#!/usr/bin/python
#
# Command-line dice roller
#
# It assumes that the Mersenne Twister is acceptable.
# Support for real entropy is an RFE

import random
import sys
import re

# Implements a "dice" - that is, a series of dice plus modifiers
# fixme: implement rerolls (currently they do nothing!)
class Dice():
    def __init__(self, num, sides, mod, drop_low=0, drop_high=0, reroll=0, reroll_times=0):
        self.num = num
        self.sides = sides
        self.mod = mod
        self.drop_low = drop_low
        self.drop_high = drop_high
        self.reroll = reroll
        self.reroll_times = reroll_times
        self.times_rolled = 0
        
    # Rolls the dice, prints the result
    def roll(self, verbose=True): # fixme: default verbose to False and add -v flag
        results = []
        rerolled = []

        # Roll the actual dice, handling rerolls
        for i in range(0, self.num):
            count = 0
            result = 0
            while result <= self.reroll or result == 0:
                if self.reroll_times and count >= self.reroll_times:
                    break

                result = random.randint(1, self.sides)
                count += 1
                if result <= self.reroll:
                    rerolled.append(result)

            results.append(result)
            

        # Drop any high or low, if specified
        if self.drop_low or self.drop_high:
            results.sort()

            dropped = []
            if self.drop_low:
                dropped.extend(results[:self.drop_low])
                results = results[self.drop_low:]

            if self.drop_high:
                dropped.extend(results[-1 * self.drop_high:])
                results = results[:-1 * self.drop_high]
            
            random.shuffle(results)
            
        # Get the results
        total = sum(results) + self.mod

        if verbose:
            drop_info = None
            reroll_info = None

            if dropped:
                drop_info = '[dropped {}]'.format(','.join(['{}'.format(x) for x in dropped]))
            if rerolled:
                reroll_info = '[rerolled {}]'.format(','.join(['{}'.format(x) for x in rerolled]))
                
            print('{dice}: {results} {drop} {reroll} {total}'.format(dice=self, results=results, total=total, drop=drop_info, reroll=reroll_info))

        else:
            print('{dice}: {total}'.format(dice=self, total=total))

        self.times_rolled += 1


    def __str__(self):
        reroll_info = ''
        drop_info = ''
        mod_info = ''

        if self.reroll:
            reroll_info = ', reroll <= {}'.format(self.reroll)

            if self.reroll_times:
                reroll_info = reroll_info + ' up to {} times'.format(self.reroll_times)

        if self.drop_low:
            drop_info = drop_info + ', drop low {}'.format(self.drop_low)
        if self.drop_high:
            drop_info = drop_info + ', drop high {}'.format(self.drop_high)

        if self.mod > 0:
            mod_info = '+{}'.format(self.mod)
        elif self.mod < 0:
            mod_info = '-{}'.format(self.mod)

        return "{num}d{sides}{mod}{drop}{reroll}".format(num=self.num, sides=self.sides, mod=mod_info, drop=drop_info, reroll=reroll_info)
        
        

# This builds dice out of a simple input format
# All of the dark regex magic is contained to this function,
# lest it corrupt innocent code
def parse_input(args):
    dice_list = []
    for arg in args:
        if not re.match(r'^\d+d\d+', arg):
            continue

        (n, s) = re.match(r'^(\d+)d(\d+)', arg).groups()
        num = int(n)
        sides = int(s)
        mod = 0
        dlow = 0
        dhigh = 0
        reroll = 0
        reroll_times = 0

        for m in re.findall(r'[hl+-]\d+', arg):
            if m[0] == '-':
                mod += int(m)
            elif m[0] == '+':
                mod += int(m[1:])
            elif m[0] == 'h':
                dhigh = int(m[1:])
            elif m[0] == 'l':
                dlow = int(m[1:])

        m = re.search(r'r(\d+)(x\d+)?', arg)
        if m:
            (r, rt) = m.groups()
            reroll = int(r)
            if rt:
                reroll_times = int(rt[1:])

        dice_list.append(Dice(num, sides, mod, drop_low=dlow, drop_high=dhigh, reroll=reroll, reroll_times=reroll_times))

    return dice_list


def main():
    # fixme: command line arguments! get some argparse over here

    dice_list = parse_input(sys.argv)

    for dice in dice_list:
        dice.roll()


if __name__ == '__main__':
    main()