import json


class FalconInterface(object):
    def __init__(self, use_async=False):
        self.use_async = use_async

    def handler(self, doc):

        class Handler(object):
            async def on_get_async(self, req, resp):
                self.on_get(req, resp)

        class SwaggerDocHandler(Handler):
            def on_get(self, req, resp):
                resp.content_type = 'text/html'
                resp.body = doc.doc_html

        class SwaggerEditorHandler(Handler):
            def on_get(self, req, resp):
                resp.content_type = 'text/html'
                resp.body = doc.editor_html

        class SwaggerConfigHandler(Handler):
            def on_get(self, req, resp):
                resp.content_type = 'application/json'
                resp.body = json.dumps(doc.get_config(f'{req.host}:{req.port}'))

        suffix = 'async' if self.use_async else None
        doc.app.add_route(doc.root_uri_absolute(slashes=True),
                          SwaggerDocHandler(), suffix=suffix)
        doc.app.add_route(doc.root_uri_absolute(slashes=False),
                          SwaggerDocHandler(), suffix=suffix)

        if doc.editor:
            doc.app.add_route(doc.editor_uri_absolute(slashes=True),
                              SwaggerEditorHandler(), suffix=suffix)
            doc.app.add_route(doc.editor_uri_absolute(slashes=False),
                              SwaggerEditorHandler(), suffix=suffix)

        if doc.config_rel_url is None:
            doc.app.add_route(doc.swagger_json_uri_absolute, SwaggerConfigHandler(), suffix=suffix)
        doc.app.add_static_route(
            prefix=doc.static_uri_absolute,
            directory='{}/'.format(doc.static_dir),
            downloadable=True,
        )


def match(doc):
    try:
        from distutils.version import StrictVersion

        import falcon

        interface = None
        if StrictVersion(falcon.__version__) >= StrictVersion('3.0.0'):
            import falcon.asgi
            if isinstance(doc.app, falcon.asgi.App):
                interface = FalconInterface(use_async=True)
            elif isinstance(doc.app, falcon.App):
                interface = FalconInterface(use_async=False)
        else:
            if isinstance(doc.app, falcon.API):
                interface = FalconInterface(use_async=False)

        if interface:
            return interface.handler
    except ImportError:
        pass
    return None
