import os

import magic
from atom.api import Atom, Bytes, Int, List, Str, observe
from enaml.image import Image
# https://pypi.org/project/natsort/
from natsort import natsorted


class ImageFolder(Atom):
    path = Str()
    image_data = Bytes()

    items = List(str)
    index = Int(default=0)
    _supported_formats = set(Image.format.items).union({'jpeg'}) - {'auto'}

    def _load_image(self):
        if self.items:
            with open(self.items[self.index], 'rb') as file:
                self.image_data = file.read()

    @observe('path')
    def _on_path(self, change):
        # Clear image, items, and reset index
        self.image_data = b''
        self.items.clear()
        self.index = 0

        # If the path is empty or doesn't exist just return
        path = change['value']
        if not os.path.isdir(path):
            return

        # Collect all images recursively
        for root, folders, file_names in os.walk(path):
            for file_name in file_names:
                path = os.path.join(root, file_name)
                mime = magic.from_file(path, mime=True)
                kind, format = mime.split('/', 1)
                if kind == 'image' and format in self._supported_formats:
                    self.items.append(path)

        self.items = natsorted(self.items)
        self._load_image()

    def next(self):
        self.index += 1
        if self.index >= len(self.items):
            self.index = 0
        self._load_image()

    def previous(self):
        self.index -= 1
        if self.index < 0:
            self.index = len(self.items) - 1
        self._load_image()