import os
from enum import Enum
from threading import Semaphore, Thread
from urllib import request
from bs4 import BeautifulSoup, Tag, ResultSet


class MessageType(Enum):
    """
    MessageType

    Is an enumeration to define the different types of messages sent by the webpic messenger.

    There are 3 types of messages.
    - log -> log
    - error -> err
    - success -> suc

    @author     Jérémi Nihart / EndMove
    @link       https://git.endmove.eu/EndMove/WebPicDownloader
    @version    1.0.0
    @since      2022-09-05
    """
    LOG = 'log'
    ERROR = 'err'
    SUCCESS = 'suc'


class WebPicDownloader(Thread):
    """
    WebPicDownloader

    Webpicdownloader is a scraping tool that allows you to browse a web page,
    find the images and download them. This tool is easily usable and implementable
    in an application. It has been designed to be executed in an integrated thread
    in an asynchronous way. This tool allows to define 3 callback functions, one for
    events, one in case of success and one in case of failure. It also has an
    integrated entry point allowing it to be directly executed in terminal mode.

    @author     EndMove <contact@endmove.eu>
    @version    1.2.1
    """
    # Variables
    __callbacks: dict = None    # Callback dictionary
    __settings: dict = None     # Webpic basics settings
    __dl_infos: dict = None     # Download informations
    __sem: Semaphore = None     # Semaphore for the webpic worker

    _exit: bool = None          # When set to True quit the thread

    # Constructor
    def __init__(self, path: str = None, headers: dict = None, messenger = None,
                    success = None, failure = None) -> None:
        """
            Constructor
        => It is important to initialize the WebPicDownloader object properly. The callback
        functions can be initialized after the creation of the object.

        * :path: -> Folder in which the tool will create the download folders and place the images.
        * :headers: -> Dictionary allowing to define the different parameters present in the header
            of the requests sent by WebPic.
        * :messenger: -> Callback function messenger (see setter).
        * :success: -> Callback function success (see setter).
        * :failure: -> Callback function failure (see setter).
        """
        super().__init__(daemon=True)
        self.__callbacks = {
            'messenger': messenger if messenger else lambda msg: print(msg),
            'success': success if success else lambda: print("Success!"),
            'failure': failure if failure else lambda: print("failure!")
        }
        self.__settings = {
            'root_path': path if path else os.getcwd(),
            'headers': headers if headers else {
                'User-Agent': "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36"
            }
        }
        self.__dl_infos = {
            'website_url': 'url',
            'download_name': 'name',
            'download_path': 'full_path',
            'running': False
        }  
        self.__sem = Semaphore(0)
        self.__exit = False

        self.start()  # start deamon


    # Internal functions
    def __get_html(self, url: str) -> str:
        """
            Internal Function #do-not-use#
        => Allow to retrieve the HTML content of a website.

        * :url: -> The url of the site for which we want to get the content of the HTML page.
        * RETURN -> Web page content.
        """
        req = request.Request(url, headers=self.__settings.get('headers'))
        response = request.urlopen(req)
        return response.read().decode('utf-8')


    def __find_all_img(self, html: str) -> ResultSet:
        """
            Internal Function #do-not-use#
        => Allow to retrieve all images of an html page.

        * :html: -> Html code in which to search for image balises.
        * RETURN -> Iterable with all image balises.
        """
        soup = BeautifulSoup(html, 'html.parser')
        return soup.find_all('img')


    def __find_img_link(self, img: Tag) -> str:
        """
            Internal Function #do-not-use#
        => Allow to retrieve the link of a picture.

        * :img: -> Image tag {@code bs4.Tag} for which to search the link of an image.
        * RETURN -> Image link.
        """
        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:
        """
            Internal Function #do-not-use#
        => Allow to retrieve the right image type (png, jpeg...)
        
        * :img_link: -> Lien de l'image pourllaquel trouver le bon type.
        * RETURN -> Type of image.
        """
        type = img_link.split('.')[-1]
        if '?' in type:
            type = type.split('?')[0]
        return type


    def __download_img(self, url: str, filename: str) -> None:
        """
            Internal Function #do-not-use#
        => Allow to download a picture from internet
        
        * :url: -> Image url on the web.
        * :filename: -> Full path with name of the future image.
        """
        req = request.Request(url, headers=self.__settings.get('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:
        """
            Internal Function #do-not-use#
        => Checks if the folder in which to place the images to be uploaded exists and if
        not chalk it up. An exception is raised if this folder already exists.
        
        * :folder_path: -> Full path to the working folder (for the download task).
        """
        if not os.path.exists(folder_path):
            os.mkdir(folder_path)
        else:
            raise ValueError("The folder already exists, it may already contain images")


    def __msg(self, message: str, type:MessageType=MessageType.LOG) -> None:
        """
            Internal Function #do-not-use#
        => Use the messenger callback to send a message.

        * :message: -> the message to send through callback
        * :type: -> message type, can be ['log', 'err', 'suc']
        """
        self.__callbacks.get('messenger')(message, type)


    # Public functions
    def set_success_callback(self, callback) -> None:
        """
        Setter to define the callback function when the download succeeded.

        * :callback: -> the callback function to call when the download is a success.
        """
        self.__callbacks['success'] = callback


    def set_failure_callback(self, callback) -> None:
        """
        Setter to define the callback function called when the download fails.

        * :callback: -> the callback function to call when the download is a failure.
        """
        self.__callbacks['failure'] = callback


    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.__callbacks['messenger'] = callback
    

    def start_downloading(self, url: str, name: str) -> None:
        """
        Start downloading all pictures of a website.
        
        * :url: -> The url of the website to annalyse.
        * :folder_name: -> The name of the folder in which to upload the photos.
        """
        if not self.is_alive:
            self.__msg("Opss, the download thread is not running, please restart webpic.", MessageType.ERROR)
        elif self.__dl_infos.get('running'):
            self.__msg("Opss, the download thread is busy.", MessageType.ERROR)
        else:
            self.__dl_infos['website_url'] = url
            self.__dl_infos['download_name'] = name
            self.__sem.release()


    def stop_downloading(self, block=False) -> None:
        """
        Stops the download after the current item is processed and exit the downloading thread.
        
        <!> Attention once called it will not be possible any more to download. <!>

        * :block: -> If true, the function will block until the worker has finished working, if
        False(default value), the stop message will be thrown and the program will continue.
        """
        self.__exit = True
        self.__sem.release()
        if block:
            self.join()
    
    
    def is_download_running(self) -> bool:
        """
        Indique si un téléchargement est en cours

        * RETURN -> True if yes, False else.
        """
        return self.__dl_infos['running'];
    

    # Thread corp function
    def run(self) -> None:
        while True:
            self.__sem.acquire()  # waiting the authorization to process

            if self.__exit:  # check if the exiting is requested
                return

            self.__dl_infos['running'] = True  # indicate that the thread is busy

            try:
                # parse infos from url
                html = self.__get_html(self.__dl_infos.get('website_url'))  # website html
                images = self.__find_all_img(html)  # find all img balises ing html

                # setting up download informaations
                tot_count = len(images)  # count total image
                dl_count = 0  # set download count to 0
                self.__dl_infos['download_path'] = f"{self.__settings.get('root_path')}/{self.__dl_infos.get('download_name')}/"  # format path

                # init working directory
                self.__initialize_folder(self.__dl_infos.get('download_path'))  # Init download folder
                self.__msg(f"WebPicDownloader found {tot_count} images on the website.")

                # start images processing
                for i, img in enumerate(images):
                    try:
                        self.__msg(f"Start downloading image {i}.")
                        
                        img_link = self.__find_img_link(img)  # find image link
                        self.__download_img(img_link, f"{self.__dl_infos.get('download_path')}image-{i}.{self.__find_image_type(img_link)}")  # download the image
                        
                        self.__msg(f"Download of image {i}, done!")
                        dl_count += 1  # increment download counter
                    except Exception as err:
                        self.__msg(f"ERROR: Unable to process image {i} -> err[{err}].")
                # end images processing

                self.__msg(f"WebPicDownloader has processed {dl_count} images out of {tot_count}.")
                self.__callbacks.get('success')()  # success, launch callback
            except Exception as err:
                self.__msg(f"ERROR: An error occured -> err[{err}]")
                self.__callbacks.get('failure')()  # error, launch callback

            self.__dl_infos['running'] = False  # inficate that the thread is free


if __name__ == "__main__":
    # Internal entry point for testing and consol use.
    wpd = WebPicDownloader()
    while True:
        url = input("Website URL ? ")
        name = input("Folder name ? ")
        wpd.start_downloading(url, name)
        if "n" == input("Do you want to continue [Y/n] ? ").lower():
            break
    wpd.stop_downloading(block=True)
    print("Good bye !")