/*
 * Copyright (C) 2022, Red Hat Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA  02110-1301, USA.
 *
 * Author: Carlos Garnacho <carlosg@gnome.org>
 */

#include <libsoup/soup.h>

#include "tracker-http-module.h"

GType
tracker_http_client_get_type (void)
{
	return g_type_from_name ("TrackerHttpClient");
}

GType
tracker_http_server_get_type (void)
{
	return g_type_from_name ("TrackerHttpServer");
}

static const gchar *mimetypes[] = {
	"application/sparql-results+json",
	"application/sparql-results+xml",
	"text/turtle",
	"application/trig",
	"application/ld+json",
};

G_STATIC_ASSERT (G_N_ELEMENTS (mimetypes) == TRACKER_N_SERIALIZER_FORMATS);

#define USER_AGENT "Tracker " PACKAGE_VERSION " (https://gitlab.gnome.org/GNOME/tracker/issues/)"

/* Server */
struct _TrackerHttpRequest
{
	TrackerHttpServer *server;
#if SOUP_CHECK_VERSION (2, 99, 2)
        SoupServerMessage *message;
#else
	SoupMessage *message;
#endif
	GTask *task;
	GInputStream *istream;
};

struct _TrackerHttpServerSoup
{
	TrackerHttpServer parent_instance;
	SoupServer *server;
	GCancellable *cancellable;
};

static void tracker_http_server_soup_initable_iface_init (GInitableIface *iface);

G_DEFINE_TYPE_WITH_CODE (TrackerHttpServerSoup,
                         tracker_http_server_soup,
                         TRACKER_TYPE_HTTP_SERVER,
                         G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
                                                tracker_http_server_soup_initable_iface_init))


static guint
get_supported_formats (TrackerHttpRequest *request)
{
	SoupMessageHeaders *request_headers;
	TrackerSerializerFormat i;
	guint formats = 0;

#if SOUP_CHECK_VERSION (2, 99, 2)
        request_headers = soup_server_message_get_request_headers (request->message);
#else
        request_headers = request->message->request_headers;
#endif

        for (i = 0; i < TRACKER_N_SERIALIZER_FORMATS; i++) {
	        if (soup_message_headers_header_contains (request_headers, "Accept",
	                                                  mimetypes[i]))
		        formats |= 1 << i;
        }

	return formats;
}

static void
set_message_format (TrackerHttpRequest      *request,
                    TrackerSerializerFormat  format)
{
	SoupMessageHeaders *response_headers;

#if SOUP_CHECK_VERSION (2, 99, 2)
        response_headers = soup_server_message_get_response_headers (request->message);
#else
        response_headers = request->message->response_headers;
#endif
        soup_message_headers_set_content_type (response_headers, mimetypes[format], NULL);
}

#if SOUP_CHECK_VERSION (2, 99, 2)
static void
server_callback (SoupServer        *server,
	         SoupServerMessage *message,
                 const char        *path,
	         GHashTable        *query,
                 gpointer           user_data)
#else
static void
server_callback (SoupServer        *server,
                 SoupMessage       *message,
                 const char        *path,
                 GHashTable        *query,
                 SoupClientContext *client,
                 gpointer           user_data)
#endif
{
	TrackerHttpServer *http_server = user_data;
	GSocketAddress *remote_address;
	TrackerHttpRequest *request;

#if SOUP_CHECK_VERSION (2, 99, 2)
        remote_address = soup_server_message_get_remote_address (message);
#else
	remote_address = soup_client_context_get_remote_address (client);
#endif

	request = g_new0 (TrackerHttpRequest, 1);
	request->server = http_server;
	request->message = message;

#if SOUP_CHECK_VERSION (3, 1, 3)
	soup_server_message_pause (message);
#else
	soup_server_pause_message (server, message);
#endif

	g_signal_emit_by_name (http_server, "request",
	                       remote_address,
	                       path,
	                       query,
	                       get_supported_formats (request),
	                       request);
}

static gboolean
tracker_http_server_initable_init (GInitable     *initable,
                                   GCancellable  *cancellable,
                                   GError       **error)
{
	TrackerHttpServerSoup *server = TRACKER_HTTP_SERVER_SOUP (initable);
	GTlsCertificate *certificate;
	guint port;

	g_object_get (initable,
	              "http-certificate", &certificate,
	              "http-port", &port,
	              NULL);

	server->server =
		soup_server_new ("tls-certificate", certificate,
		                 "server-header", USER_AGENT,
		                 NULL);
	soup_server_add_handler (server->server,
	                         "/sparql",
	                         server_callback,
	                         initable,
	                         NULL);
	g_clear_object (&certificate);

	return soup_server_listen_all (server->server,
	                               port,
	                               0, error);
}

static void
tracker_http_server_soup_initable_iface_init (GInitableIface *iface)
{
	iface->init = tracker_http_server_initable_init;
}

static void
tracker_http_server_soup_error (TrackerHttpServer       *server,
                                TrackerHttpRequest      *request,
                                gint                     code,
                                const gchar             *message)
{
	G_GNUC_UNUSED TrackerHttpServerSoup *server_soup =
		TRACKER_HTTP_SERVER_SOUP (server);

	g_assert (request->server == server);

#if SOUP_CHECK_VERSION (2, 99, 2)
	soup_server_message_set_status (request->message, code, message);
#else
	soup_message_set_status_full (request->message, code, message);
#endif

#if SOUP_CHECK_VERSION (3, 1, 3)
	soup_server_message_unpause (request->message);
#else
	soup_server_unpause_message (server_soup->server, request->message);
#endif
	g_free (request);
}

static void
handle_write_in_thread (GTask        *task,
                        gpointer      source_object,
                        gpointer      task_data,
                        GCancellable *cancellable)
{
	TrackerHttpRequest *request = task_data;
	gchar buffer[1000];
	SoupMessageBody *message_body;
	GError *error = NULL;
	gssize count;

#if SOUP_CHECK_VERSION (2, 99, 2)
        message_body = soup_server_message_get_response_body (request->message);
#else
        message_body = request->message->response_body;
#endif

	for (;;) {
		count = g_input_stream_read (request->istream,
		                             buffer, sizeof (buffer),
		                             cancellable, &error);
		if (count < 0) {
			g_task_return_error (task, error);
			g_object_unref (task);
			break;
		}

		soup_message_body_append (message_body,
		                          SOUP_MEMORY_COPY,
		                          buffer, count);

		if ((gsize) count < sizeof (buffer)) {
			break;
		}
	}

	g_input_stream_close (request->istream, cancellable, NULL);
	soup_message_body_complete (message_body);
	g_task_return_boolean (task, TRUE);
	g_object_unref (task);
}

static void
write_finished_cb (GObject      *object,
                   GAsyncResult *result,
                   gpointer      user_data)
{
	TrackerHttpRequest *request = user_data;
	G_GNUC_UNUSED TrackerHttpServerSoup *server =
		TRACKER_HTTP_SERVER_SOUP (request->server);
	GError *error = NULL;

	if (!g_task_propagate_boolean (G_TASK (result), &error)) {
		tracker_http_server_soup_error (request->server,
		                                request,
		                                500,
		                                error->message);
		g_clear_error (&error);
	} else {
#if SOUP_CHECK_VERSION (2, 99, 2)
                soup_server_message_set_status (request->message, 200, NULL);
#else
		soup_message_set_status (request->message, 200);
#endif

#if SOUP_CHECK_VERSION (3, 1, 3)
		soup_server_message_unpause (request->message);
#else
		soup_server_unpause_message (server->server, request->message);
#endif

		g_free (request);
	}
}

static void
tracker_http_server_soup_response (TrackerHttpServer       *server,
                                   TrackerHttpRequest      *request,
                                   TrackerSerializerFormat  format,
                                   GInputStream            *content)
{
	TrackerHttpServerSoup *server_soup =
		TRACKER_HTTP_SERVER_SOUP (server);

	g_assert (request->server == server);

	set_message_format (request, format);

	request->istream = content;
	request->task = g_task_new (server, server_soup->cancellable,
	                            write_finished_cb, request);

	g_task_set_task_data (request->task, request, NULL);
	g_task_run_in_thread (request->task, handle_write_in_thread);
}

static void
tracker_http_server_soup_finalize (GObject *object)
{
	TrackerHttpServerSoup *server =
		TRACKER_HTTP_SERVER_SOUP (object);

	g_cancellable_cancel (server->cancellable);
	g_object_unref (server->cancellable);

	g_clear_object (&server->server);

	G_OBJECT_CLASS (tracker_http_server_soup_parent_class)->finalize (object);
}

static void
tracker_http_server_soup_class_init (TrackerHttpServerSoupClass *klass)
{
	TrackerHttpServerClass *server_class = TRACKER_HTTP_SERVER_CLASS (klass);
	GObjectClass *object_class = G_OBJECT_CLASS (klass);

	object_class->finalize = tracker_http_server_soup_finalize;

	server_class->response = tracker_http_server_soup_response;
	server_class->error = tracker_http_server_soup_error;
}

static void
tracker_http_server_soup_init (TrackerHttpServerSoup *server)
{
	server->cancellable = g_cancellable_new ();
}

/* Client */
struct _TrackerHttpClientSoup
{
	TrackerHttpClient parent_instance;
	SoupSession *session;
};

G_DEFINE_TYPE (TrackerHttpClientSoup, tracker_http_client_soup,
               TRACKER_TYPE_HTTP_CLIENT)

static gboolean
get_content_type_format (SoupMessage              *message,
                         TrackerSerializerFormat  *format,
                         GError                  **error)
{
	SoupMessageHeaders *response_headers;
	gint status_code;
	const gchar *content_type;
	TrackerSerializerFormat i;

#if SOUP_CHECK_VERSION (2, 99, 2)
	status_code = soup_message_get_status (message);
	response_headers = soup_message_get_response_headers (message);
#else
	status_code = message->status_code;
	response_headers = message->response_headers;
#endif

	if (status_code != SOUP_STATUS_OK) {
		g_set_error (error,
		             G_IO_ERROR,
		             G_IO_ERROR_FAILED,
		             "Unhandled status code %d",
		             status_code);
		return FALSE;
	}

	content_type = soup_message_headers_get_content_type (response_headers, NULL);

	for (i = 0; i < TRACKER_N_SERIALIZER_FORMATS; i++) {
		if (g_strcmp0 (content_type, mimetypes[i]) == 0) {
			*format = i;
			return TRUE;
		}
	}

	g_set_error (error,
	             G_IO_ERROR,
	             G_IO_ERROR_FAILED,
	             "Unhandled content type '%s'",
	             soup_message_headers_get_content_type (response_headers, NULL));
	return FALSE;
}

static void
send_message_cb (GObject      *source,
                 GAsyncResult *res,
                 gpointer      user_data)
{
	GTask *task = user_data;
	GInputStream *stream;
	GError *error = NULL;
	SoupMessage *message;

	stream = soup_session_send_finish (SOUP_SESSION (source), res, &error);
	message = g_task_get_task_data (task);

	if (stream) {
		TrackerSerializerFormat format;

		if (!get_content_type_format (message, &format, &error)) {
			g_task_return_error (task, error);
		} else {
			g_task_set_task_data (task, GUINT_TO_POINTER (format), NULL);
			g_task_return_pointer (task, stream, g_object_unref);
		}
	} else {
		g_task_return_error (task, error);
	}

	g_object_unref (task);
}

static void
add_accepted_formats (SoupMessageHeaders *headers,
                      guint               formats)
{
	TrackerSerializerFormat i;

	for (i = 0; i < TRACKER_N_SERIALIZER_FORMATS; i++) {
		if ((formats & (1 << i)) == 0)
			continue;

		soup_message_headers_append (headers, "Accept", mimetypes[i]);
	}
}

static SoupMessage *
create_message (const gchar *uri,
                const gchar *query,
                guint        formats)
{
	SoupMessage *message;
	SoupMessageHeaders *headers;
	gchar *full_uri, *query_escaped;

	query_escaped = g_uri_escape_string (query, NULL, FALSE);
	full_uri = g_strconcat (uri, "?query=", query_escaped, NULL);
	g_free (query_escaped);

	message = soup_message_new ("GET", full_uri);
	g_free (full_uri);

#if SOUP_CHECK_VERSION (2, 99, 2)
	headers = soup_message_get_request_headers (message);
#else
	headers = message->request_headers;
#endif

	soup_message_headers_append (headers, "User-Agent", USER_AGENT);
	add_accepted_formats (headers, formats);

	return message;
}

static void
tracker_http_client_soup_send_message_async (TrackerHttpClient   *client,
                                             const gchar         *uri,
                                             const gchar         *query,
                                             guint                formats,
                                             GCancellable        *cancellable,
                                             GAsyncReadyCallback  callback,
                                             gpointer             user_data)
{
	TrackerHttpClientSoup *client_soup = TRACKER_HTTP_CLIENT_SOUP (client);
	SoupMessage *message;
	GTask *task;

	task = g_task_new (client, cancellable, callback, user_data);

	message = create_message (uri, query, formats);
	g_task_set_task_data (task, message, g_object_unref);

#if SOUP_CHECK_VERSION (2, 99, 2)
	soup_session_send_async (client_soup->session,
	                         message,
	                         G_PRIORITY_DEFAULT,
	                         cancellable,
	                         send_message_cb,
	                         task);
#else
	soup_session_send_async (client_soup->session,
	                         message,
	                         cancellable,
	                         send_message_cb,
	                         task);
#endif
}

static GInputStream *
tracker_http_client_soup_send_message_finish (TrackerHttpClient        *client,
                                              GAsyncResult             *res,
                                              TrackerSerializerFormat  *format,
                                              GError                  **error)
{
	if (format)
		*format = GPOINTER_TO_UINT (g_task_get_task_data (G_TASK (res)));

	return g_task_propagate_pointer (G_TASK (res), error);
}

static GInputStream *
tracker_http_client_soup_send_message (TrackerHttpClient        *client,
                                       const gchar              *uri,
                                       const gchar              *query,
                                       guint                     formats,
                                       GCancellable             *cancellable,
                                       TrackerSerializerFormat  *format,
                                       GError                  **error)
{
	TrackerHttpClientSoup *client_soup = TRACKER_HTTP_CLIENT_SOUP (client);
	SoupMessage *message;
	GInputStream *stream;

	message = create_message (uri, query, formats);

#if SOUP_CHECK_VERSION (2, 99, 2)
	stream = soup_session_send (client_soup->session,
	                            message,
	                            cancellable,
	                            error);
#else
	stream = soup_session_send (client_soup->session,
	                            message,
	                            cancellable,
	                            error);
#endif
	if (!stream)
		return NULL;

	if (!get_content_type_format (message, format, error)) {
		g_clear_object (&stream);
		return NULL;
	}

	return stream;
}

static void
tracker_http_client_soup_class_init (TrackerHttpClientSoupClass *klass)
{
	TrackerHttpClientClass *client_class =
		TRACKER_HTTP_CLIENT_CLASS (klass);

	client_class->send_message_async = tracker_http_client_soup_send_message_async;
	client_class->send_message_finish = tracker_http_client_soup_send_message_finish;
	client_class->send_message = tracker_http_client_soup_send_message;
}

static void
tracker_http_client_soup_init (TrackerHttpClientSoup *client)
{
	client->session = soup_session_new ();
}

void
initialize_types (GType *client,
                  GType *server)
{
	*client = TRACKER_TYPE_HTTP_CLIENT_SOUP;
	*server = TRACKER_TYPE_HTTP_SERVER_SOUP;
}