Kategori: blandet

from django.db import models
from django.utils import timezone
from django.contrib import admin
from django.core.exceptions import ValidationError

def validate_destination(destination):
	if "lnk.dk/" in destination.lower():
		raise ValidationError('For at undgå risiko for uendelige viderestillinger, kan du ikke tilføje korte links fra lnk.dk som destination.')
		
def validate_shortlink(shortlink):
	if shortlink == "om":
		raise ValidationError('Det korte link "om" bruger lnk.dk til at fortælle om lnk.dk. Vælg et andet selvvalgt kort link.')
	elif shortlink == "administration":
		raise ValidationError('Det korte link "administration" bruger lnk.dk til at administrere lnk.dk. Vælg et andet selvvalgt kort link.')

class Link(models.Model):
	destination = models.URLField('Destinationslink', max_length=65535, validators=[validate_destination])
	shortlink = models.SlugField('Kort link', max_length=100, unique=True, allow_unicode=True, validators=[validate_shortlink])
	LINK_TYPE_CHOICES = (
		('automatic', 'Automatisk'),
		('manual', 'Manuelt'),
	)	
	type = models.CharField('Type', max_length=10, choices=LINK_TYPE_CHOICES)
	date = models.DateTimeField(default=timezone.now, editable=False)
	
class LinkAdmin(admin.ModelAdmin):
	list_display = ('destination','shortlink','type','date')
	list_filter = ('type', )
	search_fields = ['destination']

from django.forms import ModelForm
from .models import Link

class LinkForm(ModelForm):
	def __init__(self, *args, **kwargs):
		super(LinkForm, self).__init__(*args, **kwargs)
		self.fields['destination'].widget.attrs['placeholder'] = 'https://eksempel.dk/meget/lang/url'
		self.fields['shortlink'].widget.attrs['placeholder'] = 'eksempel'
		self.fields['shortlink'].label_suffix = ""	# Remove colon after label
		self.fields['shortlink'].required = False	# Not required in form
	
	class Meta:
		model = Link
		fields = ['destination', 'shortlink']
		labels = {
			'shortlink': ('Evt. selvvalgt kort link, lnk.dk/'),
		}
		error_messages = {
			'destination': {
				'max_length': ('Din destinationsurl er for lang til denne kortlinkservice.'),
				'invalid': ('Din destinationsurl er ikke en gyldig adresse. Husk http://, https:// eller ftp:// foran dit link, hvis du har glemt det.'),
			},
			'shortlink': {
				'unique': ('Det selvvalgte link, du har valgt, er allerede i brug. Find på et andet.'),
				'max_length': ('Dit selvvalgte link må maksimalt være 100 tegn langt.'),
				'invalid': ('Du kan kun bruge unicode-bogstaver, cifre, bindestreg og understreg i din selvvalgte adresse.'),
			}
		}

from django.shortcuts import render
from django.http import HttpResponseRedirect
from .models import Link
from .forms import LinkForm
from django.urls import reverse
import hashlib
import bcrypt

# Function to create a random hash to use as short link address
def create_shortlink(destination):
	salt = bcrypt.gensalt().decode()	# Random salt
	destination = destination+salt		# Salt added to destination URL
	hash = hashlib.md5(destination.encode()).hexdigest() # Hashed to alphanumeric string
	return hash[:4]	# First 5 characters of that string 

# Front page with a form to enter destination address. Short URL returned.
def linkindex(request):
	form = LinkForm()	# Loads form
	# If a destination is submitted, a short link is returned
	if request.method == 'POST':
		form = LinkForm(request.POST) # Form instance with submitted data
		# Check whether submitted data is valid
		if form.is_valid():
			destination = form.cleaned_data['destination'] # Submitted destination
			shortlink = form.cleaned_data['shortlink'] # Submitted slug
		
			# User has specified a unique (validated) short link
			if shortlink:
				link = form.save(commit=False)
				link.type = "manual"
				link = form.save()
				site_url = reverse('redirect', args=[link.shortlink])
				sharelink = request.build_absolute_uri(site_url)
			# User wants an automatic link
			else:
				# If a short link with same destionation of same type already exists,
				# it is fetched from database  and served. No need to use up a new
				# URL for the same destination.
				try:
					link = Link.objects.get(destination=destination, type="automatic")
					site_url = reverse('redirect', args=[link.shortlink])
					sharelink = request.build_absolute_uri(site_url)
				# If a link of same type with same destination does not exist, one is
				# created.
				except:	
					# Loop to create a unique hash value for short link
					unique_link = False
					while unique_link == False:
						hash = create_shortlink(destination)	# Return hash
						# First we check whether the hash is a duplicate
						try:
							Link.objects.get(shortlink=hash)	# Check whether hash is used
						# If not a duplicate, an error is thrown, and we can save the hash
						except:
							link = form.save(commit=False)	# Prepare to save form destination data and hash
							link.shortlink = hash	# Sets short link to hash value
							link.type = "automatic"
							link.save()	# Saves destination and short link to database
							site_url = reverse('redirect', args=[link.shortlink])
							sharelink = request.build_absolute_uri(site_url)
							unique_link = True	# If check causes error, hash is unused, exit loop
			context = {'sharelink': sharelink, 'form': form}	# Dictionary with variables used in template
			return render(request, 'links/index.html', context)
		# If form is invalid, check whether a user is trying to create a duplicate manual
		# shortlink.
		else:
			# Check if there's a valid destination link
			if 'destination' in form.cleaned_data:
				# Check if there's a shortlink that's not unique
				try:
					link = Link.objects.get(shortlink=form.data['shortlink'])
					# If so, check whether the destination is the same
					if form.cleaned_data['destination'] == link.destination:
						# Show sharelink to user
						site_url = reverse('redirect', args=[link.shortlink])
						sharelink = request.build_absolute_uri(site_url)
						form.errors['shortlink'] = "" # Error replaced by empty string
					# Render form with sharelink already used error
					else:
						sharelink = ""
				# Render form with error
				except:	
					sharelink = ""
			# Render form with errors	
			else:
				sharelink = ""
		context = {'form': form, 'sharelink': sharelink}
		return render(request, 'links/index.html', context)
	# Render page with form before user has submitted
	context = {'form': form}
	return render(request, 'links/index.html', context)

# Short link redirect to destination URL
def redirect(request, shortlink):
	# Query the database for short link, if there is a hit, redirect to destination URL
	try:
		link = Link.objects.get(shortlink=shortlink)
		return HttpResponseRedirect(link.destination)
	# An error means the short link doesn't exist, so error 404 is shown
	except:
		return render(request, 'links/404.html', status=404)

# About page		
def about(request):
	context = {'request': request}
	return render(request, 'links/about.html', context)	

from django.urls import path
from . import views

urlpatterns = [
    path('', views.linkindex, name='index'),
	path('om', views.about, name='about'),
    path('<shortlink>', views.redirect, name='redirect'),
]

{% load static %}{% spaceless %}<!doctype html>
<html lang="da">
	<head>
		<title>lnk.dk: Danmarks korteste links</title>
		<meta charset="utf-8"/>
		<meta name="description" content="Lav de korteste korte kortlinks gratis på lnk.dk. Fri for annoncer og overvågning.">
		<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
		<link rel="stylesheet" href="{% static "links/style.css" %}">
		<link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png">
		<link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png">
		<link rel="icon" type="image/png" sizes="16x16" href="/favicon-16x16.png">
		<link rel="manifest" href="/site.webmanifest">
		<meta name="theme-color" content="#ffffff">
	</head>
<body>
{% block content %}{% endblock %}
<div class="footer">
	<p>Lav de korteste korte links gratis på lnk.dk. Fri for annoncer og overvågning. <a href="{% url 'about' %}">Om lnk.dk</a></p>
</div>
</body>
</html>
{% endspaceless %}

{% extends "links/base.html" %}{% block content %}{% spaceless %}
<h1>Lav et kort link</h1>
<div class="content">
	{% if form %}
		<form method="post">
		{% csrf_token %}
		<div class="form_field">
			<div class="label">
				{{ form.destination.label_tag}}
			</div>
			<div>{{ form.destination }}</div>
			{{ form.destination.errors }}
		</div>
		<div class="form_field">
			<div class="label">
				{{ form.shortlink.label_tag}}
			</div>
			<div>{{ form.shortlink }}</div>
			{{ form.shortlink.errors }}
		</div>
		<p><button type="submit" value="Giv mig et kort link">Giv mig et kort link</button></p>
		</form>

		{% if request.method == "POST" and not form.destination.errors and not form.shortlink.errors  %}
			<h1>Her er dit link:</h1>
			<p class="sharelink"><a href="{{ sharelink }}">{{ sharelink }}</a></p>
			<button class="copy">Kopier link</button>
		{% endif %} 

	{% endif %}

	{% if error %}
		<h2>Har du tastet forkert?</h2>
		<p><em>Du har prøvet at bruge et kort link. Desværre er det link, du har tastet, ikke registreret. Måske er du kommet til at taste forkert?</em></p>
		<p><a href="{% url 'index' %}">Til forsiden</a>
	{% endif %} 
</div>

{% if request.method == "POST" and not form.destination.errors %}
<script>
function fallbackCopyTextToClipboard(text) {
  var textArea = document.createElement("textarea");
  textArea.value = text;
  document.body.appendChild(textArea);
  textArea.focus();
  textArea.select();
  document.execCommand("copy");
  document.body.removeChild(textArea);
}
  
function copyTextToClipboard(text) {
  if (!navigator.clipboard) {
    fallbackCopyTextToClipboard(text);
    return;
  }
  navigator.clipboard.writeText(text);
}

var copy = document.querySelector('.copy');

copy.addEventListener('click', function(event) {
  copyTextToClipboard('{{ sharelink }}');
});
</script>
{% endif %}
{% endspaceless %}{% endblock %}