import BaseHTTPServer
import errno
import os
import re
import socket
from SocketServer import ThreadingMixIn
import ssl
import sys
import threading
import time
import traceback
import types
import urlparse

import routes as default_routes
from logger import get_logger
from request import Server, Request
from response import Response
from router import Router
from utils import HTTPException


"""HTTP server designed for testing purposes.

The server is designed to provide flexibility in the way that
requests are handled, and to provide control both of exactly
what bytes are put on the wire for the response, and in the
timing of sending those bytes.

The server is based on the stdlib HTTPServer, but with some
notable differences in the way that requests are processed.
Overall processing is handled by a WebTestRequestHandler,
which is a subclass of BaseHTTPRequestHandler. This is responsible
for parsing the incoming request. A RequestRewriter is then
applied and may change the request data if it matches a
supplied rule.

Once the request data had been finalised, Request and Reponse
objects are constructed. These are used by the other parts of the
system to read information about the request and manipulate the
response.

Each request is handled by a particular handler function. The
mapping between Request and the appropriate handler is determined
by a Router. By default handlers are installed to interpret files
under the document root with .py extensions as executable python
files (see handlers.py for the api for such files), .asis files as
bytestreams to be sent literally and all other files to be served
statically.

The handler functions are responsible for either populating the
fields of the response object, which will then be written when the
handler returns, or for directly writing to the output stream.
"""


class RequestRewriter(object):
    def __init__(self, rules):
        """Object for rewriting the request path.

        :param rules: Initial rules to add; a list of three item tuples
                      (method, input_path, output_path), defined as for
                      register()
        """
        self.rules = {}
        for rule in reversed(rules):
            self.register(*rule)
        self.logger = get_logger()

    def register(self, methods, input_path, output_path):
        """Register a rewrite rule.

        :param methods: Set of methods this should match. "*" is a
                        special value indicating that all methods should
                        be matched.

        :param input_path: Path to match for the initial request.

        :param output_path: Path to replace the input path with in
                            the request.
        """
        if type(methods) in types.StringTypes:
            methods = [methods]
        self.rules[input_path] = (methods, output_path)

    def rewrite(self, request_handler):
        """Rewrite the path in a BaseHTTPRequestHandler instance, if
           it matches a rule.

        :param request_handler: BaseHTTPRequestHandler for which to
                                rewrite the request.
        """
        split_url = urlparse.urlsplit(request_handler.path)
        if split_url.path in self.rules:
            methods, destination = self.rules[split_url.path]
            if "*" in methods or request_handler.command in methods:
                self.logger.debug("Rewriting request path %s to %s" %
                             (request_handler.path, destination))
                new_url = list(split_url)
                new_url[2] = destination
                new_url = urlparse.urlunsplit(new_url)
                request_handler.path = new_url


class WebTestServer(ThreadingMixIn, BaseHTTPServer.HTTPServer):
    allow_reuse_address = True
    acceptable_errors = (errno.EPIPE, errno.ECONNABORTED)
    request_queue_size = 2000

    # Ensure that we don't hang on shutdown waiting for requests
    daemon_threads = True

    def __init__(self, server_address, RequestHandlerClass, router, rewriter, bind_hostname,
                 config=None, use_ssl=False, key_file=None, certificate=None,
                 encrypt_after_connect=False, latency=None, **kwargs):
        """Server for HTTP(s) Requests

        :param server_address: tuple of (server_name, port)

        :param RequestHandlerClass: BaseHTTPRequestHandler-like class to use for
                                    handling requests.

        :param router: Router instance to use for matching requests to handler
                       functions

        :param rewriter: RequestRewriter-like instance to use for preprocessing
                         requests before they are routed

        :param config: Dictionary holding environment configuration settings for
                       handlers to read, or None to use the default values.

        :param use_ssl: Boolean indicating whether the server should use SSL

        :param key_file: Path to key file to use if SSL is enabled.

        :param certificate: Path to certificate to use if SSL is enabled.

        :param encrypt_after_connect: For each connection, don't start encryption
                                      until a CONNECT message has been received.
                                      This enables the server to act as a
                                      self-proxy.

        :param bind_hostname True to bind the server to both the hostname and
                             port specified in the server_address parameter.
                             False to bind the server only to the port in the
                             server_address parameter, but not to the hostname.
        :param latency: Delay in ms to wait before seving each response, or
                        callable that returns a delay in ms
        """
        self.router = router
        self.rewriter = rewriter

        self.scheme = "https" if use_ssl else "http"
        self.logger = get_logger()

        self.latency = latency

        if bind_hostname:
            hostname_port = server_address
        else:
            hostname_port = ("",server_address[1])

        #super doesn't work here because BaseHTTPServer.HTTPServer is old-style
        BaseHTTPServer.HTTPServer.__init__(self, hostname_port, RequestHandlerClass, **kwargs)

        if config is not None:
            Server.config = config
        else:
            self.logger.debug("Using default configuration")
            Server.config = {"host": server_address[0],
                             "domains": {"": server_address[0]},
                             "ports": {"http": [self.server_address[1]]}}


        self.key_file = key_file
        self.certificate = certificate
        self.encrypt_after_connect = use_ssl and encrypt_after_connect

        if use_ssl and not encrypt_after_connect:
            self.socket = ssl.wrap_socket(self.socket,
                                          keyfile=self.key_file,
                                          certfile=self.certificate,
                                          server_side=True)

    def handle_error(self, request, client_address):
        error = sys.exc_value

        if ((isinstance(error, socket.error) and
             isinstance(error.args, tuple) and
             error.args[0] in self.acceptable_errors)
            or
            (isinstance(error, IOError) and
             error.errno in self.acceptable_errors)):
            pass  # remote hang up before the result is sent
        else:
            self.logger.error(traceback.format_exc())


class WebTestRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
    """RequestHandler for WebTestHttpd"""

    protocol_version = "HTTP/1.1"

    def handle_one_request(self):
        response = None
        self.logger = get_logger()
        try:
            self.close_connection = False
            request_line_is_valid = self.get_request_line()

            if self.close_connection:
                return

            request_is_valid = self.parse_request()
            if not request_is_valid:
                #parse_request() actually sends its own error responses
                return

            self.server.rewriter.rewrite(self)

            request = Request(self)
            response = Response(self, request)

            if request.method == "CONNECT":
                self.handle_connect(response)
                return

            if not request_line_is_valid:
                response.set_error(414)
                response.write()
                return

            self.logger.debug("%s %s" % (request.method, request.request_path))
            handler = self.server.router.get_handler(request)

            if self.server.latency is not None:
                if callable(self.server.latency):
                    latency = self.server.latency()
                else:
                    latency = self.server.latency
                self.logger.warning("Latency enabled. Sleeping %i ms" % latency)
                time.sleep(latency / 1000.)

            if handler is None:
                response.set_error(404)
            else:
                try:
                    handler(request, response)
                except HTTPException as e:
                    response.set_error(e.code, e.message)
                except Exception as e:
                    if e.message:
                        err = [e.message]
                    else:
                        err = []
                    err.append(traceback.format_exc())
                    response.set_error(500, "\n".join(err))
            self.logger.debug("%i %s %s (%s) %i" % (response.status[0],
                                                    request.method,
                                                    request.request_path,
                                                    request.headers.get('Referer'),
                                                    request.raw_input.length))

            if not response.writer.content_written:
                response.write()

            # If we want to remove this in the future, a solution is needed for
            # scripts that produce a non-string iterable of content, since these
            # can't set a Content-Length header. A notable example of this kind of
            # problem is with the trickle pipe i.e. foo.js?pipe=trickle(d1)
            if response.close_connection:
                self.close_connection = True

            if not self.close_connection:
                # Ensure that the whole request has been read from the socket
                request.raw_input.read()

        except socket.timeout, e:
            self.log_error("Request timed out: %r", e)
            self.close_connection = True
            return

        except Exception as e:
            err = traceback.format_exc()
            if response:
                response.set_error(500, err)
                response.write()
            self.logger.error(err)

    def get_request_line(self):
        try:
            self.raw_requestline = self.rfile.readline(65537)
        except socket.error:
            self.close_connection = True
            return False
        if len(self.raw_requestline) > 65536:
            self.requestline = ''
            self.request_version = ''
            self.command = ''
            return False
        if not self.raw_requestline:
            self.close_connection = True
        return True

    def handle_connect(self, response):
        self.logger.debug("Got CONNECT")
        response.status = 200
        response.write()
        if self.server.encrypt_after_connect:
            self.logger.debug("Enabling SSL for connection")
            self.request = ssl.wrap_socket(self.connection,
                                           keyfile=self.server.key_file,
                                           certfile=self.server.certificate,
                                           server_side=True)
            self.setup()
        return


class WebTestHttpd(object):
    """
    :param host: Host from which to serve (default: 127.0.0.1)
    :param port: Port from which to serve (default: 8000)
    :param server_cls: Class to use for the server (default depends on ssl vs non-ssl)
    :param handler_cls: Class to use for the RequestHandler
    :param use_ssl: Use a SSL server if no explicit server_cls is supplied
    :param key_file: Path to key file to use if ssl is enabled
    :param certificate: Path to certificate file to use if ssl is enabled
    :param encrypt_after_connect: For each connection, don't start encryption
                                  until a CONNECT message has been received.
                                  This enables the server to act as a
                                  self-proxy.
    :param router_cls: Router class to use when matching URLs to handlers
    :param doc_root: Document root for serving files
    :param routes: List of routes with which to initialize the router
    :param rewriter_cls: Class to use for request rewriter
    :param rewrites: List of rewrites with which to initialize the rewriter_cls
    :param config: Dictionary holding environment configuration settings for
                   handlers to read, or None to use the default values.
    :param bind_hostname: Boolean indicating whether to bind server to hostname.
    :param latency: Delay in ms to wait before seving each response, or
                    callable that returns a delay in ms

    HTTP server designed for testing scenarios.

    Takes a router class which provides one method get_handler which takes a Request
    and returns a handler function.

    .. attribute:: host

      The host name or ip address of the server

    .. attribute:: port

      The port on which the server is running

    .. attribute:: router

      The Router object used to associate requests with resources for this server

    .. attribute:: rewriter

      The Rewriter object used for URL rewriting

    .. attribute:: use_ssl

      Boolean indicating whether the server is using ssl

    .. attribute:: started

      Boolean indictaing whether the server is running

    """
    def __init__(self, host="127.0.0.1", port=8000,
                 server_cls=None, handler_cls=WebTestRequestHandler,
                 use_ssl=False, key_file=None, certificate=None, encrypt_after_connect=False,
                 router_cls=Router, doc_root=os.curdir, routes=None,
                 rewriter_cls=RequestRewriter, bind_hostname=True, rewrites=None,
                 latency=None, config=None):

        if routes is None:
            routes = default_routes.routes

        self.host = host

        self.router = router_cls(doc_root, routes)
        self.rewriter = rewriter_cls(rewrites if rewrites is not None else [])

        self.use_ssl = use_ssl
        self.logger = get_logger()

        if server_cls is None:
            server_cls = WebTestServer

        if use_ssl:
            if key_file is not None:
                assert os.path.exists(key_file)
            assert certificate is not None and os.path.exists(certificate)

        try:
            self.httpd = server_cls((host, port),
                                    handler_cls,
                                    self.router,
                                    self.rewriter,
                                    config=config,
                                    bind_hostname=bind_hostname,
                                    use_ssl=use_ssl,
                                    key_file=key_file,
                                    certificate=certificate,
                                    encrypt_after_connect=encrypt_after_connect,
                                    latency=latency)
            self.started = False

            _host, self.port = self.httpd.socket.getsockname()
        except Exception:
            self.logger.error('Init failed! You may need to modify your hosts file. Refer to README.md.');
            raise

    def start(self, block=False):
        """Start the server.

        :param block: True to run the server on the current thread, blocking,
                      False to run on a separate thread."""
        self.logger.info("Starting http server on %s:%s" % (self.host, self.port))
        self.started = True
        if block:
            self.httpd.serve_forever()
        else:
            self.server_thread = threading.Thread(target=self.httpd.serve_forever)
            self.server_thread.setDaemon(True)  # don't hang on exit
            self.server_thread.start()

    def stop(self):
        """
        Stops the server.

        If the server is not running, this method has no effect.
        """
        if self.started:
            try:
                self.httpd.shutdown()
                self.httpd.server_close()
                self.server_thread.join()
                self.server_thread = None
                self.logger.info("Stopped http server on %s:%s" % (self.host, self.port))
            except AttributeError:
                pass
            self.started = False
        self.httpd = None

    def get_url(self, path="/", query=None, fragment=None):
        if not self.started:
            return None

        return urlparse.urlunsplit(("http" if not self.use_ssl else "https",
                                    "%s:%s" % (self.host, self.port),
                                    path, query, fragment))
