"""
An HTTP server that listens on localhost and returns a variety of responses for
mocking remote servers.
"""
from builtins import str
from builtins import range
from builtins import object
from contextlib import contextmanager
from threading import Thread
from time import sleep
from wsgiref.simple_server import make_server
from future.moves.urllib.request import urlopen
import socket
import os
from functools import reduce


class MockHTTPServer(object):
    """
    Mock HTTP server that can take the place of a remote server for testing
    fetching of remote resources.

    Uses contextmanager to allow easy setup and teardown of the WSGI server in
    a separate thread, eg::

        >>> with MockTestServer().serve() as server_address:
        ...     urlopen(server_address)
        ...

    Subclass this and override __call__ to provide your own WSGI handler function.
    """

    def __call__(self, environ, start_response):
        raise NotImplementedError()

    @contextmanager
    def serve(self, host='localhost', port_range=(8000, 9000)):
        """
        Start an instance of wsgiref.simple_server set up to handle requests in
        a separate daemon thread.
        Return the address of the server eg ('http://localhost:8000').
        This uses context manager to make sure the server is stopped::

            >>> with MockTestServer().serve() as addr:
            ...     print urlopen('%s/?content=hello+world').read()
            ...
            'hello world'
        """
        for port in range(*port_range):
            try:
                server = make_server(host, port, self)
            except socket.error:
                continue
            break
        else:
            raise Exception("Could not bind to a port in range %r" % (port_range,))

        serving = True

        def _serve_until_stopped():
            while serving:
                server.handle_request()

        thread = Thread(target=_serve_until_stopped)
        thread.daemon = True
        thread.start()
        try:
            yield 'http://%s:%d' % (host, port)
        finally:
            serving = False

            # Call the server to make sure the waiting handle_request()
            # call completes. Set a very small timeout as we don't actually need to
            # wait for a response. We don't care about exceptions here either.
            try:
                urlopen("http://%s:%s/" % (host, port), timeout=0.01)
            except Exception:
                pass

    @classmethod
    def get_content(cls, varspec):
        """
        Return the value of the variable at varspec, which must be in the
        format 'package.module:variable'. If variable is callable, it will be
        called and its return value used.
        """
        modpath, var = varspec.split(':')
        mod = reduce(getattr, modpath.split('.')[1:], __import__(modpath))
        var = reduce(getattr, var.split('.'), mod)
        try:
            return var()
        except TypeError:
            return var


class MockEchoTestServer(MockHTTPServer):
    """
    WSGI application that echos back the status, headers and
    content passed via the URL, eg:

        a 500 error response: 'http://localhost/?status=500'

        a 200 OK response, returning the function's docstring:
        'http://localhost/?status=200;content-type=text/plain;content_var
        =ckan.tests.lib.test_package_search:test_wsgi_app.__doc__'

    To specify content, use:

        content=string
        content_var=package.module:variable
    """

    def __call__(self, environ, start_response):

        from http.client import responses
        from webob import Request
        request = Request(environ)
        status = int(request.str_params.get('status', '200'))
        # if 'redirect' in redirect.str_params:
        #     params = dict([(key, value) for param in request.str_params \
        #                    if key != 'redirect'])
        #     redirect_status = int(request.str_params['redirect'])
        #     status = int(request.str_params.get('status', '200'))
        #     resp = make_response(render_template('error.html'), redirect_status)
        #     resp.headers['Location'] = url_for(request.path, params)
        #     return resp
        if 'content_var' in request.str_params:
            content = request.str_params.get('content_var')
            content = self.get_content(content)
        elif 'content_long' in request.str_params:
            content = '*' * 1000001
        else:
            content = request.str_params.get('content', '')
        if 'method' in request.str_params \
                and request.method.lower() != request.str_params['method'].lower():
            content = ''
            status = 405

        if isinstance(content, str):
            raise TypeError("Expected raw byte string for content")

        headers = [
            item
            for item in list(request.str_params.items())
            if item[0] not in ('content', 'status')
        ]
        if 'length' in request.str_params:
            cl = request.str_params.get('length')
            headers += [('Content-Length', cl)]
        elif content and 'no-content-length' not in request.str_params:
            headers += [('Content-Length', bytes(len(content)))]
        start_response(
            '%d %s' % (status, responses[status]),
            headers
        )
        return [content]


class MockTimeoutTestServer(MockHTTPServer):
    """
    Sleeps ``timeout`` seconds before responding. Make sure that your timeout value is
    less than this to check handling timeout conditions.
    """
    def __init__(self, timeout):
        super(MockTimeoutTestServer, self).__init__()
        self.timeout = timeout

    def __call__(self, environ, start_response):
        # Sleep until self.timeout or the parent thread finishes
        sleep(self.timeout)
        start_response('200 OK', [('Content-Type', 'text/plain')])
        return ['xyz']


def get_file_content(data_filename):
    filepath = os.path.join(os.path.dirname(__file__), 'data', data_filename)
    assert os.path.exists(filepath), filepath
    with open(filepath, 'rb') as f:
        return f.read()


class MockWmsServer(MockHTTPServer):
    """Acts like an OGC WMS server (well, one basic call)
    """
    def __init__(self, wms_version='1.3'):
        self.wms_version = wms_version
        super(MockWmsServer, self).__init__()

    def __call__(self, environ, start_response):
        from http.client import responses
        from webob import Request
        request = Request(environ)
        status = int(request.str_params.get('status', '200'))
        headers = {'Content-Type': 'text/plain'}
        # e.g. params ?service=WMS&request=GetCapabilities&version=1.1.1
        if request.str_params.get('service') != 'WMS':
            status = 200
            content = ERROR_WRONG_SERVICE
        elif request.str_params.get('request') != 'GetCapabilities':
            status = 405
            content = '"request" param wrong'
        elif 'version' in request.str_params and \
                request.str_params.get('version') != self.wms_version:
            status = 405
            content = '"version" not compatible - need to be %s' % self.wms_version
        elif self.wms_version == '1.1.1':
            status = 200
            content = get_file_content('wms_getcap_1.1.1.xml')
        elif self.wms_version == '1.3':
            status = 200
            content = get_file_content('wms_getcap_1.3.xml')
        start_response(
            '%d %s' % (status, responses[status]),
            list(headers.items())
        )
        return [content]


class MockWfsServer(MockHTTPServer):
    """Acts like an OGC WFS server (well, one basic call)
    """
    def __init__(self):
        super(MockWfsServer, self).__init__()

    def __call__(self, environ, start_response):
        from http.client import responses
        from webob import Request
        request = Request(environ)
        status = int(request.str_params.get('status', '200'))
        headers = {'Content-Type': 'text/plain'}
        # e.g. params ?service=WFS&request=GetCapabilities
        if request.str_params.get('service') != 'WFS':
            status = 200
            content = ERROR_WRONG_SERVICE
        elif request.str_params.get('request') != 'GetCapabilities':
            status = 405
            content = '"request" param wrong'
        else:
            status = 200
            content = get_file_content('wfs_getcap.xml')
        start_response(
            '%d %s' % (status, responses[status]),
            list(headers.items())
        )
        return [content]


ERROR_WRONG_SERVICE = "<ows:ExceptionReport version='1.1.0' language='en'" \
                      " xmlns:ows='http://www.opengis.net/ows'><ows:Exception exceptionCode='NoApplicableCode'>" \
                      "<ows:ExceptionText>Wrong service type.</ows:ExceptionText></ows:Exception></ows:ExceptionReport>"