import os.path
import time
import cPickle

def get_file():
    '''Prompt for the name of an existing file, open the file for reading,
    and return the file object.'''
    
    filename = raw_input("Please enter a filename: ")
    while not os.path.exists(filename):
        print filename, "does not exist"
        filename = raw_input("Please enter a filename: ")
    
    return open(filename,'r')

def get_line(myfile,keep_capital_letters):
    '''Read a line from open file myfile and return it, but with
       the new line character at the end removed.'''

    line = myfile.readline()
    if keep_capital_letters:
        return line[:-1]
    else:
        return line[:-1].lower()

def get_input(string,choices):
    ans = raw_input(string)
    while not ans in choices:
        print "Invalid response."
        ans = raw_input(string)
    return ans
    
def create_dicts(pfile):

    def get_items(dict,pfile,cur_pic):
         # we know there is at least one line in these sections
         line = get_line(pfile,False)
         while not line == "end":
             if line in dict:
                 dict[line].append(cur_pic)
             else:
                 dict[line] = [cur_pic]
             line = get_line(pfile,False)

    new_picture = True
    pictures = []
    faces = {}
    places = {}
    events = {}
    
    st2dict = {"faces":faces,"places":places,"events":events}

    line = get_line(pfile,new_picture)
    while line != "":
        if new_picture:
            pictures.append(line)
            new_picture = False
            cur_pic = line
        elif line == "endpic":
            new_picture = True
        # line is 'faces', 'places', or 'events'    
        else:
            get_items(st2dict[line],pfile,cur_pic)
        line = get_line(pfile,new_picture)             
    pfile.close()        
    return (pictures,faces,places,events)     

def filter(pictures,faces,places,events):

    def include_or_exclude(iore,dict,whichone,pictures):
        if iore == 'i':
            # add the chosen pictures, but only if they are not already there
            for i in dict[whichone]:
               if not i in pictures:
                   pictures.append(i)
        else:
            # exclude all photos in the pictures list that match
            copy_pictures = pictures[:]
            for i in copy_pictures:
               if i in dict[whichone]:
                  pictures.remove(i)

    ans = get_input("Would you like load in a current picture list? (y/n)? ",['y','n'])
    if ans == 'y':
        pf = get_file()
        cur_picture_list = cPickle.load(pf)
        pf.close()
    else:    
        cur_picture_list = []
    st2dict = {"f":faces,"p":places,"e":events}
    choice2question = {"f":"whose face","p":"which place","e":"what event"}
    choice2pronoun = {"f":"them","p":"it","e":"it"}
    print "There are",len(cur_picture_list), "pictures .",cur_picture_list
    notdone = get_input( "Would you like to filter the list (y/n)? ",['y','n'])

    while notdone == 'y':

        whichtype = get_input("Based on faces, places or events (f/p/e)? ",['f','p','e'])
        whichone = get_input("Based on " + choice2question[whichtype] + "? ", st2dict[whichtype].keys())
        iore = get_input("Include or exclude " +  choice2pronoun[whichtype] + "(i/e)? ",['i','e'])
        include_or_exclude(iore,st2dict[whichtype],whichone,cur_picture_list)
        print "There are",len(cur_picture_list), "pictures.",cur_picture_list
        notdone = get_input( "Would you like to filter the list (y/n)? ",['y','n'])
    return cur_picture_list    

def give_slide_show(pictures):
    s = int(raw_input("How many seconds would you like to view each picture? "))
    for p in pictures:
        pic = media.load_picture(p)
        media.show(pic)
        time.sleep(s)
        media.close(pic)


def print_pictures(pictures):
    print "Your picture list is:"
    for p in pictures[:-1]:
       print "%s; " % (p),
    print "%s" % pictures[-1]   

if __name__ == '__main__':
    pfile = get_file()
    (pictures,faces,places,events) = create_dicts(pfile)
    new_pictures = filter(pictures,faces,places,events)
    print_pictures(new_pictures)
    ans = get_input("Would you like to see a slide show? (y/n)? ",['y','n'])
    if ans == 'y':
       give_slide_show(new_pictures) 
    ans = get_input("Would you like to save the current picture list? (y/n)? ",['y','n'])
    if ans == 'y':
        ans = raw_input("Enter a file name.  ")
        f = open(ans,'w')
        cPickle.dump(new_pictures,f)
        f.close()