/*
 * Copyright © 2020 Red Hat, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include "config.h"

#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

#include "util-bits.h"
#include "util-io.h"
#include "util-logger.h"
#include "util-macros.h"
#include "util-mem.h"
#include "util-sources.h"
#include "util-strings.h"

#include "libeis-private.h"

/* The message type for the wire format */
enum message_type {
	MESSAGE_CONNECT,
	MESSAGE_DISCONNECT,
	MESSAGE_ADD_DEVICE,
	MESSAGE_REMOVE_DEVICE,
	MESSAGE_POINTER_REL,
};

struct message {
	enum message_type type;
	union {
		struct message_connect {
			char *name;
		} connect;
		struct message_disconnect {
			uint8_t pad; /* no data */
		} disconnect;
		struct message_add_device {
			uint32_t deviceid;
			uint32_t capabilities;
		} add_device;
		struct message_remove_device {
			uint32_t deviceid;
		} remove_device;
		struct message_pointer_rel {
			uint32_t deviceid;
			int32_t x;
			int32_t y;
		} pointer_rel;
	};
};

static void
message_free(struct message *msg)
{
	switch (msg->type) {
	case MESSAGE_CONNECT:
		free(msg->connect.name);
		break;
	default:
		break;
	}
	free(msg);
}

DEFINE_TRIVIAL_CLEANUP_FUNC(struct message*, message_free);

static void
eis_client_destroy(struct eis_client *client)
{
	free(client->name);
	source_unref(client->source);
	list_remove(&client->link);
}
OBJECT_DECLARE_CREATE(eis_client);
static
OBJECT_DECLARE_PARENT(eis_client, eis);

_public_
OBJECT_DECLARE_REF(eis_client);

_public_
OBJECT_DECLARE_UNREF(eis_client);

_public_
OBJECT_DECLARE_GETTER(eis_client, name, const char*);

_public_ struct eis*
eis_client_get_context(struct eis_client *client)
{
	return eis_client_parent(client);
}

static int
client_send_hello(struct eis_client *client)
{
	const char buf[] = "hello\n";
	return min(0, xwrite(source_get_fd(client->source), buf, sizeof(buf)));
}

static int
client_send_disconnect(struct eis_client *client)
{
	const char buf[] = "disconnected\n";
	return min(0, xwrite(source_get_fd(client->source), buf, sizeof(buf)));
}

static int
client_send_connect(struct eis_client *client)
{
	const char buf[] = "connected\n";
	return min(0, xwrite(source_get_fd(client->source), buf, sizeof(buf)));
}

static int
client_send_accepted(struct eis_client *client, struct eis_device *device)
{
	char buf[64];

	if (!xsnprintf(buf, sizeof(buf), "accept %d\n", device->id))
		return -ENOMEM;

	return min(0, xwrite(source_get_fd(client->source), buf, strlen(buf)));
}

_public_ void
eis_client_connect(struct eis_client *client)
{
	switch(client->state) {
	case EIS_CLIENT_STATE_CONNECTING:
		break;
	default:
		return;
	}

	int rc = client_send_connect(client);
	if (rc) {
		eis_client_disconnect(client);
	} else {
		client->state = EIS_CLIENT_STATE_CONNECTED;
	}
}

_public_ void
eis_client_disconnect(struct eis_client *client)
{
	switch(client->state) {
	case EIS_CLIENT_STATE_DISCONNECTED:
		/* Client already disconnected? don't bother sending an
		 * event */
		return;
	case EIS_CLIENT_STATE_CONNECTING:
	case EIS_CLIENT_STATE_CONNECTED:
		eis_queue_disconnect_event(client);
		/* fallthrough */
	case EIS_CLIENT_STATE_HELLO:
		client_send_disconnect(client);
		client->state = EIS_CLIENT_STATE_DISCONNECTED;
		source_unref(client->source);
		break;
	}
}

static int
client_new_device(struct eis_client *client,
		  uint32_t id, uint32_t capabilities)
{
	/* Check for duplicate IDs */
	struct eis_device *d;
	list_for_each(d, &client->devices, link) {
		if (d->id == id)
			return -EINVAL;
	}

	if (capabilities == 0 ||
	    capabilities & ~(bit(EIS_DEVICE_CAP_POINTER) |
			     bit(EIS_DEVICE_CAP_POINTER_ABSOLUTE) |
			     bit(EIS_DEVICE_CAP_KEYBOARD) |
			     bit(EIS_DEVICE_CAP_TOUCH)))
		return -EINVAL;

	struct eis_device *device = eis_device_new(client, id, capabilities);
	list_append(&client->devices, &device->link);

	log_debug(eis_client_parent(client), "New device %d caps: %#x\n",
		  id, capabilities);

	eis_queue_added_event(device);

	return 0;
}

static int
client_pointer_rel(struct eis_client *client, uint32_t deviceid,
		   int32_t x, int32_t y)
{
	struct eis_device *device;

	list_for_each(device, &client->devices, link) {
		if (device->id == deviceid) {
			return eis_device_pointer_rel(device, x, y);
		}
	}
	return -EINVAL;
}

static int
client_hello_handle_msg(struct eis_client *client, struct message *msg)
{
	int rc = 0;

	switch (msg->type) {
	case MESSAGE_CONNECT:
		eis_queue_connect_event(client);
		client->name = steal(&msg->connect.name);
		client->state = EIS_CLIENT_STATE_CONNECTING;
		break;
	case MESSAGE_DISCONNECT:
		rc = -ECANCELED;
		break;
	case MESSAGE_ADD_DEVICE:
	case MESSAGE_REMOVE_DEVICE:
	case MESSAGE_POINTER_REL:
		rc = -EPROTO;
		break;
	}

	return rc;
}

static int
client_connecting_handle_msg(struct eis_client *client, const struct message *msg)
{
	int rc = 0;

	switch (msg->type) {
	case MESSAGE_CONNECT:
		rc = -EPROTO;
		break;
	case MESSAGE_DISCONNECT:
		rc = -ECANCELED;
		break;
	case MESSAGE_ADD_DEVICE:
	case MESSAGE_REMOVE_DEVICE:
	case MESSAGE_POINTER_REL:
		rc = -EPROTO;
		break;
	}

	return rc;
}

static int
client_connected_handle_msg(struct eis_client *client,
			    const struct message *msg)
{
	int rc = 0;

	switch (msg->type) {
	case MESSAGE_CONNECT:
		rc = -EPROTO;
		break;
	case MESSAGE_DISCONNECT:
		client->state = EIS_CLIENT_STATE_DISCONNECTED;
		rc = -ECANCELED;
		break;
	case MESSAGE_ADD_DEVICE:
		rc = client_new_device(client, msg->add_device.deviceid,
				       msg->add_device.capabilities);
		break;
	case MESSAGE_REMOVE_DEVICE:
		/* FIXME: remove device */
		break;
	case MESSAGE_POINTER_REL:
		rc = client_pointer_rel(client, msg->pointer_rel.deviceid,
					msg->pointer_rel.x, msg->pointer_rel.y);
		break;
	}
	return rc;
}

static struct message *
client_parse_message(const char *data_in, size_t len)
{
	_cleanup_(message_freep) struct message *msg = xalloc(sizeof(*msg));
	_cleanup_free_ char *data = strstrip(data_in, "\n");
	_cleanup_(strv_freep) char **tokens = strv_from_string(data, " ");

	if (streq(tokens[0], "connect")) {
		if (!tokens[1])
			goto error;

		char *name = tokens[1];
		*msg = (struct message) {
			.type = MESSAGE_CONNECT,
			.connect.name = xstrdup(name),
		};
	} else if (streq(tokens[0], "disconnect")) {
		*msg = (struct message) {
			.type = MESSAGE_DISCONNECT,
		};
	} else if (streq(tokens[0], "add")) {
		if (!tokens[1] || !tokens[2])
			goto error;

		uint32_t deviceid;
		if (!xatou(tokens[1], &deviceid))
			goto error;

		uint32_t capabilities;
		if (!xatou(tokens[2], &capabilities))
			goto error;

		*msg = (struct message) {
			.type = MESSAGE_ADD_DEVICE,
			.add_device.deviceid = deviceid,
			.add_device.capabilities = capabilities,
		};
	} else if (streq(tokens[0], "remove")) {
		if (!tokens[1])
			goto error;

		uint32_t deviceid;
		if (!xatou(tokens[1], &deviceid))
			goto error;

		*msg = (struct message) {
			.type = MESSAGE_REMOVE_DEVICE,
			.add_device.deviceid = deviceid,
		};
	} else if (streq(tokens[0], "rel")) {
		if (!tokens[1] || !tokens[2] || !tokens[3])
			return NULL;

		uint32_t deviceid;
		if (!xatou(tokens[1], &deviceid))
			goto error;

		int x, y;
		if (!xatoi(tokens[2], &x) || !xatoi(tokens[3], &y))
			goto error;

		*msg = (struct message) {
			.type = MESSAGE_POINTER_REL,
			.pointer_rel.deviceid = deviceid,
			.pointer_rel.x = x,
			.pointer_rel.y = y,
		};
	} else {
		goto error;
	}

	return steal(&msg);
error:
	return NULL;
}

static void
client_dispatch(struct source *source, void *data)
{
	struct eis_client *client = data;
	enum eis_client_state old_state = client->state;

	_cleanup_iobuf_ struct iobuf *buf = iobuf_new(64);
	int rc = iobuf_append_from_fd(buf, source_get_fd(source));
	if (rc == -EAGAIN)
		return;
	else if (rc < 0)
		goto error;

	_cleanup_(message_freep) struct message *msg =
		client_parse_message(iobuf_data(buf), iobuf_len(buf));
	if (!msg) {
		rc = -EBADMSG;
		goto error;
	}

	switch (client->state) {
		case EIS_CLIENT_STATE_HELLO:
			rc = client_hello_handle_msg(client, msg);
			break;
		case EIS_CLIENT_STATE_CONNECTING:
			/* Client is waiting for us, shouldn't send anything
			 * but disconnect */
			rc = client_connecting_handle_msg(client, msg);
			break;
		case EIS_CLIENT_STATE_CONNECTED:
			rc = client_connected_handle_msg(client, msg);
			break;
		case EIS_CLIENT_STATE_DISCONNECTED:
			abort();
	}

error:
	if (rc < 0)
		eis_client_disconnect(client);

	static const char *client_states[] = {
		"HELLO",
		"CONNECTING",
		"CONNECTED",
		"DISCONNECTED",
	};
	if (rc)
		log_warn(eis_client_parent(client), "Client error: %s\n",
			 strerror(-rc));
	log_debug(eis_client_parent(client), "Client dispatch: %s -> %s\n",
		  client_states[old_state],
		  client_states[client->state]);

}

struct eis_client *
eis_client_new(struct eis *eis, int fd)
{
	static uint32_t client_id;
	struct eis_client *client = eis_client_create(&eis->object);

	client->id = ++client_id;
	list_init(&client->devices);

	list_append(&eis->clients, &client->link);
	client->source = source_add_autoclose(eis->sink, fd,
					      client_dispatch, client);

	client->state = EIS_CLIENT_STATE_HELLO;
	int rc = client_send_hello(client);
	if (rc != 0)
		client = eis_client_unref(client);

	return client;
}

void
eis_client_connect_device(struct eis_client *client, struct eis_device *device)
{
	client_send_accepted(client, device);
}