Kent-logistics-Laravel/app/Models/Invoice.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Invoice extends Model
{
    use HasFactory;

 protected $fillable = [
    'order_id',
    'customer_id',
    'mark_no',

    'invoice_number',
    'invoice_date',
    'due_date',

    'payment_method',
    'reference_no',
    'status',

    'final_amount', // without tax

    'tax_type',     // gst / igst
    'gst_percent',  // only used for gst UI input
    'cgst_percent',
    'sgst_percent',
    'igst_percent',

    'gst_amount',   // total tax amount
    'final_amount_with_gst',

    'customer_name',
    'company_name',
    'customer_email',
    'customer_mobile',
    'customer_address',
    'pincode',

    'pdf_path',
    'notes',
];


    /****************************
     * Relationships
     ****************************/

    public function items()
    {
        return $this->hasMany(InvoiceItem::class)->orderBy('id', 'ASC');
    }

    public function order()
    {
        return $this->belongsTo(Order::class);
    }

    public function customer()
    {
        return $this->belongsTo(User::class, 'customer_id');
    }

    /****************************
     * Helper Functions
     ****************************/

    // Auto calculate GST fields (you can call this in controller before saving)
    public function calculateTotals()
    {
        $gst = ($this->final_amount * $this->gst_percent) / 100;
        $this->gst_amount = $gst;
        $this->final_amount_with_gst = $this->final_amount + $gst;
    }

    // Check overdue status condition
    public function isOverdue()
    {
        return $this->status === 'pending' && now()->gt($this->due_date);
    }

    public function getShipment()
    {
        return $this->order?->shipments?->first();
    }

    public function installments()
{
    return $this->hasMany(InvoiceInstallment::class);
}

// App\Models\Invoice.php

public function totalPaid()
{
    return $this->installments()->sum('amount');
}

public function remainingAmount()
{
    return max(
        ($this->final_amount_with_gst ?? 0) - $this->totalPaid(),
        0
    );
}


}