<?php
namespace Zadex\Dynamic;

defined('ABSPATH') || exit;

/**
 * What a dynamic tag renders against: the post, the viewing user, the query string and the queried term.
 *
 *  - Context::current()        the post in the loop / queried object of the current request (frontend).
 *  - Context::for_post($id)    a specific post (REST previews, theme-builder templates rendering another post).
 */
final class Context
{
    public int $post_id;
    public int $user_id;
    /** Queried term (archives): object with term_id, name, description, taxonomy, or null. */
    public ?object $term;
    /** @var array<string, mixed> query-string parameters (url-param tag) */
    public array $query;

    /** @param array<string, mixed> $query */
    public function __construct(int $post_id = 0, int $user_id = 0, ?object $term = null, array $query = [])
    {
        $this->post_id = max(0, $post_id);
        $this->user_id = max(0, $user_id);
        $this->term = $term;
        $this->query = $query;
    }

    public static function current(): self
    {
        $post_id = function_exists('get_the_ID') ? (int) get_the_ID() : 0;
        $term = null;
        if (function_exists('get_queried_object')) {
            $queried = get_queried_object();
            if (is_object($queried) && isset($queried->term_id, $queried->taxonomy)) {
                $term = $queried;
            }
        }
        return new self($post_id, self::current_user_id(), $term, self::request_query());
    }

    public static function for_post(int $post_id): self
    {
        return new self($post_id, self::current_user_id(), null, self::request_query());
    }

    /** @param array<string, mixed> $query */
    public function with_query(array $query): self
    {
        $clone = clone $this;
        $clone->query = $query;
        return $clone;
    }

    /** @return \WP_Post|null */
    public function post(): ?object
    {
        if ($this->post_id <= 0 || !function_exists('get_post')) {
            return null;
        }
        $post = get_post($this->post_id);
        return is_object($post) ? $post : null;
    }

    private static function current_user_id(): int
    {
        return function_exists('get_current_user_id') ? (int) get_current_user_id() : 0;
    }

    /** @return array<string, mixed> */
    private static function request_query(): array
    {
        // Public query-string values for the read-only "URL parameter" dynamic tag (e.g. ?utm_source=x printed on
        // a landing page). Nothing is changed by them, so there is no nonce; every value is unslashed and
        // sanitized here, and nested arrays are dropped.
        $query = map_deep(wp_unslash($_GET), 'sanitize_text_field'); // phpcs:ignore WordPress.Security.NonceVerification.Recommended
        return is_array($query) ? array_filter($query, 'is_scalar') : [];
    }
}