import tempfile
import os
import shutil
from io import BytesIO
import os
import json
import re
import socket
from threading import Thread


try:
    # py3k
    from urllib.request import urlopen
    from http.server import BaseHTTPRequestHandler, HTTPServer    
except ImportError:
    # py2.7
    from urllib2 import urlopen
    from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
    



FILE_CONTENT = 'x' * 100000


class MockServerRequestHandler(BaseHTTPRequestHandler):
    '''local http server serving chunked file on GET'''
    USERS_PATTERN = re.compile(r'/downloads/.*')
    CHUNK_SIZE = 1024

    def do_GET(self):
        if re.search(self.USERS_PATTERN, self.path):
            # Add response status code.
            self.send_response(200)

            # Add response headers.
            self.send_header('Content-Type', 'application/text;')
            self.send_header('Transfer-Encoding', 'chunked')
            self.send_header('Connection', 'close')
            self.end_headers()

            # Add response content.
            stream = BytesIO(FILE_CONTENT.encode('utf-8'))
            # self.wfile.write(FILE_CONTENT) # nonchunked
            while True:
                data = stream.read(self.CHUNK_SIZE)
                self.wfile.write(b"%X\r\n%s\r\n" % (len(data), data))
                
                # If there's no more data to read, stop streaming
                if not data:
                    break

            # Ensure any buffered output has been transmitted and close the stream
            self.wfile.flush()
            return
        else:
            self.send_response(404)
            self.end_headers()

def get_free_port():
    s = socket.socket(socket.AF_INET, type=socket.SOCK_STREAM)
    s.bind(('localhost', 0))
    address, port = s.getsockname()
    s.close()
    return port


def start_mock_server(port):
    mock_server = HTTPServer(('localhost', port), MockServerRequestHandler)
    mock_server_thread = Thread(target=mock_server.serve_forever)
    mock_server_thread.setDaemon(True)
    mock_server_thread.start()


if __name__ == "__main__":
    mock_server_port = get_free_port()
    start_mock_server(mock_server_port)

    resp = urlopen('http://localhost:{port}/downloads/1.0.tar.gz'.format(port=mock_server_port))
    fdesc, fname = tempfile.mkstemp()
    fhand = os.fdopen(fdesc, "wb")
    shutil.copyfileobj(resp.fp, fhand)
    fhand.close()
    with open(fname, 'r') as rfh:
        data = rfh.read();
    assert data == FILE_CONTENT, '%s, %s'%(len(FILE_CONTENT), len(data))