import os
import sys
import traceback
from PIL import Image, ImageOps
from multiprocessing import Process


# style tuples: max x, max y, rotate ok)
# rotate ok means x and y maxes can be swapped if it fits the image's aspect ratio better
THUMB_STYLES = {"tiny": (80, 80, False),
                "small": (100, 100, False),
                "feed": (250, 250, False),
                "preview": (1024, 768, True),
                "big": (2048, 1536, True)}


def thumb_path(style_name, uuid):
    return os.path.join("thumbs", style_name, uuid[0:2], "{}.jpg".format(uuid))


def image_style(image, style_name, orientation):
    """
    Given an input PIL Image object, return a scaled/cropped image object of style_name
    """
    thumb_width, thumb_height, flip_ok = THUMB_STYLES[style_name]
    i_width, i_height = image.size

    im_is_rotated = orientation % 2 != 0 or i_height > i_width

    if im_is_rotated and flip_ok:
        thumb_width, thumb_height = thumb_height, thumb_width

    # prevents scale-up (why do i want this?)
    thumb_width = min(thumb_width, i_width) if i_width > 0 else thumb_width
    thumb_height = min(thumb_height, i_height) if i_height > 0 else thumb_height

    image = image.rotate(90 * orientation, expand=True)
    return ImageOps.fit(image, (thumb_width, thumb_height), Image.ANTIALIAS)


def image_file_style(src_path, output_path, style_name, orientation):
    """
    Given an input and output image paths, create a scaled/cropped image file of style_name
    """
    image = Image.open(src_path)
    if image.mode != "RGB":
        image = image.convert("RGB")
    output = image_style(image, style_name, orientation)
    output.save(output_path, 'JPEG')


def _image_file_style_process_worker(src_path, output_path, style_name, orientation):
    try:
        image_file_style(src_path, output_path, style_name, orientation)
    except Exception:
        traceback.print_exc()
        if os.path.exists(output_path):
            os.unlink(output_path)
        sys.exit(1)


def image_file_style_process(src_path, output_path, style_name, orientation):
    """
    Same as image_file_style but the image manipulation is done in a background process
    """
    p = Process(target=_image_file_style_process_worker,
                args=(src_path, output_path, style_name, orientation))
    p.start()
    p.join()
    if p.exitcode != 0:
        return False

    return True