<?php
if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

/**
 * Handles the generation of weighted pools of target URLs.
 *
 * @since      1.0
 * @package    AILinkMaster
 * @subpackage AILinkMaster/includes
 */
class AILM_Pool_Generator {

    /**
     * Generates a weighted and cached pool of target URLs based on a rule.
     *
     * @since 1.0
     * @param array $rule The linking rule.
     * @param int $pool_size The desired size of the pool.
     * @param bool $debug_mode Whether debug mode is active.
     * @return array The array of target URLs.
     */
    public function generate_pool( $rule, $pool_size, $debug_mode, $shuffle = true ) {
        $cache_hours = get_option( 'ailm_cache_hours', 24 );
        $cache_seconds = $cache_hours * 3600;
        $target_limit = get_option( 'ailm_target_limit', 10 );

        $mix_fingerprint = '';
        if ( ! empty( $rule['mix_rules'] ) ) {
            foreach ( $rule['mix_rules'] as $m ) {
                $mix_fingerprint .= $m['cat'] . '-' . $m['pct'];
            }
        }
        
        $transient_key = 'ailm_pool_' . $rule['cat_id'] . '_' . $rule['target_age'] . '_' . md5( $mix_fingerprint . ( $shuffle ? '_s' : '' ) );

        if ( ! $debug_mode ) {
            $cached = get_transient( $transient_key );
            if ( $cached ) {
                return ( $cached === 'empty' ) ? [] : $cached;
            }
        }

        $final_urls = [];
        $used_pct = 0;

        if ( ! empty( $rule['mix_rules'] ) ) {
            foreach ( $rule['mix_rules'] as $mix ) {
                $m_cat = intval( $mix['cat'] );
                $m_pct = intval( $mix['pct'] );
                if ( $m_pct <= 0 || $m_cat == 0 ) {
                    continue;
                }

                $limit_for_mix = ceil( $pool_size * ( $m_pct / 100 ) );
                $used_pct += $m_pct;

                $args = [
                    'post_type'      => 'post',
                    'posts_per_page' => $limit_for_mix,
                    'orderby'        => 'date',
                    'order'          => 'DESC',
                    'post_status'    => 'publish',
                    'cat'            => $m_cat,
                    'date_query'     => [ [ 'after' => $rule['target_age'] . ' days ago' ] ]
                ];
                $q = new WP_Query( $args );
                if ( $q->have_posts() ) {
                    foreach ( $q->posts as $p ) {
                        if ( $this->is_noindex( $p->ID ) ) {
                            continue;
                        }
                        $inbound = (int) get_post_meta( $p->ID, '_ailm_inbound_count', true );
                        if ( $inbound >= $target_limit ) {
                            continue;
                        }
                        $final_urls[] = get_permalink( $p->ID );
                    }
                }
            }
        }

        $main_pct = 100 - $used_pct;
        if ( $main_pct > 0 ) {
            $limit_for_main = ceil( $pool_size * ( $main_pct / 100 ) );
            $args = [
                'post_type'      => 'post',
                'posts_per_page' => $limit_for_main,
                'orderby'        => 'date',
                'order'          => 'DESC',
                'post_status'    => 'publish',
                'date_query'     => [ [ 'after' => $rule['target_age'] . ' days ago' ] ]
            ];
            if ( $rule['cat_id'] != 0 ) {
                $args['cat'] = $rule['cat_id'];
            }

            $q = new WP_Query( $args );
            if ( $q->have_posts() ) {
                foreach ( $q->posts as $p ) {
                    if ( $this->is_noindex( $p->ID ) ) {
                        continue;
                    }
                    $inbound = (int) get_post_meta( $p->ID, '_ailm_inbound_count', true );
                    if ( $inbound >= $target_limit ) {
                        continue;
                    }
                    $final_urls[] = get_permalink( $p->ID );
                }
            }
        }

        if ( empty( $final_urls ) ) {
            if ( ! $debug_mode ) {
                set_transient( $transient_key, 'empty', $cache_seconds );
            }
            return [];
        }
        
        if ($shuffle) {
            shuffle( $final_urls );
        }

        if ( count( $final_urls ) > $pool_size ) {
            $final_urls = array_slice( $final_urls, 0, $pool_size );
        }

        if ( ! $debug_mode ) {
            set_transient( $transient_key, $final_urls, $cache_seconds );
        }

        return $final_urls;
    }

    /**
     * Helper function to check for noindex meta from popular SEO plugins.
     *
     * @since 1.0
     * @param int $pid The Post ID.
     * @return bool True if the post is marked as noindex.
     */
    private function is_noindex( $pid ) {
        // Yoast SEO
        $yoast_noindex = get_post_meta( $pid, '_yoast_wpseo_meta-robots-noindex', true );
        if ( $yoast_noindex == 1 || $yoast_noindex == 2 ) {
            return true;
        }
        // Rank Math
        $rm_robots = get_post_meta( $pid, 'rank_math_robots', true );
        if ( is_array( $rm_robots ) && in_array( 'noindex', $rm_robots ) ) {
            return true;
        }
        return false;
    }
}