'''
Created on Nov 13, 2017

@author: Haodong Huang and Alden Radoncic
I pledge my honor that I have abided by the Stevens Honor System
-hhuang21
-aradonci
'''
import sys
def readInData():
    """Reads the data from the file musicrecplus.txt"""
    database = {}
    try:
        handle = open("musicrecplus.txt", "r")
        lines = handle.read().splitlines()
        handle.close()
        for line in lines:
            name, artists = line.split(":")
            database[name] = sorted(artists.split(","))
    except:
        return database
    return database
def getUser():
    """Gets the username from the user"""
    print("Enter your name (put a $ symbol after your name if you wish your preferences to remain private):")
    username = input()
    return username
def myMap(fn, iterable):
    """applies a function over a list"""
    ret = [0]*len(iterable)
    i = 0
    for thing in iterable:
        ret[i] = fn(thing)
        i += 1
    return ret
def onePerLine(iterable):
    """Prints a list one iterable on each line"""
    for thing in iterable:
        print(thing)
def saveUserPreferences(user, database):
    ''' Writes out the user's preferences to the file. '''
    def getPreferences():
        """Gets the user's preferences"""
        prefs = []
        print("Enter an artist that you like (Enter to finish)")
        newPref = input()
        while newPref != '':
            prefs.append(newPref)
            print("Enter an artist that you like (Enter to finish)")
            newPref = input()
        prefs.sort()
        return prefs
    database[user] = getPreferences()
    file = open("musicrecplus.txt", "w")
    for user in database:
        toSave = str(user) + ":" + ",".join(database[user]) + \
                    "\n"
        file.write(toSave)
    file.close()
    menu(user, database)
def getRecommendations(user, database):
    """Prints out the recommendations for the user"""
    def compare(userArtists, otherArtists, otherUName):
        if otherUName[-1] == "$":
            return -1
        iUser = 0
        iOther = 0
        score = 0
        while iUser < len(userArtists) and iOther < len(otherArtists):
            aUser = userArtists[iUser]
            aOther = otherArtists[iOther]
            if aUser == aOther:
                score += 1
                iUser += 1
                iOther += 1
            elif aUser < aOther:
                iUser += 1
            else:
                iOther += 1
        if len(userArtists) == score:
            return -1
        return score
    def diff(userArtists, otherArtists):
        iUser = 0
        iOther = 0
        diffs = []
        while iUser < len(userArtists) and iOther < len(otherArtists):
            aUser = userArtists[iUser]
            aOther = otherArtists[iOther]
            if aUser == aOther:
                iUser += 1
                iOther += 1
            elif aUser < aOther:
                iUser += 1
            else:
                diffs.append(aOther)
                iOther += 1
        if iOther < len(otherArtists):
            diffs.extend(otherArtists[iOther:])
        return diffs
    userArtists = database[user]
    ranked = sorted(myMap(lambda uname:(compare(userArtists, database[uname], uname), uname), database), reverse = True)
    if len(ranked) == 0 or ranked[0][0] == -1:
        print("No recommendations available at this time")
        menu(user, database)

    maxScore = ranked[0][0]
    iMax = 0
    for result in ranked:
        if maxScore != result[0]:
            break
        iMax += 1
    artists = []
    for i in range(iMax):
        artists.extend(diff(userArtists, database[ranked[i][1]]))
    artists = sorted(list(set(artists)))
    onePerLine(artists)
    menu(user, database)
def artistLikes(database):
    """Returns a dictionary of the artists and the likes they have"""
    likes = {}
    databaseCopy = dict(database)
    for users, artists in database.items():
        if users[-1] == "$":
            del databaseCopy[users]
    for user, artists in databaseCopy.items():
        for artist in artists:
            if artist in likes:
                likes[artist] += 1
            else:
                likes[artist] = 1
    return likes
def mostPopular(user, database):
    """Returns the most popular artists"""
    popularArtist = []
    likes = artistLikes(database)
    for artist in likes:
        if popularArtist == []:
            popularArtist = [artist]
        elif likes[artist] > likes[popularArtist[0]]:
            popularArtist = [artist]
        elif likes[artist] == likes[popularArtist[0]]:
            popularArtist.append(artist)
    if popularArtist == []:
        print("Sorry, no artists found")
    onePerLine(popularArtist)
    menu(user, database)

def howPopular(user, database):
    """Returns the number of likes that the most popular artist has"""
    popularArtist = []
    mostLikes = 0
    likes = artistLikes(database)
    for artist, votes in likes.items():
        if popularArtist == []:
            popularArtist = [artist]
            mostLikes = votes
        elif likes[artist] > likes[popularArtist[0]]:
            popularArtist = [artist]
            mostLikes = votes
        elif likes[artist] == likes[popularArtist[0]]:
            popularArtist.append(artist)
            mostLikes = votes
    if mostLikes == 0:
        print("Sorry, no artists found")
    print(mostLikes)

    menu(user, database)
def mostLikes(user, database):
    """Returns the users with the most amount of likes"""
    userLikes = {}
    for user, artists in database.items():
        likes = 0
        for artist in range(len(artists)):
            likes += 1
        userLikes[user] = likes
    userLikesCopy = dict(userLikes)
    for user, likes in userLikes.items():
        if user[-1] == "$":
            del userLikesCopy[user]
    maxLikes = 0
    maxLikesUser = []
    for user, likes in userLikesCopy.items():
        if likes > maxLikes:
            maxLikes = likes
            maxLikesUser = [user]
        elif likes == maxLikes:
            maxLikesUser.append(user)
    if maxLikes == 0:
        print("Sorry, no user found")
    else:
        onePerLine(maxLikesUser)
    menu(user, database)
def quitSave():
    """Safely exits the program.
    Does not need to write to file because saveUserPreference already does that"""
    sys.exit(0)
def menu(user, database):
    """Prints out the menu"""
    print("""Enter a letter to choose an option
e - Enter preferences
r - Get recommendations
p - Show most popular artist
h - How popular is the most popular
m - Which user has the most likes
q - Quit and save""")
    option = input()
    if option == 'e':
        saveUserPreferences(user, database)
    elif option == 'r':
        getRecommendations(user, database)
    elif option == 'p':
        mostPopular(user, database)
    elif option == 'h':
        howPopular(user, database)
    elif option == 'm':
        mostLikes(user, database)
    elif option == 'q':
        quitSave()
    else:
        menu(user, database)
def main():
    """The main function that starts the program"""
    database = readInData()
    user = getUser()
    if user in database:
        menu(user, database)
    else:
        saveUserPreferences(user, database)
if __name__ == "__main__": main()