<?php

declare(strict_types=1);

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Controller;
use App\Models\CustomSubject;
use App\Models\CustomSubjectQuestion;
use App\Models\TokenUsage;
use App\Services\AIService;
use App\Services\PdfExtractionService;
use Illuminate\Http\RedirectResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\Storage;
use Illuminate\View\View;

/**
 * Controller for managing user custom subjects created from PDFs.
 */
class CustomSubjectController extends Controller
{
    /**
     * Display a listing of the user's custom subjects.
     */
    public function index(): View
    {
        /** @var \App\Models\User $user */
        $user = Auth::user();

        $customSubjects = CustomSubject::where('user_id', $user->id)
            ->orderByDesc('created_at')
            ->get();

        return view('admin.custom-subjects.index', compact('customSubjects'));
    }

    /**
     * Store a newly created custom subject from a PDF upload.
     */
    public function store(Request $request): RedirectResponse
    {
        $validated = $request->validate([
            'name' => ['required', 'string', 'max:255'],
            'pdf' => ['required', 'file', 'mimetypes:application/pdf', 'max:10240'],
        ]);

        /** @var \App\Models\User $user */
        $user = Auth::user();

        $pdfFile = $request->file('pdf');

        if (!$pdfFile->isValid()) {
            return back()->with('error', __('Failed to upload PDF. Please try again.'));
        }

        $fileName = time() . '_' . uniqid() . '.pdf';
        $storagePath = 'custom_subjects/' . $user->id;
        $pdfPath = $pdfFile->storeAs($storagePath, $fileName, 'local');

        $customSubject = CustomSubject::create([
            'user_id' => $user->id,
            'name' => $validated['name'],
            'pdf_path' => $pdfPath,
            'processing_status' => 'processing',
        ]);

        // Extract text asynchronously (in real app, use a queue job)
        $pdfExtractionService = new PdfExtractionService();
        $fullPath = Storage::disk('local')->path($pdfPath);
        $result = $pdfExtractionService->extract($fullPath);

        if ($result['success']) {
            $customSubject->update([
                'extracted_content' => $result['content'],
                'processing_status' => 'completed',
            ]);
        } else {
            $customSubject->update([
                'processing_status' => 'failed',
                'error_message' => $result['error'],
            ]);
        }

        if ($result['success']) {
            return back()->with('success', __('Custom subject created successfully.'));
        }

        return back()->with('error', __('Failed to process PDF: :error', ['error' => $result['error']]));
    }

    /**
     * Show the form for editing the specified custom subject.
     */
    public function edit(CustomSubject $customSubject): View
    {
        /** @var \App\Models\User $user */
        $user = Auth::user();

        if ($customSubject->user_id !== $user->id) {
            abort(403);
        }

        return view('admin.custom-subjects.edit', compact('customSubject'));
    }

    /**
     * Update the specified custom subject.
     */
    public function update(Request $request, CustomSubject $customSubject): \Illuminate\Http\RedirectResponse
    {
        $validated = $request->validate([
            'name' => ['required', 'string', 'max:255'],
            'is_active' => ['boolean'],
        ]);

        /** @var \App\Models\User $user */
        $user = Auth::user();

        if ($customSubject->user_id !== $user->id) {
            abort(403);
        }

        $customSubject->update([
            'name' => $validated['name'],
            'is_active' => $request->has('is_active'),
        ]);

        return back()->with('success', __('Custom subject updated successfully.'));
    }

    /**
     * Display the specified custom subject with Q&A interface.
     */
    public function show(CustomSubject $customSubject): View
    {
        /** @var \App\Models\User $user */
        $user = Auth::user();

        if ($customSubject->user_id !== $user->id) {
            abort(403);
        }

        $questions = $customSubject->questions()
            ->orderByDesc('created_at')
            ->get();

        // Get AI settings from DB (unified for all subjects), fallback to config
        $provider = \App\Models\Setting::where('key', 'ai_default_provider')->value('value');
        $model = \App\Models\Setting::where('key', 'ai_default_model')->value('value');

        if (!$provider) {
            $provider = config('services.ai.default_provider', 'openrouter');
        }

        if (!$model) {
            $model = config('services.ai.providers.' . $provider . '.model', 'inclusionai/ling-3.0-tiny:free');
        }

        return view('admin.custom-subjects.show', compact('customSubject', 'questions', 'provider', 'model'));
    }

    /**
     * Ask a question about the custom subject and get an AI answer.
     */
    public function ask(Request $request, CustomSubject $customSubject): \Illuminate\Http\RedirectResponse
    {
        /** @var \App\Models\User $user */
        $user = Auth::user();

        if ($customSubject->user_id !== $user->id) {
            abort(403);
        }

        if ($customSubject->processing_status !== 'completed' || empty($customSubject->extracted_content)) {
            return back()->with('error', __('This PDF is still being processed or has no content.'));
        }

        $validated = $request->validate([
            'question' => ['required', 'string', 'max:2000'],
        ]);

        $question = trim($validated['question']);

        // Get AI settings from DB (unified for all subjects), fallback to config
        $provider = \App\Models\Setting::where('key', 'ai_default_provider')->value('value');
        $model = \App\Models\Setting::where('key', 'ai_default_model')->value('value');

        if (!$provider) {
            $provider = config('services.ai.default_provider', 'openrouter');
        }

        if (!$model) {
            $model = config('services.ai.providers.' . $provider . '.model', 'inclusionai/ling-3.0-tiny:free');
        }

        $language = $user->locale ?? 'en';
        $languageNames = [
            'pt_BR' => 'Brazilian Portuguese',
            'en' => 'English',
            'es' => 'Spanish',
        ];
        $languageName = $languageNames[$language] ?? 'English';

        $systemPrompt = "You are an expert assistant analyzing the content of a document titled '{$customSubject->name}'. "
            . "Your task is to answer questions based ONLY on the provided document content. "
            . "If the answer is not found in the document, say so clearly. "
            . "Do NOT make up information. "
            . "CRITICAL LANGUAGE INSTRUCTION: You MUST respond ONLY in {$languageName} ({$language}). "
            . "Do NOT use any other language.";

        $userMessage = "Document content:\n\n{$customSubject->extracted_content}\n\n"
            . "Question: {$question}\n\n"
            . "CRITICAL: Answer EXCLUSIVELY in {$languageName}. Do NOT use English. Do NOT translate. "
            . "The entire response must be ONLY in {$languageName}.";

        $messages = [
            ['role' => 'system', 'content' => $systemPrompt],
            ['role' => 'user', 'content' => $userMessage],
        ];

        $aiService = new AIService($provider, $model);
        $result = $aiService->chat($messages);

        if (!$result['success']) {
            return back()->with('error', __('Failed to get response: :error', [
                'error' => $result['error'] ?? __('Unknown error'),
            ]));
        }

        $answer = $result['content'];
        $inputTokens = $result['input_tokens'] ?? 0;
        $outputTokens = $result['output_tokens'] ?? 0;

        CustomSubjectQuestion::create([
            'custom_subject_id' => $customSubject->id,
            'user_id' => $user->id,
            'question' => $question,
            'answer' => $answer,
            'provider' => $provider,
            'model' => $model,
            'input_tokens' => $inputTokens,
            'output_tokens' => $outputTokens,
            'asked_at' => now(),
        ]);

        // Track token usage
        if ($inputTokens > 0 || $outputTokens > 0) {
            TokenUsage::create([
                'user_id' => $user->id,
                'input_tokens' => $inputTokens,
                'output_tokens' => $outputTokens,
                'total_tokens' => $inputTokens + $outputTokens,
                'model' => $model,
                'provider' => $provider,
            ]);
        }

        return back()->with('success', __('Question answered successfully!'));
    }

    /**
     * Remove the specified custom subject.
     */
    public function destroy(CustomSubject $customSubject): RedirectResponse
    {
        /** @var \App\Models\User $user */
        $user = Auth::user();

        if ($customSubject->user_id !== $user->id) {
            abort(403);
        }

        // Delete PDF file from storage
        if ($customSubject->pdf_path && Storage::disk('local')->exists($customSubject->pdf_path)) {
            Storage::disk('local')->delete($customSubject->pdf_path);
        }

        $customSubject->delete();

        return back()->with('success', __('Custom subject deleted successfully.'));
    }

    /**
     * Remove the specified question from the custom subject.
     */
    public function destroyQuestion(CustomSubject $customSubject, CustomSubjectQuestion $question): RedirectResponse
    {
        /** @var \App\Models\User $user */
        $user = Auth::user();

        if ($question->custom_subject_id !== $customSubject->id || $question->user_id !== $user->id) {
            abort(403);
        }

        $question->delete();

        return back()->with('success', __('Question deleted successfully.'));
    }

    /**
     * Translate a question answer to the user's preferred language.
     */
    public function translateQuestion(Request $request, CustomSubject $customSubject, CustomSubjectQuestion $question): RedirectResponse
    {
        /** @var \App\Models\User $user */
        $user = Auth::user();

        if ($question->custom_subject_id !== $customSubject->id || $question->user_id !== $user->id) {
            abort(403);
        }

        if (!$question->answer) {
            return back()->with('error', __('This question has no answer to translate.'));
        }

        $validated = $request->validate([
            'target_language' => ['required', 'string', 'max:10'],
        ]);

        $targetLanguage = $validated['target_language'];

        // Get AI settings
        $provider = \App\Models\Setting::where('key', 'ai_default_provider')->value('value');
        $model = \App\Models\Setting::where('key', 'ai_default_model')->value('value');

        if (!$provider) {
            $provider = config('services.ai.default_provider', 'openrouter');
        }

        if (!$model) {
            $model = config('services.ai.providers.' . $provider . '.model', 'inclusionai/ling-3.0-tiny:free');
        }

        $aiService = new AIService($provider, $model);
        $result = $aiService->translate($question->answer, $targetLanguage, $customSubject->name);

        if (!$result['success']) {
            return back()->with('error', __('Failed to translate question: :error', [
                'error' => $result['error'] ?? __('Unknown error'),
            ]));
        }

        // Update question with translated answer
        $question->update([
            'answer' => $result['content'],
        ]);

        // Track token usage
        $inputTokens = $result['input_tokens'] ?? 0;
        $outputTokens = $result['output_tokens'] ?? 0;

        if ($inputTokens > 0 || $outputTokens > 0) {
            TokenUsage::create([
                'user_id' => $user->id,
                'input_tokens' => $inputTokens,
                'output_tokens' => $outputTokens,
                'total_tokens' => $inputTokens + $outputTokens,
                'model' => $model,
                'provider' => $provider,
            ]);
        }

        return back()->with('success', __('Question translated successfully!'));
    }
}