#!/usr/bin/env python3
"""
calc - Quick calculator and unit converter

Math and conversions from the command line.
"""

import sys
import math
from datetime import datetime, timedelta

# Common conversions
CONVERSIONS = {
    # Length
    'km_to_mi': lambda x: x * 0.621371,
    'mi_to_km': lambda x: x * 1.60934,
    'm_to_ft': lambda x: x * 3.28084,
    'ft_to_m': lambda x: x * 0.3048,
    'in_to_cm': lambda x: x * 2.54,
    'cm_to_in': lambda x: x / 2.54,
    
    # Weight
    'kg_to_lb': lambda x: x * 2.20462,
    'lb_to_kg': lambda x: x / 2.20462,
    'oz_to_g': lambda x: x * 28.3495,
    'g_to_oz': lambda x: x / 28.3495,
    
    # Temperature
    'c_to_f': lambda x: x * 9/5 + 32,
    'f_to_c': lambda x: (x - 32) * 5/9,
    
    # Volume
    'l_to_gal': lambda x: x * 0.264172,
    'gal_to_l': lambda x: x * 3.78541,
    
    # Data
    'mb_to_gb': lambda x: x / 1024,
    'gb_to_mb': lambda x: x * 1024,
    'gb_to_tb': lambda x: x / 1024,
    'tb_to_gb': lambda x: x * 1024,
}

def calculate(expr: str):
    """Evaluate a math expression."""
    # Add math functions to namespace
    namespace = {
        'sqrt': math.sqrt,
        'sin': math.sin,
        'cos': math.cos,
        'tan': math.tan,
        'log': math.log,
        'log10': math.log10,
        'exp': math.exp,
        'pi': math.pi,
        'e': math.e,
        'abs': abs,
        'pow': pow,
        'round': round,
    }
    
    try:
        result = eval(expr, {"__builtins__": {}}, namespace)
        print(f"= {result}")
    except Exception as e:
        print(f"Error: {e}")

def convert(value: float, conversion: str):
    """Convert between units."""
    if conversion in CONVERSIONS:
        result = CONVERSIONS[conversion](value)
        units = conversion.split('_to_')
        print(f"{value} {units[0]} = {result:.4f} {units[1]}")
    else:
        print(f"Unknown conversion: {conversion}")
        print("Available:", ', '.join(CONVERSIONS.keys()))

def time_until(target: str):
    """Calculate time until a date."""
    try:
        if len(target) == 10:  # YYYY-MM-DD
            target_date = datetime.strptime(target, "%Y-%m-%d")
        else:
            target_date = datetime.strptime(target, "%Y-%m-%d %H:%M")
        
        diff = target_date - datetime.now()
        
        if diff.total_seconds() < 0:
            print("That date has passed")
            return
        
        days = diff.days
        hours, rem = divmod(diff.seconds, 3600)
        minutes = rem // 60
        
        print(f"Time until {target}:")
        print(f"  {days} days, {hours} hours, {minutes} minutes")
    except:
        print("Date format: YYYY-MM-DD or YYYY-MM-DD HH:MM")

def percentage(part: float, whole: float):
    """Calculate percentage."""
    pct = (part / whole) * 100
    print(f"{part} / {whole} = {pct:.2f}%")

def main():
    if len(sys.argv) < 2:
        print("Usage:")
        print("  calc <expression>          - Math calculation")
        print("  calc <value> <conversion>  - Unit conversion")
        print("  calc until <YYYY-MM-DD>    - Time until date")
        print("  calc pct <part> <whole>    - Percentage")
        print("")
        print("Examples:")
        print("  calc '2 + 2'")
        print("  calc 'sqrt(16) + pi'")
        print("  calc 100 km_to_mi")
        print("  calc 72 f_to_c")
        print("  calc until 2026-12-31")
        print("")
        print("Conversions:", ', '.join(sorted(CONVERSIONS.keys())))
        return
    
    cmd = sys.argv[1]
    
    if cmd == 'until' and len(sys.argv) > 2:
        time_until(' '.join(sys.argv[2:]))
    
    elif cmd == 'pct' and len(sys.argv) > 3:
        percentage(float(sys.argv[2]), float(sys.argv[3]))
    
    elif len(sys.argv) == 3 and sys.argv[2] in CONVERSIONS:
        convert(float(sys.argv[1]), sys.argv[2])
    
    else:
        # Treat as expression
        expr = ' '.join(sys.argv[1:])
        calculate(expr)

if __name__ == "__main__":
    main()