<?php

if (!defined('ABSPATH')) {
    exit;
}

class AdGhost_Ads_Txt {

    public static function path() {
        if (!function_exists('get_home_path')) {
            require_once ABSPATH . 'wp-admin/includes/file.php';
        }
        return trailingslashit(get_home_path()) . 'ads.txt';
    }

    public static function detect_ads_txt() {
        return file_exists(self::path());
    }

    private static function filesystem() {
        global $wp_filesystem;
        if (empty($wp_filesystem)) {
            require_once ABSPATH . 'wp-admin/includes/file.php';
            WP_Filesystem();
        }
        return $wp_filesystem ?: null;
    }

    public static function read_ads_txt() {
        $fs = self::detect_ads_txt() ? self::filesystem() : null;
        if ($fs) {
            return (string) $fs->get_contents(self::path());
        }

        return (string) get_option('adghost_ads_txt_virtual', '');
    }

    public static function write_ads_txt($content) {
        $fs = self::filesystem();
        if (!$fs) {
            return false;
        }

        if (get_option('adghost_ads_txt_backup', null) === null) {
            add_option('adghost_ads_txt_backup', [
                'content' => self::read_ads_txt(),
                'existed' => self::detect_ads_txt(),
                'time'    => time(),
            ], '', false);
        }

        if ($fs->put_contents(self::path(), $content, FS_CHMOD_FILE)) {
            delete_option('adghost_ads_txt_virtual');
            return true;
        }

        update_option('adghost_ads_txt_virtual', (string) $content, false);
        return true;
    }

    public static function init() {
        add_action('init', [__CLASS__, 'maybe_serve'], 0);
    }

    public static function maybe_serve() {

        $path = (string) wp_parse_url(isset($_SERVER['REQUEST_URI']) ? sanitize_text_field(wp_unslash($_SERVER['REQUEST_URI'])) : '', PHP_URL_PATH);
        if (strtolower(trim($path, '/')) !== 'ads.txt') {
            return;
        }
        $stored = get_option('adghost_ads_txt_virtual', '');
        if ($stored === '' || !get_option('adghost_ads_txt_managed', false)) {
            return;
        }
        if (!headers_sent()) {
            header('Content-Type: text/plain; charset=utf-8');

            header('Cache-Control: max-age=86400');
        }

        echo $stored; // phpcs:ignore WordPress.Security.EscapeOutput -- text/plain document, sanitised on save.
        exit;
    }

    public static function is_virtual() {
        return get_option('adghost_ads_txt_virtual', '') !== '' && !self::detect_ads_txt();
    }

    public static function validate_ads_txt($content) {
        $lines = explode("\n", $content);
        $errors = [];
        $warnings = [];
        $seen = [];

        foreach ($lines as $index => $line) {

            $hash = strpos($line, '#');
            $line = trim($hash === false ? $line : substr($line, 0, $hash));
            if ($line === '') {
                continue;
            }

            if (preg_match('/^[A-Za-z]+\s*=/', $line)) {
                continue;
            }

            $parts = explode(',', $line);
            if (count($parts) < 3 || count($parts) > 4) {
                $errors[] = "Line " . ($index + 1) . ": Invalid field count (expected 3 or 4)";
                continue;
            }

            $domain = trim($parts[0]);
            $pub_id = trim($parts[1]);
            $type = strtoupper(trim($parts[2]));

            $fingerprint = strtolower($domain . '|' . $pub_id . '|' . $type);
            if (isset($seen[$fingerprint])) {
                $warnings[] = 'Line ' . ($index + 1) . ": Duplicate of line {$seen[$fingerprint]}";
            } else {
                $seen[$fingerprint] = $index + 1;
            }

            if (!filter_var('http://' . $domain, FILTER_VALIDATE_URL)) {
                $warnings[] = "Line " . ($index + 1) . ": Possible invalid domain '$domain'";
            }

            if ($type !== 'DIRECT' && $type !== 'RESELLER') {
                $errors[] = "Line " . ($index + 1) . ": Invalid relationship type '$type' (expected DIRECT or RESELLER)";
            }
        }

        return [
            'errors' => $errors,
            'warnings' => $warnings,
            'isValid' => empty($errors)
        ];
    }

    public static function get_assisted_entries() {
        return [
            'gam' => "# Google Ad Manager (verify your pub ID before uncommenting)\n# google.com, pub-1234567890, DIRECT, f08c47fec0942fa0",
            'adsense' => "# AdSense (verify your pub ID before uncommenting)\n# google.com, pub-1234567890, DIRECT, f08c47fec0942fa0",
            'common' => "# Common SSP Template\n# example-ssp.com, 12345, DIRECT, c08c47fec0942fa0"
        ];
    }
}