<?php

namespace App\Services;

use App\Http\Controllers\ExamPdfController;
use App\Models\Paper;
use App\Models\PaperQuestion;
use App\Models\Student;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\File;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Facades\URL;
use App\Services\LearningAnalyticsService;
use App\Services\QuestionBankService;
use App\Services\QuestionServiceApi;
use App\Services\PdfStorageService;
use Symfony\Component\Process\Exception\ProcessSignaledException;
use Symfony\Component\Process\Exception\ProcessTimedOutException;
use Symfony\Component\Process\Process;

class ExamPdfExportService
{
    private ExamPdfController $controller;
    private LearningAnalyticsService $learningAnalyticsService;
    private QuestionBankService $questionBankService;
    private PdfStorageService $pdfStorageService;

    public function __construct(
        ExamPdfController $controller,
        LearningAnalyticsService $learningAnalyticsService,
        QuestionBankService $questionBankService,
        PdfStorageService $pdfStorageService
    )
    {
        $this->controller = $controller;
        $this->learningAnalyticsService = $learningAnalyticsService;
        $this->questionBankService = $questionBankService;
        $this->pdfStorageService = $pdfStorageService;
    }

    /**
        生成试卷 PDF（不含答案）
     */
    public function generateExamPdf(string $paperId): ?string
    {
        $url = $this->renderAndStore($paperId, includeAnswer: false, suffix: 'exam');

        // 如果生成成功，将 URL 写入数据库
        if ($url) {
            try {
                $paper = Paper::where('paper_id', $paperId)->first();
                if ($paper) {
                    $paper->update(['exam_pdf_url' => $url]);
                    Log::info('ExamPdfExportService: 试卷PDF URL已写入数据库', [
                        'paper_id' => $paperId,
                        'url' => $url,
                    ]);
                }
            } catch (\Throwable $e) {
                Log::error('ExamPdfExportService: 写入试卷PDF URL失败', [
                    'paper_id' => $paperId,
                    'error' => $e->getMessage(),
                ]);
            }
        }

        return $url;
    }

    /**
        生成判卷 PDF（含答案与解析）
     */
    public function generateGradingPdf(string $paperId): ?string
    {
        $url = $this->renderAndStore($paperId, includeAnswer: true, suffix: 'grading', useGradingView: true);

        // 如果生成成功，将 URL 写入数据库
        if ($url) {
            try {
                $paper = Paper::where('paper_id', $paperId)->first();
                if ($paper) {
                    $paper->update(['grading_pdf_url' => $url]);
                    Log::info('ExamPdfExportService: 判卷PDF URL已写入数据库', [
                        'paper_id' => $paperId,
                        'url' => $url,
                    ]);
                }
            } catch (\Throwable $e) {
                Log::error('ExamPdfExportService: 写入判卷PDF URL失败', [
                    'paper_id' => $paperId,
                    'error' => $e->getMessage(),
                ]);
            }
        }

        return $url;
    }

    /**
     * 生成学情分析 PDF
     */
    public function generateAnalysisReportPdf(string $paperId, string $studentId, ?string $recordId = null): ?string
    {
        if (function_exists('set_time_limit')) {
            @set_time_limit(240);
        }

        try {
            $payload = $this->buildAnalysisPayload($paperId, $studentId);
            if (!$payload) {
                return null;
            }

            $html = view('exam-analysis.pdf-report', $payload)->render();
            $pdfBinary = $this->buildPdf($html);
            if (!$pdfBinary) {
                return null;
            }

            $version = time();
            $path = "analysis_reports/{$paperId}_{$studentId}_{$version}.pdf";
            $url = $this->pdfStorageService->put($path, $pdfBinary);
            if (!$url) {
                Log::error('ExamPdfExportService: 保存学情 PDF 失败', [
                    'path' => $path,
                ]);
                return null;
            }

            // 根据记录类型将 URL 写入不同表
            try {
                if ($recordId) {
                    // OCR 记录：写入 ocr_records 表
                    $ocrRecord = \App\Models\OCRRecord::find($recordId);
                    if ($ocrRecord) {
                        $ocrRecord->update(['analysis_pdf_url' => $url]);
                        Log::info('ExamPdfExportService: OCR记录学情分析PDF URL已写入数据库', [
                            'record_id' => $recordId,
                            'paper_id' => $paperId,
                            'student_id' => $studentId,
                            'url' => $url,
                        ]);
                    }
                } else {
                    // 学生记录：写入 students 表
                    $student = \App\Models\Student::where('student_id', $studentId)->first();
                    if ($student) {
                        $student->update(['student_report_pdf_url' => $url]);
                        Log::info('ExamPdfExportService: 学生学情报告PDF URL已写入数据库', [
                            'student_id' => $studentId,
                            'paper_id' => $paperId,
                            'url' => $url,
                        ]);
                    }
                }
            } catch (\Throwable $e) {
                Log::error('ExamPdfExportService: 写入学情分析PDF URL失败', [
                    'paper_id' => $paperId,
                    'student_id' => $studentId,
                    'record_id' => $recordId,
                    'error' => $e->getMessage(),
                ]);
            }

            return $url;
        } catch (\Throwable $e) {
            Log::error('ExamPdfExportService: 生成学情分析 PDF 失败', [
                'paper_id' => $paperId,
                'student_id' => $studentId,
                'record_id' => $recordId,
                'error' => $e->getMessage(),
                'exception' => get_class($e),
                'trace' => $e->getTraceAsString(),
            ]);
            return null;
        }
    }

    private function renderAndStore(
        string $paperId,
        bool $includeAnswer,
        string $suffix,
        bool $useGradingView = false
    ): ?string {
        // 放宽脚本执行时间，避免长耗时渲染被 PHP 全局超时打断
        if (function_exists('set_time_limit')) {
            @set_time_limit(240);
        }

        try {
            $html = $this->renderHtml($paperId, $includeAnswer, $useGradingView);
            if (!$html) {
                Log::error('ExamPdfExportService: 渲染 HTML 为空', [
                    'paper_id' => $paperId,
                    'include_answer' => $includeAnswer,
                    'use_grading_view' => $useGradingView,
                ]);
                return null;
            }

            $pdfBinary = $this->buildPdf($html);
            if (!$pdfBinary) {
                return null;
            }

            $path = "exams/{$paperId}_{$suffix}.pdf";
            $url = $this->pdfStorageService->put($path, $pdfBinary);
            if (!$url) {
                Log::error('ExamPdfExportService: 保存 PDF 失败', [
                    'path' => $path,
                ]);
                return null;
            }

            return $url;
        } catch (\Throwable $e) {
            Log::error('ExamPdfExportService: 生成 PDF 失败', [
                'paper_id' => $paperId,
                'suffix' => $suffix,
                'error' => $e->getMessage(),
                'exception' => get_class($e),
                'trace' => $e->getTraceAsString(),
            ]);
            return null;
        }
    }

    private function renderHtml(string $paperId, bool $includeAnswer, bool $useGradingView): ?string
    {
        // 复用已有控制器的渲染逻辑，保证版式一致
        $request = Request::create(
            '/admin/intelligent-exam/' . ($useGradingView ? 'grading' : 'pdf') . '/' . $paperId,
            'GET',
            ['answer' => $includeAnswer ? 'true' : 'false']
        );

        $view = $useGradingView
            ? $this->controller->showGrading($request, $paperId)
            : $this->controller->show($request, $paperId);

        if (is_object($view) && method_exists($view, 'render')) {
            return $this->ensureUtf8Html($view->render());
        }

        return null;
    }

    private function buildPdf(string $html): ?string
    {
        $tmpHtml = tempnam(sys_get_temp_dir(), 'exam_html_') . '.html';
        $utf8Html = $this->ensureUtf8Html($html);
        file_put_contents($tmpHtml, $utf8Html);

        // 仅使用 Chrome 渲染，去掉 wkhtmltopdf 兜底以暴露真实问题
        $chromePdf = $this->renderWithChrome($tmpHtml);
        @unlink($tmpHtml);
        return $chromePdf;
    }

    private function renderWithChrome(string $htmlPath): ?string
    {
        $tmpPdf = tempnam(sys_get_temp_dir(), 'exam_pdf_') . '.pdf';
        // 每次使用唯一的临时用户目录，彻底避免钥匙串问题
        $userDataDir = sys_get_temp_dir() . '/chrome-profile-' . uniqid();

        $chromeBinary = env('PDF_CHROME_BINARY');
        if (!$chromeBinary) {
            $candidates = [
                '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome',
                '/usr/bin/google-chrome-stable',
                '/usr/bin/google-chrome',
                '/usr/bin/chromium-browser',
                '/usr/bin/chromium',
            ];
            foreach ($candidates as $path) {
                if (is_file($path) && is_executable($path)) {
                    $chromeBinary = $path;
                    break;
                }
            }
        }

        if (!$chromeBinary) {
            Log::error('ExamPdfExportService: 未找到可用的 Chrome/Chromium，已停止导出', [
                'html_path' => $htmlPath,
                'path_env' => env('PATH'),
                'candidates_checked' => $candidates ?? [],
            ]);
            return null;
        }

        // 为无权限环境设置可写的 HOME/XDG 目录，避免创建 /var/www/.local 报错
        $runtimeHome = sys_get_temp_dir() . '/chrome-home';
        $runtimeXdg = sys_get_temp_dir() . '/chrome-xdg';
        if (!File::exists($runtimeHome)) {
            @File::makeDirectory($runtimeHome, 0755, true);
        }
        if (!File::exists($runtimeXdg)) {
            @File::makeDirectory($runtimeXdg, 0755, true);
        }

        $process = new Process([
            $chromeBinary,
            '--headless',
            '--disable-gpu',
            '--no-sandbox',
            '--disable-setuid-sandbox',
            '--disable-dev-shm-usage',
            '--no-zygote',
            '--disable-features=VizDisplayCompositor',
            '--disable-software-rasterizer',
            '--disable-extensions',
            '--disable-background-networking',
            '--disable-component-update',
            '--disable-client-side-phishing-detection',
            '--disable-default-apps',
            '--disable-domain-reliability',
            '--disable-sync',
            '--safebrowsing-disable-auto-update',
            '--no-first-run',
            '--no-default-browser-check',
            '--disable-crash-reporter',
            '--disable-print-preview',
            '--disable-features=PrintHeaderFooter',
            '--disable-features=TranslateUI',
            '--disable-features=OptimizationHints',
            '--disable-ipc-flooding-protection',
            '--disable-background-networking',
            '--disable-background-timer-throttling',
            '--disable-backgrounding-occluded-windows',
            '--disable-renderer-backgrounding',
            '--disable-features=AudioServiceOutOfProcess',
            '--user-data-dir=' . $userDataDir,
            '--print-to-pdf=' . $tmpPdf,
            '--print-to-pdf-no-header',
            '--allow-file-access-from-files',
            'file://' . $htmlPath,
        ], null, [
            'HOME' => $runtimeHome,
            'XDG_RUNTIME_DIR' => $runtimeXdg,
        ]);
        $process->setTimeout(60);

        $killSignal = \defined('SIGKILL') ? \SIGKILL : 9;

        try {
            $startedAt = microtime(true);
            Log::info('ExamPdfExportService: Chrome 渲染启动', [
                'cmd' => $process->getCommandLine(),
                'html_path' => $htmlPath,
                'tmp_pdf' => $tmpPdf,
                'user_data_dir' => $userDataDir,
                'html_exists' => file_exists($htmlPath),
                'html_size' => file_exists($htmlPath) ? filesize($htmlPath) : null,
                'cwd' => $process->getWorkingDirectory(),
            ]);
            $process->start();
            $pdfGenerated = false;

            // 轮询检测 PDF 是否生成，尽快返回，避免等待 Chrome 完整退出
            $pollStart = microtime(true);
            $maxPollSeconds = 30;
            while ($process->isRunning() && (microtime(true) - $pollStart) < $maxPollSeconds) {
                if (file_exists($tmpPdf) && filesize($tmpPdf) > 0) {
                    $pdfGenerated = true;
                    Log::info('ExamPdfExportService: 发现 PDF 已生成，提前结束 Chrome', [
                        'duration_sec' => round(microtime(true) - $startedAt, 3),
                        'tmp_pdf_size' => filesize($tmpPdf),
                    ]);
                    $process->stop(5, $killSignal);
                    break;
                }
                usleep(200_000); // 200ms
            }

            // 如果仍在运行且超过轮询窗口，则强制结束
            if ($process->isRunning()) {
                Log::warning('ExamPdfExportService: Chrome 轮询超时，强制结束', [
                    'duration_sec' => round(microtime(true) - $startedAt, 3),
                ]);
                $process->stop(5, $killSignal);
            }

            $process->wait();
            Log::info('ExamPdfExportService: Chrome 渲染完成', [
                'duration_sec' => round(microtime(true) - $startedAt, 3),
                'exit_code' => $process->getExitCode(),
                'tmp_pdf_exists' => file_exists($tmpPdf),
                'tmp_pdf_size' => file_exists($tmpPdf) ? filesize($tmpPdf) : null,
                'stderr' => $process->getErrorOutput(),
                'stdout' => $process->getOutput(),
                'pdf_generated_during_poll' => $pdfGenerated,
            ]);
        } catch (ProcessTimedOutException|ProcessSignaledException $e) {
            Log::error('ExamPdfExportService: Chrome 进程异常', [
                'cmd' => $process->getCommandLine(),
                'signal' => method_exists($process, 'getTermSignal') ? $process->getTermSignal() : null,
                'error' => $process->getErrorOutput(),
                'output' => $process->getOutput(),
                'exit_code' => $process->getExitCode(),
                'exception' => $e->getMessage(),
                'trace' => $e->getTraceAsString(),
            ]);
            if ($process->isRunning()) {
                $process->stop(5, $killSignal);
            }
            $pdfExists = file_exists($tmpPdf);
            $pdfSize = $pdfExists ? filesize($tmpPdf) : null;
            if ($pdfExists && $pdfSize > 0) {
                Log::warning('ExamPdfExportService: Chrome 异常但产生了 PDF，尝试继续返回', [
                    'tmp_pdf_exists' => $pdfExists,
                    'tmp_pdf_size' => $pdfSize,
                    'duration_sec' => isset($startedAt) ? round(microtime(true) - $startedAt, 3) : null,
                ]);
                $pdfBinary = file_get_contents($tmpPdf);
                @unlink($tmpPdf);
                File::deleteDirectory($userDataDir);
                return $pdfBinary ?: null;
            }
            @unlink($tmpPdf);
            File::deleteDirectory($userDataDir);
            return null;
        } catch (\Throwable $e) {
            Log::error('ExamPdfExportService: Chrome 调用异常', [
                'cmd' => $process->getCommandLine(),
                'error' => $e->getMessage(),
                'exit_code' => $process->getExitCode(),
                'stderr' => $process->getErrorOutput(),
                'stdout' => $process->getOutput(),
                'trace' => $e->getTraceAsString(),
            ]);
            if ($process->isRunning()) {
                $process->stop(5, $killSignal);
            }
            $pdfExists = file_exists($tmpPdf);
            $pdfSize = $pdfExists ? filesize($tmpPdf) : null;
            if ($pdfExists && $pdfSize > 0) {
                Log::warning('ExamPdfExportService: Chrome 调用异常但产生了 PDF，尝试继续返回', [
                    'tmp_pdf_exists' => $pdfExists,
                    'tmp_pdf_size' => $pdfSize,
                    'duration_sec' => isset($startedAt) ? round(microtime(true) - $startedAt, 3) : null,
                ]);
                $pdfBinary = file_get_contents($tmpPdf);
                @unlink($tmpPdf);
                File::deleteDirectory($userDataDir);
                return $pdfBinary ?: null;
            }
            @unlink($tmpPdf);
            File::deleteDirectory($userDataDir);
            return null;
        }

        $pdfExists = file_exists($tmpPdf);
        $pdfSize = $pdfExists ? filesize($tmpPdf) : null;

        if (!$process->isSuccessful()) {
            if ($pdfExists && $pdfSize > 0) {
                Log::warning('ExamPdfExportService: Chrome 进程异常但生成了 PDF，继续使用', [
                    'cmd' => implode(' ', (array) $process->getCommandLine()),
                    'exit_code' => $process->getExitCode(),
                    'error' => $process->getErrorOutput(),
                    'output' => $process->getOutput(),
                    'tmp_pdf_exists' => $pdfExists,
                    'tmp_pdf_size' => $pdfSize,
                    'html_path' => $htmlPath,
                    'user_data_dir' => $userDataDir,
                ]);
            } else {
                Log::error('ExamPdfExportService: Chrome 渲染失败', [
                    'cmd' => implode(' ', (array) $process->getCommandLine()),
                    'exit_code' => $process->getExitCode(),
                    'error' => $process->getErrorOutput(),
                    'output' => $process->getOutput(),
                    'tmp_pdf_exists' => $pdfExists,
                    'tmp_pdf_size' => $pdfSize,
                    'html_path' => $htmlPath,
                    'user_data_dir' => $userDataDir,
                ]);
                @unlink($tmpPdf);
                File::deleteDirectory($userDataDir);
                return null;
            }
        }

        $pdfBinary = $pdfExists ? file_get_contents($tmpPdf) : null;
        @unlink($tmpPdf);
        File::deleteDirectory($userDataDir);
        return $pdfBinary ?: null;
    }

    private function buildAnalysisPayload(string $paperId, string $studentId): ?array
    {
        $paper = Paper::with(['questions' => function ($query) {
            $query->orderBy('question_number')->orderBy('id');
        }])->find($paperId);
        if (!$paper) {
            Log::error('ExamPdfExportService: 未找到试卷，无法生成学情报告', [
                'paper_id' => $paperId,
                'student_id' => $studentId,
            ]);
            return null;
        }

        $student = Student::find($studentId);
        $studentInfo = [
            'id' => $student?->student_id ?? $studentId,
            'name' => $student?->name ?? $studentId,
            'grade' => $student?->grade ?? '未知年级',
            'class' => $student?->class_name ?? '未知班级',
        ];

        // 调用学习分析服务获取本卷分析与掌握度
        $analysisData = [];
        if (!empty($paper->analysis_id)) {
            $analysis = $this->learningAnalyticsService->getAnalysisResult($paper->analysis_id);
            if (!empty($analysis['data'])) {
                $analysisData = $analysis['data'];
            }
        }

        $masteryData = [];
        $masteryResponse = $this->learningAnalyticsService->getStudentMastery($studentId);
        if (!empty($masteryResponse['data'])) {
            $masteryData = $masteryResponse['data'];
        }

        $recommendations = [];
        $recommendationResponse = $this->learningAnalyticsService->getLearningRecommendations($studentId);
        if (!empty($recommendationResponse['data'])) {
            $recommendations = $recommendationResponse['data'];
        }

        $kpNameMap = $this->buildKnowledgePointNameMap();

        // 预取题库详情用于解析/解题思路
        $questionDetails = [];
        $questionIds = $paper->questions->pluck('question_id')->filter()->unique()->values();
        foreach ($questionIds as $qid) {
            try {
                $detail = $this->questionBankService->getQuestion((string) $qid);
                if (!empty($detail)) {
                    $questionDetails[(string) $qid] = $detail;
                }
            } catch (\Throwable $e) {
                Log::warning('ExamPdfExportService: 获取题库题目详情失败', [
                    'question_id' => $qid,
                    'error' => $e->getMessage(),
                ]);
            }
        }

        // 分组保持卷面顺序：选择题 -> 填空题 -> 解答题
        $grouped = [
            'choice' => [],
            'fill' => [],
            'answer' => [],
        ];

        $sortedQuestions = $paper->questions
            ->sortBy(function (PaperQuestion $q, int $idx) {
                $number = $q->question_number ?? $idx + 1;
                return is_numeric($number) ? (float) $number : ($q->id ?? $idx);
            });

        foreach ($sortedQuestions as $idx => $question) {
            $kpCode = $question->knowledge_point ?? '';
            $kpName = $kpNameMap[$kpCode] ?? $kpCode ?: '未标注';
            $detail = $questionDetails[(string) ($question->question_id ?? '')] ?? [];
            $solution = $detail['solution'] ?? $detail['解析'] ?? $detail['analysis'] ?? null;
            // 题型优先使用试卷记录，其次题库详情
            $typeRaw = $question->question_type ?? ($detail['question_type'] ?? $detail['type'] ?? '');
            $normalizedType = $this->normalizeQuestionType($typeRaw);
            $number = $question->question_number ?? ($idx + 1);

            $payload = [
                'question_number' => $number,
                'question_text' => is_array($question->question_text) ? json_encode($question->question_text, JSON_UNESCAPED_UNICODE) : ($question->question_text ?? ''),
                'question_type' => $normalizedType,
                'knowledge_point' => $kpCode,
                'knowledge_point_name' => $kpName,
                'score' => $question->score,
                'solution' => $solution,
            ];

            $grouped[$normalizedType][] = $payload;
        }

        $ordered = array_merge($grouped['choice'], $grouped['fill'], $grouped['answer']);

        // 按卷面顺序重新编号以匹配判卷/显示
        foreach ($ordered as $i => &$q) {
            $q['display_number'] = $i + 1;
        }
        unset($q);

        $questions = $ordered;

        $questionInsights = $analysisData['question_results'] ?? [];
        $masterySummary = $this->buildMasterySummary($masteryData, $kpNameMap);

        return [
            'paper' => [
                'id' => $paper->paper_id,
                'name' => $paper->paper_name,
                'total_questions' => $paper->question_count,
                'total_score' => $paper->total_score,
                'created_at' => $paper->created_at,
            ],
            'student' => $studentInfo,
            'questions' => $questions,
            'mastery' => $masterySummary,
            'question_insights' => $questionInsights,
            'recommendations' => $recommendations,
            'analysis_data' => $analysisData,
        ];
    }

    private function buildKnowledgePointNameMap(): array
    {
        try {
            // 优先使用 QuestionServiceApi（已有知识点名称缓存）
            if (class_exists(QuestionServiceApi::class)) {
                /** @var QuestionServiceApi $service */
                $service = app(QuestionServiceApi::class);
                $options = $service->getKnowledgePointOptions();
                if (!empty($options)) {
                    return $options;
                }
            }

            // 退回 QuestionBankService（可能缺少此方法）
            if (method_exists($this->questionBankService, 'getKnowledgePointOptions')) {
                $options = $this->questionBankService->getKnowledgePointOptions();
                $map = [];
                foreach ($options as $item) {
                    if (is_array($item)) {
                        $code = $item['kp_code'] ?? null;
                        $name = $item['kp_name'] ?? $item['name'] ?? null;
                        if ($code && $name) {
                            $map[$code] = $name;
                        }
                    }
                }
                if (!empty($map)) {
                    return $map;
                }
            }
        } catch (\Throwable $e) {
            Log::warning('ExamPdfExportService: 获取知识点名称失败，退回使用编码', [
                'error' => $e->getMessage(),
            ]);
        }

        return [];
    }

    private function buildMasterySummary(array $masteryData, array $kpNameMap): array
    {
        $items = [];
        $total = 0;
        $count = 0;
        $hasMap = !empty($kpNameMap);

        foreach ($masteryData as $row) {
            $code = $row['kp_code'] ?? null;
            if ($hasMap && $code && !isset($kpNameMap[$code])) {
                // 不在知识图谱中的知识点不呈现
                continue;
            }
            $name = $row['kp_name'] ?? ($code ? ($kpNameMap[$code] ?? $code) : '未知知识点');
            $level = (float) ($row['mastery_level'] ?? 0);
            $delta = $row['mastery_change'] ?? null;
            $items[] = [
                'kp_code' => $code,
                'kp_name' => $name,
                'mastery_level' => $level,
                'mastery_change' => $delta,
            ];
            $total += $level;
            $count++;
        }

        $average = $count > 0 ? round($total / $count, 2) : null;

        // 按掌握度从低到高排序，便于突出薄弱点
        usort($items, fn($a, $b) => ($a['mastery_level'] <=> $b['mastery_level']));

        return [
            'items' => $items,
            'average' => $average,
            'weak_list' => array_slice($items, 0, 5),
        ];
    }

    private function normalizeQuestionType(?string $type): string
    {
        $t = strtolower(trim((string) $type));
        return match (true) {
            str_contains($t, 'choice') || str_contains($t, '选择') => 'choice',
            str_contains($t, 'fill') || str_contains($t, 'blank') || str_contains($t, '填空') => 'fill',
            default => 'answer',
        };
    }

    private function ensureUtf8Html(string $html): string
    {
        $meta = '<meta charset="UTF-8">';
        if (stripos($html, '<head>') !== false) {
            return preg_replace('/<head>/i', "<head>{$meta}", $html, 1);
        }
        return $meta . $html;
    }

}