add data analytics (top 3 vehicle makes)

cli_demo.py

@@ -6,13 +6,17 @@ Date: August 24, 2025
 
 A simple command-line application for a car dealership that allows users 
 to look up vehicle information (year, make, and model) by VIN number. 
+The app also lets a user view top 3 looked up vehicle makes.
 The data is retrieved from the NHTSA (National Highway Traffic Safety 
 Administration) VIN decoding API via the helper module `nhtsa_api_call.py`.
 
 Usage:
     python cli_demo.py
 """
-import nhtsa_api_call, re
+import nhtsa_api_call, re, csv, os
+import pandas as pd
+
+TOP3 = 3
 
 def is_valid_vin (vin):
     """
@@ -27,6 +31,44 @@ def is_valid_vin (vin):
         return False
     return True
 
+def save_vehicle(year, make, model, filename = "vin_lookup_history.csv"):
+    """Append VIN lookup result to a CSV file."""
+    file_exists = os.path.isfile(filename)
+    with open(filename, "a", newline="") as f:
+        writer = csv.writer(f)
+        if not file_exists:
+            # add first row
+            writer.writerow(["year", "make", "model"])  
+        writer.writerow([year, make, model])
+
+def display_top3(filename = "vin_lookup_history.csv"):
+    """Show top 3 car makes by lookup frequency"""
+    # if file does not exist then there is no history yet
+    if not os.path.isfile(filename):
+        print("\nNo VIN lookup history found. Please look up some VINs first.\n")
+        return
+    # create a dataframe using file data 
+    df = pd.read_csv(filename)
+    # save number each make appears in the log as a series
+    counts = df['make'].value_counts()
+    # file exists but no data has been added yet
+    if len(counts) == 0:
+        print("\n No data in the log yet.\n")
+        return
+    # if there are  fewer than 3 data entries in the log then the program will 
+    # at least display 1 or 2 most looked up makes
+    if len(counts) < TOP3:
+        print(f"\nNot enough data for displaying top 3. Showing top {len(counts)} instead:\n")
+        top_makes = counts.head(len(counts))
+    else:
+        print(f"\n Top {TOP3} Car Makes from Lookups:\n")
+        top_makes = counts.head(TOP3)
+
+    for make, count in top_makes.items():
+        print(f"   {make}: {count} lookups")
+    # an empty line print to space out CLI prompts
+    print()  
+
 def main():
     """
     Run the command-line VIN lookup loop.
@@ -38,25 +80,42 @@ def main():
     print("🚗 Welcome to the Car Dealership VIN Lookup!\n")
    
     while True:
-        vin = input("Please enter a valid VIN or 0 (zero) to exit: \n").strip()
+        print("Choose an option from the menu:")
+        print("1. Lookup a VIN")
+        print("2. Show Top 3 Most Looked-up Makes")
+        print("0. Exit")
+        choice = input("Enter your choice: ").strip()
+        
         # exit condition gets checked first
-        if vin == "0":
+        if choice == "0":
             print("👋 You chose to exit VIN lookup. Goodbye!")
             break
-        # check if vin is valid, and if not print error message
-        if not is_valid_vin(vin): 
-            print("⚠️ Invalid VIN format. Must be 17 letters/numbers (no I, O, Q). Try again.\n")
-            continue
-         # vin is valid, perform VIN lookup
-        else:
-            year, make, model = nhtsa_api_call.get_vehicle_info(vin)
-            if year and make and model:
-                print(f"✅ VIN {vin}")
-                print(f"   Year: {year}")
-                print(f"   Make: {make}")
-                print(f"   Model: {model}")
+        # user selected to add a VIN
+        elif choice == "1": 
+            vin = input("Please enter a valid VIN or 0 (zero) to exit: \n").strip()
+            if vin == "0":
+                continue
+            # check if vin is valid, and if not print error message
+            if not is_valid_vin(vin): 
+                print("Invalid VIN format. Must be 17 letters/numbers (no I, O, Q). Try again.\n")
+                continue
+            # vin is valid, perform VIN lookup
             else:
-                print(f"❌ VIN {vin} not found in database. Try again.")
+                year, make, model = nhtsa_api_call.get_vehicle_info(vin)
+                if year and make and model:
+                    print(f"✅ VIN {vin}")
+                    print(f"   Year: {year}")
+                    print(f"   Make: {make}")
+                    print(f"   Model: {model}")
+                    save_vehicle(year, make, model)     #save the data in the lookup history file
+                else:
+                    print(f"❌ VIN {vin} not found in database. Try again.")
+        # user selected to view top3 vehicle makes 
+        elif choice == "2":
+            display_top3()
+        # user entered something other than 1,2 or 0
+        else:
+            print("Invalid option. Please choose 1, 2, or 0.\n")
 
 if __name__ == "__main__":
     main()