<?php

namespace App\Services;

use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Schema;

/**
 * 题目质检服务
 *
 * 校验规则：题干、答案、解析、选项、公式、PDF 呈现、AI 答案校验
 * 结果由命令输出，不落库（避免本地库覆盖）
 */
class QuestionQualityCheckService
{
    private ?AiClientService $aiClient = null;

    public function __construct(?AiClientService $aiClient = null)
    {
        $this->aiClient = $aiClient ?? (app()->bound(AiClientService::class) ? app(AiClientService::class) : null);
    }
    public const RULES = [
        'STEM_EMPTY' => ['name' => '题干为空', 'severity' => 'error'],
        'ANSWER_EMPTY' => ['name' => '答案为空', 'severity' => 'error'],
        'SOLUTION_EMPTY' => ['name' => '解析为空', 'severity' => 'warning'],
        'CHOICE_OPTIONS_MISSING' => ['name' => '选择题缺选项', 'severity' => 'error'],
        'CHOICE_OPTIONS_JSON_INVALID' => ['name' => '选择题选项JSON无效', 'severity' => 'error'],
        'CHOICE_OPTION_TEXT_EMPTY' => ['name' => '选择题存在空白选项', 'severity' => 'warning'],
        'ANSWER_OPTION_MISMATCH' => ['name' => '选择题答案不在选项中', 'severity' => 'error'],
        'FORMULA_INVALID' => ['name' => '公式异常', 'severity' => 'error'],
        'CONTENT_TOO_SHORT' => ['name' => '题干过短', 'severity' => 'warning'],
        'AI_ANSWER_INVALID' => ['name' => 'AI 判定答案错误', 'severity' => 'error'],
        'AI_ANSWER_MISMATCH' => ['name' => 'AI 判定答案与题目不匹配', 'severity' => 'error'],
    ];

    /**
     * 对单道题目执行自动质检
     *
     * @param array $question 题目数据，需包含 stem, answer, solution, question_type, options；
     *                         可选 options_json_invalid=true（options 字段为字符串但 JSON 解析失败）
     * @param int|null $questionTemId questions_tem 表 ID
     * @param int|null $questionId questions 表 ID
     * @param array $options ['ai_check' => bool] 是否启用 AI 校验（答案正确性、与题目匹配）
     * @return array ['passed' => bool, 'results' => array, 'errors' => array]
     */
    public function runAutoCheck(array $question, ?int $questionTemId = null, ?int $questionId = null, array $options = []): array
    {
        $stem = $question['stem'] ?? $question['content'] ?? '';
        $answer = $question['answer'] ?? '';
        $solution = $question['solution'] ?? '';
        $questionType = $this->normalizeQuestionType(
            (string) ($question['question_type'] ?? $question['tags'] ?? '')
        );
        $options = $question['options'] ?? null;
        $optionsJsonInvalid = ! empty($question['options_json_invalid']);

        $results = [];
        $errors = [];

        // STEM_EMPTY / CONTENT_TOO_SHORT
        $stemLen = mb_strlen(trim((string) $stem));
        if ($stemLen === 0) {
            $results[] = $this->recordCheck('STEM_EMPTY', false, '题干为空');
            $errors[] = 'STEM_EMPTY';
        } elseif ($stemLen < 5) {
            $results[] = $this->recordCheck('CONTENT_TOO_SHORT', false, "题干过短({$stemLen}字)");
            $errors[] = 'CONTENT_TOO_SHORT';
        } else {
            $results[] = $this->recordCheck('STEM_EMPTY', true);
        }

        // ANSWER_EMPTY
        if (trim((string) $answer) === '') {
            $results[] = $this->recordCheck('ANSWER_EMPTY', false, '答案为空');
            $errors[] = 'ANSWER_EMPTY';
        } else {
            $results[] = $this->recordCheck('ANSWER_EMPTY', true);
        }

        // SOLUTION_EMPTY（解答题强校验）
        $isAnswerType = $questionType === 'answer';
        if ($isAnswerType && trim((string) $solution) === '') {
            $results[] = $this->recordCheck('SOLUTION_EMPTY', false, '解答题解析为空');
            $errors[] = 'SOLUTION_EMPTY';
        } else {
            $results[] = $this->recordCheck('SOLUTION_EMPTY', true);
        }

        // CHOICE_OPTIONS_*（与 PDF 导出口径：选项 JSON、非空文案数量）
        $isChoice = $questionType === 'choice';
        if ($isChoice) {
            if ($optionsJsonInvalid) {
                $results[] = $this->recordCheck('CHOICE_OPTIONS_JSON_INVALID', false, 'options 字段不是合法 JSON');
                $errors[] = 'CHOICE_OPTIONS_JSON_INVALID';
                $results[] = $this->recordCheck('CHOICE_OPTIONS_MISSING', true, null, 'skip');
                $results[] = $this->recordCheck('CHOICE_OPTION_TEXT_EMPTY', true, null, 'skip');
            } else {
                $optionTexts = $this->extractOptionTexts(is_array($options) ? $options : null);
                $nonEmpty = array_values(array_filter($optionTexts, fn ($t) => mb_strlen(trim((string) $t)) > 0));

                if (count($nonEmpty) < 2) {
                    $results[] = $this->recordCheck('CHOICE_OPTIONS_MISSING', false, '选择题有效选项不足2个');
                    $errors[] = 'CHOICE_OPTIONS_MISSING';
                } else {
                    $results[] = $this->recordCheck('CHOICE_OPTIONS_MISSING', true);
                }

                $hasEmptySlot = count($optionTexts) > 0
                    && count($nonEmpty) < count($optionTexts);
                if ($hasEmptySlot) {
                    $results[] = $this->recordCheck('CHOICE_OPTION_TEXT_EMPTY', false, '存在空白选项项');
                    $errors[] = 'CHOICE_OPTION_TEXT_EMPTY';
                } else {
                    $results[] = $this->recordCheck('CHOICE_OPTION_TEXT_EMPTY', true);
                }
            }
        } else {
            $results[] = $this->recordCheck('CHOICE_OPTIONS_MISSING', true, null, 'skip');
            $results[] = $this->recordCheck('CHOICE_OPTIONS_JSON_INVALID', true, null, 'skip');
            $results[] = $this->recordCheck('CHOICE_OPTION_TEXT_EMPTY', true, null, 'skip');
        }

        // ANSWER_OPTION_MISMATCH：选择题答案必须在选项中
        if ($isChoice && ! $optionsJsonInvalid && is_array($options)) {
            $answerLetter = $this->extractChoiceAnswerLetter((string) $answer);
            $optionKeysRaw = array_keys($options);
            $optionLetters = array_map(fn ($k) => strtoupper(substr((string) $k, 0, 1)), $optionKeysRaw);
            if ($answerLetter !== null && ! in_array($answerLetter, $optionLetters, true)) {
                $results[] = $this->recordCheck('ANSWER_OPTION_MISMATCH', false, "答案 {$answerLetter} 不在选项 " . implode(',', $optionLetters) . " 中");
                $errors[] = 'ANSWER_OPTION_MISMATCH';
            } elseif ($answerLetter === null && trim((string) $answer) !== '') {
                $results[] = $this->recordCheck('ANSWER_OPTION_MISMATCH', false, '答案格式无法识别为选项（应为 A/B/C/D）');
                $errors[] = 'ANSWER_OPTION_MISMATCH';
            } else {
                $results[] = $this->recordCheck('ANSWER_OPTION_MISMATCH', true);
            }
        } else {
            $results[] = $this->recordCheck('ANSWER_OPTION_MISMATCH', true, null, 'skip');
        }

        // FORMULA_INVALID（题干、答案、解析、选择题各选项；捕获异常）
        try {
            $processed = MathFormulaProcessor::processFormulas($stem);
            $processedAnswer = MathFormulaProcessor::processFormulas($answer);
            $processedSolution = MathFormulaProcessor::processFormulas($solution);

            $hasError = $this->detectFormulaError($processed)
                || $this->detectFormulaError($processedAnswer)
                || $this->detectFormulaError($processedSolution);

            if ($isChoice && ! $optionsJsonInvalid && is_array($options)) {
                foreach ($this->extractOptionTexts($options) as $optText) {
                    if (trim((string) $optText) === '') {
                        continue;
                    }
                    $po = MathFormulaProcessor::processFormulas((string) $optText);
                    if ($this->detectFormulaError($po)) {
                        $hasError = true;
                        break;
                    }
                }
            }

            if ($hasError) {
                $results[] = $this->recordCheck('FORMULA_INVALID', false, '公式定界符不匹配或存在异常');
                $errors[] = 'FORMULA_INVALID';
            } else {
                $results[] = $this->recordCheck('FORMULA_INVALID', true);
            }
        } catch (\Throwable $e) {
            $results[] = $this->recordCheck('FORMULA_INVALID', false, $e->getMessage());
            $errors[] = 'FORMULA_INVALID';
        }

        // AI 校验：答案正确性、答案与题目匹配（需开启 ai_check，且基础校验通过时再调 AI）
        $aiCheck = $options['ai_check'] ?? false;
        if ($aiCheck && $this->aiClient && empty($errors) && trim((string) $answer) !== '') {
            try {
                $aiResult = $this->runAiAnswerCheck($question);
                if (is_array($aiResult)) {
                    if (! ($aiResult['answer_correct'] ?? true)) {
                        $results[] = $this->recordCheck('AI_ANSWER_INVALID', false, $aiResult['reason'] ?? 'AI 判定答案错误');
                        $errors[] = 'AI_ANSWER_INVALID';
                    } else {
                        $results[] = $this->recordCheck('AI_ANSWER_INVALID', true);
                    }
                    if (! ($aiResult['answer_matches_question'] ?? true)) {
                        $results[] = $this->recordCheck('AI_ANSWER_MISMATCH', false, $aiResult['reason'] ?? 'AI 判定答案与题目不匹配');
                        $errors[] = 'AI_ANSWER_MISMATCH';
                    } else {
                        $results[] = $this->recordCheck('AI_ANSWER_MISMATCH', true);
                    }
                } else {
                    $results[] = $this->recordCheck('AI_ANSWER_INVALID', true, null, 'skip');
                    $results[] = $this->recordCheck('AI_ANSWER_MISMATCH', true, null, 'skip');
                }
            } catch (\Throwable $e) {
                Log::warning('QuestionQualityCheckService: AI 校验异常', ['error' => $e->getMessage()]);
                $results[] = $this->recordCheck('AI_ANSWER_INVALID', true, null, 'skip');
                $results[] = $this->recordCheck('AI_ANSWER_MISMATCH', true, null, 'skip');
            }
        } else {
            $results[] = $this->recordCheck('AI_ANSWER_INVALID', true, null, 'skip');
            $results[] = $this->recordCheck('AI_ANSWER_MISMATCH', true, null, 'skip');
        }

        $passed = empty($errors);

        return [
            'passed' => $passed,
            'results' => $results,
            'errors' => $errors,
        ];
    }

    /**
     * 与组卷/PDF 口径一致：归一化为 choice | fill | answer
     */
    private function normalizeQuestionType(string $raw): string
    {
        $t = strtolower(trim($raw));
        if ($t === '') {
            return 'answer';
        }

        return match (true) {
            str_contains($t, 'choice') || str_contains($t, '选择') => 'choice',
            str_contains($t, 'fill') || str_contains($t, 'blank') || str_contains($t, '填空') => 'fill',
            in_array($t, ['single_choice', 'multiple_choice', 'select'], true) => 'choice',
            in_array($t, ['fill_in_the_blank'], true) => 'fill',
            in_array($t, ['answer', 'calculation', 'word_problem', 'proof', '解答', '简答'], true) => 'answer',
            default => 'answer',
        };
    }

    /**
     * 将 options 转为选项文案列表（与 ExamPdfController::normalizeOptions 语义对齐）
     *
     * @param array|null $options
     * @return list<string>
     */
    private function extractOptionTexts(?array $options): array
    {
        if ($options === null || $options === []) {
            return [];
        }

        if (! isset($options[0]) && $options !== []) {
            return array_values(array_map(static fn ($v) => (string) $v, $options));
        }

        if (isset($options[0]) && is_array($options[0])) {
            $normalized = [];
            foreach ($options as $opt) {
                if (! is_array($opt)) {
                    $normalized[] = (string) $opt;

                    continue;
                }
                if (isset($opt['text'])) {
                    $normalized[] = (string) $opt['text'];
                } elseif (isset($opt['value'])) {
                    $normalized[] = (string) $opt['value'];
                } else {
                    $normalized[] = (string) reset($opt);
                }
            }

            return $normalized;
        }

        return array_values(array_map(static fn ($v) => (string) $v, $options));
    }

    /**
     * 检测公式处理后的内容是否仍有明显错误（如未闭合的 $）
     */
    private function detectFormulaError(string $content): bool
    {
        $len = strlen($content);
        $dollarCount = 0;
        $inEscape = false;
        for ($i = 0; $i < $len; $i++) {
            $c = $content[$i];
            if ($c === '\\' && !$inEscape) {
                $inEscape = true;
                continue;
            }
            if ($c === '$') {
                $dollarCount++;
            }
            $inEscape = false;
        }
        return ($dollarCount % 2) !== 0;
    }

    /**
     * 提取选择题答案字母（A/B/C/D）
     */
    private function extractChoiceAnswerLetter(string $answer): ?string
    {
        $answer = trim($answer);
        if (preg_match('/^([A-D])$/i', $answer, $m)) {
            return strtoupper($m[1]);
        }
        if (preg_match('/答案[：:]\s*([A-D])/iu', $answer, $m)) {
            return strtoupper($m[1]);
        }
        if (preg_match('/([A-D])[\.、．:]/u', $answer, $m)) {
            return strtoupper($m[1]);
        }
        if (preg_match('/([A-D])/i', $answer, $m)) {
            return strtoupper($m[1]);
        }

        return null;
    }

    /**
     * AI 校验：答案是否正确、是否与题目匹配
     */
    private function runAiAnswerCheck(array $question): ?array
    {
        $stem = $question['stem'] ?? $question['content'] ?? '';
        $answer = $question['answer'] ?? '';
        $solution = $question['solution'] ?? '';
        $questionType = $question['question_type'] ?? ($question['tags'] ?? 'answer');
        $options = $question['options'] ?? null;

        $optionsStr = '无';
        if (is_array($options)) {
            $parts = [];
            foreach ($options as $k => $v) {
                $v = is_string($v) ? $v : json_encode($v);
                $parts[] = "{$k}: " . mb_substr($v, 0, 200);
            }
            $optionsStr = implode("\n", $parts);
        } elseif (is_string($options)) {
            $optionsStr = mb_substr($options, 0, 500);
        }

        $prompt = str_replace(
            ['{question_type}', '{stem}', '{options}', '{answer}', '{solution}'],
            [$questionType, mb_substr((string) $stem, 0, 1500), $optionsStr, (string) $answer, mb_substr((string) $solution, 0, 800)],
            config('ai.answer_validation_prompt', '')
        );

        if ($prompt === '') {
            return null;
        }

        $data = $this->aiClient->callJson($prompt);

        return is_array($data) && isset($data['answer_correct']) ? $data : null;
    }

    private function recordCheck(string $ruleCode, bool $passed, ?string $detail = null, string $result = 'pass'): array
    {
        $info = self::RULES[$ruleCode] ?? ['name' => $ruleCode, 'severity' => 'error'];
        return [
            'rule_code' => $ruleCode,
            'rule_name' => $info['name'],
            'passed' => $passed,
            'auto_result' => $passed ? 'pass' : ($result === 'skip' ? 'skip' : 'fail'),
            'detail' => $detail,
        ];
    }

    /**
     * 获取下学期章节关联的、题少的 KP 列表（用于筛选 questions_tem）
     *
     * @param int|null $textbookId 教材 ID，null 则取默认教材
     * @param int $semesterCode 学期 1=上 2=下
     * @param int $limit 返回前 N 个题少的 KP
     * @return array [['kp_code' => string, 'question_count' => int], ...]
     */
    public function getKpsWithFewQuestions(?int $textbookId = null, int $semesterCode = 2, int $limit = 50): array
    {
        $textbooksQuery = DB::table('textbooks');
        if (Schema::hasColumn('textbooks', 'is_deleted')) {
            $textbooksQuery->where('is_deleted', 0);
        }
        if ($textbookId) {
            $textbooksQuery->where('id', $textbookId);
        }
        if (Schema::hasColumn('textbooks', 'semester_code')) {
            $textbooksQuery->where('semester_code', $semesterCode);
        }

        $textbookIds = $textbooksQuery->pluck('id')->toArray();
        if (empty($textbookIds)) {
            Log::warning('QuestionQualityCheckService: 未找到下学期教材');
            return [];
        }

        $kpCodes = DB::table('textbook_chapter_knowledge_relation as tckr')
            ->join('textbook_catalog_nodes as tcn', 'tckr.catalog_chapter_id', '=', 'tcn.id')
            ->whereIn('tcn.textbook_id', $textbookIds)
            ->where(function ($q) {
                $q->where('tckr.is_deleted', 0)->orWhereNull('tckr.is_deleted');
            })
            ->distinct()
            ->pluck('tckr.kp_code')
            ->toArray();

        if (empty($kpCodes)) {
            return [];
        }

        $counts = DB::table('questions')
            ->whereIn('kp_code', $kpCodes)
            ->where('audit_status', 0)
            ->selectRaw('kp_code, count(*) as cnt')
            ->groupBy('kp_code')
            ->pluck('cnt', 'kp_code')
            ->toArray();

        $result = [];
        foreach ($kpCodes as $kp) {
            $result[] = [
                'kp_code' => $kp,
                'question_count' => $counts[$kp] ?? 0,
            ];
        }

        usort($result, fn ($a, $b) => $a['question_count'] <=> $b['question_count']);
        return array_slice($result, 0, $limit);
    }

    /**
     * 获取待质检题目（与 questions 不重复），按知识点分组
     * 用于按 KP 生成 PDF
     *
     * @param string $table 待质检表名，默认 questions_tem
     * @param int|null $textbookId 教材 ID
     * @param int $semesterCode 学期 1=上 2=下
     * @param int $kpLimit 取前 N 个题少的 KP（当 $singleKp 为 null 时生效）
     * @param int|null $perKpLimit 每个 KP 最多取题数，null 不限制
     * @param string|null $singleKp 指定单个 KP，则只返回该 KP
     * @return array<string, Collection> [kp_code => Collection of question rows]
     */
    public function getQcQuestionsGroupedByKp(
        string $table = 'questions_tem',
        ?int $textbookId = null,
        int $semesterCode = 2,
        int $kpLimit = 10,
        ?int $perKpLimit = null,
        ?string $singleKp = null
    ): array {
        if (! Schema::hasTable($table)) {
            return [];
        }

        $kpCodes = $singleKp
            ? [$singleKp]
            : array_column($this->getKpsWithFewQuestions($textbookId, $semesterCode, $kpLimit), 'kp_code');
        if (empty($kpCodes)) {
            return [];
        }
        $query = DB::table($table)->whereIn('kp_code', $kpCodes);

        if ($table === 'questions_tem'
            && Schema::hasTable('questions')
            && Schema::hasColumn($table, 'question_code')
            && Schema::hasColumn('questions', 'question_code')
        ) {
            $query->whereNotIn('question_code', DB::table('questions')->select('question_code'));
        }

        $all = $query->orderBy('kp_code')->orderBy('id')->get();
        $grouped = [];
        foreach ($all as $row) {
            $kp = $row->kp_code ?? '';
            if ($kp === '') {
                continue;
            }
            if ($perKpLimit !== null && isset($grouped[$kp]) && $grouped[$kp]->count() >= $perKpLimit) {
                continue;
            }
            $grouped[$kp] ??= new Collection;
            $grouped[$kp]->push($row);
        }

        return $grouped;
    }
}