Add VISITS criteria type and implement visit counting logic in goals_criteria

- Introduce `VISITS` as a new goal criteria type in `goals_criteria_type` enum.
- Extend `goals_criteria` with `countVisits` method to compute unique visit counts based on criteria filters.
- Update result computation logic in `goals_criteria` to support `VISITS`.

services/nginx/app/modules/goals/classes/goals_criteria.php

@@ -190,6 +190,7 @@ class goals_criteria implements goals_criteria_i
         return match ($this->type) {
             goals_criteria_type::PRODUCT => $this->products->count($this),
             goals_criteria_type::REVENUE => $this->sumRevenue(),
+            goals_criteria_type::VISITS => $this->countVisits(),
             default => 0,
         };
     }
@@ -221,6 +222,33 @@ class goals_criteria implements goals_criteria_i
         return $sum;
     }
 
+    /**
+     * Count visits within the criteria filters.
+     * In this domain a "visit" corresponds to unique order records.
+     */
+    private function countVisits(): int
+    {
+        $datetime_start = $this->start ?? new \DateTime();
+        $datetime_end = $this->end ?? new \DateTime();
+
+        $items = order_items_o::getListByCriteria(
+            department_ids: $this->departments?->listIDs() ?? [],
+            product_ids: $this->products?->listIDs() ?? [],
+            customer_numbers: $this->users?->listCustomerNumbers() ?? [],
+            datetime_start: $datetime_start,
+            datetime_end: $datetime_end,
+        );
+
+        // Use an associative array to track unique order IDs
+        $unique_orders = [];
+        foreach ($items as $item) {
+            $order_id = (int)$item->order_id->value();
+            $unique_orders[$order_id] = true; // Value doesn't matter
+        }
+
+        return count($unique_orders);
+    }
+
     /**
      * Public accessor for the current result based on criteria type.
      * Allows external callers (e.g., goals class) to retrieve the computed result

services/nginx/app/modules/goals/helpers/goals_criteria_type.php

@@ -6,6 +6,7 @@ enum goals_criteria_type
 {
     case PRODUCT; // When the goal is related to a product
     case REVENUE;  // When the goal is related to revenue
+    case VISITS;   // When the goal is related to visits
     case NONE;    // When there is no specific criteria
 
     public static function tryFrom(string $param): ?goals_criteria_type
@@ -13,6 +14,7 @@ enum goals_criteria_type
         return match (strtoupper($param)) {
             'PRODUCT' => goals_criteria_type::PRODUCT,
             'REVENUE' => goals_criteria_type::REVENUE,
+            'VISITS' => goals_criteria_type::VISITS,
             'NONE' => goals_criteria_type::NONE,
             default => null,
         };