#!/usr/bin/env python3
"""
Dice rolling, the core function of any IRC bot.
"""
import re
import random

import module


@module.commands("roll", "dice", "d")
@module.example(".roll 3d1+1", "You roll 3d1+1: (1+1+1)+1 = 4")
def roll(bot, trigger):
	"""
	.dice XdY[+Z], rolls dice and reports the result.

	X is the number of dice. Y is the number of faces in the dice. Z is
	the constant to be applied to the end result.
	"""
	if len(trigger.args) < 2:
		return bot.reply("Roll what?")
	regex = re.compile(r'(\d+)?d(\d+)([+-]\d+)?')
	reg = re.match(regex, trigger.args[1])
	if not reg:
		return bot.reply("Invalid dice notation.")
	num_dice = int(reg.groups()[0]) if reg.groups()[0] else 1
	num_sides = int(reg.groups()[1])
	modifier = int(reg.groups()[2]) if reg.groups()[2] else 0

	num_dice = min(num_dice, 100)
	num_sides = min(num_sides, 1000)

	results = []
	for _ in range(num_dice):
		result = random.randint(1, num_sides)
		results.append(result)
	total = sum(results) + modifier

	msg = f"You roll {num_dice}d{num_sides}"
	if modifier:
		if modifier > 0:
			msg += '+'
		msg += str(modifier)
	msg += ': '
	msg += '(' + '+'.join([str(a) for a in results]) + ')'
	if modifier:
		if modifier > 0:
			msg += '+'
		msg += str(modifier)
	msg += " = " + str(total)
	bot.reply(msg)