#!/usr/bin/python3

import re
import sys
from pathlib import Path
from random import shuffle

cardRegex = "CARD: "
prefixLength = len(cardRegex)

# Returns a list of Path objects, containing the path to each valid file provided
def getFileList():
    fileList = []
    if len(sys.argv) > 1:
        for f in sys.argv[1:]:
            path = Path(f)
            if path.exists() and path.is_file():
                fileList.append(f)
        return fileList
    else:
        print("Missing arguments")
        sys.exit()

# Returns cards in the form [(front, back)]
def createCardList(files):
    cards = []
    for f in files:
        cards = cards + extractCards(f)
    return cards

# Extracts cards from a single file into a list of the form [(front, back)]
def extractCards(f):
    front = ""
    back = ""
    cards = []
    with open(f) as cardFile:
        for l in cardFile:
            match = re.match(cardRegex, l)
            if match:
                if front != "":
                    cards.append([front.strip(), back.strip()])
                    back = ""
                front = match.string[prefixLength:]
            else:
                back += l
    # do the last front-back pair before returning
    cards.append([front.strip(), back.strip()])
    return cards

# Loops serving cards to the user until the program is exited
def serveCards(cards):
    while True:
        for card in cards:
            print("----------------------------------------------------------------------------")
            print(card[0])
            input()
            print(card[1])
            input()

def debugCards(cardList):
    for c in cardList:
        print("Front:", c[0])
        print("Back:", c[1])

def main():
    files = getFileList()
    cards = createCardList(files)
    shuffle(cards)
    serveCards(cards)

if __name__ == "__main__":
    main()