#! /usr/bin/env python3
# -*- coding: utf-8 -*-
"""
ASCII.
"""
from io import BytesIO

import requests
from PIL import Image, ImageFont, ImageDraw
#import imageio
import numpy as np
import numpngw

ASCII_CHARS = "$@%#*+=-:. "
HEADERS = {'User-Agent': 'Gimme the ascii.'}


def scale_image(image, size=(100,100)):
	"""
	Resizes an image while preserving the aspect ratio. Chooses the
	dimension to scale by based on whichever is larger, ensuring that
	neither width or height is ever larger than the accepted size tuple.

	Because text characters are typically pretty close to a 1:2 rectangle,
	we weight the width twice as much.
	"""
	original_width, original_height = image.size
	original_width = original_width * 2
	if original_width > original_height:
		if original_width > size[0]:
			new_width = size[0]
			aspect_ratio = original_height/float(original_width)
			new_height = int(aspect_ratio * new_width)
		else:
			new_width, new_height = image.size
	else:
		if original_height > size[1]:
			new_height = size[1]
			aspect_ratio = original_width/float(original_height)
			new_width = int(aspect_ratio * new_height)
		else:
			new_width, new_height = image.size
	image = image.resize((new_width, new_height))
	return image


def pixels_to_chars(image, reverse=False):
	"""
	Maps each pixel to an ascii char based on where it falls in the range
	0-255 normalized to the length of ASCII_CHARS.
	"""
	range_width = int(255 / len(ASCII_CHARS)) + (255 % len(ASCII_CHARS) > 0)

	pixels_in_image = list(image.getdata())
	pixels_to_chars = []
	for pixel_value in pixels_in_image:
		if reverse:
			index = -int(pixel_value/range_width)-1
		else:
			index = int(pixel_value/range_width)
		pixels_to_chars.append(ASCII_CHARS[index])

	return "".join(pixels_to_chars)


def open_image(imagePath):
	"""
	Opens the image at the supplied file path in PIL. If an internet URL
	is supplied, it will download the image and then open it.
	"""
	try:
		if imagePath.startswith("http"):
			res = requests.get(imagePath, headers=HEADERS, verify=True,
				timeout=20)
			res.raise_for_status()
			image = Image.open(BytesIO(res.content))
		else:
			image = Image.open(imagePath)
	except FileNotFoundError as e:
		return e
	except OSError:
		return e
	except Exception as e:
		return("Error opening image file: " + imagePath)

	return image


def image_to_ascii(image, reverse=False):
	"""
	Reads an image file and converts it to ascii art. Returns a
	newline-delineated string. If reverse is True, the ascii scale is
	reversed.
	"""
	image = scale_image(image)
	image = image.convert('L')	# convert to grayscale

	chars = pixels_to_chars(image, reverse)

	image_ascii = []
	for index in range(0, len(chars), image.size[0]):
		image_ascii.append(chars[index: index + image.size[0]])
	image.close()
	del(image)
	return "\n".join(image_ascii)


def ascii_to_image(image_ascii):
	"""
	Creates a plain image and draws text on it.
	"""
	# TODO: make font type, size, and image size non-fixed
	width = len(image_ascii[:image_ascii.index("\n")]) * 8
	height = (image_ascii.count("\n")+1) * 12 + 4

	font = ImageFont.truetype("LiberationMono-Regular.ttf", 14)
	image = Image.new("RGB", (width, height), (255,255,255))
	draw = ImageDraw.Draw(image)
	draw.text((0,0), image_ascii, (0,0,0), font=font, spacing=0)
	return image


def handle_gif(output, reverse=False):
	image = open_image(args.imagePath)
	ascii_seq = []
	new_image = ascii_to_image(image_to_ascii(image, reverse))
	image.seek(1)
	while True:
		try:
			im = ascii_to_image(image_to_ascii(image, reverse))
			ascii_seq.append(im)
			image.seek(image.tell()+1)
		except EOFError:
			break # end of sequence

	#new_image.save(output, save_all=True, append_images=ascii_seq,
	#	duration=60, loop=0, optimize=True)
	ascii_seq = [new_image] + ascii_seq
	np_ascii_seq = [np.array(im) for im in ascii_seq]
	#images2gif.writeGif(output, ascii_seq, nq=10, subRectangles=False)
	#imageio.mimsave(output, np_ascii_seq)
	with open(output, "wb") as file:
		numpngw.write_apng(file, np_ascii_seq)


if __name__=='__main__':
	import argparse

	parser = argparse.ArgumentParser(
		description="Converts an image file to ascii art.")
	parser.add_argument(
		"imagePath",
		help="The full path to the image file.")
	parser.add_argument(
		"-r",
		"--reverse",
		action="store_true",
		help="Reverses the ascii scale.")
	parser.add_argument(
		"-o",
		"--output",
		help="Outputs the ascii art into a file at the specified path.")
	parser.add_argument(
		"-i",
		"--image",
		action="store_true",
		help="Outputs the ascii art as an image rather than plain text. \
		Requires --output.")
	parser.add_argument(
		"-a",
		"--animated",
		action="store_true",
		help="Handles animated GIFs. Includes --image.")
	parser.set_defaults(reverse=False, image=False, animated=False)
	args = parser.parse_args()
	
	if args.animated:	# --animated includes --image
		args.image = True
	if args.image:		# --image requires --output
		if not args.output:
			parser.error("--image requires --output")

	if args.animated:
		handle_gif(args.output, args.reverse)
	else:
		image = open_image(args.imagePath)
		image_ascii = image_to_ascii(image, args.reverse)
		if args.image:
			image = ascii_to_image(image_ascii)
			image.save(args.output, "PNG")
		elif args.output:
			with open(args.output, "w+") as file:
				file.write(image_ascii)
		else:
			print(image_ascii)