"""Provides context manager that runs local webserver."""

import contextlib
import os
import posixpath
import requests
import time
from multiprocessing import Process
from http.server import HTTPServer, SimpleHTTPRequestHandler
from urllib.parse import unquote


class MyHTTPRequestHandler(SimpleHTTPRequestHandler):
    """Copy of SimpleHTTPRequestHandler with base_dir."""

    base_dir = None  # Must be set before use

    def translate_path(self, path):
        """Translate a /-separated PATH to the local filename syntax.

        **Based on code in http.server.SimpleHTTPRequestHandler with
        modification of base path to come from self.base_dir**
        """
        # abandon query parameters
        path = path.split('?', 1)[0]
        path = path.split('#', 1)[0]
        # Don't forget explicit trailing slash when normalizing. Issue17324
        trailing_slash = path.rstrip().endswith('/')
        path = unquote(path)
        path = posixpath.normpath(path)
        words = path.split('/')
        words = filter(None, words)
        # Now make path from self.base_dir and words
        tpath = self.base_dir
        for word in words:
            if word != '..':
                tpath = os.path.join(tpath, word)
        if trailing_slash:
            tpath += '/'
        return tpath


def run_webserver(dir, host, port):
    """Run webserver.

    dir - base directory for files to serve
    host & port - hostname and port of server
    """
    # Up until Python 3.7 is worked to set .base_dir in webserver(...) before
    # creating the Process(...). This changed in 3.8 after which the value was
    # not seen when running the server. Setting the class variable here instead
    # works across different version
    MyHTTPRequestHandler.base_dir = dir
    server_address = (host, port)
    httpd = HTTPServer(server_address, MyHTTPRequestHandler)
    httpd.serve_forever()


@contextlib.contextmanager
def webserver(dir='/tmp/htdocs', host='localhost', port=9999):
    """Context Manager that provides a webserver serving files from dir."""
    p = Process(target=run_webserver, args=(dir, host, port))
    p.start()
    # Wait for the server to be launched
    base_url = 'http://%s:%d/' % (host, port)
    for j in range(0, 10):
        try:
            requests.get(base_url, timeout=0.1)
            break
        except requests.exceptions.ConnectionError:
            pass
        time.sleep(0.1)
    else:
        print("Failed to start test webserver from %s at host=%s port=%d" % (dir, host, port))
    # Setup complete, yield to execute with clause
    try:
        yield
    finally:
        # Close the server
        p.terminate()
        time.sleep(0.1)


if __name__ == '__main__':
    print('Will start webserver at localhost:9999 serving from /tmp/htdocs for 10s')
    with webserver():
        print('Started...')
        time.sleep(10)
        # Things with server go in here
    print('Exited server')