#!/usr/bin/env python3
from argparse import ArgumentParser
from os import remove
from sys import exit
from signal import signal, SIGINT
from multiprocessing import Pool, cpu_count

from imgrate import imgrate


class Cli:
    def __init__(self):
        self.args = None
        self.image_ratings = None
        self.best_image = None

    def __call__(self):
        self.parse_arguments()

        if not hasattr(imgrate, self.args.method):
            exit('Invalid --method option!')

        self.calculate_ratings()
        self.best_image = max(self.image_ratings, key=self.image_ratings.get)
        self.print_ratings()

        if self.args.delete:
            self.keep_best_quality_image_only()

    def parse_arguments(self):
        ap = ArgumentParser(description='Find the best quality one among similar images.'
                                        'Note: image dimensions should match!')
        ap.add_argument('images', type=str, nargs='+',
                        help='')
        ap.add_argument('-d', '--delete', action='store_true',
                        help='Delete all but the best quality image.')
        ap.add_argument('-q', '--quiet', action='store_true',
                        help='Print quality measurements only.')
        ap.add_argument('-m', '--method', type=str, default='quality',
                        help='Select quality measurement to use.')
        self.args = ap.parse_args()

    def calculate_ratings(self):
        with Pool(processes=cpu_count()) as pool:
            ratings = [(image, pool.apply_async(self.rate_image,
                                                (image, self.args.method)))
                       for image in self.args.images]
            self.image_ratings = {image: promise.get() for image, promise in ratings}

    @staticmethod
    def rate_image(image, method):
        return getattr(imgrate(image), method)

    def print_ratings(self):
        for image in self.image_ratings.keys():
            if self.args.quiet:
                print(self.image_ratings[image])
            else:
                max_marker = '*' if image == self.best_image and len(self.image_ratings) > 1 else ' '
                print(f'{max_marker}imgrate("{image}") = {self.image_ratings[image]}')

    def keep_best_quality_image_only(self):
        for image in self.image_ratings.keys():
            if image != self.best_image:
                remove(image)


if __name__ == '__main__':
    signal(SIGINT, lambda a, b: exit('\nExiting!'))
    Cli()()