<?php
namespace Zadex\Forms\Integrations;

defined('ABSPATH') || exit;

use WP_Error;
use Zadex\Forms\Fields;
use Zadex\Forms\Shortcodes;
use Zadex\Forms\Submission;

/**
 * "Slack" action: posts to a Slack incoming webhook (`https://hooks.slack.com/services/…`).
 *
 * Settings: `slack_webhook_url`, `slack_message` (template with shortcodes, Slack mrkdwn), `slack_blocks`
 * (Block Kit: a header with the form name, the message, then the fields as `*Label*\nvalue` pairs, ten per
 * section), `slack_username`, `slack_icon` (an image URL or an `:emoji:`; honoured by legacy webhooks),
 * `slack_required`. Visitor values are escaped for mrkdwn (`&`, `<`, `>`), so they cannot inject links or
 * `<!channel>` mentions; the message template itself is the site owner's and is sent as typed.
 */
final class Slack
{
    public const ID = 'slack';
    public const URL_PATTERN = '#^https://hooks\.slack\.com/(?:services|workflows|triggers)/[A-Za-z0-9_\-/]+$#';

    /** @return null|WP_Error */
    public static function handle(Submission $s, array $settings)
    {
        $payload = self::payload($s, $settings);
        if ($payload instanceof WP_Error) {
            Log::error(self::ID, $payload->get_error_message(), ['form' => $s->form_id]);
            return $payload;
        }
        $r = Http::json('POST', trim((string) $settings['slack_webhook_url']), $payload);
        if ($r instanceof WP_Error) {
            Log::error(self::ID, $r->get_error_message(), ['form' => $s->form_id, 'submission' => $s->id]);
            return $r;
        }
        return null;
    }

    public static function escape(string $text): string
    {
        return str_replace(['&', '<', '>'], ['&amp;', '&lt;', '&gt;'], $text);
    }

    /** @return array<string, mixed>|WP_Error */
    public static function payload(Submission $s, array $settings)
    {
        $get = static fn(string $k): string => isset($settings['slack_' . $k]) && is_scalar($settings['slack_' . $k]) ? trim((string) $settings['slack_' . $k]) : '';
        if (!preg_match(self::URL_PATTERN, $get('webhook_url'))) {
            return new WP_Error('zadex_slack_url', 'Slack: missing or invalid webhook URL.');
        }
        // Render the template against escaped values: the template stays as typed, visitor input is inert.
        $safe = clone $s;
        $safe->values = array_map(static fn($v) => is_array($v) ? array_map(static fn($x): string => self::escape((string) $x), $v) : self::escape((string) $v), $s->values);
        $safe->form_name = self::escape($s->form_name);
        $template = $get('message');
        $text = Shortcodes::render($template !== '' ? $template : 'New submission: *[form:name]*', $safe, 'plain');
        $blocks = !array_key_exists('slack_blocks', $settings) || !empty($settings['slack_blocks']);
        $payload = ['text' => mb_substr($text, 0, 3000)];
        if ($blocks) {
            $out = [['type' => 'header', 'text' => ['type' => 'plain_text', 'text' => mb_substr($s->form_name !== '' ? $s->form_name : 'New submission', 0, 150), 'emoji' => true]]];
            if ($text !== '') {
                $out[] = ['type' => 'section', 'text' => ['type' => 'mrkdwn', 'text' => mb_substr($text, 0, 3000)]];
            }
            $pairs = [];
            foreach (Fields::inputs($s->fields) as $id => $field) {
                if ($field['type'] === 'password') {
                    continue;
                }
                $value = $s->text($id);
                $pairs[] = ['type' => 'mrkdwn', 'text' => mb_substr('*' . self::escape($s->label($id)) . "*\n" . ($value !== '' ? self::escape($value) : '—'), 0, 2000)];
            }
            foreach (array_chunk($pairs, 10) as $chunk) {
                $out[] = ['type' => 'section', 'fields' => $chunk];
            }
            $payload['blocks'] = array_slice($out, 0, 50);
        }
        if ($get('username') !== '') {
            $payload['username'] = mb_substr(Shortcodes::render($get('username'), $s, 'header'), 0, 80);
        }
        $icon = $get('icon');
        if (preg_match('/^:[a-z0-9_+\-]+:$/i', $icon)) {
            $payload['icon_emoji'] = $icon;
        } elseif (preg_match('#^https://\S+$#i', $icon)) {
            $payload['icon_url'] = esc_url_raw($icon);
        }
        return $payload;
    }
}