<?php

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Controller;
use App\Models\AuditLog;
use App\Models\Document;
use App\Models\DocumentCategory;
use App\Models\DocumentVersion;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Storage;

class DocumentController extends Controller
{
    /**
     * Display a listing of documents
     */
    public function index(Request $request)
    {
        $query = Document::with(['category', 'currentVersion', 'createdBy'])
            ->orderBy('created_at', 'desc');

        // Filter by category
        if ($request->filled('category')) {
            $query->where('document_category_id', $request->category);
        }

        // Filter by access level
        if ($request->filled('access_level')) {
            $query->where('access_level', $request->access_level);
        }

        // Filter by status
        if ($request->filled('status')) {
            $query->where('status', $request->status);
        }

        // Search
        if ($request->filled('search')) {
            $search = $request->search;
            $query->where(function($q) use ($search) {
                $q->where('title', 'like', "%{$search}%")
                  ->orWhere('document_number', 'like', "%{$search}%")
                  ->orWhere('description', 'like', "%{$search}%");
            });
        }

        $documents = $query->paginate(20);
        $categories = DocumentCategory::orderBy('sort_order')->get();

        return view('admin.documents.index', compact('documents', 'categories'));
    }

    /**
     * Show the form for creating a new document
     */
    public function create()
    {
        $categories = DocumentCategory::orderBy('sort_order')->get();
        return view('admin.documents.create', compact('categories'));
    }

    /**
     * Store a newly created document with initial version
     */
    public function store(Request $request)
    {
        $validated = $request->validate([
            'document_category_id' => 'required|exists:document_categories,id',
            'title' => 'required|string|max:255',
            'document_number' => 'nullable|string|max:255|unique:documents,document_number',
            'description' => 'nullable|string',
            'access_level' => 'required|in:public,members,admin,board',
            'file' => 'required|file|max:10240', // 10MB max
            'version_notes' => 'nullable|string',
        ]);

        // Upload file
        $file = $request->file('file');
        $path = $file->store('documents', 'private');

        // Create document
        $document = Document::create([
            'document_category_id' => $validated['document_category_id'],
            'title' => $validated['title'],
            'document_number' => $validated['document_number'] ?? null,
            'description' => $validated['description'] ?? null,
            'access_level' => $validated['access_level'],
            'status' => 'active',
            'created_by_user_id' => auth()->id(),
            'version_count' => 0,
        ]);

        // Add first version
        $document->addVersion(
            filePath: $path,
            originalFilename: $file->getClientOriginalName(),
            mimeType: $file->getMimeType(),
            fileSize: $file->getSize(),
            uploadedBy: auth()->user(),
            versionNotes: $validated['version_notes'] ?? '初始版本'
        );

        // Audit log
        AuditLog::create([
            'user_id' => auth()->id(),
            'action' => 'document.created',
            'description' => "建立文件：{$document->title}",
            'ip_address' => request()->ip(),
        ]);

        return redirect()
            ->route('admin.documents.show', $document)
            ->with('status', '文件已成功建立');
    }

    /**
     * Display the specified document
     */
    public function show(Document $document)
    {
        $document->load(['category', 'versions.uploadedBy', 'createdBy', 'lastUpdatedBy', 'accessLogs.user']);
        $versionHistory = $document->getVersionHistory();

        return view('admin.documents.show', compact('document', 'versionHistory'));
    }

    /**
     * Show the form for editing the document metadata
     */
    public function edit(Document $document)
    {
        $categories = DocumentCategory::orderBy('sort_order')->get();
        return view('admin.documents.edit', compact('document', 'categories'));
    }

    /**
     * Update the document metadata (not the file)
     */
    public function update(Request $request, Document $document)
    {
        $validated = $request->validate([
            'document_category_id' => 'required|exists:document_categories,id',
            'title' => 'required|string|max:255',
            'document_number' => 'nullable|string|max:255|unique:documents,document_number,' . $document->id,
            'description' => 'nullable|string',
            'access_level' => 'required|in:public,members,admin,board',
        ]);

        $document->update([
            ...$validated,
            'last_updated_by_user_id' => auth()->id(),
        ]);

        // Audit log
        AuditLog::create([
            'user_id' => auth()->id(),
            'action' => 'document.updated',
            'description' => "更新文件資訊：{$document->title}",
            'ip_address' => request()->ip(),
        ]);

        return redirect()
            ->route('admin.documents.show', $document)
            ->with('status', '文件資訊已成功更新');
    }

    /**
     * Upload a new version of the document
     */
    public function uploadNewVersion(Request $request, Document $document)
    {
        $validated = $request->validate([
            'file' => 'required|file|max:10240', // 10MB max
            'version_notes' => 'required|string',
        ]);

        // Upload file
        $file = $request->file('file');
        $path = $file->store('documents', 'private');

        // Add new version
        $version = $document->addVersion(
            filePath: $path,
            originalFilename: $file->getClientOriginalName(),
            mimeType: $file->getMimeType(),
            fileSize: $file->getSize(),
            uploadedBy: auth()->user(),
            versionNotes: $validated['version_notes']
        );

        // Audit log
        AuditLog::create([
            'user_id' => auth()->id(),
            'action' => 'document.version_uploaded',
            'description' => "上傳新版本：{$document->title} (版本 {$version->version_number})",
            'ip_address' => request()->ip(),
        ]);

        return back()->with('status', "新版本 {$version->version_number} 已成功上傳");
    }

    /**
     * Promote an old version to current
     */
    public function promoteVersion(Document $document, DocumentVersion $version)
    {
        if ($version->document_id !== $document->id) {
            return back()->with('error', '版本不符合');
        }

        $document->promoteVersion($version, auth()->user());

        // Audit log
        AuditLog::create([
            'user_id' => auth()->id(),
            'action' => 'document.version_promoted',
            'description' => "提升版本為當前版本：{$document->title} (版本 {$version->version_number})",
            'ip_address' => request()->ip(),
        ]);

        return back()->with('status', "版本 {$version->version_number} 已設為當前版本");
    }

    /**
     * Download a specific version
     */
    public function downloadVersion(Document $document, DocumentVersion $version)
    {
        if ($version->document_id !== $document->id) {
            abort(404);
        }

        if (!$version->fileExists()) {
            abort(404, '檔案不存在');
        }

        // Log access
        $document->logAccess('download', auth()->user());

        return Storage::disk('private')->download(
            $version->file_path,
            $version->original_filename
        );
    }

    /**
     * Archive a document
     */
    public function archive(Document $document)
    {
        $document->archive();

        // Audit log
        AuditLog::create([
            'user_id' => auth()->id(),
            'action' => 'document.archived',
            'description' => "封存文件：{$document->title}",
            'ip_address' => request()->ip(),
        ]);

        return back()->with('status', '文件已封存');
    }

    /**
     * Restore an archived document
     */
    public function restore(Document $document)
    {
        $document->unarchive();

        // Audit log
        AuditLog::create([
            'user_id' => auth()->id(),
            'action' => 'document.restored',
            'description' => "恢復文件：{$document->title}",
            'ip_address' => request()->ip(),
        ]);

        return back()->with('status', '文件已恢復');
    }

    /**
     * Delete a document permanently
     */
    public function destroy(Document $document)
    {
        $title = $document->title;

        // Delete all version files
        foreach ($document->versions as $version) {
            if ($version->fileExists()) {
                Storage::disk('private')->delete($version->file_path);
            }
        }

        $document->delete();

        // Audit log
        AuditLog::create([
            'user_id' => auth()->id(),
            'action' => 'document.deleted',
            'description' => "刪除文件：{$title}",
            'ip_address' => request()->ip(),
        ]);

        return redirect()
            ->route('admin.documents.index')
            ->with('status', '文件已永久刪除');
    }

    /**
     * Display document statistics dashboard
     */
    public function statistics()
    {
        // Check if statistics feature is enabled
        $settings = app(\App\Services\SettingsService::class);
        if (!$settings->isFeatureEnabled('statistics')) {
            abort(404, '統計功能未啟用');
        }

        // Check user permission
        if (!auth()->user()->can('view_document_statistics')) {
            abort(403, '您沒有檢視文件統計的權限');
        }

        $stats = [
            'total_documents' => Document::where('status', 'active')->count(),
            'total_versions' => \App\Models\DocumentVersion::count(),
            'total_downloads' => Document::sum('download_count'),
            'total_views' => Document::sum('view_count'),
            'archived_documents' => Document::where('status', 'archived')->count(),
        ];

        // Documents by category
        $documentsByCategory = DocumentCategory::withCount(['activeDocuments'])
            ->orderBy('active_documents_count', 'desc')
            ->get();

        // Most viewed documents
        $mostViewed = Document::with(['category', 'currentVersion'])
            ->where('status', 'active')
            ->orderBy('view_count', 'desc')
            ->limit(10)
            ->get();

        // Most downloaded documents
        $mostDownloaded = Document::with(['category', 'currentVersion'])
            ->where('status', 'active')
            ->orderBy('download_count', 'desc')
            ->limit(10)
            ->get();

        // Recent activity (last 30 days)
        $recentActivity = \App\Models\DocumentAccessLog::with(['user', 'document'])
            ->where('accessed_at', '>=', now()->subDays(30))
            ->latest('accessed_at')
            ->limit(50)
            ->get();

        // Monthly upload trends (last 6 months)
        $uploadTrends = Document::selectRaw("strftime('%Y-%m', created_at) as month, COUNT(*) as count")
            ->where('created_at', '>=', now()->subMonths(6))
            ->groupBy('month')
            ->orderBy('month', 'desc')
            ->get();

        // Access level distribution
        $accessLevelStats = Document::selectRaw('access_level, COUNT(*) as count')
            ->where('status', 'active')
            ->groupBy('access_level')
            ->get();

        return view('admin.documents.statistics', compact(
            'stats',
            'documentsByCategory',
            'mostViewed',
            'mostDownloaded',
            'recentActivity',
            'uploadTrends',
            'accessLevelStats'
        ));
    }
}