Calculatorpython.py

"""
╔══════════════════════════════════════════════════════════╗
║           PYTHON CALCULATOR APPLICATION                  ║
║     Basic + Scientific | History | File Export           ║
╚══════════════════════════════════════════════════════════╝

A beginner-friendly yet professionally structured calculator
supporting basic arithmetic, scientific functions, history
tracking, and saving results to a text file.
"""

import math
import os
from datetime import datetime

# ── Globals ──────────────────────────────────────────────
history = []          # Stores every calculation performed this session
HISTORY_FILE = "calc_history.txt"


# ════════════════════════════════════════════════════════
#  DISPLAY HELPERS
# ════════════════════════════════════════════════════════

def clear_screen():
    """Clear the terminal for a cleaner UI."""
    os.system("cls" if os.name == "nt" else "clear")


def separator(char="─", width=54):
    """Print a horizontal divider line."""
    print(char * width)


def welcome_screen():
    """Display the welcome banner when the program starts."""
    clear_screen()
    print()
    separator("═")
    print("  ██████╗ █████╗ ██╗      ██████╗")
    print(" ██╔════╝██╔══██╗██║     ██╔════╝")
    print(" ██║     ███████║██║     ██║     ")
    print(" ██║     ██╔══██║██║     ██║     ")
    print(" ╚██████╗██║  ██║███████╗╚██████╗")
    print("  ╚═════╝╚═╝  ╚═╝╚══════╝ ╚═════╝")
    separator("═")
    print("   Python Calculator  |  v2.0")
    print("   Basic + Scientific | History | Export")
    separator("═")
    print()
    input("  Press ENTER to start...")


def print_menu():
    """Print the main menu."""
    clear_screen()
    separator("═")
    print("  CALCULATOR MENU")
    separator("═")
    print("  BASIC OPERATIONS")
    print("   1. Addition          (+)")
    print("   2. Subtraction       (−)")
    print("   3. Multiplication    (×)")
    print("   4. Division          (÷)")
    print("   5. Modulus           (%)")
    print("   6. Power             (xⁿ)")
    separator()
    print("  SCIENTIFIC OPERATIONS")
    print("   7. Square Root       (√x)")
    print("   8. Logarithm         (log/ln)")
    print("   9. Trigonometry      (sin/cos/tan)")
    print("  10. Factorial         (n!)")
    print("  11. Absolute Value    (|x|)")
    separator()
    print("  HISTORY & TOOLS")
    print("  12. View History")
    print("  13. Save History to File")
    print("  14. Clear History")
    separator()
    print("   0. Exit")
    separator("═")


# ════════════════════════════════════════════════════════
#  INPUT HELPERS
# ════════════════════════════════════════════════════════

def get_number(prompt="  Enter number: "):
    """
    Safely read a float from the user.
    Keeps asking until a valid number is entered.
    """
    while True:
        try:
            return float(input(prompt))
        except ValueError:
            print("  ⚠  Invalid input — please enter a numeric value.\n")


def get_two_numbers():
    """Convenience wrapper: read two operands."""
    a = get_number("  Enter first number : ")
    b = get_number("  Enter second number: ")
    return a, b


# ════════════════════════════════════════════════════════
#  HISTORY HELPERS
# ════════════════════════════════════════════════════════

def record(expression: str, result):
    """
    Append a calculation to the in-memory history list.
    Each entry carries a timestamp for the saved file.
    """
    timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
    history.append({"time": timestamp, "expr": expression, "result": result})


def show_history():
    """Display every calculation made this session."""
    clear_screen()
    separator("═")
    print("  CALCULATION HISTORY")
    separator("═")
    if not history:
        print("  No calculations yet.")
    else:
        for i, entry in enumerate(history, 1):
            print(f"  {i:>3}. {entry['expr']} = {entry['result']}")
    separator("═")
    input("\n  Press ENTER to return to menu...")


def save_history():
    """Write the full history to a text file on disk."""
    if not history:
        print("\n  Nothing to save yet.")
        input("  Press ENTER to continue...")
        return

    with open(HISTORY_FILE, "w", encoding="utf-8") as f:
        f.write("PYTHON CALCULATOR — SESSION HISTORY\n")
        f.write(f"Saved on: {datetime.now().strftime('%Y-%m-%d %H:%M:%S')}\n")
        f.write("=" * 54 + "\n")
        for i, entry in enumerate(history, 1):
            f.write(f"{i:>3}. [{entry['time']}]  "
                    f"{entry['expr']} = {entry['result']}\n")
        f.write("=" * 54 + "\n")
        f.write(f"Total calculations: {len(history)}\n")

    print(f"\n  ✔  History saved to '{HISTORY_FILE}'")
    input("  Press ENTER to continue...")


def clear_history():
    """Wipe the in-memory history after confirmation."""
    confirm = input("\n  Clear all history? (y/n): ").strip().lower()
    if confirm == "y":
        history.clear()
        print("  ✔  History cleared.")
    else:
        print("  Cancelled.")
    input("  Press ENTER to continue...")


# ════════════════════════════════════════════════════════
#  BASIC OPERATIONS
# ════════════════════════════════════════════════════════

def add(a, b):
    """Return the sum of a and b."""
    return a + b


def subtract(a, b):
    """Return a minus b."""
    return a - b


def multiply(a, b):
    """Return the product of a and b."""
    return a * b


def divide(a, b):
    """
    Return a divided by b.
    Raises ZeroDivisionError if b is 0.
    """
    if b == 0:
        raise ZeroDivisionError("Cannot divide by zero.")
    return a / b


def modulus(a, b):
    """
    Return the remainder of a ÷ b.
    Raises ZeroDivisionError if b is 0.
    """
    if b == 0:
        raise ZeroDivisionError("Cannot compute modulus with zero divisor.")
    return a % b


def power(a, b):
    """Return a raised to the power b."""
    return a ** b


# ════════════════════════════════════════════════════════
#  SCIENTIFIC OPERATIONS
# ════════════════════════════════════════════════════════

def square_root(a):
    """
    Return the square root of a.
    Raises ValueError for negative inputs.
    """
    if a < 0:
        raise ValueError("Square root of a negative number is not real.")
    return math.sqrt(a)


def logarithm():
    """
    Compute log base-10 or natural log (ln) based on user choice.
    Raises ValueError for non-positive inputs.
    """
    print("\n  Logarithm type:")
    print("   1. Log base-10  (log₁₀)")
    print("   2. Natural log  (ln / logₑ)")
    choice = input("  Choose (1/2): ").strip()
    a = get_number("  Enter number: ")
    if a <= 0:
        raise ValueError("Logarithm is undefined for zero or negative numbers.")
    if choice == "1":
        result = math.log10(a)
        expr = f"log₁₀({a})"
    else:
        result = math.log(a)
        expr = f"ln({a})"
    return expr, result


def trigonometry():
    """
    Compute sin, cos, or tan of an angle.
    User can choose degrees or radians.
    Returns (expression_string, result).
    """
    print("\n  Trig function:")
    print("   1. Sine    (sin)")
    print("   2. Cosine  (cos)")
    print("   3. Tangent (tan)")
    func_choice = input("  Choose (1/2/3): ").strip()

    print("\n  Angle unit:")
    print("   1. Degrees")
    print("   2. Radians")
    unit_choice = input("  Choose (1/2): ").strip()

    angle = get_number("  Enter angle: ")

    # Convert to radians if degrees were given
    rad = math.radians(angle) if unit_choice == "1" else angle
    unit_label = "°" if unit_choice == "1" else " rad"

    if func_choice == "1":
        result = math.sin(rad)
        expr = f"sin({angle}{unit_label})"
    elif func_choice == "2":
        result = math.cos(rad)
        expr = f"cos({angle}{unit_label})"
    elif func_choice == "3":
        # tan is undefined at 90°, 270°, etc.
        if unit_choice == "1" and angle % 180 == 90:
            raise ValueError("tan is undefined at 90° + 180°·n.")
        result = math.tan(rad)
        expr = f"tan({angle}{unit_label})"
    else:
        raise ValueError("Invalid trig function choice.")

    return expr, result


def factorial(a):
    """
    Return n! for a non-negative integer a.
    Raises ValueError for negatives or non-integers.
    """
    if a < 0:
        raise ValueError("Factorial is undefined for negative numbers.")
    if a != int(a):
        raise ValueError("Factorial requires a whole number.")
    return math.factorial(int(a))


def absolute_value(a):
    """Return the absolute value of a."""
    return abs(a)


# ════════════════════════════════════════════════════════
#  OPERATION RUNNERS  (connect menu → functions → history)
# ════════════════════════════════════════════════════════

def run_basic(op_number):
    """
    Handle menu options 1–6 (basic arithmetic).
    op_number maps to the operator chosen.
    """
    ops = {
        1: ("+",  add),
        2: ("−",  subtract),
        3: ("×",  multiply),
        4: ("÷",  divide),
        5: ("%",  modulus),
        6: ("**", power),
    }
    symbol, func = ops[op_number]

    print(f"\n  {'─'*40}")
    a, b = get_two_numbers()

    try:
        result = func(a, b)
        # Format cleanly: drop unnecessary decimal for whole results
        display = int(result) if isinstance(result, float) and result.is_integer() else round(result, 10)
        expr = f"{a} {symbol} {b}"
        print(f"\n  ✔  Result: {expr} = {display}")
        record(expr, display)
    except ZeroDivisionError as e:
        print(f"\n  ✘  Math Error: {e}")
    except Exception as e:
        print(f"\n  ✘  Error: {e}")

    input("\n  Press ENTER to continue...")


def run_sqrt():
    """Handle Square Root (menu 7)."""
    print("\n  ──────────────────────────────────────────")
    a = get_number("  Enter number: ")
    try:
        result = square_root(a)
        display = round(result, 10)
        expr = f"√({a})"
        print(f"\n  ✔  Result: {expr} = {display}")
        record(expr, display)
    except ValueError as e:
        print(f"\n  ✘  Error: {e}")
    input("\n  Press ENTER to continue...")


def run_log():
    """Handle Logarithm (menu 8)."""
    print("\n  ──────────────────────────────────────────")
    try:
        expr, result = logarithm()
        display = round(result, 10)
        print(f"\n  ✔  Result: {expr} = {display}")
        record(expr, display)
    except ValueError as e:
        print(f"\n  ✘  Error: {e}")
    input("\n  Press ENTER to continue...")


def run_trig():
    """Handle Trigonometry (menu 9)."""
    print("\n  ──────────────────────────────────────────")
    try:
        expr, result = trigonometry()
        display = round(result, 10)
        print(f"\n  ✔  Result: {expr} = {display}")
        record(expr, display)
    except ValueError as e:
        print(f"\n  ✘  Error: {e}")
    input("\n  Press ENTER to continue...")


def run_factorial():
    """Handle Factorial (menu 10)."""
    print("\n  ──────────────────────────────────────────")
    a = get_number("  Enter number: ")
    try:
        result = factorial(a)
        expr = f"{int(a)}!"
        print(f"\n  ✔  Result: {expr} = {result}")
        record(expr, result)
    except ValueError as e:
        print(f"\n  ✘  Error: {e}")
    input("\n  Press ENTER to continue...")


def run_abs():
    """Handle Absolute Value (menu 11)."""
    print("\n  ──────────────────────────────────────────")
    a = get_number("  Enter number: ")
    result = absolute_value(a)
    expr = f"|{a}|"
    print(f"\n  ✔  Result: {expr} = {result}")
    record(expr, result)
    input("\n  Press ENTER to continue...")


# ════════════════════════════════════════════════════════
#  MAIN LOOP
# ════════════════════════════════════════════════════════

def main():
    """
    Entry point.
    Displays the welcome screen, then loops through the
    menu until the user selects option 0 (Exit).
    """
    welcome_screen()

    while True:
        print_menu()
        choice = input("  Enter your choice: ").strip()

        # ── Basic operations ──────────────────────────
        if choice in ("1", "2", "3", "4", "5", "6"):
            run_basic(int(choice))

        # ── Scientific operations ─────────────────────
        elif choice == "7":
            run_sqrt()
        elif choice == "8":
            run_log()
        elif choice == "9":
            run_trig()
        elif choice == "10":
            run_factorial()
        elif choice == "11":
            run_abs()

        # ── History & tools ───────────────────────────
        elif choice == "12":
            show_history()
        elif choice == "13":
            save_history()
        elif choice == "14":
            clear_history()

        # ── Exit ──────────────────────────────────────
        elif choice == "0":
            clear_screen()
            separator("═")
            print("  Thanks for using Python Calculator!")
            print(f"  Total calculations this session: {len(history)}")
            if history:
                save_prompt = input("\n  Save history before exiting? (y/n): ").strip().lower()
                if save_prompt == "y":
                    save_history()
            separator("═")
            print()
            break

        else:
            print("\n  ⚠  Invalid choice. Please enter a number from the menu.")
            input("  Press ENTER to continue...")


# ════════════════════════════════════════════════════════
#  PROGRAM ENTRY POINT
# ════════════════════════════════════════════════════════

if __name__ == "__main__":
    main()