<?php

declare(strict_types=1);

namespace VPlugins\WPCloudClient\Handler;

/**
 * Checks for available updates for WordPress themes.
 *
 * Action name: check_theme_updates
 *
 * Optional params:
 *   - slug (string) - Specific theme stylesheet to check (e.g., "twentytwentyfour").
 *                     If not provided, checks all installed themes for updates.
 *
 * Example response for all themes:
 * {
 *   "has_updates": true,
 *   "updates": [
 *     {
 *       "slug": "twentytwentyfive",
 *       "name": "Twenty Twenty-Five",
 *       "current_version": "1.0",
 *       "new_version": "1.1",
 *       "download_url": "https://...",
 *       "requires_wp": "6.0",
 *       "requires_php": "7.4"
 *     }
 *   ]
 * }
 */
final class CheckThemeUpdatesHandler extends AbstractHandler {

	/**
	 * Return the action name.
	 *
	 * @return string
	 */
	public function action(): string {
		return 'check_theme_updates';
	}

	/**
	 * Check for theme updates.
	 *
	 * @param array<string, mixed> $params Action parameters.
	 * @return array<string, mixed> Update status.
	 * @throws \InvalidArgumentException When required parameters are invalid.
	 */
	public function execute( array $params ): array {
		$slug = isset( $params['slug'] ) ? (string) $params['slug'] : null;

		if ( null !== $slug && empty( $slug ) ) {
			throw new \InvalidArgumentException( 'Theme slug cannot be empty.' );
		}

		// Get the theme update transient.
		$transient = get_site_transient( 'update_themes' );
		$updates   = [];

		if ( null !== $slug ) {
			// Check specific theme.
			$theme = wp_get_theme( $slug );
			if ( ! $theme->exists() ) {
				throw new \InvalidArgumentException( sprintf( 'Theme "%s" not found.', $slug ) );
			}

			if ( $this->hasUpdate( $transient, $slug ) ) {
				$updateData = $this->extractUpdateInfo( $slug, $theme, $transient );
				if ( null !== $updateData ) {
					$updates[] = $updateData;
				}
			}
		} else {
			// Check all themes.
			$themes = wp_get_themes();

			foreach ( $themes as $themeSlug => $theme ) {
				if ( $this->hasUpdate( $transient, $themeSlug ) ) {
					$updateData = $this->extractUpdateInfo( $themeSlug, $theme, $transient );
					if ( null !== $updateData ) {
						$updates[] = $updateData;
					}
				}
			}
		}

		return [
			'has_updates' => ! empty( $updates ),
			'updates'     => $updates,
		];
	}

	/**
	 * Check if a theme has an available update.
	 *
	 * @param mixed  $transient Update transient object.
	 * @param string $slug      Theme slug.
	 * @return bool True if update is available.
	 */
	private function hasUpdate( $transient, string $slug ): bool {
		if ( ! is_object( $transient ) || ! isset( $transient->response ) ) {
			return false;
		}

		if ( ! is_array( $transient->response ) && ! is_object( $transient->response ) ) {
			return false;
		}

		return isset( $transient->response[ $slug ] );
	}

	/**
	 * Extract update information from transient.
	 *
	 * @param string    $slug      Theme slug.
	 * @param \WP_Theme $theme     Theme object.
	 * @param mixed     $transient Update transient.
	 * @return array<string, mixed>|null Extracted update info or null.
	 */
	private function extractUpdateInfo( string $slug, \WP_Theme $theme, $transient ): ?array {
		if ( ! is_object( $transient ) || ! isset( $transient->response[ $slug ] ) ) {
			return null;
		}

		$updateData     = $transient->response[ $slug ];
		$currentVersion = $theme->get( 'Version' );
		$newVersion     = $updateData['new_version'] ?? '';
		$themeName      = $theme->get( 'Name' );

		return [
			'slug'            => $slug,
			'name'            => $themeName,
			'current_version' => $currentVersion,
			'new_version'     => $newVersion,
			'download_url'    => $updateData['package'] ?? '',
			'requires_wp'     => $updateData['requires'] ?? '',
			'requires_php'    => $updateData['requires_php'] ?? '',
			'tested_up_to'    => $updateData['tested'] ?? '',
			'theme_url'       => $theme->get( 'ThemeURI' ),
		];
	}
}