"""
CS146 Image Analysis Examples

Adapted from: https://ethicalcs.github.io/#manipulators
"""

import PIL.Image
import urllib.request
from io import BytesIO

# Python has rejected the certificate used for the CS dept. server so we bypass some of those checks
import ssl
ssl._create_default_https_context = ssl._create_unverified_context

BASE_URL = "https://www.cs.middlebury.edu/~mlinderman/courses/cs146/f24/classes/"

class Pixel:
    """Single RGB pixel

    Public Attributes:
        red (int): Red color component as integer in range [0,255]
        green (int): Green color component as integer in range [0,255]
        blue (int): Blue color component as integer in range [0,255]
    """
    def __init__(self, red=0, green=0, blue=0):
        """Create a new RGB pixel

        Args:
            red (int, optional): Red color component. Defaults to 0.
            green (int, optional): Green color component. Defaults to 0.
            blue (int, optional): Blue color component. Defaults to 0.
        """
        self.red = red
        self.green = green
        self.blue = blue

class Image:
    """Image class providing a simple interface to a PIL image

    Public attributes:
        None
    """
    def __init__(self, url):
        """Load an image from a URL

        Args:
            url: Image URL, e.g,, http://....
        """
        with urllib.request.urlopen(url) as url:
            self.img = PIL.Image.open(BytesIO(url.read()))
            self.img_pix = self.img.load()

        self.width = self.img.size[0]
        self.height = self.img.size[1]

    def get_width(self):
        """Return image width in pixels"""
        return self.width

    def get_height(self):
        """Return image height in pixels"""
        return self.height

    def get_pixel(self, row, col):
        """Return Pixel object at location starting at (0,0) in upper left corner

        Args:
            row: Integer row index
            col: Integer column index

        Returns:
            Pixel object with RGB values
        """
        pix = self.img_pix[col, row]
        return Pixel(pix[0], pix[1], pix[2])

    def set_pixel(self, row, col, pixel):
        """Set pixel at location starting at (0,0) in upper left corner

        Args:
            row: Integer row index
            col: Integer column index
            pixel: New pixel value with red, green and blue components
        """
        self.img_pix[col, row] = (pixel.red, pixel.green, pixel.blue)

    def save_image(self, filename):
        """Save image to local file

        Args:
            filename: String filename with image extension, e.g., "result.jpg"
        """
        try:
            self.img.save(filename)
        except IOError:
            print(f"Cannot save image to {filename}")

    def show(self):
        """Display image in a new window"""
        self.img.show()


def red_shift(in_file, out_file):
    """Red shift image, saving result to local file

    Args:
        in_file: String with URL to original image
        out_file: String filename with image extension to save modified image
    """
    # Load image from URL
    img = Image(in_file)

    # Iterate over all pixels, shifting red component by 100
    for row in range(img.get_height()):
        for col in range(img.get_width()):
            pix = img.get_pixel(row, col)
            img.set_pixel(row, col, Pixel(pix.red + 100, pix.green, pix.blue))
    
    # Save modified image to local file
    img.save_image(out_file)

# Example testing code for `red_shift` function.
# red_shift(BASE_URL + "linderman.jpg", "linderman_red.jpg")

# Horizontal blur filter window (declared here to keep examples together)
WINDOW = 4

def blur(in_file, out_file):
    """Apply horizontal blur filter to image, saving result to local file

    Args:
        in_file: String with URL to original image
        out_file: String filename with image extension to save modified image
    """
    # Load image from URL
    img = Image(in_file)

    for row in range(img.get_height()):
        # We will ignore right-most pixels in the image (where blur filter would extend
        # beyond the image boundary)
        for col in range(img.get_width()-WINDOW+1):
            
            pix = Pixel(0, 0, 0)
            for idx in range(WINDOW):
                blur_pix = img.get_pixel(row, col+idx)
                pix.red += blur_pix.red
                pix.green += blur_pix.green
                pix.blue += blur_pix.blue
            img.set_pixel(row, col, Pixel(pix.red // WINDOW, pix.green // WINDOW, pix.blue // WINDOW))
    
    # Save modified image to local file
    img.save_image(out_file)
 
# Example testing code for `blur` function.
# blur(BASE_URL + "linderman.jpg", "linderman_blur.jpg")

def average(in_files, out_file):
    """Average a set of images, saving result to local file

    Args:
        in_files: List of string URLs for original images
        out_file: String filename with image extension to save modified image
    """
    # Load original images as Image objects from URLs
    imgs = []
    for url in in_files:
        imgs.append(Image(url))

    # Update first image with average of all images    
    first_img = imgs[0]    
    for row in range(first_img.get_height()):
        for col in range(first_img.get_width()):
            pix = Pixel()
            for i in range(len(imgs)):
                avg_pix = imgs[i].get_pixel(row, col)
                pix.red += avg_pix.red
                pix.green += avg_pix.green
                pix.blue += avg_pix.blue
            first_img.set_pixel(row, col, Pixel(pix.red // len(imgs), pix.green // len(imgs), pix.blue // len(imgs)))
    
    # Save modified image to local file
    first_img.save_image(out_file)

# Example testing code for `average` function.
# Experiment with different (sub)sets of faces

# # Face files adapted from Peck E. et al. and faceresearch.org
# face_files = ["alex.jpg", "alexander.jpg", "alfred.jpg", "ambroz.jpg", "arnold.jpg"]
# # face_files = ["zelmira.jpg","zita.jpg", "zlata.jpg", "zlatica.jpg", "zora.jpg"]
# 
# # Transform the list of face files into a list of URLs
# face_urls = []
# for face in face_files:
#     face_urls.append(BASE_URL + "faces/" + face)
# 
# average(face_urls, "average_face.jpg")