import os
from urllib import request
from urllib.error import HTTPError, URLError
from bs4 import BeautifulSoup, Tag, ResultSet


class WebPicDownloader():
    """
    WebPicDownloader

    webpicdownloader is a simple tool able to
    find and download all pictures on a webpage.

    @author     EndMove <contact@endmove.eu>
    @version    1.1.0
    """
    # Variables
    path: str = None
    messenger = None
    headers: dict = None

    # Constructor
    def __init__(self, path: str = os.getcwd()) -> None:
        """Constructor"""
        self.path = path
        self.messenger = lambda message: print(message)
        self.headers = {'User-Agent': "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36"}

    # Internal functions
    def __get_html(self, url: str) -> str:
        """Allow to retrieve the HTML content of a website"""
        req = request.Request(url, headers=self.headers)
        response = request.urlopen(req)
        return response.read().decode('utf-8')

    def __find_all_img(self, html: str) -> ResultSet:
        """Allow to retrieve all images of an html page"""
        soup = BeautifulSoup(html, 'html.parser')
        return soup.find_all('img')

    def __find_img_link(self, img: Tag) -> str:
        """Allow to retrieve the link of a picture"""
        if img.get('src'):
            link = img.get('src')
        elif img.get('data-src'):
            link = img.get('data-src')
        elif img.get('data-srcset'):
            link = img.get('data-srcset')
        elif img.get('data-fallback-src'):
            link = img.get('data-fallback-src')
        else:
            raise ValueError("Unable to find image url")
        if not 'http' in link:
            raise ValueError("Bad image url")
        return link

    def __find_image_type(self, img_link: str) -> str:
        """Allow to retrieve the right image type"""
        type = img_link.split('.')[-1]
        if '?' in type:
            type = type.split('?')[0]
        return type

    def __download_img(self, url: str, filename: str) -> None:
        """Allow to download a picture from internet"""
        req = request.Request(url, headers=self.headers)
        raw_img = request.urlopen(req).read()
        with open(filename, 'wb') as img:
            img.write(raw_img)

    def __initialize_folder(self, folder_path: str) -> None:
        """Init the folder on which put downloaded images"""
        if not os.path.exists(folder_path):
            os.mkdir(folder_path)
        else:
            raise ValueError("the folder already exists, it may already contain images")

    # Public functions
    def set_messenger_callback(self, callback) -> None:
        """
        Setter to define the callback function called when new messages arrive.

        :callback: -> the callback function to call when a message event is emited.
        """
        self.messenger = callback

    def download(self, url: str, folder_name: str) -> bool:
        """
        Start downloading all pictures of a website
        
        :url: -> The url of the website to annalyse.\n
        :folder_name: -> The name of the folder in which to upload the photos.
        """
        try:
            count = 0
            folder_path = f"{self.path}/{folder_name}/"
            html = self.__get_html(url)
            images = self.__find_all_img(html)

            self.__initialize_folder(folder_path)
            self.messenger(f"WebPicDownloader found {len(images)} images on the website.")

            for i, img in enumerate(images):
                try:
                    self.messenger(f"Start downloading image {i}.")
                    img_link = self.__find_img_link(img)
                    self.__download_img(img_link, f"{folder_path}image-{i}.{self.__find_image_type(img_link)}")
                    self.messenger(f"Download of image {i}, done!")
                    count += 1
                except Exception as err:
                    self.messenger(f"ERROR: Unable to process image {i} -> err[{err}].")
                    
            self.messenger(f"WebPicDownloader has processed {count} images out of {len(images)}.")
            return True
        except HTTPError as err:
            self.messenger(f"ERROR: An http error occured -> err[{err}].")
        except (ValueError, URLError) as err:
            self.messenger(f"ERROT: An error occured with the url -> err[{err}].")
        except Exception as err:
            self.messenger(f"ERROR: An unknown error occured -> err[{err}]")
        return False

if __name__ == "__main__":
    wpd = WebPicDownloader()
    wpd.set_messenger_callback(lambda msg: print(f"--> {msg}"))
    while True:
        url = input("Website URL ? ")
        name = input("Folder name ? ")
        wpd.download(url, name)
        if "n" == input("Do you want to continue [Y/n] ? ").lower():
            break
    print("Good bye !")