Allow invoice balances to change - but do no allow them to go negative

app/Helpers/Invoice/InvoiceSum.php

@@ -183,6 +183,16 @@ class InvoiceSum
         return $this;
     }
 
+    /**
+     * Allow us to get the entity without persisting it
+     * @return Invoice the temp
+     */
+    public function getTempEntity()
+    {
+        $this->setCalculatedAttributes();
+        return $this->invoice;
+    }
+
     public function getInvoice()
     {
         //Build invoice values here and return Invoice

app/Helpers/Invoice/InvoiceSumInclusive.php

@@ -196,6 +196,12 @@ class InvoiceSumInclusive
         return $this->invoice;
     }
 
+    public function getTempEntity()
+    {
+        $this->setCalculatedAttributes();
+        return $this->invoice;
+    }
+
     public function getInvoice()
     {
         //Build invoice values here and return Invoice

app/Http/Requests/Invoice/UpdateInvoiceRequest.php

@@ -12,7 +12,9 @@
 namespace App\Http\Requests\Invoice;
 
 use App\Http\Requests\Request;
+use App\Http\ValidationRules\Invoice\InvoiceBalanceSanity;
 use App\Http\ValidationRules\Invoice\LockedInvoiceRule;
+use App\Models\Invoice;
 use App\Utils\Traits\ChecksEntityStatus;
 use App\Utils\Traits\CleanLineItems;
 use App\Utils\Traits\MakesHash;
@@ -55,6 +57,9 @@ class UpdateInvoiceRequest extends Request
 
         $rules['line_items'] = 'array';
 
+        if($this->input('status_id') != Invoice::STATUS_DRAFT)
+            $rules['balance'] = new InvoiceBalanceSanity($this->invoice, $this->all());
+
         return $rules;
     }
 

app/Http/ValidationRules/Invoice/InvoiceBalanceSanity.php

@@ -0,0 +1,77 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2021. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/AAL
+ */
+
+namespace App\Http\ValidationRules\Invoice;
+
+use App\Models\Invoice;
+use Illuminate\Contracts\Validation\Rule;
+use Illuminate\Support\Facades\DB;
+
+/**
+ * Class LockedInvoiceRule.
+ */
+class InvoiceBalanceSanity implements Rule
+{
+    public $invoice;
+
+    public $input;
+
+    private $message;
+
+
+    public function __construct(Invoice $invoice, $input)
+    {
+        $this->invoice = $invoice;
+        $this->input = $input;
+    }
+
+    /**
+     * @param string $attribute
+     * @param mixed $value
+     * @return bool
+     */
+    public function passes($attribute, $value)
+    {
+        return $this->checkIfInvoiceBalanceIsSane(); //if it exists, return false!
+    }
+
+    /**
+     * @return string
+     */
+    public function message()
+    {
+        return $this->message;
+    }
+
+    /**
+     * @return bool
+     */
+    private function checkIfInvoiceBalanceIsSane() : bool
+    {
+
+        $this->invoice->line_items = $this->input['line_items'];
+
+        DB::beginTransaction();
+ 
+            $temp_invoice = $this->invoice->calc()->getTempEntity();
+ 
+        DB::rollBack();
+
+        if($temp_invoice->balance < 0){
+            $this->message = 'Invoice balance cannot go negative';
+            return false;
+        }
+
+
+        return true;
+
+    }
+}

app/Repositories/BaseRepository.php

@@ -302,8 +302,14 @@ class BaseRepository
         /* Perform model specific tasks */
         if ($model instanceof Invoice) {
 
+nlog("in base");
+nlog($state['finished_amount']);
+nlog($state['starting_amount']);
+nlog($model->status_id);
+
             if (($state['finished_amount'] != $state['starting_amount']) && ($model->status_id != Invoice::STATUS_DRAFT)) {
 
+                $model->service()->updateStatus()->save();
                 $model->ledger()->updateInvoiceBalance(($state['finished_amount'] - $state['starting_amount']), "Update adjustment for invoice {$model->number}");
                 $model->client->service()->updateBalance(($state['finished_amount'] - $state['starting_amount']))->save();