Tariff-Based Electricity Bill Calculator for West Zone Power Distribution Company.

electricity_bill.py

import typer
from rich.console import Console
from rich.table import Table
from rich.panel import Panel
from rich.text import Text
import math  # Added for ceiling function

# Initialize typer app and rich console
app = typer.Typer()
console = Console()

def calculate_bill(units_consumed: float) -> tuple:
    """
    Calculate electricity bill based on units consumed with tariff breakdown
    
    Args:
        units_consumed (float): Number of units (kWh) consumed
        
    Returns:
        tuple: (total_bill, breakdown_dict)
    """
    # Tariff rates in Taka
    tariff_rates = {
        "0-50": 4.63,
        "0-75": 5.26,
        "76-200": 7.20,
        "201-300": 7.59,
        "301-400": 8.02,
        "401-600": 12.67,
        "600+": 14.61
    }
    
    # Fixed demand charge in BDT
    DEMAND_CHARGE = 126.00
    # VAT rate (5%)
    VAT_RATE = 0.05
    
    breakdown = {}
    total_bill = 0
    
    # Calculate bill based on consumption slabs
    if units_consumed <= 50:
        amount = units_consumed * tariff_rates["0-50"]
        breakdown["0-50"] = math.ceil(amount)
        total_bill = breakdown["0-50"]
    
    elif units_consumed <= 75:
        amount = units_consumed * tariff_rates["0-75"]
        breakdown["0-75"] = math.ceil(amount)
        total_bill = breakdown["0-75"]
    
    elif units_consumed <= 200:
        breakdown["0-75"] = math.ceil(75 * tariff_rates["0-75"])
        breakdown["76-200"] = math.ceil((units_consumed - 75) * tariff_rates["76-200"])
        total_bill = sum(breakdown.values())
    
    elif units_consumed <= 300:
        breakdown["0-75"] = math.ceil(75 * tariff_rates["0-75"])
        breakdown["76-200"] = math.ceil(125 * tariff_rates["76-200"])
        breakdown["201-300"] = math.ceil((units_consumed - 200) * tariff_rates["201-300"])
        total_bill = sum(breakdown.values())
    
    elif units_consumed <= 400:
        breakdown["0-75"] = math.ceil(75 * tariff_rates["0-75"])
        breakdown["76-200"] = math.ceil(125 * tariff_rates["76-200"])
        breakdown["201-300"] = math.ceil(100 * tariff_rates["201-300"])
        breakdown["301-400"] = math.ceil((units_consumed - 300) * tariff_rates["301-400"])
        total_bill = sum(breakdown.values())
    
    elif units_consumed <= 600:
        breakdown["0-75"] = math.ceil(75 * tariff_rates["0-75"])
        breakdown["76-200"] = math.ceil(125 * tariff_rates["76-200"])
        breakdown["201-300"] = math.ceil(100 * tariff_rates["201-300"])
        breakdown["301-400"] = math.ceil(100 * tariff_rates["301-400"])
        breakdown["401-600"] = math.ceil((units_consumed - 400) * tariff_rates["401-600"])
        total_bill = sum(breakdown.values())
    
    else:  # More than 600 units
        breakdown["0-75"] = math.ceil(75 * tariff_rates["0-75"])
        breakdown["76-200"] = math.ceil(125 * tariff_rates["76-200"])
        breakdown["201-300"] = math.ceil(100 * tariff_rates["201-300"])
        breakdown["301-400"] = math.ceil(100 * tariff_rates["301-400"])
        breakdown["401-600"] = math.ceil(200 * tariff_rates["401-600"])
        breakdown["600+"] = math.ceil((units_consumed - 600) * tariff_rates["600+"])
        total_bill = sum(breakdown.values())
    
    # Add demand charge (rounded up)
    breakdown["Demand Charge"] = math.ceil(DEMAND_CHARGE)
    total_bill += breakdown["Demand Charge"]
    
    # Calculate VAT (rounded up)
    vat_amount = total_bill * VAT_RATE
    breakdown["VAT (5%)"] = math.ceil(vat_amount)
    total_bill += breakdown["VAT (5%)"]
    
    return total_bill, breakdown

def display_bill_rich(units_consumed: float):
    """
    Display the electricity bill with breakdown using rich formatting
    
    Args:
        units_consumed (float): Number of units consumed
    """
    total_bill, breakdown = calculate_bill(units_consumed)
    
    # Create title
    title = Text("Electricity Bill Breakdown", style="bold magenta")
    console.print(Panel(title, style="bold blue"))
    
    # Create units consumed info
    console.print(f"\nUnits Consumed: [bold cyan]{units_consumed:.2f}[/bold cyan]")
    
    # Create table for breakdown
    table = Table(show_header=True, header_style="bold green")
    table.add_column("Slab", style="dim")
    table.add_column("Amount (Taka)", justify="right", style="green")
    
    # Add rows to table
    for slab, amount in breakdown.items():
        if slab == "VAT (5%)":
            table.add_row(slab, f"{amount}", style="bold yellow")  # Removed .2f as amounts are now integers
        else:
            table.add_row(slab, f"{amount}")  # Removed .2f as amounts are now integers
    
    # Add total
    table.add_row("Total Bill", f"{total_bill}", style="bold red")  # Removed .2f as amount is now integer
    
    # Print table
    console.print(table)

@app.command()
def calculate(units: float = typer.Option(..., prompt="Enter units consumed", help="Number of units consumed")):
    """
    Calculate and display electricity bill for given units
    """
    try:
        if units < 0:
            console.print("[bold red]Error: Units consumed cannot be negative![/bold red]")
            raise typer.Exit(1)
        
        display_bill_rich(units)
    except ValueError as e:
        console.print(f"[bold red]Error: {str(e)}[/bold red]")
        raise typer.Exit(1)

if __name__ == "__main__":
    app() 

requirements.txt

rich==13.7.0
typer[all]==0.9.0