<?php
/**
 * A Content Studio document in its Markdown layout.
 *
 * @package MazeAi
 * @since   0.1.0
 */

declare(strict_types=1);

namespace MazeAi\Support;

defined('ABSPATH') || exit;

/**
 * The `studio-content` agent answers in one layout: `# Title`, a `> excerpt` line, then the body. This reads that
 * layout (tolerating a missing excerpt, text before the title, or a fenced answer) and writes it back for a refine
 * request. It also fills a template's `{field}` placeholders.
 *
 * @since 0.1.0
 */
final class StudioDocument
{
    /**
     * @since 0.1.0
     * @return array{title: string, excerpt: string, body: string}
     */
    public static function parse(string $markdown): array
    {
        $text = trim(str_replace(["\r\n", "\r"], "\n", $markdown));
        if (preg_match('/^```(?:markdown|md)?\n(.*)\n```$/s', $text, $m)) {
            $text = trim($m[1]);
        }
        $lines = explode("\n", $text);
        $title = '';
        foreach ($lines as $i => $line) {
            if (preg_match('/^#\s+(.+?)\s*#*\s*$/', $line, $m)) {
                $title = trim($m[1]);
                $lines = array_slice($lines, $i + 1);
                break;
            }
        }
        while ($lines !== [] && trim($lines[0]) === '') {
            array_shift($lines);
        }
        $excerpt = [];
        while ($lines !== [] && str_starts_with(ltrim($lines[0]), '>')) {
            $excerpt[] = trim((string) preg_replace('/^\s*>\s?/', '', (string) array_shift($lines)));
        }

        return ['title' => $title, 'excerpt' => trim(implode(' ', $excerpt)), 'body' => trim(implode("\n", $lines))];
    }

    /**
     * @since 0.1.0
     * @param array{title: string, excerpt: string, body: string} $document
     */
    public static function compose(array $document): string
    {
        return trim('# ' . $document['title'] . "\n\n" . ($document['excerpt'] !== '' ? '> ' . $document['excerpt'] . "\n\n" : '') . $document['body']);
    }

    /**
     * Fill `{field}` placeholders; a field left empty reads "not specified".
     *
     * @since 0.1.0
     * @param array<string, string> $values
     */
    public static function fill(string $instructions, array $values): string
    {
        return (string) preg_replace_callback('/\{([a-z][a-z0-9_]{0,30})\}/', static function (array $m) use ($values): string {
            $value = trim($values[$m[1]] ?? '');

            return $value !== '' ? $value : 'not specified';
        }, $instructions);
    }
}