<?php

namespace Advanced_Media_Offloader\Observers;

use Advanced_Media_Offloader\Abstracts\S3_Provider;
use Advanced_Media_Offloader\Interfaces\ObserverInterface;
use Advanced_Media_Offloader\Traits\OffloaderTrait;

class ImageSrcsetObserver implements ObserverInterface
{
    use OffloaderTrait;

    /**
     * @var S3_Provider
     */
    private S3_Provider $cloudProvider;

    /**
     * The base URL for uploads.
     *
     * @var string
     */
    private string $upload_base_url;

    /**
     * Constructor.
     *
     * @param S3_Provider $cloudProvider
     */
    public function __construct(S3_Provider $cloudProvider)
    {
        $this->cloudProvider = $cloudProvider;
        $upload_dir = wp_get_upload_dir();
        $this->upload_base_url = trailingslashit($upload_dir['baseurl']);
    }

    /**
     * Register the observer with WordPress hooks.
     *
     * @return void
     */
    public function register(): void
    {
        add_filter('wp_calculate_image_srcset', [$this, 'run'], 10, 5);
    }

    /**
     * Modify the image srcset.
     * @param array $sources
     * @param array $size_array
     * @param array $image_src
     * @param array $image_meta
     * @param int $attachment_id
     * @return array
     */
    public function run(array $sources, array $size_array, string $image_src,   array $image_meta,  int $attachment_id)
    {
        if (! $this->is_offloaded($attachment_id)) {
            return $sources;
        }

        $domain = $this->cloudProvider->getDomain();
        if (empty($domain)) {
            // No custom domain provided, leave the original sources intact.
            return $sources;
        }

        $subDir = $this->get_attachment_subdir($attachment_id);
        $domain = rtrim($domain, '/');

        return array_map(function ($source) use ($subDir, $domain) {
            $source['url'] = $domain . '/' . ltrim($subDir, '/') . basename($source['url']);
            return $source;
        }, $sources);
    }
}