topnotch_website/app/Models/InvoiceReport.php

<?php

namespace App\Models;

use App\Enums\InvoiceStatus;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\BelongsToMany;

class InvoiceReport extends Model
{
    use HasFactory;

    protected $fillable = [
        'internal_id',
        'customer_id',
        'date_start',
        'date_end',
        'filter_paid',
        'subtotal',
        'pst',
        'gst',
    ];

    protected $appends = [
        'total',
        'balance',
    ];

    protected $casts = [
        'date_start' => 'date',
        'date_end'   => 'date',
    ];

    public static function boot(): void
    {
        parent::boot();

        static::created(function (InvoiceReport $model) {
            $model->attributes['internal_id'] = 'TNR'.str_pad($model->id, 4, '0', STR_PAD_LEFT);

            $invoices = Invoice::whereBetween('date', [$model->date_start, $model->date_end])
                ->where('customer_id', $model->customer_id)
                ->when($model->filter_paid, function ($query) {
                    $query->where('status', InvoiceStatus::UNPAID)
                        ->orWhere('status', InvoiceStatus::PARTIALLY_PAID);
                });

            $model->invoices()->sync($invoices->pluck('id')->toArray());

            $model->save();
        });
    }

    public function getTotalAttribute()
    {
        return $this->invoices()->sum('total');
    }

    public function getBalanceAttribute()
    {
        return $this->invoices->sum(fn (Invoice $invoice) => $invoice->remainingBalance());
    }

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

    public function invoices(): BelongsToMany
    {
        return $this->BelongsToMany(Invoice::class);
    }

    public function orders()
    {
        return $this->invoices()->with('orders')->get()->pluck('orders')->flatten()->unique('id');
    }
}