API

- Refactor comments/client id var
- Add basic read endpoint for docs, products, expenses, quotes and invoices

api/v1/invoices/read.php

@@ -0,0 +1,19 @@
+<?php
+
+require_once('../validate_api_key.php');
+require_once('../require_get_method.php');
+
+if (isset($_GET['invoice_id'])) {
+    // Invoice via ID (single)
+
+    $id = intval($_GET['invoice_id']);
+    $sql = mysqli_query($mysqli, "SELECT * FROM invoices WHERE invoice_id = '$id' AND invoice_client_id LIKE '$client_id' AND company_id = '$company_id'");
+
+} else {
+    // All invoices
+
+    $sql = mysqli_query($mysqli, "SELECT * FROM invoices WHERE invoice_client_id LIKE '$client_id' AND company_id = '$company_id' ORDER BY invoice_id LIMIT $limit OFFSET $offset");
+}
+
+// Output
+require_once("../read_output.php");