<?php

declare(strict_types=1);

namespace Tests\Framework\Queue\Performance;

use App\Framework\Database\DatabaseManager;
use App\Framework\Queue\Distribution\JobDistributionService;
use App\Framework\Queue\Distribution\LoadBalancer;
use App\Framework\Queue\Jobs\JobPriority;
use App\Framework\Queue\Queue\QueueName;
use App\Framework\Queue\Workers\WorkerRegistry;
use App\Framework\Queue\Workers\WorkerStatus;
use PHPUnit\Framework\TestCase;

final class LoadBalancingPerformanceTest extends TestCase
{
    private DatabaseManager $database;

    private WorkerRegistry $workerRegistry;

    private JobDistributionService $distributionService;

    private LoadBalancer $loadBalancer;

    protected function setUp(): void
    {
        $this->database = $this->createTestDatabase();
        $this->workerRegistry = new WorkerRegistry($this->database);
        $this->loadBalancer = new LoadBalancer($this->workerRegistry);
        $this->distributionService = new JobDistributionService(
            $this->database,
            $this->workerRegistry
        );

        $this->cleanupTestData();
        PerformanceTestHelper::warmupDatabase($this->database->getConnection());
    }

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

    public function testWorkerSelectionLatency(): void
    {
        // Create workers with different loads
        $workers = [
            PerformanceTestHelper::createTestWorker('worker_1', 20),
            PerformanceTestHelper::createTestWorker('worker_2', 15),
            PerformanceTestHelper::createTestWorker('worker_3', 10),
            PerformanceTestHelper::createTestWorker('worker_4', 25),
            PerformanceTestHelper::createTestWorker('worker_5', 30),
        ];

        $this->registerWorkers($workers);

        $selectionTimes = [];
        $iterations = 1000;

        for ($i = 0; $i < $iterations; $i++) {
            $time = PerformanceTestHelper::measureTime(function () {
                $this->loadBalancer->selectWorker(new QueueName('test_queue'));
            });
            $selectionTimes[] = $time;
        }

        $stats = PerformanceTestHelper::calculateStatistics($selectionTimes);

        // Validate performance benchmarks
        $this->assertLessThan(5.0, $stats['avg'], 'Average worker selection time exceeds 5ms');
        $this->assertLessThan(10.0, $stats['p95'], 'P95 worker selection time exceeds 10ms');
        $this->assertLessThan(20.0, $stats['p99'], 'P99 worker selection time exceeds 20ms');

        echo "\nWorker Selection Latency Results:\n";
        echo "Iterations: {$iterations}\n";
        echo "Performance: " . PerformanceTestHelper::formatStatistics($stats) . "\n";

        PerformanceTestHelper::assertPerformance(
            $selectionTimes,
            5.0,
            10.0,
            'Worker selection'
        );
    }

    public function testJobDistributionLatency(): void
    {
        $workers = $this->createBalancedWorkers(10, 20);
        $this->registerWorkers($workers);

        $distributionTimes = [];
        $iterations = 500;

        for ($i = 0; $i < $iterations; $i++) {
            $job = PerformanceTestHelper::createTestJob("dist_job_{$i}");

            $time = PerformanceTestHelper::measureTime(function () use ($job) {
                $this->distributionService->distributeJob($job);
            });

            $distributionTimes[] = $time;
        }

        $stats = PerformanceTestHelper::calculateStatistics($distributionTimes);

        // Validate performance benchmarks
        $this->assertLessThan(10.0, $stats['avg'], 'Average job distribution time exceeds 10ms');
        $this->assertLessThan(20.0, $stats['p95'], 'P95 job distribution time exceeds 20ms');
        $this->assertLessThan(50.0, $stats['p99'], 'P99 job distribution time exceeds 50ms');

        echo "\nJob Distribution Latency Results:\n";
        echo "Iterations: {$iterations}\n";
        echo "Performance: " . PerformanceTestHelper::formatStatistics($stats) . "\n";

        PerformanceTestHelper::assertPerformance(
            $distributionTimes,
            10.0,
            20.0,
            'Job distribution'
        );
    }

    public function testHighThroughputDistribution(): void
    {
        $workers = $this->createBalancedWorkers(15, 25);
        $this->registerWorkers($workers);

        $jobsPerSecond = 1000;
        $testDuration = 10; // seconds
        $totalJobs = $jobsPerSecond * $testDuration;

        echo "\nHigh Throughput Distribution Test:\n";
        echo "Target: {$jobsPerSecond} jobs/second for {$testDuration} seconds\n";

        $loadResult = PerformanceTestHelper::simulateLoad(
            function ($index) {
                $job = PerformanceTestHelper::createTestJob("load_job_{$index}");

                return $this->distributionService->distributeJob($job);
            },
            $totalJobs,
            50, // High concurrency
            $testDuration
        );

        $actualThroughput = $loadResult['throughput_ops_per_sec'];
        $distributionTimes = array_column($loadResult['results'], 'time_ms');
        $stats = PerformanceTestHelper::calculateStatistics($distributionTimes);

        echo "Actual Throughput: {$actualThroughput} jobs/second\n";
        echo "Distribution Performance: " . PerformanceTestHelper::formatStatistics($stats) . "\n";

        // Should achieve at least 80% of target throughput
        $this->assertGreaterThan(
            $jobsPerSecond * 0.8,
            $actualThroughput,
            'High throughput distribution below 80% of target'
        );

        // Distribution times should remain reasonable under high load
        $this->assertLessThan(30.0, $stats['avg'], 'Average distribution time too high under load');
        $this->assertLessThan(100.0, $stats['p95'], 'P95 distribution time too high under load');
    }

    public function testFairDistributionUnderLoad(): void
    {
        $workers = [
            PerformanceTestHelper::createTestWorker('worker_1', 10),
            PerformanceTestHelper::createTestWorker('worker_2', 20),
            PerformanceTestHelper::createTestWorker('worker_3', 30),
            PerformanceTestHelper::createTestWorker('worker_4', 15),
            PerformanceTestHelper::createTestWorker('worker_5', 25),
        ];

        $this->registerWorkers($workers);

        $jobCount = 1000;
        $workerAssignments = [];

        for ($i = 0; $i < $jobCount; $i++) {
            $job = PerformanceTestHelper::createTestJob("fair_job_{$i}");
            $selectedWorker = $this->distributionService->distributeJob($job);

            if ($selectedWorker) {
                $workerId = $selectedWorker->id->toString();
                $workerAssignments[$workerId] = ($workerAssignments[$workerId] ?? 0) + 1;
            }
        }

        echo "\nFair Distribution Results:\n";
        $totalCapacity = array_sum(array_map(fn ($w) => $w->capacity->value, $workers));

        foreach ($workers as $worker) {
            $workerId = $worker->id->toString();
            $assignments = $workerAssignments[$workerId] ?? 0;
            $expectedRatio = $worker->capacity->value / $totalCapacity;
            $actualRatio = $assignments / $jobCount;
            $efficiency = ($actualRatio / $expectedRatio) * 100;

            echo sprintf(
                "Worker %s: Capacity=%d, Assignments=%d, Expected=%.1f%%, Actual=%.1f%%, Efficiency=%.1f%%\n",
                $workerId,
                $worker->capacity->value,
                $assignments,
                $expectedRatio * 100,
                $actualRatio * 100,
                $efficiency
            );

            // Each worker should get jobs roughly proportional to their capacity
            // Allow 20% variance for fair distribution
            $this->assertGreaterThan(
                80.0,
                $efficiency,
                "Worker {$workerId} received fewer jobs than expected (efficiency: {$efficiency}%)"
            );

            $this->assertLessThan(
                120.0,
                $efficiency,
                "Worker {$workerId} received more jobs than expected (efficiency: {$efficiency}%)"
            );
        }
    }

    public function testMixedCapacityLoadBalancing(): void
    {
        // Create workers with very different capacities
        $workers = [
            PerformanceTestHelper::createTestWorker('small_worker', 5),
            PerformanceTestHelper::createTestWorker('medium_worker_1', 15),
            PerformanceTestHelper::createTestWorker('medium_worker_2', 20),
            PerformanceTestHelper::createTestWorker('large_worker', 50),
            PerformanceTestHelper::createTestWorker('xlarge_worker', 100),
        ];

        $this->registerWorkers($workers);

        $selectionTimes = [];
        $iterations = 500;

        for ($i = 0; $i < $iterations; $i++) {
            $time = PerformanceTestHelper::measureTime(function () {
                $this->loadBalancer->selectWorker(new QueueName('test_queue'));
            });
            $selectionTimes[] = $time;
        }

        $stats = PerformanceTestHelper::calculateStatistics($selectionTimes);

        echo "\nMixed Capacity Load Balancing Results:\n";
        echo "Worker capacities: 5, 15, 20, 50, 100\n";
        echo "Selection performance: " . PerformanceTestHelper::formatStatistics($stats) . "\n";

        // Selection should still be fast even with mixed capacities
        $this->assertLessThan(8.0, $stats['avg'], 'Mixed capacity selection average time too high');
        $this->assertLessThan(15.0, $stats['p95'], 'Mixed capacity selection P95 time too high');
    }

    public function testPriorityJobDistribution(): void
    {
        $workers = $this->createBalancedWorkers(8, 15);
        $this->registerWorkers($workers);

        $priorities = [JobPriority::LOW, JobPriority::NORMAL, JobPriority::HIGH, JobPriority::CRITICAL];
        $distributionTimes = [];

        foreach ($priorities as $priority) {
            $iterationsPerPriority = 100;

            for ($i = 0; $i < $iterationsPerPriority; $i++) {
                $job = PerformanceTestHelper::createTestJob(
                    "priority_job_{$priority->value}_{$i}",
                    $priority
                );

                $time = PerformanceTestHelper::measureTime(function () use ($job) {
                    $this->distributionService->distributeJob($job);
                });

                $distributionTimes[$priority->value][] = $time;
            }
        }

        echo "\nPriority Job Distribution Results:\n";

        foreach ($priorities as $priority) {
            $stats = PerformanceTestHelper::calculateStatistics($distributionTimes[$priority->value]);
            echo "Priority {$priority->value}: " . PerformanceTestHelper::formatStatistics($stats) . "\n";

            // All priorities should have similar distribution performance
            $this->assertLessThan(15.0, $stats['avg'], "Priority {$priority->value} distribution too slow");
        }
    }

    public function testWorkerOverloadHandling(): void
    {
        // Create workers that will quickly become overloaded
        $workers = [
            PerformanceTestHelper::createTestWorker('worker_1', 2),
            PerformanceTestHelper::createTestWorker('worker_2', 3),
            PerformanceTestHelper::createTestWorker('worker_3', 2),
        ];

        $this->registerWorkers($workers);

        $distributionTimes = [];
        $successfulDistributions = 0;
        $failedDistributions = 0;

        // Try to distribute more jobs than total worker capacity
        $jobCount = 20; // Total capacity is only 7

        for ($i = 0; $i < $jobCount; $i++) {
            $job = PerformanceTestHelper::createTestJob("overload_job_{$i}");

            $result = PerformanceTestHelper::measureTimeWithResult(function () use ($job) {
                return $this->distributionService->distributeJob($job);
            });

            $distributionTimes[] = $result['time_ms'];

            if ($result['result'] !== null) {
                $successfulDistributions++;
            } else {
                $failedDistributions++;
            }
        }

        $stats = PerformanceTestHelper::calculateStatistics($distributionTimes);

        echo "\nWorker Overload Handling Results:\n";
        echo "Total jobs: {$jobCount}\n";
        echo "Successful distributions: {$successfulDistributions}\n";
        echo "Failed distributions: {$failedDistributions}\n";
        echo "Distribution performance: " . PerformanceTestHelper::formatStatistics($stats) . "\n";

        // Should successfully distribute up to total capacity
        $this->assertGreaterThanOrEqual(7, $successfulDistributions, 'Should distribute at least 7 jobs');

        // Distribution times should remain reasonable even when workers are overloaded
        $this->assertLessThan(20.0, $stats['avg'], 'Distribution time too high during overload');
    }

    private function createBalancedWorkers(int $count, int $capacity): array
    {
        $workers = [];
        for ($i = 1; $i <= $count; $i++) {
            $workers[] = PerformanceTestHelper::createTestWorker(
                "balanced_worker_{$i}",
                $capacity,
                WorkerStatus::AVAILABLE
            );
        }

        return $workers;
    }

    private function registerWorkers(array $workers): void
    {
        foreach ($workers as $worker) {
            $this->workerRegistry->registerWorker($worker);
        }
    }

    private function createTestDatabase(): DatabaseManager
    {
        $pdo = new \PDO('sqlite::memory:');
        $pdo->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);

        // Create required tables with indexes for performance
        $pdo->exec('
            CREATE TABLE workers (
                id TEXT PRIMARY KEY,
                queue_names TEXT NOT NULL,
                capacity INTEGER NOT NULL,
                status TEXT NOT NULL,
                last_heartbeat TEXT NOT NULL,
                metadata TEXT
            )
        ');

        $pdo->exec('
            CREATE TABLE jobs (
                id TEXT PRIMARY KEY,
                type TEXT NOT NULL,
                payload TEXT NOT NULL,
                queue_name TEXT NOT NULL,
                priority INTEGER NOT NULL,
                status TEXT NOT NULL,
                worker_id TEXT,
                created_at TEXT NOT NULL,
                started_at TEXT,
                completed_at TEXT,
                attempts INTEGER DEFAULT 0,
                error_message TEXT
            )
        ');

        // Performance-optimized indexes
        $pdo->exec('CREATE INDEX idx_workers_status_capacity ON workers(status, capacity DESC)');
        $pdo->exec('CREATE INDEX idx_workers_queue_status ON workers(queue_names, status)');
        $pdo->exec('CREATE INDEX idx_jobs_worker_status ON jobs(worker_id, status)');
        $pdo->exec('CREATE INDEX idx_jobs_priority_created ON jobs(priority DESC, created_at)');

        return new DatabaseManager($pdo);
    }

    private function cleanupTestData(): void
    {
        $pdo = $this->database->getConnection();
        $pdo->exec('DELETE FROM workers');
        $pdo->exec('DELETE FROM jobs');
    }
}