<?php

namespace App\Services;

class AiQuestionStructService
{
    public function buildQuestionFromSourcePrompt(string $sourceText): string
    {
        return app(QuestionPromptService::class)->buildQuestionFromSourcePrompt($sourceText);
    }

    public function detectQuestionBlocks(string $rawMarkdown): array
    {
        return [
            [
                'raw_markdown' => $rawMarkdown,
                'index' => 1,
            ],
        ];
    }

    public function extractFields(string $questionText): array
    {
        return [
            'stem' => trim($questionText),
            'options' => $this->extractOptions($questionText),
            'answer' => null,
            'solution' => null,
        ];
    }

    public function classifyQuestionType(string $questionText, array $options = []): string
    {
        if (!empty($options)) {
            return 'choice';
        }

        if (preg_match('/\b填空\b|\b选择\b/u', $questionText)) {
            return 'fill';
        }

        return 'short';
    }

    public function estimateDifficulty(string $questionText, array $meta = []): int
    {
        $length = mb_strlen($questionText);
        if ($length <= 60) {
            return 1;
        }
        if ($length <= 120) {
            return 2;
        }
        return 3;
    }

    public function buildStructuredQuestion(array $raw, array $context = []): array
    {
        $fields = $this->extractFields((string) ($raw['raw_markdown'] ?? ''));
        $questionType = $this->classifyQuestionType((string) ($fields['stem'] ?? ''), $fields['options'] ?? []);

        return array_merge($raw, [
            'question_type' => $questionType,
            'difficulty' => $this->estimateDifficulty((string) ($fields['stem'] ?? ''), $context),
        ], $fields);
    }

    private function extractOptions(string $text): array
    {
        $options = [];
        preg_match_all('/^\s*([A-D])[\\.|．、\\)]\\s*(.+)$/m', $text, $matches, PREG_SET_ORDER);
        foreach ($matches as $match) {
            $options[] = [
                'label' => $match[1],
                'text' => trim($match[2]),
            ];
        }

        return $options;
    }
}