value averging model bulild, can use yahoo and csv fron other sources

app.py

@@ -1,6 +1,6 @@
-from flask import Flask, render_template, jsonify
+from flask import Flask, render_template,request, jsonify
 from datetime import datetime, timedelta
-from engine import DataEngine
+from engine import DataEngine, StrategyEngine
 import concurrent.futures
 from flask_caching import Cache
 import csv, os, logging
@@ -9,10 +9,6 @@ from concurrent.futures import ThreadPoolExecutor
 app = Flask(__name__)
 cache = Cache(app, config={'CACHE_TYPE': 'SimpleCache'})
 
-import os
-import csv
-
-
 @cache.memoize(timeout=3600)
 def fetch_and_calculate(config):
     engine = DataEngine(config['symbol'], config['url'], config['provider'])
@@ -63,5 +59,57 @@ def run_sync():
     report = engine.global_sync()
     return jsonify(report)
 
+@app.route('/api/backtest', methods=['POST'])
+def api_backtest():
+    data = request.get_json() or {}
+    
+    # 1. Extract and Sanitize Symbol
+    symbol = data.get('symbol', '').strip().upper()
+    print(f"DEBUG: Processing {symbol}")
+
+    if not symbol:
+        return jsonify({"error": "Symbol is required"}), 400
+
+    try:
+        # 2. Extract Numerical and Logic Inputs (Matching updated JS keys)
+        initial = float(data.get('initial_inv', 0))
+        monthly = float(data.get('monthly_target', 0))
+        start_date = data.get('start_date', '2024-01-01')
+        
+        # Robust Boolean Check for toggles
+        allow_sell = data.get('allow_sell') is True
+        allow_frac = data.get('allow_fractional') is True
+
+        # 3. Initialize Engines
+        # DataEngine __init__ now calls ensure_data() to download if missing
+        data_eng = DataEngine(symbol=symbol)
+        
+        if not os.path.exists(data_eng.file_path):
+            return jsonify({"error": f"Data for {symbol} could not be retrieved."}), 404
+            
+        strat_eng = StrategyEngine(data_eng)
+        
+        # 4. Calculation
+        history = strat_eng.calculate_va_vs_dca(
+            initial_inv=initial, 
+            monthly_target=monthly, 
+            start_date=start_date, 
+            allow_sell=allow_sell, 
+            allow_fractional=allow_frac
+        )
+
+        return jsonify(history)
+
+    except Exception as e:
+        import traceback
+        print("CRITICAL ERROR in /api/backtest:")
+        print(traceback.format_exc()) 
+        return jsonify({"error": "Internal Server Error. Check terminal logs."}), 500
+
+@app.route('/backtest') # This is the URL you will actually visit
+def backtest_ui():
+    # This sends the HTML file to your browser
+    return render_template('val_avg_cal.html')
+
 if __name__ == '__main__':
     app.run(debug=True, host='0.0.0.0', port=5000)