600, fn () => ['other']));
    }
}