cost-calculator.py

#!/usr/bin/env python3
"""
AC Filter Cost Calculator

Estimates annual filter costs based on your home setup, filter preference,
and climate conditions. Helps compare different filter strategies.

Usage:
    python3 cost-calculator.py --size 20x25x1 --merv 11 --pets true --climate hot-humid
    python3 cost-calculator.py --interactive
"""

import argparse
import sys

# Average retail prices (USD) as of 2026
# Format: (merv_min, merv_max, thickness, price_per_filter)
FILTER_PRICES = {
    "fiberglass_1in": {"merv": (1, 4), "thickness": 1, "price": 2.50, "label": "Fiberglass 1\""},
    "pleated_1in_m8": {"merv": (5, 8), "thickness": 1, "price": 8.00, "label": "Pleated 1\" MERV 8"},
    "pleated_1in_m11": {"merv": (9, 11), "thickness": 1, "price": 14.00, "label": "Pleated 1\" MERV 11"},
    "pleated_1in_m13": {"merv": (12, 13), "thickness": 1, "price": 22.00, "label": "Pleated 1\" MERV 13"},
    "pleated_4in_m8": {"merv": (5, 8), "thickness": 4, "price": 18.00, "label": "Deep Pleated 4\" MERV 8"},
    "pleated_4in_m11": {"merv": (9, 11), "thickness": 4, "price": 28.00, "label": "Deep Pleated 4\" MERV 11"},
    "pleated_4in_m13": {"merv": (12, 13), "thickness": 4, "price": 38.00, "label": "Deep Pleated 4\" MERV 13"},
}

# Base replacement intervals in days
BASE_INTERVALS = {
    "fiberglass_1in": 30,
    "pleated_1in_m8": 90,
    "pleated_1in_m11": 90,
    "pleated_1in_m13": 60,
    "pleated_4in_m8": 180,
    "pleated_4in_m11": 180,
    "pleated_4in_m13": 120,
}

# Climate multipliers (1.0 = baseline, lower = replace more often)
CLIMATE_FACTORS = {
    "temperate": 1.0,
    "hot-dry": 0.85,
    "hot-humid": 0.60,  # South Florida, Gulf Coast
    "cold-dry": 0.90,
    "cold-humid": 0.80,
}

# Adjustment factors
PET_FACTOR = 0.70         # 30% faster clogging with pets
SMOKER_FACTOR = 0.60      # 40% faster with indoor smokers
CONSTRUCTION_FACTOR = 0.40 # 60% faster near construction


def calculate_annual_cost(filter_key, climate="temperate", pets=False,
                          smoker=False, construction=False):
    """Calculate annual filter cost for a given configuration."""
    base_days = BASE_INTERVALS[filter_key]
    price = FILTER_PRICES[filter_key]["price"]

    # Apply factors
    effective_days = base_days * CLIMATE_FACTORS.get(climate, 1.0)
    if pets:
        effective_days *= PET_FACTOR
    if smoker:
        effective_days *= SMOKER_FACTOR
    if construction:
        effective_days *= CONSTRUCTION_FACTOR

    effective_days = max(effective_days, 14)  # minimum 2 weeks

    replacements_per_year = 365 / effective_days
    annual_cost = replacements_per_year * price

    return {
        "filter": FILTER_PRICES[filter_key]["label"],
        "price_each": price,
        "interval_days": round(effective_days),
        "replacements_per_year": round(replacements_per_year, 1),
        "annual_cost": round(annual_cost, 2),
    }


def find_matching_filters(merv, thickness=None):
    """Find filter keys matching the given MERV and optional thickness."""
    matches = []
    for key, info in FILTER_PRICES.items():
        merv_min, merv_max = info["merv"]
        if merv_min <= merv <= merv_max:
            if thickness is None or info["thickness"] == thickness:
                matches.append(key)
    return matches


def parse_size(size_str):
    """Parse filter size string like '20x25x1' into dimensions."""
    parts = size_str.lower().replace("\"", "").split("x")
    if len(parts) != 3:
        return None, None, None
    try:
        return int(parts[0]), int(parts[1]), int(parts[2])
    except ValueError:
        return None, None, None


def print_comparison(climate, pets, smoker, construction):
    """Print a cost comparison table for all filter types."""
    print("\n" + "=" * 72)
    print("  AC Filter Annual Cost Comparison")
    print("=" * 72)
    print(f"\n  Climate: {climate}")

    conditions = []
    if pets:
        conditions.append("pets")
    if smoker:
        conditions.append("indoor smoker")
    if construction:
        conditions.append("nearby construction")
    if conditions:
        print(f"  Conditions: {', '.join(conditions)}")
    else:
        print("  Conditions: standard")

    print(f"\n  {'Filter Type':<30} {'Each':>7} {'Days':>6} {'Changes/Yr':>11} {'Annual':>9}")
    print("  " + "-" * 66)

    results = []
    for key in FILTER_PRICES:
        result = calculate_annual_cost(key, climate, pets, smoker, construction)
        results.append(result)
        print(f"  {result['filter']:<30} ${result['price_each']:>5.2f} "
              f"{result['interval_days']:>5}d "
              f"{result['replacements_per_year']:>10.1f} "
              f"${result['annual_cost']:>7.2f}")

    # Find best value (lowest cost with MERV >= 8)
    good_filters = [r for r in results if "MERV" in r["filter"]
                    and int(r["filter"].split("MERV ")[1]) >= 8]
    if good_filters:
        best = min(good_filters, key=lambda x: x["annual_cost"])
        print(f"\n  >>> Best value (MERV 8+): {best['filter']} "
              f"at ${best['annual_cost']:.2f}/year")

    print()


def interactive_mode():
    """Walk the user through filter selection."""
    print("\n  AC Filter Cost Calculator — Interactive Mode\n")

    print("  What climate zone are you in?")
    for i, (key, _) in enumerate(CLIMATE_FACTORS.items(), 1):
        print(f"    {i}. {key}")
    choice = input("\n  Enter number (default: 1): ").strip()
    climates = list(CLIMATE_FACTORS.keys())
    try:
        climate = climates[int(choice) - 1]
    except (ValueError, IndexError):
        climate = "temperate"

    pets = input("  Do you have pets? (y/n, default: n): ").strip().lower() == "y"
    smoker = input("  Indoor smoker? (y/n, default: n): ").strip().lower() == "y"
    construction = input("  Construction nearby? (y/n, default: n): ").strip().lower() == "y"

    print_comparison(climate, pets, smoker, construction)


def main():
    parser = argparse.ArgumentParser(
        description="Estimate annual AC filter costs based on your setup."
    )
    parser.add_argument("--size", type=str, help="Filter size, e.g., 20x25x1")
    parser.add_argument("--merv", type=int, default=8,
                        help="MERV rating (default: 8)")
    parser.add_argument("--climate", type=str, default="temperate",
                        choices=list(CLIMATE_FACTORS.keys()),
                        help="Climate zone (default: temperate)")
    parser.add_argument("--pets", type=str, default="false",
                        help="Have pets? true/false (default: false)")
    parser.add_argument("--smoker", type=str, default="false",
                        help="Indoor smoker? true/false (default: false)")
    parser.add_argument("--construction", type=str, default="false",
                        help="Nearby construction? true/false (default: false)")
    parser.add_argument("--interactive", action="store_true",
                        help="Run in interactive mode")
    parser.add_argument("--compare-all", action="store_true",
                        help="Show cost comparison for all filter types")

    args = parser.parse_args()

    if args.interactive:
        interactive_mode()
        return

    pets = args.pets.lower() in ("true", "yes", "1", "y")
    smoker = args.smoker.lower() in ("true", "yes", "1", "y")
    construction = args.construction.lower() in ("true", "yes", "1", "y")

    if args.compare_all:
        print_comparison(args.climate, pets, smoker, construction)
        return

    # Parse size to get thickness
    thickness = None
    if args.size:
        _, _, thickness = parse_size(args.size)

    matches = find_matching_filters(args.merv, thickness)
    if not matches:
        print(f"No filter found for MERV {args.merv}"
              + (f" at {thickness}\" thickness" if thickness else ""))
        print("Try --compare-all to see all options.")
        sys.exit(1)

    for key in matches:
        result = calculate_annual_cost(key, args.climate, pets,
                                       smoker, construction)
        print(f"\n  {result['filter']}")
        print(f"  Price per filter:      ${result['price_each']:.2f}")
        print(f"  Replacement interval:  {result['interval_days']} days")
        print(f"  Replacements per year: {result['replacements_per_year']}")
        print(f"  Estimated annual cost: ${result['annual_cost']:.2f}")
    print()


if __name__ == "__main__":
    main()