Update app.py

app.py

@@ -458,31 +458,63 @@ def get_farmer_report(farmer_name, end_date=None, interest_rate=None):
         df = df.sort_values('Date')
         
         # Calculate running balance with interest
-        balance = 0
+        principal_due = 0        # actual loan outstanding
+        total_interest = 0       # accumulated interest
         total_lent = 0
         total_returned = 0
         last_date = None
+        surplus_to_farmer = 0    # if farmer paid extra
+
         
         transactions_with_interest = []
-        
+
         for idx, row in df.iterrows():
             amount = row['Amount']
             current_date = row['Date'].strftime("%Y-%m-%d")
-            
-            # Calculate interest on outstanding balance since last transaction
-            if balance < 0 and last_date:
-                interest = calculate_interest(abs(balance), last_date, current_date, interest_rate)
-                balance -= interest
+        
+            # 1) Apply interest ONLY on principal_due (only when farmer owes us)
+            if principal_due > 0 and last_date:
+                interest = calculate_interest(principal_due, last_date, current_date, interest_rate)
+                total_interest += interest
+                principal_due += interest
+        
                 transactions_with_interest.append({
                     'Date': current_date,
                     'Description': 'Interest Accrued',
                     'Bank Account': '-',
                     'Amount': -interest,
-                    'Balance': balance
+                    'Balance': -principal_due
                 })
-            
-            # Add transaction
-            balance += amount
+        
+            # 2) Process transaction
+            if amount < 0:
+                # We lent money
+                lend = abs(amount)
+                principal_due += lend
+                total_lent += lend
+        
+            else:
+                # Farmer paid money
+                payment = amount
+                total_returned += payment
+        
+                if payment <= principal_due:
+                    principal_due -= payment
+                else:
+                    surplus_to_farmer += (payment - principal_due)
+                    principal_due = 0
+        
+            # Record transaction
+            transactions_with_interest.append({
+                'Date': current_date,
+                'Description': row['Type'],
+                'Bank Account': row['Bank Account'],
+                'Amount': amount,
+                'Balance': -principal_due if principal_due > 0 else surplus_to_farmer
+            })
+        
+            last_date = current_date
+
             
             if amount < 0:
                 total_lent += abs(amount)
@@ -500,16 +532,19 @@ def get_farmer_report(farmer_name, end_date=None, interest_rate=None):
             last_date = current_date
         
         # Calculate interest up to end date
-        if balance < 0 and last_date:
-            interest = calculate_interest(abs(balance), last_date, end_date_str, interest_rate)
-            balance -= interest
+        if principal_due > 0 and last_date:
+            interest = calculate_interest(principal_due, last_date, end_date_str, interest_rate)
+            total_interest += interest
+            principal_due += interest
+        
             transactions_with_interest.append({
                 'Date': end_date_str,
                 'Description': f'Interest Accrued (to {format_date_display(end_date_str)})',
                 'Bank Account': '-',
                 'Amount': -interest,
-                'Balance': balance
+                'Balance': -principal_due
             })
+
         
         # Create detailed transaction DataFrame
         detailed_df = pd.DataFrame(transactions_with_interest)
@@ -522,7 +557,13 @@ def get_farmer_report(farmer_name, end_date=None, interest_rate=None):
         
         # Summary statistics
         remaining_balance = balance
-        interest_accrued = abs(remaining_balance) - (total_lent - total_returned)
+        interest_accrued = total_interest
+
+        remaining_balance = (
+            -principal_due if principal_due > 0 
+            else surplus_to_farmer
+        )
+
         
         # Create summary HTML
         summary_html = f"""