<?php

declare(strict_types=1);

namespace KTXF\Preview;

use InvalidArgumentException;

final readonly class PreviewRequest
{
    public string $preferredMimeType;

    public function __construct(
        public string $variant,
        public int $maxWidth,
        public int $maxHeight,
        string $preferredMimeType,
        public int $quality,
        public ?int $page = null,
        public ?float $timestamp = null,
    ) {
        if (preg_match('/^[a-z][a-z0-9-]*$/', $this->variant) !== 1) {
            throw new InvalidArgumentException('Preview variant must use lowercase letters, numbers, and hyphens');
        }
        if ($this->maxWidth < 1 || $this->maxHeight < 1) {
            throw new InvalidArgumentException('Preview dimensions must be positive');
        }
        if ($this->quality < 1 || $this->quality > 100) {
            throw new InvalidArgumentException('Preview quality must be between 1 and 100');
        }
        if ($this->page !== null && $this->page < 1) {
            throw new InvalidArgumentException('Preview page numbers start at 1');
        }
        if ($this->timestamp !== null && $this->timestamp < 0) {
            throw new InvalidArgumentException('Preview timestamps cannot be negative');
        }
        $this->preferredMimeType = MimeType::normalize($preferredMimeType);
    }

    /**
     * Fixed-order scalar representation for cache-key generation.
     *
     * @return array{variant:string,maxWidth:int,maxHeight:int,preferredMimeType:string,quality:int,page:?int,timestamp:?float}
     */
    public function normalized(): array
    {
        return [
            'variant' => $this->variant,
            'maxWidth' => $this->maxWidth,
            'maxHeight' => $this->maxHeight,
            'preferredMimeType' => $this->preferredMimeType,
            'quality' => $this->quality,
            'page' => $this->page,
            'timestamp' => $this->timestamp,
        ];
    }
}