start web app

app.py

@@ -0,0 +1,161 @@
+from flask import Flask, render_template, request, redirect, url_for, session, jsonify
+
+app = Flask(__name__)
+app.secret_key = 'SUPER-SECRET-KEY'  # Replace with something more secure in production
+
+# Demo user dictionary (store hashed credentials in a real system)
+USERS = {
+    "testuser": "testpass"
+}
+
+@app.route('/', methods=['GET', 'POST'])
+def login():
+    if request.method == 'POST':
+        username = request.form.get('username')
+        password = request.form.get('password')
+        if USERS.get(username) == password:
+            session['logged_in'] = True
+            return redirect(url_for('calculator'))
+        else:
+            return render_template('login.html', error="Invalid username/password.")
+    else:
+        if session.get('logged_in'):
+            return redirect(url_for('calculator'))
+        return render_template('login.html')
+
+@app.route('/logout')
+def logout():
+    session.clear()
+    return redirect(url_for('login'))
+
+@app.route('/calculator')
+def calculator():
+    if not session.get('logged_in'):
+        return redirect(url_for('login'))
+    return render_template('calculator.html')
+
+@app.route('/compute', methods=['POST'])
+def compute():
+    """
+    AJAX endpoint that receives user inputs (via JSON),
+    then calculates renting vs. buying outcomes.
+    This version dynamically updates taxes, insurance,
+    and maintenance based on the house's changing value.
+    """
+    data = request.json
+
+    # User inputs
+    current_age = float(data.get('current_age', 30))
+    age_at_death = float(data.get('age_at_death', 90))
+    monthly_salary = float(data.get('monthly_salary', 5000))
+    monthly_rent = float(data.get('monthly_rent', 1500))
+    home_cost = float(data.get('home_cost', 400000))
+    down_payment = float(data.get('down_payment', 80000))
+    monthly_expenses = float(data.get('monthly_expenses', 1500))
+    investment_return = float(data.get('investment_return', 6)) / 100.0
+
+    # Time horizon
+    years = age_at_death - current_age
+    months = int(years * 12)
+
+    # Simple monthly investment rate
+    monthly_investment_rate = investment_return / 12
+
+    # ------------------
+    # Renter Scenario
+    # ------------------
+    # Start with a lump sum (down payment) in investments
+    renter_investment_balance = down_payment
+    current_monthly_salary = monthly_salary
+
+    # We won't change rent monthly here in detail,
+    # but you could add rent growth if desired.
+    # For now, keep it fixed for simplicity.
+
+    for _ in range(months):
+        leftover_rent = current_monthly_salary - (monthly_rent + monthly_expenses)
+        if leftover_rent > 0:
+            renter_investment_balance += leftover_rent
+        # Grow investment
+        renter_investment_balance *= (1 + monthly_investment_rate)
+
+        # We’ll skip monthly salary growth to keep it straightforward
+        # but you could easily incorporate that as well.
+
+    renter_net_worth = renter_investment_balance
+
+    # ------------------
+    # Buyer Scenario
+    # ------------------
+    # Mortgage logic: Very simplified example
+    principal = home_cost - down_payment
+    mortgage_rate_annual = 0.04        # 4% annual, for demonstration
+    monthly_mortgage_rate = mortgage_rate_annual / 12
+    mortgage_term_years = 30
+    num_payments = mortgage_term_years * 12
+
+    if principal > 0:
+        # Standard formula
+        monthly_mortgage_payment = (
+            principal *
+            (monthly_mortgage_rate * (1 + monthly_mortgage_rate) ** num_payments) /
+            ((1 + monthly_mortgage_rate) ** num_payments - 1)
+        )
+    else:
+        monthly_mortgage_payment = 0
+
+    # Let's assume a 1% property tax and 0.3% insurance, 0.2% maintenance, all annual,
+    # but it will scale with changing house value
+    property_tax_annual_rate = 0.01
+    insurance_annual_rate = 0.003
+    maintenance_annual_rate = 0.002
+
+    # House appreciation
+    annual_appreciation_rate = 0.02  # 2% annual
+    monthly_appreciation_rate = annual_appreciation_rate / 12
+
+    house_value = home_cost
+    buyer_investment_balance = 0
+    total_upfront = down_payment  # ignoring closing costs for simplicity here
+
+    for month_index in range(months):
+        # Each month, update the house value first
+        house_value *= (1 + monthly_appreciation_rate)
+
+        # Recalc these costs based on the updated house value
+        monthly_taxes = (house_value * property_tax_annual_rate) / 12
+        monthly_insurance = (house_value * insurance_annual_rate) / 12
+        monthly_maintenance = (house_value * maintenance_annual_rate) / 12
+
+        # If mortgage is still active
+        if month_index < num_payments:
+            monthly_costs = monthly_mortgage_payment + monthly_taxes + monthly_insurance + monthly_maintenance
+        else:
+            monthly_costs = monthly_taxes + monthly_insurance + monthly_maintenance
+
+        leftover_buy = monthly_salary - (monthly_expenses + monthly_costs)
+        if leftover_buy > 0:
+            buyer_investment_balance += leftover_buy
+
+        # Grow leftover investment
+        buyer_investment_balance *= (1 + monthly_investment_rate)
+
+    homeowner_net_worth = buyer_investment_balance + house_value
+
+    # Compare
+    difference = homeowner_net_worth - renter_net_worth
+
+    results = {
+        "renter_investment_balance": f"${renter_investment_balance:,.2f}",
+        "homeowner_investment_balance": f"${buyer_investment_balance:,.2f}",
+        "final_house_value": f"${house_value:,.2f}",
+        "homeowner_net_worth": f"${homeowner_net_worth:,.2f}",
+        "renter_net_worth": f"${renter_net_worth:,.2f}",
+        "difference": difference
+    }
+
+    return jsonify(results)
+
+if __name__ == '__main__':
+    app.run(debug=True)
+

own_vs_buy2.py

@@ -23,7 +23,7 @@ def main():
     total_months = total_years * 12
 
     # --- Income & Growth ---
-    MONTHLY_SALARY = 5000.0          # Initial monthly salary
+    MONTHLY_SALARY = 10000.0          # Initial monthly salary
     ANNUAL_SALARY_GROWTH = 0.02      # 2% annual salary increase
 
     # --- Inflation for Monthly Expenses ---
@@ -34,13 +34,13 @@ def main():
     BASE_TRAVEL = 200.0
     BASE_SCHOOLING = 300.0
     BASE_HEALTHCARE = 400.0
-    BASE_INCIDENTALS = 2500  # "catch-all" category
+    BASE_INCIDENTALS = 2500.0        # "catch-all" category
 
     # --- Investment Growth ---
-    ANNUAL_INVESTMENT_RETURN = 0.06  # 6% annual
+    ANNUAL_INVESTMENT_RETURN = 0.07  # 7% annual
 
     # --- Renting Details ---
-    RENT_PER_MONTH = 1500.0
+    RENT_PER_MONTH = 2000.0
     ANNUAL_RENT_GROWTH = 0.025       # 2.5% annual
 
     # --- Buying Details ---
@@ -55,7 +55,7 @@ def main():
     AVERAGE_YEARLY_MAINTENANCE = 5000.0
 
     # Home appreciation (positive or negative)
-    ANNUAL_HOME_APPRECIATION = 0.02  # 2% per year
+    ANNUAL_HOME_APPRECIATION = 0.05  # 5% per year
 
     # ================
     # Display Assumptions
@@ -118,9 +118,11 @@ def main():
     else:
         monthly_mortgage_payment = 0.0
 
-    monthly_property_tax = (HOME_COST * PROPERTY_TAX_RATE) / 12
+    # Convert your annual property tax, insurance, and maintenance to percentage rates relative to HOME_COST:
-    monthly_insurance = HOME_INSURANCE_PER_YEAR / 12
+    # We'll do this so we can recalculate them each month based on the new house_value.
-    monthly_maintenance = AVERAGE_YEARLY_MAINTENANCE / 12
+    property_tax_annual_rate = PROPERTY_TAX_RATE  # e.g., 0.01
+    insurance_annual_rate = HOME_INSURANCE_PER_YEAR / HOME_COST  # e.g., 1200 / 350000
+    maintenance_annual_rate = AVERAGE_YEARLY_MAINTENANCE / HOME_COST  # e.g., 5000 / 350000
 
     # ================
     # Part 3: Tracking & Simulation
@@ -155,31 +157,36 @@ def main():
             rent_investment_balance += leftover_rent
         rent_investment_balance *= (1 + monthly_investment_growth)
 
-        # --- Buying: Pay Mortgage/Costs, Invest Leftover
+        # --- Buying: Update House Value, then compute monthly taxes, insurance, maintenance
+        house_value *= (1 + monthly_home_appreciation)
+
+        # Recalc monthly property tax, insurance, maintenance based on current house_value
+        dynamic_monthly_property_tax = (house_value * property_tax_annual_rate) / 12
+        dynamic_monthly_insurance = (house_value * insurance_annual_rate) / 12
+        dynamic_monthly_maintenance = (house_value * maintenance_annual_rate) / 12
+
         if month <= number_of_payments:
             monthly_ownership_cost = (
                 monthly_mortgage_payment +
-                monthly_property_tax +
+                dynamic_monthly_property_tax +
-                monthly_insurance +
+                dynamic_monthly_insurance +
-                monthly_maintenance
+                dynamic_monthly_maintenance
             )
         else:
             monthly_ownership_cost = (
-                monthly_property_tax +
+                dynamic_monthly_property_tax +
-                monthly_insurance +
+                dynamic_monthly_insurance +
-                monthly_maintenance
+                dynamic_monthly_maintenance
             )
 
         total_buy_cost += monthly_ownership_cost
+
         leftover_buy = current_monthly_salary - current_standard_expenses - monthly_ownership_cost
         if leftover_buy > 0:
             buy_investment_balance += leftover_buy
         buy_investment_balance *= (1 + monthly_investment_growth)
 
-        # House Appreciation
+        # --- Increase Salary, Rent, Standard Expenses (monthly growth)
-        house_value *= (1 + monthly_home_appreciation)
-
-        # Increase Salary, Rent, Standard Expenses (monthly growth)
         current_monthly_salary *= (1 + monthly_salary_growth)
         current_rent *= (1 + monthly_rent_growth)
         current_standard_expenses *= (1 + monthly_inflation)