<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\Storage;

class DocumentVersion extends Model
{
    use HasFactory;

    protected $fillable = [
        'document_id',
        'version_number',
        'version_notes',
        'is_current',
        'file_path',
        'original_filename',
        'mime_type',
        'file_size',
        'file_hash',
        'uploaded_by_user_id',
        'uploaded_at',
    ];

    protected $casts = [
        'is_current' => 'boolean',
        'uploaded_at' => 'datetime',
    ];

    // Versions are immutable - disable updating
    protected static function booted()
    {
        static::updating(function ($version) {
            // Only allow updating is_current flag
            $dirty = $version->getDirty();
            if (count($dirty) > 1 || !isset($dirty['is_current'])) {
                throw new \Exception('Document versions are immutable and cannot be modified');
            }
        });
    }

    // ==================== Relationships ====================

    /**
     * Get the document this version belongs to
     */
    public function document()
    {
        return $this->belongsTo(Document::class);
    }

    /**
     * Get the user who uploaded this version
     */
    public function uploadedBy()
    {
        return $this->belongsTo(User::class, 'uploaded_by_user_id');
    }

    // ==================== File Methods ====================

    /**
     * Get the full file path
     */
    public function getFullPath(): string
    {
        return storage_path('app/' . $this->file_path);
    }

    /**
     * Check if file exists
     */
    public function fileExists(): bool
    {
        return Storage::exists($this->file_path);
    }

    /**
     * Get file download URL
     */
    public function getDownloadUrl(): string
    {
        return route('admin.documents.download-version', [
            'document' => $this->document_id,
            'version' => $this->id,
        ]);
    }

    /**
     * Verify file integrity
     */
    public function verifyIntegrity(): bool
    {
        if (!$this->fileExists()) {
            return false;
        }

        $currentHash = hash_file('sha256', $this->getFullPath());
        return $currentHash === $this->file_hash;
    }

    // ==================== Helper Methods ====================

    /**
     * Get human-readable file size
     */
    public function getFileSizeHuman(): string
    {
        $bytes = $this->file_size;
        $units = ['B', 'KB', 'MB', 'GB'];

        for ($i = 0; $bytes > 1024; $i++) {
            $bytes /= 1024;
        }

        return round($bytes, 2) . ' ' . $units[$i];
    }

    /**
     * Get file extension
     */
    public function getFileExtension(): string
    {
        return pathinfo($this->original_filename, PATHINFO_EXTENSION);
    }

    /**
     * Get file icon based on mime type
     */
    public function getFileIcon(): string
    {
        return match(true) {
            str_contains($this->mime_type, 'pdf') => '📄',
            str_contains($this->mime_type, 'word') || str_contains($this->mime_type, 'document') => '📝',
            str_contains($this->mime_type, 'sheet') || str_contains($this->mime_type, 'excel') => '📊',
            str_contains($this->mime_type, 'image') => '🖼️',
            str_contains($this->mime_type, 'zip') || str_contains($this->mime_type, 'compressed') => '🗜️',
            default => '📎',
        };
    }

    /**
     * Check if version is current
     */
    public function isCurrent(): bool
    {
        return $this->is_current;
    }

    /**
     * Get version badge class for UI
     */
    public function getBadgeClass(): string
    {
        return $this->is_current ? 'bg-green-100 text-green-800' : 'bg-gray-100 text-gray-800';
    }

    /**
     * Get version badge text
     */
    public function getBadgeText(): string
    {
        return $this->is_current ? '當前版本' : '歷史版本';
    }
}