<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\HasMany;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Support\Facades\Storage;

class DocumentVersion extends Model
{
    protected $fillable = [
        'document_id',
        'version_number',
        'original_filename',
        'stored_path',
        'mime_type',
        'file_size',
        'file_hash',
        'page_count',
        'processing_status',
        'processing_error',
        'processing_started_at',
        'processing_completed_at',
        'is_current',
        'change_notes',
        'uploaded_by',
    ];

    protected $casts = [
        'is_current'               => 'boolean',
        'file_size'                => 'integer',
        'page_count'               => 'integer',
        'processing_started_at'    => 'datetime',
        'processing_completed_at'  => 'datetime',
    ];

    // Status constants
    const STATUS_PENDING           = 'pending';
    const STATUS_PROCESSING        = 'processing';
    const STATUS_EXTRACTING        = 'extracting';
    const STATUS_CHUNKING          = 'chunking';
    const STATUS_EMBEDDING         = 'embedding';
    const STATUS_INDEXED           = 'indexed';
    const STATUS_FAILED            = 'failed';
    const STATUS_EXTRACTION_FAILED = 'extraction_failed';

    // === Relationships ===

    public function document(): BelongsTo
    {
        return $this->belongsTo(Document::class);
    }

    public function chunks(): HasMany
    {
        return $this->hasMany(DocumentChunk::class)->orderBy('chunk_index');
    }

    public function uploader(): BelongsTo
    {
        return $this->belongsTo(User::class, 'uploaded_by');
    }

    // === Scopes ===

    public function scopeCurrent(Builder $query): Builder
    {
        return $query->where('is_current', true);
    }

    public function scopeIndexed(Builder $query): Builder
    {
        return $query->where('processing_status', self::STATUS_INDEXED);
    }

    // === Helpers ===

    public function getStorageUrl(): string
    {
        return Storage::url($this->stored_path);
    }

    public function getFileSizeFormattedAttribute(): string
    {
        $bytes = $this->file_size;
        if ($bytes < 1024) return $bytes . ' B';
        if ($bytes < 1048576) return round($bytes / 1024, 1) . ' KB';
        return round($bytes / 1048576, 1) . ' MB';
    }

    public function isProcessed(): bool
    {
        return $this->processing_status === self::STATUS_INDEXED;
    }

    public function hasFailed(): bool
    {
        return in_array($this->processing_status, [
            self::STATUS_FAILED,
            self::STATUS_EXTRACTION_FAILED,
        ]);
    }

    public function updateStatus(string $status, ?string $error = null): void
    {
        $data = ['processing_status' => $status];

        if ($status === self::STATUS_PROCESSING) {
            $data['processing_started_at'] = now();
        }

        if ($status === self::STATUS_INDEXED) {
            $data['processing_completed_at'] = now();
        }

        if ($error !== null) {
            $data['processing_error'] = $error;
        }

        $this->update($data);
    }
}