<?php

declare(strict_types=1);

namespace App\Framework\ApiGateway\Metrics;

use App\Framework\Metrics\MetricsCollection;

/**
 * Collects and tracks metrics for API Gateway operations
 */
final class ApiMetrics
{
    /** @var array<string, array{requests: int, successes: int, failures: int, total_duration_ms: float, avg_duration_ms: float}> */
    private array $statsByService = [];

    /** @var array<string, array{requests: int, successes: int, failures: int, total_duration_ms: float, avg_duration_ms: float}> */
    private array $statsByRequestName = [];

    private int $totalRequests = 0;
    private int $totalSuccesses = 0;
    private int $totalFailures = 0;
    private float $totalDurationMs = 0.0;

    /** @var array<string, int> */
    private array $retryCountByService = [];

    /** @var array<string, int> */
    private array $circuitBreakerOpenCountByService = [];

    public function recordRequest(
        string $service,
        string $requestName,
        float $durationMs,
        bool $success,
        int $retryAttempts = 0,
        bool $circuitBreakerTriggered = false
    ): void {
        // Total stats
        $this->totalRequests++;
        if ($success) {
            $this->totalSuccesses++;
        } else {
            $this->totalFailures++;
        }
        $this->totalDurationMs += $durationMs;

        // Per-service stats
        if (!isset($this->statsByService[$service])) {
            $this->statsByService[$service] = [
                'requests' => 0,
                'successes' => 0,
                'failures' => 0,
                'total_duration_ms' => 0.0,
                'avg_duration_ms' => 0.0,
            ];
        }

        $this->statsByService[$service]['requests']++;
        if ($success) {
            $this->statsByService[$service]['successes']++;
        } else {
            $this->statsByService[$service]['failures']++;
        }
        $this->statsByService[$service]['total_duration_ms'] += $durationMs;
        $this->statsByService[$service]['avg_duration_ms'] =
            $this->statsByService[$service]['total_duration_ms'] / $this->statsByService[$service]['requests'];

        // Per-request-name stats
        if (!isset($this->statsByRequestName[$requestName])) {
            $this->statsByRequestName[$requestName] = [
                'requests' => 0,
                'successes' => 0,
                'failures' => 0,
                'total_duration_ms' => 0.0,
                'avg_duration_ms' => 0.0,
            ];
        }

        $this->statsByRequestName[$requestName]['requests']++;
        if ($success) {
            $this->statsByRequestName[$requestName]['successes']++;
        } else {
            $this->statsByRequestName[$requestName]['failures']++;
        }
        $this->statsByRequestName[$requestName]['total_duration_ms'] += $durationMs;
        $this->statsByRequestName[$requestName]['avg_duration_ms'] =
            $this->statsByRequestName[$requestName]['total_duration_ms'] / $this->statsByRequestName[$requestName]['requests'];

        // Retry tracking
        if ($retryAttempts > 0) {
            if (!isset($this->retryCountByService[$service])) {
                $this->retryCountByService[$service] = 0;
            }
            $this->retryCountByService[$service] += $retryAttempts;
        }

        // Circuit breaker tracking
        if ($circuitBreakerTriggered) {
            if (!isset($this->circuitBreakerOpenCountByService[$service])) {
                $this->circuitBreakerOpenCountByService[$service] = 0;
            }
            $this->circuitBreakerOpenCountByService[$service]++;
        }
    }

    public function getStats(): array
    {
        return [
            'total' => [
                'requests' => $this->totalRequests,
                'successes' => $this->totalSuccesses,
                'failures' => $this->totalFailures,
                'success_rate' => $this->getSuccessRate(),
                'avg_duration_ms' => $this->getAverageDuration(),
            ],
            'by_service' => $this->statsByService,
            'by_request_name' => $this->statsByRequestName,
            'retry_counts' => $this->retryCountByService,
            'circuit_breaker_opens' => $this->circuitBreakerOpenCountByService,
        ];
    }

    public function getSuccessRate(): float
    {
        if ($this->totalRequests === 0) {
            return 0.0;
        }

        return $this->totalSuccesses / $this->totalRequests;
    }

    public function getAverageDuration(): float
    {
        if ($this->totalRequests === 0) {
            return 0.0;
        }

        return $this->totalDurationMs / $this->totalRequests;
    }

    public function getServiceStats(string $service): ?array
    {
        return $this->statsByService[$service] ?? null;
    }

    public function getRequestNameStats(string $requestName): ?array
    {
        return $this->statsByRequestName[$requestName] ?? null;
    }

    /**
     * Collect metrics for Prometheus export
     */
    public function collectMetrics(MetricsCollection $collection): void
    {
        // Total request counter
        $collection->counter(
            'api_gateway_requests_total',
            (float) $this->totalRequests,
            'Total number of API gateway requests'
        );

        // Success counter
        $collection->counter(
            'api_gateway_requests_success_total',
            (float) $this->totalSuccesses,
            'Total number of successful API gateway requests'
        );

        // Failure counter
        $collection->counter(
            'api_gateway_requests_failure_total',
            (float) $this->totalFailures,
            'Total number of failed API gateway requests'
        );

        // Success rate gauge
        $collection->gauge(
            'api_gateway_success_rate',
            $this->getSuccessRate(),
            'Success rate of API gateway requests (0.0 to 1.0)'
        );

        // Average duration gauge
        $collection->gauge(
            'api_gateway_request_duration_ms',
            $this->getAverageDuration(),
            'Average duration of API gateway requests in milliseconds'
        );

        // Per-service metrics
        foreach ($this->statsByService as $service => $stats) {
            $labels = ['service' => $service];

            $collection->counter(
                'api_gateway_requests_total',
                (float) $stats['requests'],
                'Total requests per service',
                $labels
            );

            $collection->counter(
                'api_gateway_requests_success_total',
                (float) $stats['successes'],
                'Successful requests per service',
                $labels
            );

            $collection->counter(
                'api_gateway_requests_failure_total',
                (float) $stats['failures'],
                'Failed requests per service',
                $labels
            );

            $collection->gauge(
                'api_gateway_request_duration_ms',
                $stats['avg_duration_ms'],
                'Average request duration per service in milliseconds',
                $labels
            );

            // Success rate per service
            $successRate = $stats['requests'] > 0
                ? $stats['successes'] / $stats['requests']
                : 0.0;

            $collection->gauge(
                'api_gateway_success_rate',
                $successRate,
                'Success rate per service',
                $labels
            );
        }

        // Per-request-name metrics
        foreach ($this->statsByRequestName as $requestName => $stats) {
            $labels = ['request_name' => $requestName];

            $collection->counter(
                'api_gateway_requests_total',
                (float) $stats['requests'],
                'Total requests per request name',
                $labels
            );

            $collection->counter(
                'api_gateway_requests_success_total',
                (float) $stats['successes'],
                'Successful requests per request name',
                $labels
            );

            $collection->counter(
                'api_gateway_requests_failure_total',
                (float) $stats['failures'],
                'Failed requests per request name',
                $labels
            );

            $collection->gauge(
                'api_gateway_request_duration_ms',
                $stats['avg_duration_ms'],
                'Average request duration per request name in milliseconds',
                $labels
            );
        }

        // Retry metrics per service
        foreach ($this->retryCountByService as $service => $retryCount) {
            $collection->counter(
                'api_gateway_retries_total',
                (float) $retryCount,
                'Total number of retry attempts per service',
                ['service' => $service]
            );
        }

        // Circuit breaker metrics per service
        foreach ($this->circuitBreakerOpenCountByService as $service => $openCount) {
            $collection->counter(
                'api_gateway_circuit_breaker_open_total',
                (float) $openCount,
                'Total number of circuit breaker opens per service',
                ['service' => $service]
            );
        }
    }

    public function reset(): void
    {
        $this->statsByService = [];
        $this->statsByRequestName = [];
        $this->totalRequests = 0;
        $this->totalSuccesses = 0;
        $this->totalFailures = 0;
        $this->totalDurationMs = 0.0;
        $this->retryCountByService = [];
        $this->circuitBreakerOpenCountByService = [];
    }
}