constructBarcode at CouponBarcodeView

@@ -14,6 +14,34 @@ import UIKit
 // import AVFoundation
 
 
+
+extension String {
+
+    var length: Int {
+        return count
+    }
+
+    subscript (i: Int) -> String {
+        return self[i ..< i + 1]
+    }
+
+    func substring(fromIndex: Int) -> String {
+        return self[min(fromIndex, length) ..< length]
+    }
+
+    func substring(toIndex: Int) -> String {
+        return self[0 ..< max(0, toIndex)]
+    }
+
+    subscript (r: Range<Int>) -> String {
+        let range = Range(uncheckedBounds: (lower: max(0, min(length, r.lowerBound)),
+                                            upper: min(length, max(0, r.upperBound))))
+        let start = index(startIndex, offsetBy: range.lowerBound)
+        let end = index(start, offsetBy: range.upperBound - range.lowerBound)
+        return String(self[start ..< end])
+    }
+}
+
 extension CouponBarcodeView {
     struct headerView: View {
         var goBack: () -> ()
@@ -96,6 +124,41 @@ extension CouponBarcodeView {
         }
         
         
+        func constructBarcode() -> String? {
+            // EAN 13 barcode construction
+            let couponData = coupon["coupon_data"] as? [String: Any] ?? ["":""]
+            let couponString = couponData["coupon"] as? String ?? ""
+            
+            if (!couponString.isEmpty) {
+                var checkDigit = 0;
+                var result = 0;
+                
+                var fixedCouponCode = couponString;
+                if (fixedCouponCode.count < 12) {
+                    let loops = 12 - fixedCouponCode.count;
+                    var zerosStr = "";
+                    for i in 0 ..< loops {
+                        zerosStr += "0"
+                    }
+                    fixedCouponCode = zerosStr + fixedCouponCode;
+                }
+
+                var multiplier = 3;
+                for idx in (0 ... (fixedCouponCode.count - 1)).reversed() {
+                    let curChar = fixedCouponCode[idx];
+                    result += (Int(curChar) ?? 0) * multiplier;
+                    multiplier = multiplier == 3 ? 1 : 3;
+                }
+                checkDigit = 10 - (result % 10);
+
+                let barcodeStr = fixedCouponCode + String(checkDigit);
+                return barcodeStr;
+            }
+
+            return ""
+        }
+
+        
         var body: some View {
             let couponData = coupon["coupon_data"] as? [String: Any] ?? ["":""]
             
@@ -197,7 +260,7 @@ extension CouponBarcodeView {
 //                                    .aspectRatio(contentMode: .fit)
 //                                    .frame(width: self.uiscreen.width, height: self.uiscreen.height * 0.1)
                                 
-                                Text(couponData["coupon"] as? String ?? "")
+                                Text(constructBarcode() ?? "")
                                     .fontWeight(.regular)
                                     .font(.system(size: 22))
                                     .foregroundColor(Color(red: 0.2549019607843137, green: 0.3333333333333333, blue: 0.39215686274509803))