From abc08eeafd307c4e39c7dcc962481f1c20a80b8f Mon Sep 17 00:00:00 2001
From: Hillel Coren <hillelcoren@gmail.com>
Date: Tue, 14 Sep 2021 09:24:42 +0300
Subject: [PATCH] Correct tax report

---
 lib/data/models/invoice_model.dart        | 26 +++++++----
 lib/data/models/mixins/invoice_mixin.dart | 54 +++++++++++++++++++++--
 2 files changed, 68 insertions(+), 12 deletions(-)

diff --git a/lib/data/models/invoice_model.dart b/lib/data/models/invoice_model.dart
index b91e8bf26..34386bfb6 100644
--- a/lib/data/models/invoice_model.dart
+++ b/lib/data/models/invoice_model.dart
@@ -988,11 +988,18 @@ abstract class InvoiceEntity extends Object
   /// Gets taxes in the form { taxName1: { amount: 0, paid: 0} , ... }
   Map<String, Map<String, dynamic>> getTaxes(int precision) {
     final taxes = <String, Map<String, dynamic>>{};
-    final taxable = calculateTaxes(
-        useInclusiveTaxes: usesInclusiveTaxes, precision: precision);
+    final taxable = getTaxable();
+
+    double calculateAmount(double taxable, double rate) {
+      if (usesInclusiveTaxes) {
+        return round(taxable - (taxable / (1 + (rate / 100))), 2);
+      } else {
+        return round(taxable * (rate / 100), 2);
+      }
+    }
 
     if (taxRate1 != 0) {
-      final invoiceTaxAmount = taxable[taxName1];
+      final invoiceTaxAmount = calculateAmount(taxable, taxRate1);
       final invoicePaidAmount = (amount * invoiceTaxAmount != 0)
           ? (paidToDate / amount * invoiceTaxAmount)
           : 0.0;
@@ -1001,7 +1008,7 @@ abstract class InvoiceEntity extends Object
     }
 
     if (taxRate2 != 0) {
-      final invoiceTaxAmount = taxable[taxName2];
+      final invoiceTaxAmount = calculateAmount(taxable, taxRate2);
       final invoicePaidAmount = (amount * invoiceTaxAmount != 0)
           ? (paidToDate / amount * invoiceTaxAmount)
           : 0.0;
@@ -1010,7 +1017,7 @@ abstract class InvoiceEntity extends Object
     }
 
     if (taxRate3 != 0) {
-      final invoiceTaxAmount = taxable[taxName3];
+      final invoiceTaxAmount = calculateAmount(taxable, taxRate3);
       final invoicePaidAmount = (amount * invoiceTaxAmount != 0)
           ? (paidToDate / amount * invoiceTaxAmount)
           : 0.0;
@@ -1019,19 +1026,22 @@ abstract class InvoiceEntity extends Object
     }
 
     for (final item in lineItems) {
+      final itemTaxable = getItemTaxable(item, amount, precision);
+
       if (item.taxRate1 != 0) {
-        final itemTaxAmount = taxable[item.taxName1];
+        final itemTaxAmount = calculateAmount(itemTaxable, item.taxRate1);
         final itemPaidAmount = amount != null &&
                 itemTaxAmount != null &&
                 amount * itemTaxAmount != 0
             ? (paidToDate / amount * itemTaxAmount)
             : 0.0;
+
         _calculateTax(
             taxes, item.taxName1, item.taxRate1, itemTaxAmount, itemPaidAmount);
       }
 
       if (item.taxRate2 != 0) {
-        final itemTaxAmount = taxable[item.taxName2];
+        final itemTaxAmount = calculateAmount(itemTaxable, item.taxRate2);
         final itemPaidAmount = amount != null &&
                 itemTaxAmount != null &&
                 amount * itemTaxAmount != 0
@@ -1042,7 +1052,7 @@ abstract class InvoiceEntity extends Object
       }
 
       if (item.taxRate3 != 0) {
-        final itemTaxAmount = taxable[item.taxName3];
+        final itemTaxAmount = calculateAmount(itemTaxable, item.taxRate3);
         final itemPaidAmount = amount != null &&
                 itemTaxAmount != null &&
                 amount * itemTaxAmount != 0
diff --git a/lib/data/models/mixins/invoice_mixin.dart b/lib/data/models/mixins/invoice_mixin.dart
index 26d3fa026..ac62b3d53 100644
--- a/lib/data/models/mixins/invoice_mixin.dart
+++ b/lib/data/models/mixins/invoice_mixin.dart
@@ -124,18 +124,64 @@ abstract class CalculateInvoiceTotal {
     return map;
   }
 
+  double getTaxable() {
+    double total = 0;
+
+    lineItems.forEach((invoiceItem) {
+      double lineTotal = invoiceItem.quantity * invoiceItem.cost;
+
+      if (invoiceItem.discount != 0) {
+        if (isAmountDiscount) {
+          lineTotal -= invoiceItem.discount;
+        } else {
+          lineTotal -= lineTotal * invoiceItem.discount / 100;
+        }
+      }
+
+      total += lineTotal;
+    });
+
+    if (discount > 0) {
+      if (isAmountDiscount) {
+        total -= discount;
+      } else {
+        total *= (100 - discount) / 100;
+        total = round(total, 2);
+      }
+    }
+
+    if (customTaxes1) {
+      total += customSurcharge1;
+    }
+    if (customTaxes2) {
+      total += customSurcharge2;
+    }
+    if (customTaxes3) {
+      total += customSurcharge3;
+    }
+    if (customTaxes4) {
+      total += customSurcharge4;
+    }
+
+    return total;
+  }
+
   double getItemTaxable(
       InvoiceItemEntity item, double invoiceTotal, int precision) {
-    final double qty = round(item.quantity, 4);
+    final double qty = round(item.quantity, 5);
     final double cost = round(item.cost, 4);
     final double itemDiscount = round(item.discount, precision);
     double lineTotal = qty * cost;
 
     if (discount != 0) {
       if (isAmountDiscount) {
-        if (invoiceTotal != 0) {
-          lineTotal -= round(lineTotal / invoiceTotal * discount, 4);
+        if (invoiceTotal + discount != 0) {
+          lineTotal -= invoiceTotal != 0
+              ? (lineTotal / (invoiceTotal + discount) * discount)
+              : 0;
         }
+      } else {
+        lineTotal *= (100 - discount) / 100;
       }
     }
 
@@ -143,7 +189,7 @@ abstract class CalculateInvoiceTotal {
       if (isAmountDiscount) {
         lineTotal -= itemDiscount;
       } else {
-        lineTotal -= round(lineTotal * itemDiscount / 100, 4);
+        lineTotal -= lineTotal * itemDiscount / 100;
       }
     }