<?php

namespace App\Services;

use App\Models\OCRRecord;
use App\Models\Paper;
use App\Models\Student;
use App\Models\Teacher;
use Illuminate\Support\Facades\Log;

class ExamPaperService
{
    protected QuestionBankService $questionBankService;

    public function __construct(QuestionBankService $questionBankService)
    {
        $this->questionBankService = $questionBankService;
    }

    /**
     * 获取所有老师列表
     */
    public function getTeachers(?string $currentTeacherId = null): array
    {
        try {
            $query = Teacher::query()
                ->leftJoin('users as u', 'teachers.teacher_id', '=', 'u.user_id')
                ->select(
                    'teachers.teacher_id',
                    'teachers.name',
                    'teachers.subject',
                    'u.username',
                    'u.email'
                );

            // 如果指定了当前老师ID，只返回该老师
            if ($currentTeacherId) {
                $query->where('teachers.teacher_id', $currentTeacherId);
            }

            $teachers = $query->orderBy('teachers.name')->get();

            // 检查是否有学生没有对应的老师记录
            $teacherIds = $teachers->pluck('teacher_id')->toArray();
            $missingTeacherIds = Student::query()
                ->distinct()
                ->whereNotIn('teacher_id', $teacherIds)
                ->pluck('teacher_id')
                ->toArray();

            $teachersArray = $teachers->all();

            if (!empty($missingTeacherIds)) {
                foreach ($missingTeacherIds as $missingId) {
                    $teachersArray[] = (object) [
                        'teacher_id' => $missingId,
                        'name' => '未知老师 (' . $missingId . ')',
                        'subject' => '未知',
                        'username' => null,
                        'email' => null
                    ];
                }

                usort($teachersArray, function($a, $b) {
                    return strcmp($a->name, $b->name);
                });
            }

            return $teachersArray;
        } catch (\Exception $e) {
            Log::error('ExamPaperService: 加载老师列表失败', [
                'error' => $e->getMessage()
            ]);
            return [];
        }
    }

    /**
     * 获取指定老师的学生列表
     */
    public function getStudents(?string $teacherId): array
    {
        if (empty($teacherId)) {
            return [];
        }

        try {
            return Student::query()
                ->leftJoin('users as u', 'students.student_id', '=', 'u.user_id')
                ->where('students.teacher_id', $teacherId)
                ->select(
                    'students.student_id',
                    'students.name',
                    'students.grade',
                    'students.class_name',
                    'u.username',
                    'u.email'
                )
                ->orderBy('students.grade')
                ->orderBy('students.class_name')
                ->orderBy('students.name')
                ->get()
                ->all();
        } catch (\Exception $e) {
            Log::error('ExamPaperService: 加载学生列表失败', [
                'teacher_id' => $teacherId,
                'error' => $e->getMessage()
            ]);
            return [];
        }
    }

    /**
     * 获取最近的记录（OCR和试卷）
     */
    public function getRecentRecords(?string $studentId = null, int $limit = 10): array
    {
        // 1. 获取OCR记录(图片上传)
        $ocrQuery = OCRRecord::with('student');

        if (!empty($studentId)) {
            $ocrQuery->where('student_id', $studentId);
        }

        $ocrRecords = $ocrQuery->latest()->take(5)->get()
            ->map(function($record) {
                $studentName = $record->student?->name ?: ('学生ID: ' . $record->student_id);

                return [
                    'type' => 'ocr_upload',
                    'id' => $record->id,
                    'record_id' => $record->id,
                    'paper_id' => null,
                    'student_id' => $record->student_id,
                    'student_name' => $studentName,
                    'paper_type' => $record->paper_type_label,
                    'paper_name' => $record->image_filename ?: '未命名图片',
                    'status' => $record->status,
                    'total_questions' => $record->total_questions,
                    'processed_questions' => $record->processed_questions ?? 0,
                    'created_at' => $record->created_at->format('Y-m-d H:i'),
                    'is_completed' => $record->status === 'completed',
                ];
            })->toArray();

        // 2. 获取所有Paper记录(包括草稿和已评分)
        $paperQuery = Paper::with('student');

        if (!empty($studentId)) {
            $paperQuery->where('student_id', $studentId);
        }

        $allPapers = $paperQuery->latest()->take(5)->get()
            ->map(function($paper) {
                $type = $paper->status === 'completed' ? 'graded_paper' : 'generated';
                $paperType = $paper->status === 'completed' ? '已评分试卷' : '系统生成试卷';
                $iconColor = $paper->status === 'completed' ? 'text-green-500' : 'text-blue-500';

                $studentName = $paper->student?->name ?: ('学生ID: ' . $paper->student_id);

                return [
                    'type' => $type,
                    'id' => $paper->paper_id,
                    'record_id' => null,
                    'paper_id' => $paper->paper_id,
                    'student_id' => $paper->student_id,
                    'student_name' => $studentName,
                    'paper_type' => $paperType,
                    'paper_name' => $paper->paper_name ?? '未命名试卷',
                    'status' => $paper->difficulty_category,
                    'total_questions' => $paper->question_count ?? 0,
                    'created_at' => $paper->created_at->format('Y-m-d H:i'),
                    'is_completed' => $paper->status === 'completed',
                    'icon_color' => $iconColor,
                ];
            })->toArray();

        // 3. 合并并按时间排序
        $allRecords = array_merge($ocrRecords, $allPapers);
        usort($allRecords, function($a, $b) {
            return strcmp($b['created_at'], $a['created_at']);
        });

        return array_slice($allRecords, 0, $limit);
    }

    /**
     * 获取学生的试卷列表
     */
    public function getStudentPapers(?string $studentId): array
    {
        if (empty($studentId)) {
            return [];
        }

        try {
            $student = Student::find($studentId);
            if (!$student) {
                Log::warning('ExamPaperService: 未找到指定学生', ['student_id' => $studentId]);
                return [];
            }

            return $student->papers()
                ->withCount('questions')
                ->orderBy('created_at', 'desc')
                ->take(20)
                ->get()
                ->map(function($paper) {
                    return [
                        'paper_id' => $paper->paper_id,
                        'paper_name' => $paper->paper_name ?? '未命名试卷',
                        'total_questions' => $paper->questions_count ?? 0,
                        'total_score' => $paper->total_score ?? 0,
                        'created_at' => $paper->created_at->format('Y-m-d H:i'),
                    ];
                })
                ->toArray();
        } catch (\Exception $e) {
            Log::error('ExamPaperService: 获取学生试卷列表失败', [
                'student_id' => $studentId,
                'error' => $e->getMessage()
            ]);
            return [];
        }
    }

    /**
     * 获取试卷题目详情
     */
    public function getPaperQuestions(?string $paperId): array
    {
        if (empty($paperId)) {
            return [];
        }

        try {
            // 首先检查试卷是否存在
            $paper = Paper::where('paper_id', $paperId)->first();
            if (!$paper) {
                Log::warning('ExamPaperService: 未找到指定试卷', ['paper_id' => $paperId]);
                return [];
            }

            // 使用关联关系查询题目 - 按题型和题号排序
            $paperWithQuestions = Paper::with(['questions' => function($query) {
                // 自定义排序：选择题、填空题、解答题的顺序
                $query->orderByRaw("
                    CASE question_type
                        WHEN 'choice' THEN 1
                        WHEN 'fill' THEN 2
                        WHEN 'answer' THEN 3
                        ELSE 4
                    END
                ")->orderBy('question_number');
            }])->where('paper_id', $paperId)->first();

            $questions = $paperWithQuestions ? $paperWithQuestions->questions : collect([]);

            // 处理数据不一致的情况：如果题目为空但试卷显示有题目
            if ($questions->isEmpty() && ($paper->question_count ?? 0) > 0) {
                Log::warning('ExamPaperService: 试卷显示有题目但实际题目数据缺失', [
                    'paper_id' => $paperId,
                    'expected_questions' => $paper->question_count,
                    'actual_questions' => 0
                ]);

                return [
                    [
                        'id' => 'missing_data',
                        'question_number' => 1,
                        'question_bank_id' => null,
                        'question_type' => 'info',
                        'content' => "⚠️ 数据异常：试卷显示应有 {$paper->question_count} 道题目，但未找到题目数据。这通常是试卷创建过程中断导致的。请联系管理员或重新创建试卷。",
                        'answer' => '',
                        'score' => 0,
                        'is_missing_data' => true
                    ]
                ];
            }

            if ($questions->isEmpty()) {
                Log::info('ExamPaperService: 试卷确实没有题目', ['paper_id' => $paperId]);
                return [
                    [
                        'id' => 'no_questions',
                        'question_number' => 1,
                        'question_bank_id' => null,
                        'question_type' => 'info',
                        'content' => '该试卷暂无题目数据',
                        'answer' => '',
                        'score' => 0,
                        'is_empty' => true
                    ]
                ];
            }

            // 获取题目详情
            $questionIds = $questions->pluck('question_bank_id')->filter()->unique()->toArray();

            if (empty($questionIds)) {
                Log::info('ExamPaperService: 题目没有关联题库ID', ['paper_id' => $paperId]);
                return $questions->map(function($q) {
                    return [
                        'id' => $q->id,
                        'question_number' => $q->question_number,
                        'question_bank_id' => $q->question_bank_id,
                        'question_type' => $q->question_type,
                        'content' => '题目内容未关联到题库',
                        'answer' => '',
                        'score' => $q->score ?? 5,
                    ];
                })->toArray();
            }

            $questionsResponse = $this->questionBankService->getQuestionsByIds($questionIds);
            $questionDetails = collect($questionsResponse['data'] ?? [])->keyBy('id');

            return $questions->map(function($q) use ($questionDetails) {
                $detail = $questionDetails->get($q->question_bank_id);

                // 获取题目内容，优先从 Question Bank 获取 stem，然后fallback
                $questionContent = null;
                if ($detail) {
                    $questionContent = $detail['stem'] ?? $detail['content'] ?? $detail['question_text'] ?? null;
                }

                // 如果 Question Bank 中没有内容，尝试从本地数据库的 question_text 获取
                if (!$questionContent && $q->question_text) {
                    $questionContent = $q->question_text;
                }

                // 如果还是没有内容，显示友好提示
                if (!$questionContent) {
                    $questionContent = '⚠️ 题目内容暂未加载完整';
                }

                return [
                    'id' => $q->id,
                    'question_number' => $q->question_number,
                    'question_bank_id' => $q->question_bank_id,
                    'question_type' => $q->question_type,
                    'content' => $questionContent,
                    'answer' => $detail['answer'] ?? $detail['correct_answer'] ?? $q->answer ?? '',
                    'score' => $q->score ?? 5,
                    'kp_code' => $q->knowledge_point, // 从本地数据库获取知识点代码
                ];
            })->toArray();
        } catch (\Exception $e) {
            Log::error('ExamPaperService: 获取试卷题目失败', [
                'paper_id' => $paperId,
                'error' => $e->getMessage(),
                'trace' => $e->getTraceAsString()
            ]);
            return [
                [
                    'id' => 'error',
                    'question_number' => 1,
                    'question_bank_id' => null,
                    'question_type' => 'error',
                    'content' => '获取题目数据时发生错误：' . $e->getMessage(),
                    'answer' => '',
                    'score' => 0,
                    'is_error' => true
                ]
            ];
        }
    }
}