source files

source/eBookmaker.py

+#!/usr/bin/env python
+# coding: utf-8
+
+# In[1]:
+
+
+import tkinter as tk
+from tkinter import ttk
+from tkinter.ttk import *
+from tkinter import filedialog as fd, Text
+from tkinter import messagebox as msg
+from PIL import Image, ImageTk
+import socket
+import requests
+from bs4 import BeautifulSoup
+import os
+from urllib.parse import urljoin, urlparse
+from tqdm import tqdm
+import shutil
+import ebooklib
+from ebooklib import epub
+import codecs
+from PIL import Image
+from PIL import ImageFont
+from PIL import ImageDraw
+import io
+from time import sleep
+import sys
+
+HEIGHT = 500
+WIDTH = 800
+
+root = tk.Tk()
+root.title("Welcome to eBook Maker")
+
+# placing GUI window at the center of the screen
+windowWidth = root.winfo_reqwidth()
+windowHeight = root.winfo_reqheight()
+positionRight = int(root.winfo_screenwidth()/4 - windowWidth/3) + 20
+positionDown = int(root.winfo_screenheight()/4 - windowHeight/3) + 20
+root.geometry("+{}+{}".format(positionRight, positionDown))
+
+# GUI variables
+dirpath = tk.StringVar()
+url = tk.StringVar()
+
+# variables for progress bar
+progress_bar = None
+progress_var = tk.DoubleVar()
+progress=0
+popup = None
+pb_label = tk.StringVar()
+
+
+# In[3]:
+
+
+# ---------------- directories for keeping temporary files ---------------->>>
+pathTemp = '__tempdir__'
+pathImg = 'images'
+textfilepath = ''
+
+
+listOfFiles = []
+listofImg = []
+book_title=''
+
+
+# # Step 3 : creating epub from all the links
+# (Sanjana's code)
+
+# In[4]:
+
+
+def generate_epub(url, path):
+    '''
+    Generate epub document at the given path, taking list of html file names of listOfFiles and taking images from listofImg.
+    Each html file is added as a new chapter.
+    
+    Parameters
+    -----------
+        path : Path to which epub is saved, as given by the user in the GUI.
+        
+    Returns
+    ---------
+        Status of execution: "Okay" if successful ; Exception otherwise.
+        
+    '''
+    global pb_label
+    global progress
+    global progress_var
+    global popup
+    # setting progress in progress bar
+    popup.title("Generating Epub...")
+    pb_label.set("Now generating epub from extracted contents....")
+    popup.update()
+    sleep(5/1000) # lauch task
+    progress = 85
+    progress_var.set(progress)
+    
+    try:
+        book = epub.EpubBook()
+        # add metadata
+        book.set_identifier('sample12345678')
+        
+        book.set_title(book_title)
+        book.set_language('en')
+        object_list = []
+        spine_list = ['cover', 'nav']
+        
+        book.add_author('We_did_our_best')
+
+        img = Image.open("cover.jpg")
+        draw = ImageDraw.Draw(img)
+        font = ImageFont.truetype("arial.ttf", size=20)
+        MAX_W, MAX_H = img.size
+        w, h = draw.textsize(book_title, font=font)
+        draw.text(((MAX_W - h) / 2, (MAX_H - h) / 2), book_title, fill="black", font=font, anchor="ms", align="center")
+
+        img.save('cover-out.jpg')
+        book.set_cover("cover-out.jpg", open('cover-out.jpg', 'rb').read())
+        
+        j = 0
+        global listOfFiles
+        global listofImg
+        for i in listOfFiles:
+            htmlfile = i + ".html"
+            pathForTemp = os.path.join(path, pathTemp)
+            htmlfilepath = pathForTemp + "/" + htmlfile
+            file = codecs.open(htmlfilepath, "r", "utf-8")
+            
+            content = file.read()
+            soup1 = BeautifulSoup(content, "html.parser")
+            chaptertitle = soup1.find('title').string
+            # Adding chapters
+            chaptertitle = chaptertitle.strip()
+
+            c1 = epub.EpubHtml(title=chaptertitle, file_name=chaptertitle + '.xhtml', lang='en')
+            c1.content = content
+            object_list.append(c1)
+            spine_list.append(c1)
+            book.add_item(c1)
+            j = j + 1
+
+        # adding images
+        for img in listofImg:
+            ext = img.split(".")[-1]
+            if ext == "svg":
+                continue
+            elif ext == "jpg":
+                ext1 = "JPEG"
+            else:
+                ext1 = ext
+
+            i = Image.open(img)
+            b = io.BytesIO();
+            i.save(b, ext1)
+            j = b.getvalue()
+            ei = epub.EpubImage()
+            ei.file_name = img
+            ei.media_type = 'image/' + ext
+            ei.content = j
+            book.add_item(ei)
+
+            # add table of contents
+        book.toc = object_list
+
+        # add navigation files
+        book.add_item(epub.EpubNcx())
+        book.add_item(epub.EpubNav())
+
+        # define css style
+        style = '''
+    @namespace epub "http://www.idpf.org/2007/ops";
+    body {
+        font-family: Cambria, Liberation Serif, Bitstream Vera Serif, Georgia, Times, Times New Roman, serif;
+    }
+    h2 {
+         text-align: left;
+         text-transform: uppercase;
+         font-weight: 200;     
+    }
+    ol {
+            list-style-type: none;
+    }
+    ol > li:first-child {
+            margin-top: 0.3em;
+    }
+    nav[epub|type~='toc'] > ol > li > ol  {
+        list-style-type:square;
+    }
+    nav[epub|type~='toc'] > ol > li > ol > li {
+            margin-top: 0.3em;
+    }
+    '''
+
+        # add css file
+        nav_css = epub.EpubItem(uid="style_nav", file_name="style/nav.css", media_type="text/css", content=style)
+        book.add_item(nav_css)
+
+        # spine
+        book.spine = spine_list
+
+        # create epub file
+        
+        epubname = os.path.join(path, book_title + '.epub')
+        
+        epub.write_epub(epubname, book, {})
+        
+    except Exception as e:
+        listOfFiles=[]
+        listofImg=[]
+        print(e)
+        return "Exception"
+    
+    listOfFiles=[]
+    listofImg=[]
+    
+    # setting progress in progress bar
+    popup.update()
+    sleep(5/1000) # lauch task
+    progress = 100
+    pb_label.set("saved epub doc at: \n{} ....".format(path))
+    progress_var.set(progress)
+    popup.update()
+    sleep(3)
+    popup.withdraw()
+    
+    print("saved epub doc at {}".format(path))
+    return "Okay"
+   
+    
+
+
+# # Step 2: Extracting content from nested URLs
+# (Manjusree's code)
+
+# In[5]:
+
+
+# ---------------- for each link in links.txt, call function to extract HTML contents  ---------------->>>
+def extract_contents(url, path, textfilepath):
+    '''
+    For each link present in __links__.txt , call extractPerLink() to extract HTML contents.
+    
+    Parameters
+    -----------
+        path : Path to which epub is saved, as given by the user in the GUI.
+        textfilepath : Path to the file __links__.txt that contains the urls to be extracted.
+        
+    Returns
+    --------
+        Status of execution: "Okay" if successful ; Exception otherwise.
+    '''
+    global pb_label
+    global progress
+    global popup
+    popup.title("Extracting contents...")
+    try:
+        
+        pathForTemp = os.path.join(path, pathTemp)
+        if os.path.isdir(pathForTemp):
+            shutil.rmtree(pathForTemp)
+
+        os.makedirs(pathForTemp)
+        ipfile = open(textfilepath, 'r')
+        for urls in ipfile:
+            
+            try:
+                retname = extractPerLink(urls, pathForTemp)
+                listOfFiles.append(retname)
+                
+            except (requests.ConnectionError, requests.Timeout) as y:
+                return "No internet"
+            
+            except Exception as e:
+                pass
+                
+
+        # ---------------- storing the list of files in listoffiles.txt ---------------->>>
+        flist = open(os.path.join(pathForTemp, "listoffiles.txt"), "w")
+        for htmlfilename in listOfFiles:
+            flist.write(htmlfilename + ".html\n")
+        flist.close()
+        
+        
+        
+        popup.update()
+        pb_label.set("Extraction done....")
+        popup.update()
+        sleep(5/1000) # lauch task
+        progress = 65
+        progress_var.set(progress)
+        
+    except (requests.ConnectionError, requests.Timeout) as y:
+        return "No internet"
+    
+    except Exception as e:
+        return "Exception"
+    
+    return "Okay"
+
+# ---------------- for given URL, extract HTML contents  ---------------->>>
+def extractPerLink(url, pathArg):
+    '''
+    For a given URL, extract HTML contents, save as .html file in a temporary directory created.
+    
+    Parameters
+    ------------
+        url : The URL from which the content is to be extracted.
+        pathArg : Path to the temporary directory created at the path specified by user in GUI for saving epub.
+        
+    Returns
+    ---------
+        The name of the html file created.
+        
+    '''
+    global listofImg
+    url = url.strip()
+    page = requests.get(url)
+    soup = BeautifulSoup(page.content, 'html.parser')
+    titlePage = soup.find('title')
+    # ---------------- declare two lists to store class tag and id tag to be removed from main content ---------------->>>
+    taglistClass = []
+    taglistId = []
+    h2listClass = []
+    mainContent = ''
+
+    # ---------------- define the lists to store class tag and id tag specific to website to be removed from main content ---------------->>>
+    if "tutorialspoint.com" in url:
+        taglistClass = ['center-aligned tutorial-menu', 'mui-container-fluid button-borders', 'tutorial-home-menu']
+        taglistId = ['bottom_navigation', 'google-bottom-ads', 'google-top-ads']
+        mainContent = 'mui-col-md-6 tutorial-content'
+    elif "geeksforgeeks.org" in url:
+        taglistClass = ['clear hideIt', 'plugins', 'recommendedPostsDiv', 'code-gutter', 'code-editor-container', 'code-output-container']
+        taglistId = ['AP_G4GR_5', 'AP_G4GR_6']
+        h2listClass = ['tabtitle']
+        mainContent = 'entry-content'
+    elif "geeksquiz.com" in url:
+        taglistClass = ['clear hideIt', 'plugins', 'recommendedPostsDiv', 'code-gutter', 'code-editor-container', 'code-output-container']
+        taglistId = ['AP_G4GR_5', 'AP_G4GR_6']
+        h2listClass = ['tabtitle']
+        mainContent = 'entry-content'
+    elif "docs.python.org" in url:
+        taglistClass = ['toctree-wrapper compound']
+        mainContent = 'section'
+    elif "numpy.org" in url:
+        taglistClass = ['admonition seealso']
+        mainContent = 'bodywrapper'
+
+    # ---------------- extracting main content ---------------->>>
+    # ---------------- mainContent for URLs with # (fragment specifier) ---------------->>>
+    if "#" in url:
+        fragid = url.split("#")[-1]
+        mainContent = fragid
+        results = soup.find(id=mainContent)
+    else:
+        # ---------------- mainContent for complete webpage ---------------->>>
+        results = soup.find(class_=mainContent)
+
+    # ---------------- remove the tags mentioned in the lists if present ---------------->>>
+    for itemClass in taglistClass:
+        if results.find_all("div", {"class": itemClass}):
+            for eachdivClass in results.find_all("div", {"class": itemClass}):
+                eachdivClass.decompose()
+
+    for itemId in taglistId:
+        if results.find_all("div", {'id': itemId}):
+            for eachdivId in results.find_all('div', {'id': itemId}):
+                eachdivId.decompose()
+
+    for itemh2Class in h2listClass:
+        if results.find_all("h2", {"class": itemh2Class}):
+            for eachh2Class in results.find_all("h2", {"class": itemh2Class}):
+                eachh2Class.decompose()
+    
+    global pb_label
+    global progress
+    global popup
+    popup.update()
+    sleep(5/1000) # lauch task
+    progress = 45
+    progress_var.set(progress)
+    pb_label.set("Extracting contents from...\n{}".format(url))
+    
+    # ---------------- extracting Images ---------------->>>
+    urls = []
+    for img in results.find_all("img"):
+        img_url = img.attrs.get("src")
+        if not img_url:
+            # no src attribute
+            continue
+        # join domain with the URL that is just extracted
+        img_url = urljoin(url, img_url)
+        # check if the url is valid
+        if is_valid(img_url):
+            urls.append(img_url)
+
+    for img in urls:
+        # for each img, download it
+        oppath = os.path.join(pathArg, pathImg)
+        downloadImg(img, oppath)
+
+    
+    for img in results.find_all("img"):
+        img_url = img.attrs.get("src")
+        img_new_url = os.path.join(pathArg, pathImg, img_url.split("/")[-1])
+        img['src'] = img_new_url
+        listofImg.append(img_new_url)
+        
+    listofImg = list(set(listofImg))
+    # ---------------- writing the content to file ---------------->>>
+    if url.split("/")[-1] == '':
+        # ---------------- URLs ending with / ---------------->>>
+        htmlfilename = url.split("/")[-2]
+    else:
+        htmlfilename = url.split("/")[-1]
+
+    f = open(os.path.join(pathArg, htmlfilename + ".html"), "w", encoding="utf-8")
+    f.write(titlePage.prettify())
+    f.write(results.prettify())
+    f.close()
+
+    return htmlfilename
+
+
+# ---------------- functions for extracting images ---------------->>>
+def is_valid(url):
+    '''
+    Check if the url of image present in the webpage is valid or not.
+    Parameters
+    -----------
+        url : URL of the image to be downloaded.
+    Returns
+    ----------
+        True or False 
+    '''
+    parsed = urlparse(url)
+    return bool(parsed.netloc) and bool(parsed.scheme)
+
+def downloadImg(url, pathname):
+    '''
+    Downloads the image specified by the URL to the temporary images folder.
+    
+    Parameters
+    ------------
+        url : URL of the image contained in the webpage.
+        pathname : Path to the "images" folder inside the temporary directory created.
+        
+    No Return Value
+    '''
+    # ---------------- downloads the image file given by url to the pathname path ---------------->>>
+    # if path doesn't exist, make that path dir
+    if not os.path.isdir(pathname):
+        os.makedirs(pathname)
+    # download the body of response by chunk, not immediately
+    response = requests.get(url, stream=True)
+
+    # get the total file size
+    file_size = int(response.headers.get("Content-Length", 0))
+
+    # get the file name
+    filename = os.path.join(pathname, url.split("/")[-1])
+
+    # progress bar, changing the unit to bytes instead of iteration (default by tqdm)
+    progress = tqdm(response.iter_content(1024), f"Downloading {filename}", total=file_size, unit="B", unit_scale=True,unit_divisor=1024)
+    with open(filename, "wb") as f:
+        for data in progress:
+            f.write(data)
+            # update the progress bar manually
+            progress.update(len(data))
+    
+
+
+# # Step 1 : Extracting links from the input URL
+# (Sneha's code)
+
+# In[6]:
+
+
+def extract_links(url, path, doctype=1):
+    '''
+    It fetches the useful links of content from the webpage of given URL.
+    
+    Parameters
+    -------------
+        url : It is URL inputted by the user in the GUI
+        path : Path to which epub is saved, as given by the user in the GUI.
+        doctype : Whether the user wants to convert a "Single Page" or "Complete Tutorial" into epub. By default "Complete Tutorial"(1)
+        
+    Returns
+    ---------
+        Status of execution: "Okay" if successful ; Exception otherwise.
+        
+    '''
+    tables = []
+    list = []
+    ulist = []
+
+    try:
+        r = requests.get(url)
+        soup = BeautifulSoup(r.text, 'html.parser')
+        title = soup.find("title")
+        global book_title
+        global textfilepath
+        book_title = title.string
+        textfilepath = path + "/__links__.txt"
+        if (doctype == 2):
+
+            # -----------------------------to get main url-------------------------------------------->>>
+            if ".com" in url:
+                url_without_extension = url.split('.com')
+                url_with_extension = url_without_extension[0] + ".com"
+            elif ".org" in url:
+                url_without_extension = url.split('.org')
+                url_with_extension = url_without_extension[0] + ".org"
+            elif ".net" in url:
+                url_without_extension = url.split('.net')
+                url_with_extension = url_without_extension[0] + ".net"
+            elif ".in" in url:
+                url_without_extension = url.split('.in')
+                url_with_extension = url_without_extension[0] + ".in"
+            else:
+                print("Please enter valid URL")
+
+            if "python.org" in url:
+                url_with_extension = url
+                if (url_with_extension[-1] == "/"):
+                    url_with_extension = url_with_extension[:-1]
+
+            if "numpy.org" in url:
+                url_with_extension = url
+                if (url_with_extension[-1] == "/"):
+                    url_with_extension = url_with_extension[:-1]
+
+            if "geeksforgeeks.org" in url:
+                url_with_extension = ""
+            
+
+            # ----------------------to get main content----------------------------------------------->>>
+            testing_links = [ "/must-do-coding-questions-for-companies-like-amazon-microsoft-adobe/", 
+                         "/must-coding-questions-company-wise/", 
+                         "/top-10-programming-languages-to-learn-in-2020-demand-jobs-career-growth/", 
+                         "/quadratic-probing-in-hashing/", 
+                         "/how-to-fix-the-height-of-rows-in-the-table/", 
+                         "geeksforgeeks.org/top-40-python-interview-questions-answers/", 
+                         "/upload-and-retrieve-image-on-mongodb-using-mongoose/", 
+                         "/how-to-set-input-type-date-in-dd-mm-yyyy-format-using-html/", 
+                         "/pass-by-reference-vs-value-in-python/", 
+                         "geeksforgeeks.org/contribute/", 
+                         "/write-interview-experience/", 
+                         "/internship/",
+                         "/how-to-contribute-videos-to-geeksforgeeks/",
+                         "/copyright-information/",
+                         "geeksforgeeks.org/tag/",
+                         "auth.geeksforgeeks",
+                         "linkedin.com",
+                         "practice.geeksforgeeks",
+                         "quiz.geeksforgeeks",
+                         "geeksquiz.com/", 
+                         "youtube.com/"
+                         ]
+            if "geeksforgeeks.org" in url:
+                main_list = []
+                ol_list = soup.find_all('ol')
+                if (len(ol_list)>3):
+                    content_olist = []
+                    for i in ol_list:
+                        content_list = []
+                        content_list.clear()
+                        for j in i.find_all('a', href=True):
+                            alist = j['href']
+                            if alist != []:
+                                content_list.append(alist) 
+                        if content_list != []:
+                            content_olist.append(content_list)
+                        main_list.append(content_olist)
+                    
+                else:
+                    for div in soup.find_all("p"): 
+                        div.decompose()
+                    for div in soup.find_all("footer"): 
+                        div.decompose()            
+                    for div in soup.find_all("article"): 
+                        div.decompose()
+                    for div in soup.find_all('ul', {'class':'leftBarList'}):
+                        div.decompose()
+                    for div in soup.find_all("div", {'class':'leftSideBarParent'}): 
+                        div.decompose()
+                    for div in soup.find_all("div", {'class':'header-main__wrapper'}): 
+                        div.decompose()
+                    for div in soup.find_all("div", {'class':'cookie-consent hide-consent'}): 
+                        div.decompose()
+
+                    alist = []
+                    main_list = []
+                    for j in soup.find_all('a', href=True):
+                        alist.append(j['href'])
+                    print(len(alist))
+
+                    true_false = []
+                    for i in alist:
+                        for j in testing_links:
+                            if j in i:
+                                true_false.append(j)
+                        
+                        if len(true_false)==0:
+                            main_list.append(i)
+                        true_false.clear()
+                    MyFile = open(textfilepath,'w')
+
+                    for element in main_list:
+                        MyFile.write(element)
+                        MyFile.write('\n')
+                    MyFile.close()
+                    exit()
+
+            elif "tutorialspoint" in url:
+                ul_list = soup.find_all('ul')
+                content_ulist = []
+                for i in ul_list:
+                    content_list = []
+                    content_list.clear()
+                    for j in i.find_all('a', href=True):
+                        alist = j['href']
+                        if alist != []:
+                            content_list.append(alist) 
+                    if content_list != []:
+                        content_ulist.append(content_list)
+                #-------------name of tutorial
+                a = url.split("/")
+                for i in a:
+                    if (i == "www.tutorialspoint.com"):
+                        j =a.index(i)
+                        j +=1
+                    if (a.index(i) == j):
+                        topic = i
+                temp_link = topic+"/index.htm"
+                
+                #---------------------extract links from tutorialspoint
+                main_list = []
+                main_list1 = []
+                for i in content_ulist:
+                        for j in i:
+                            if temp_link in j:
+                                main_list1.append(i)
+                for i in main_list1:
+                    for j in i:
+                        main_list.append(j)
+                
+            
+            else:
+                ul_list = soup.find_all('ul')
+                content_ulist = []
+                for i in ul_list:
+                    content_list = []
+                    content_list.clear()
+                    for j in i.find_all('a', href=True):
+                        alist = j['href']
+                        if alist != []:
+                            content_list.append(alist) 
+                    if content_list != []:
+                        content_ulist.append(content_list)
+                main_list = max(content_ulist, key=len)
+                    
+            global pb_label
+            global progress
+            global popup
+            popup.update()
+            sleep(5/1000) # lauch task
+            progress = 20
+            progress_var.set(progress)
+            # ---------------------to check list elements starts with slash otherwise add it---------->>>
+            if "geeksforgeeks.org" not in url:
+                main_list1 = [i[0] for i in main_list]
+                if "/" in main_list1:
+                    main_list = main_list
+                else:
+                    main_list = ["/" + list_ele for list_ele in main_list]
+                    
+            # -------------------check if list has unnecessary string starts with #------------------->>>
+            if "geeksforgeeks.org" not in url:
+                main_list = [i.split("#")[0] for i in main_list]
+            
+
+            # ------------------get only unique urls-------------------------------------------------->>>
+            unique_list = []
+            for x in main_list:
+                if (x[-1] == "/"):
+                    x = x[:-1]
+                if x not in unique_list:
+                    unique_list.append(x)
+            main_list.clear()
+            main_list = [None] * len(unique_list)
+            for i in range(len(unique_list)):
+                main_list[i] = unique_list[i]
+
+            # ------------------to attach url with list elements-------------------------------------->>>
+            if "geeksforgeeks.org" not in url:
+                final_list = [url_with_extension + list_ele for list_ele in main_list]
+            
+            else:
+                final_list = []
+                for i in main_list:
+                    for j in i:
+                        for k in j:
+                            final_list.append(k)
+
+            # -----------------writing links in text file--------------------------------------------->>>
+            MyFile = open(textfilepath, 'w')
+
+            for element in final_list:
+                MyFile.write(element)
+                MyFile.write('\n')
+            MyFile.close()
+           
+        else:
+            MyFile = open(textfilepath, 'w')
+            MyFile.write(url)
+            MyFile.close()
+            
+        
+    except (requests.ConnectionError, requests.Timeout) as y:
+        return "No internet"
+    
+    except socket.error as e:
+        print(e)
+        return "Invalid URL"
+    
+    except Exception as e:
+        return "Exception"
+    else:
+        pb_label.set("Now saving links in a text file..")
+        popup.update()
+        sleep(5/1000) # lauch task
+        progress = 30
+        progress_var.set(progress)
+        
+    return "Okay" 
+        
+
+
+# # GUI code
+
+# In[ ]:
+
+
+def delete_temp_folder(path):
+    '''
+    Deletes temporary files and folders, if created, that were necessary for the execution and creation of epub document.
+    
+    Parameters:
+    -------------
+        path : Path to temporary files and folders; which is same as the path inputted by the user in GUI.
+        
+    No Return values.
+    '''
+    # deleting all the temporary files and folders
+    global textfilepath
+    path = os.path.join(path,'__tempdir__')
+    if os.path.isdir(path):
+        shutil.rmtree(path)
+        
+    if os.path.isfile(textfilepath):
+        os.remove(textfilepath)
+
+    if os.path.isfile('cover-out.jpg'):
+        os.remove('cover-out.jpg')
+        
+def on_closing():
+    '''
+    When user wants to close the application, it displays a prompt, and once user confirms quitting, closes all the windows and terminates all the background processes.
+    
+    No parameters
+    
+    No Return Values
+    '''
+    if msg.askokcancel("Quit", "Do you want to quit?"):
+        if popup:
+            popup.destroy()
+        root.destroy()
+        os._exit(0)
+
+def take_path():
+    '''
+    This function is bound to "Browse" button of GUI and it allows the user to browse through all the locations on his computer to select the destination for epub document.
+    
+    No parameters.
+    
+    No Return Values.
+    
+    '''
+    path = fd.askdirectory()
+    pathEntry.config(state='normal')
+    pathEntry.delete(0, "end")
+    pathEntry.insert(0, path)
+    pathEntry.config(state="disabled")
+    dirpath.set(path)
+    
+
+
+def validate_entries():
+    '''
+    This function is bound to "Generate epub" button. It checks if all the input fields are non-empty.
+    Calls extract_links(), extract_contents(), and generate_epub() and handles exceptions.
+    Calls delete_temp_folder() at the end.
+    
+    No parameters.
+    
+    No Return Values.
+    
+    '''
+    invalid = False
+    url = URLentry.get()
+    path = pathEntry.get()
+    
+
+    # checking if entries are empty
+    if url == "" or url == 'Enter URL:' or path == "Browse to select location" or path == "":
+        msg.showerror("Invalid arguments:",
+                      "Error: URL and location can't be empty. \n Please insert url or select a location.")
+        invalid = True
+
+    elif pagevar.get() == 0:
+        msg.showerror("Document type not selected:",
+                      "Error: please select whether you want single page epub or complete tutorial.")
+        invalid = True
+    else:
+        invalid = False
+        # a variable to check if user wants complete tutorial epub or single page epub.
+        tutorial = pagevar.get()
+        pagevar.set(0)
+
+    response = True
+    # if entries are non-empty , then proceed.
+    if invalid == False:
+        # code for progress bar:
+        global popup
+        global progress_var
+        global progress_bar
+        global progress
+        global pb_label
+        global textfilepath
+        
+        # a popup window for progress bar
+        popup = tk.Toplevel(root)
+        
+        # placing popup window at the center of root window
+        windowWidth = root.winfo_reqwidth()
+        windowHeight = root.winfo_reqheight()
+        positionRight = int(WIDTH/4 - windowWidth/3) + 500
+        positionDown = int(HEIGHT/4 - windowHeight/3) +340
+        popup.geometry("+{}+{}".format(positionRight, positionDown))
+        
+        popup.geometry('600x150')
+        popup.title("Extracting Links....")
+        popup.transient(root)
+        popup.iconbitmap("book_icon.ico") # adding an icon
+        
+        progress_frame = tk.Frame(popup)
+        progress_frame.place(relx=0.5, rely=0.05, relwidth=0.95, relheight=0.80, anchor='n')
+        
+        progress_label= tk.Label(progress_frame ,textvariable = pb_label).place(relx=0.1, rely=0, relwidth = 0.80, relheight = 0.3)
+        pb_label.set("Generating Epub doc....")
+        
+        progress = 0
+        progress_bar = ttk.Progressbar(progress_frame, variable=progress_var, maximum=100)
+        progress_bar.place(relx=0.1,rely=0.40,relwidth=0.75 , relheight=0.25)
+        popup.pack_slaves()
+        
+        bookbutton['state'] = "disabled"
+        browseButton['state'] = 'disabled'
+        # <======== STEP 1  ============================================= >>
+        response = extract_links(url, path, tutorial)
+        if response == "Invalid URL":
+            msg.showerror("Invalid url:", "Error: Please enter a valid url")
+            popup.withdraw()
+        elif response == "No internet":
+            msg.showerror("Unable to connect:", "Error: Please check your internet connection!")
+            popup.withdraw()
+        elif response=="Exception":
+            msg.showerror("Unable to process:", "Error: Some error occured while processing.\n Please try again.")
+            popup.withdraw()
+           
+        else:
+             # <======== STEP 2  ============================================= >>
+            response = extract_contents(url, path, textfilepath) # step 2
+            if response == "No internet":
+                msg.showerror("Unable to connect:", "Error: Please check your internet connection!")
+                popup.withdraw()
+            elif response == "Exception":
+                msg.showerror("Unable to process:", "Error: Some error occured while processing.\n Please try again.")
+                popup.withdraw()
+               
+            else:
+                 # <======== STEP 3  ============================================= >>
+                response = generate_epub(url, path) # step 3
+                if response == "Exception":
+                    msg.showerror("Unable to process:", "Error: Some error occured while processing.\n Please try again.")
+                    popup.withdraw()
+                    
+    delete_temp_folder(path)
+    browseButton['state'] = 'normal'   
+    bookbutton['state'] = "normal"
+    
+def URLentry_click(event):
+    '''
+    This function is bound to "URLentry" entry widget of GUI. When user FOCUS-IN, it takes appropriate action.
+    
+    Parameter:
+    -----------
+        event : call-back event.
+    
+    No Return Values.
+    
+    '''
+    if URLentry.get() == 'Enter URL:':
+        URLentry.delete(0, "end")
+        URLentry.insert(0, '')
+
+
+def singlepage():
+    '''
+    It is bound to "Single Page" radio button, indicates contents from a single page to be extracted.
+    
+    No Parameters
+    
+    No Return Values
+    
+    '''
+    pagevar.set(1)
+
+
+def multipage():
+    '''
+    It is bound to "Complete Tutorial" radio button, indicates contents from the whole tutorial to be extracted.
+    
+    No Parameters
+    
+    No Return Values
+    
+    '''
+    pagevar.set(2)
+
+
+def resize_image(event):
+    '''
+    Resizing the background image to the size of the GUI window.
+    
+    Parameter:
+    ------------
+        event : callback event.
+        
+    No return values.
+    
+    '''
+    new_width = event.width
+    new_height = event.height
+    image = copy_of_image.resize((new_width, new_height))
+    photo = ImageTk.PhotoImage(image)
+    back_label.config(image=photo)
+    back_label.image = photo  
+
+if __name__ == '__main__' : 
+    '''
+    Creating a GUI structure, adding widgets, binding events to widgets.
+    
+    '''
+    # adding canvas to the root window
+    canvas = tk.Canvas(root, height=HEIGHT, width=WIDTH)
+    canvas.pack()
+    
+    # adding background image to the root window
+    bg_image = Image.open('bg_gif.gif')
+    copy_of_image = bg_image.copy()
+    back_img = ImageTk.PhotoImage(bg_image)
+    back_label = ttk.Label(root, image=back_img)
+    back_label.place(x=0.75, y=0.75, relwidth=1, relheight=1)
+    back_label.bind('<Configure>', resize_image)
+    
+    
+    # creating a frame for URLentry widget
+    urlframe = tk.Frame(root, bg='#fae4a7', bd=5)
+    urlframe.place(relx=0.5, rely=0.1, relwidth=0.75, relheight=0.1, anchor='n')
+
+    # placing an entry widget in URL frame for taking input URL 
+    URLentry = tk.Entry(urlframe, font=("Times", 15))
+    URLentry.place(relwidth=1, relheight=1)
+    URLentry.insert(0, 'Enter URL:')
+    URLentry.bind('<FocusIn>', URLentry_click)
+    
+    # create label for URL frame
+    urlLabel = tk.Label(urlframe, text="Enter URL", bg='white')
+    urlLabel.place(relx=0.255, rely=0, relwidth=0.45, relheight=0.25)
+
+    #creating a frame for pathentry and Browse button widgets
+    pathframe = tk.Frame(root, bg='#fae4a7', bd=5)
+    pathframe.place(relx=0.5, rely=0.25, relwidth=0.75, relheight=0.1, anchor='n')
+
+    pathEntry = tk.Entry(pathframe, font=("courier", 10, "italic", "bold"))
+    pathEntry.place(relwidth=0.84, relheight=1)
+    pathEntry.insert(0, 'Browse to select location')
+    pathEntry.config(state="disabled")
+
+    browseButton = tk.Button(pathframe, text='Browse', bg='gray', fg='white', command=take_path)
+    browseButton.place(relx=0.85, relwidth=0.15, relheight=0.8)
+
+    createbookframe = tk.Frame(root, bg='#fae4a7', bd=5)
+    createbookframe.place(relx=0.5, rely=0.40, relwidth=0.75, relheight=0.25, anchor='n')
+
+    pagevar = tk.IntVar()
+    pagevar.set(0)
+    onepage = tk.Radiobutton(createbookframe, text="Single Page", font=("Times", 15, "bold"), bg='#fae4a7',
+                             command=singlepage, variable=pagevar, value=1, anchor='n')
+    onepage.place(relx=0.05, rely=0.075, relwidth=0.30, relheight=0.5)
+
+    multipage = tk.Radiobutton(createbookframe, text='Complete Tutorial', font=("Times", 15, "bold"), bg='#fae4a7',
+                               command=multipage, variable=pagevar, value=2, anchor='n')
+    multipage.place(relx=0.4, rely=0.075, relwidth=0.60, relheight=0.5)
+
+    
+    bookbutton = tk.Button(createbookframe, text='Generate Epub', bg='gray', fg='white', command=validate_entries)
+    bookbutton.place(relx=0.35, rely=0.5, relwidth=0.25, relheight=0.3)
+
+    # when closing window...pop message 'Do you want to quit?'
+    root.protocol("WM_DELETE_WINDOW", on_closing)
+    
+    # adding icon
+    root.iconbitmap("book_icon.ico")
+    
+    root.mainloop()
+
+
+# ## Test links
+# 1. tutorialspoint done
+# 2. python.org done
+# 3. numpy.org done
+# 4. geeksforgeeks done
+# 
+#     
+# ## for testing tutorials links
+# 1. https://www.tutorialspoint.com/cprogramming/index.htm 
+# 2. https://www.geeksforgeeks.org/c-programming-language/ 
+# 3. https://numpy.org/doc/stable/user/quickstart.html 
+# 4. https://docs.python.org/3/tutorial/ 
+# 
+# ### for testing specific from those tutorials
+# 1. https://www.tutorialspoint.com/cprogramming/c_variables.htm
+# 2. https://numpy.org/doc/stable/user/quickstart.html#universal-functions
+# 3. https://docs.python.org/3/tutorial/introduction.html
+# 
+# 
+
+# In[ ]:
+
+
+
+
+
+# In[ ]:
+
+
+
+