<?php
namespace Zadex\Theme;

defined('ABSPATH') || exit;

use Zadex\Editor\EditorLoader;
use Zadex\Frontend\Templates;

/**
 * Single / archive / search / 404 templates (T113): on `template_include` (priority 999, after the page
 * templates) the request is served by views/page.php when a template of the matching location resolves.
 *
 * Not applied in the editor (?zadex=edit|preview keeps the canvas mount point in the theme's content), to
 * theme templates themselves, or to posts that picked a Zadex page layout (Canvas / Full Width) explicitly.
 */
final class Locations
{
    /** @var callable(string): ?int */
    private $resolve;
    private int $current = 0;

    public function __construct(?callable $resolve = null)
    {
        $this->resolve = $resolve ?? [Resolver::class, 'for_location'];
    }

    public function register(): void
    {
        add_filter('template_include', [$this, 'template_include'], 999);
        add_filter('zadex/theme/location_candidates', [$this, 'front_page_candidates'], 5, 2);
    }

    /** Adds cross-location fallback on front page so a front-targeted template applies regardless of whether the front is single or archive. */
    public function front_page_candidates(array $candidates, string $location): array
    {
        if (function_exists('is_front_page') && is_front_page()) {
            if ($location === 'archive' && !in_array('single', $candidates, true)) {
                $candidates[] = 'single';
            } elseif ($location === 'single' && !in_array('archive', $candidates, true)) {
                $candidates[] = 'archive';
            }
        }
        return $candidates;
    }

    /** Location of the current request: 404 | search | single | archive | ''. */
    public static function location(): string
    {
        if (is_404()) {
            return '404';
        }
        if (is_search()) {
            return 'search';
        }
        if (is_singular()) {
            return 'single';
        }
        if (is_archive() || is_home()) {
            return 'archive';
        }
        return '';
    }

    /**
     * Template types tried for a location, most specific first. Filter `zadex/theme/location_candidates`
     * (string[] $types, string $location): WooCommerce puts `product` before `single` on product pages and
     * `product_archive` before `archive` on the shop / product taxonomy archives.
     *
     * @return string[]
     */
    public static function candidates(string $location): array
    {
        if ($location === '') {
            return [];
        }
        $list = apply_filters('zadex/theme/location_candidates', [$location], $location);
        return is_array($list) ? array_values(array_unique(array_filter($list, static fn($t): bool => is_string($t) && $t !== ''))) : [$location];
    }

    public function template_include($template)
    {
        if (EditorLoader::mode() !== '' || is_singular(TemplatePost::POST_TYPE)) {
            return $template;
        }
        $location = self::location();
        if ($location === '') {
            return $template;
        }
        if ($location === 'single' && Templates::get((int) get_queried_object_id()) !== '') {
            return $template;
        }
        $id = 0;
        foreach (self::candidates($location) as $candidate) {
            $found = ($this->resolve)($candidate);
            if (is_int($found) && $found > 0) {
                $id = $found;
                break;
            }
        }
        if ($id <= 0) {
            return $template;
        }
        $this->current = $id;
        return __DIR__ . '/views/page.php';
    }

    /** Template chosen for this request by template_include (0 when the theme's template is used). */
    public function current(): int
    {
        return $this->current;
    }
}