<?php

declare(strict_types=1);

namespace App\Framework\ErrorAggregation;

use App\Framework\Exception\Core\ErrorSeverity;
use App\Framework\Ulid\Ulid;

/**
 * Represents a pattern of similar errors for analysis and alerting
 */
final readonly class ErrorPattern
{
    public function __construct(
        public Ulid $id,
        public string $fingerprint,
        public string $service,
        public string $component,
        public string $operation,
        public string $errorCode,
        public string $normalizedMessage,
        public ErrorSeverity $severity,
        public int $occurrenceCount,
        public \DateTimeImmutable $firstOccurrence,
        public \DateTimeImmutable $lastOccurrence,
        public array $affectedUsers = [],
        public array $affectedIps = [],
        public bool $isActive = true,
        public bool $isAcknowledged = false,
        public ?string $acknowledgedBy = null,
        public ?\DateTimeImmutable $acknowledgedAt = null,
        public ?string $resolution = null,
        public array $metadata = [],
    ) {
    }

    /**
     * Creates new pattern from first error event
     */
    public static function fromErrorEvent(ErrorEvent $event, \App\Framework\DateTime\Clock $clock): self
    {
        return new self(
            id: new Ulid($clock),
            fingerprint: $event->getFingerprint(),
            service: $event->service,
            component: $event->component,
            operation: $event->operation,
            errorCode: $event->errorCode->value,
            normalizedMessage: $event->errorMessage,
            severity: $event->severity,
            occurrenceCount: 1,
            firstOccurrence: $event->occurredAt,
            lastOccurrence: $event->occurredAt,
            affectedUsers: $event->userId ? [$event->userId] : [],
            affectedIps: $event->clientIp ? [$event->clientIp] : [],
        );
    }

    /**
     * Updates pattern with new error occurrence
     */
    public function withNewOccurrence(ErrorEvent $event): self
    {
        $affectedUsers = $this->affectedUsers;
        if ($event->userId && ! in_array($event->userId, $affectedUsers)) {
            $affectedUsers[] = $event->userId;
        }

        $affectedIps = $this->affectedIps;
        if ($event->clientIp && ! in_array($event->clientIp, $affectedIps)) {
            $affectedIps[] = $event->clientIp;
        }

        return new self(
            id: $this->id,
            fingerprint: $this->fingerprint,
            service: $this->service,
            component: $this->component,
            operation: $this->operation,
            errorCode: $this->errorCode,
            normalizedMessage: $this->normalizedMessage,
            severity: $this->severity,
            occurrenceCount: $this->occurrenceCount + 1,
            firstOccurrence: $this->firstOccurrence,
            lastOccurrence: $event->occurredAt,
            affectedUsers: $affectedUsers,
            affectedIps: $affectedIps,
            isActive: $this->isActive,
            isAcknowledged: $this->isAcknowledged,
            acknowledgedBy: $this->acknowledgedBy,
            acknowledgedAt: $this->acknowledgedAt,
            resolution: $this->resolution,
            metadata: $this->metadata,
        );
    }

    /**
     * Marks pattern as acknowledged
     */
    public function acknowledge(string $acknowledgedBy, ?string $resolution = null): self
    {
        return new self(
            id: $this->id,
            fingerprint: $this->fingerprint,
            service: $this->service,
            component: $this->component,
            operation: $this->operation,
            errorCode: $this->errorCode,
            normalizedMessage: $this->normalizedMessage,
            severity: $this->severity,
            occurrenceCount: $this->occurrenceCount,
            firstOccurrence: $this->firstOccurrence,
            lastOccurrence: $this->lastOccurrence,
            affectedUsers: $this->affectedUsers,
            affectedIps: $this->affectedIps,
            isActive: $this->isActive,
            isAcknowledged: true,
            acknowledgedBy: $acknowledgedBy,
            acknowledgedAt: new \DateTimeImmutable(),
            resolution: $resolution,
            metadata: $this->metadata,
        );
    }

    /**
     * Marks pattern as resolved (inactive)
     */
    public function resolve(string $resolution): self
    {
        return new self(
            id: $this->id,
            fingerprint: $this->fingerprint,
            service: $this->service,
            component: $this->component,
            operation: $this->operation,
            errorCode: $this->errorCode,
            normalizedMessage: $this->normalizedMessage,
            severity: $this->severity,
            occurrenceCount: $this->occurrenceCount,
            firstOccurrence: $this->firstOccurrence,
            lastOccurrence: $this->lastOccurrence,
            affectedUsers: $this->affectedUsers,
            affectedIps: $this->affectedIps,
            isActive: false,
            isAcknowledged: true,
            acknowledgedBy: $this->acknowledgedBy,
            acknowledgedAt: $this->acknowledgedAt ?? new \DateTimeImmutable(),
            resolution: $resolution,
            metadata: $this->metadata,
        );
    }

    /**
     * Gets error frequency (errors per minute)
     */
    public function getFrequency(): float
    {
        $duration = $this->lastOccurrence->getTimestamp() - $this->firstOccurrence->getTimestamp();

        if ($duration <= 0) {
            return $this->occurrenceCount; // All errors in same second
        }

        return $this->occurrenceCount / ($duration / 60); // errors per minute
    }

    /**
     * Checks if pattern indicates a critical issue
     */
    public function isCriticalPattern(): bool
    {
        // High frequency errors
        if ($this->getFrequency() > 10) { // More than 10 errors per minute
            return true;
        }

        // Many affected users
        if (count($this->affectedUsers) > 50) {
            return true;
        }

        // Critical severity with multiple occurrences
        if ($this->severity === ErrorSeverity::CRITICAL && $this->occurrenceCount >= 3) {
            return true;
        }

        // Error severity with very high occurrence count
        if ($this->severity === ErrorSeverity::ERROR && $this->occurrenceCount >= 100) {
            return true;
        }

        return false;
    }

    /**
     * Gets alert threshold based on pattern characteristics
     */
    public function getAlertThreshold(): int
    {
        return match ($this->severity) {
            ErrorSeverity::CRITICAL => 1,  // Alert on first occurrence
            ErrorSeverity::ERROR => 5,     // Alert after 5 occurrences
            ErrorSeverity::WARNING => 20,  // Alert after 20 occurrences
            ErrorSeverity::INFO => 100,    // Alert after 100 occurrences
            ErrorSeverity::DEBUG => 500,   // Alert after 500 occurrences
        };
    }

    /**
     * Checks if pattern should trigger alert
     */
    public function shouldAlert(): bool
    {
        if ($this->isAcknowledged) {
            return false;
        }

        if (! $this->isActive) {
            return false;
        }

        return $this->occurrenceCount >= $this->getAlertThreshold();
    }

    /**
     * Gets urgency for alerting
     */
    public function getAlertUrgency(): AlertUrgency
    {
        if ($this->isCriticalPattern()) {
            return AlertUrgency::URGENT;
        }

        return match ($this->severity) {
            ErrorSeverity::CRITICAL => AlertUrgency::URGENT,
            ErrorSeverity::ERROR => AlertUrgency::HIGH,
            ErrorSeverity::WARNING => AlertUrgency::MEDIUM,
            default => AlertUrgency::LOW,
        };
    }

    /**
     * Converts to array for storage/transmission
     */
    public function toArray(): array
    {
        return [
            'id' => (string) $this->id,
            'fingerprint' => $this->fingerprint,
            'service' => $this->service,
            'component' => $this->component,
            'operation' => $this->operation,
            'error_code' => $this->errorCode,
            'normalized_message' => $this->normalizedMessage,
            'severity' => $this->severity->value,
            'occurrence_count' => $this->occurrenceCount,
            'first_occurrence' => $this->firstOccurrence->format('c'),
            'last_occurrence' => $this->lastOccurrence->format('c'),
            'affected_users' => $this->affectedUsers,
            'affected_ips' => $this->affectedIps,
            'is_active' => $this->isActive,
            'is_acknowledged' => $this->isAcknowledged,
            'acknowledged_by' => $this->acknowledgedBy,
            'acknowledged_at' => $this->acknowledgedAt?->format('c'),
            'resolution' => $this->resolution,
            'metadata' => $this->metadata,
            'frequency' => $this->getFrequency(),
            'is_critical' => $this->isCriticalPattern(),
        ];
    }

    /**
     * Creates from array (for deserialization)
     */
    public static function fromArray(array $data): self
    {
        return new self(
            id: Ulid::fromString($data['id']),
            fingerprint: $data['fingerprint'],
            service: $data['service'],
            component: $data['component'],
            operation: $data['operation'],
            errorCode: $data['error_code'],
            normalizedMessage: $data['normalized_message'],
            severity: ErrorSeverity::from($data['severity']),
            occurrenceCount: $data['occurrence_count'],
            firstOccurrence: new \DateTimeImmutable($data['first_occurrence']),
            lastOccurrence: new \DateTimeImmutable($data['last_occurrence']),
            affectedUsers: $data['affected_users'] ?? [],
            affectedIps: $data['affected_ips'] ?? [],
            isActive: $data['is_active'] ?? true,
            isAcknowledged: $data['is_acknowledged'] ?? false,
            acknowledgedBy: $data['acknowledged_by'],
            acknowledgedAt: $data['acknowledged_at'] ? new \DateTimeImmutable($data['acknowledged_at']) : null,
            resolution: $data['resolution'],
            metadata: $data['metadata'] ?? [],
        );
    }
}