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"""A simple URL shortener using Werkzeug and redis."""
import os
import redis
from jinja2 import Environment
from jinja2 import FileSystemLoader
from werkzeug.exceptions import HTTPException
from werkzeug.exceptions import NotFound
from werkzeug.middleware.shared_data import SharedDataMiddleware
from werkzeug.routing import Map
from werkzeug.routing import Rule
from werkzeug.urls import url_parse
from werkzeug.utils import redirect
from werkzeug.wrappers import Request
from werkzeug.wrappers import Response
def base36_encode(number):
assert number >= 0, "positive integer required"
if number == 0:
return "0"
base36 = []
while number != 0:
number, i = divmod(number, 36)
base36.append("0123456789abcdefghijklmnopqrstuvwxyz"[i])
return "".join(reversed(base36))
def is_valid_url(url):
parts = url_parse(url)
return parts.scheme in ("http", "https")
def get_hostname(url):
return url_parse(url).netloc
class Shortly:
def __init__(self, config):
self.redis = redis.Redis(
config["redis_host"], config["redis_port"], decode_responses=True
)
template_path = os.path.join(os.path.dirname(__file__), "templates")
self.jinja_env = Environment(
loader=FileSystemLoader(template_path), autoescape=True
)
self.jinja_env.filters["hostname"] = get_hostname
self.url_map = Map(
[
Rule("/", endpoint="new_url"),
Rule("/<short_id>", endpoint="follow_short_link"),
Rule("/<short_id>+", endpoint="short_link_details"),
]
)
def on_new_url(self, request):
error = None
url = ""
if request.method == "POST":
url = request.form["url"]
if not is_valid_url(url):
error = "Please enter a valid URL"
else:
short_id = self.insert_url(url)
return redirect(f"/{short_id}+")
return self.render_template("new_url.html", error=error, url=url)
def on_follow_short_link(self, request, short_id):
link_target = self.redis.get(f"url-target:{short_id}")
if link_target is None:
raise NotFound()
self.redis.incr(f"click-count:{short_id}")
return redirect(link_target)
def on_short_link_details(self, request, short_id):
link_target = self.redis.get(f"url-target:{short_id}")
if link_target is None:
raise NotFound()
click_count = int(self.redis.get(f"click-count:{short_id}") or 0)
return self.render_template(
"short_link_details.html",
link_target=link_target,
short_id=short_id,
click_count=click_count,
)
def error_404(self):
response = self.render_template("404.html")
response.status_code = 404
return response
def insert_url(self, url):
short_id = self.redis.get(f"reverse-url:{url}")
if short_id is not None:
return short_id
url_num = self.redis.incr("last-url-id")
short_id = base36_encode(url_num)
self.redis.set(f"url-target:{short_id}", url)
self.redis.set(f"reverse-url:{url}", short_id)
return short_id
def render_template(self, template_name, **context):
t = self.jinja_env.get_template(template_name)
return Response(t.render(context), mimetype="text/html")
def dispatch_request(self, request):
adapter = self.url_map.bind_to_environ(request.environ)
try:
endpoint, values = adapter.match()
return getattr(self, f"on_{endpoint}")(request, **values)
except NotFound:
return self.error_404()
except HTTPException as e:
return e
def wsgi_app(self, environ, start_response):
request = Request(environ)
response = self.dispatch_request(request)
return response(environ, start_response)
def __call__(self, environ, start_response):
return self.wsgi_app(environ, start_response)
def create_app(redis_host="localhost", redis_port=6379, with_static=True):
app = Shortly({"redis_host": redis_host, "redis_port": redis_port})
if with_static:
app.wsgi_app = SharedDataMiddleware(
app.wsgi_app, {"/static": os.path.join(os.path.dirname(__file__), "static")}
)
return app
if __name__ == "__main__":
from werkzeug.serving import run_simple
app = create_app()
run_simple("127.0.0.1", 5000, app, use_debugger=True, use_reloader=True)
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