/*
 * Copyright (c) 2024 Trackunit Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/kernel.h>
#include <zephyr/shell/shell.h>
#include <zephyr/modem/chat.h>
#include <zephyr/modem/pipelink.h>
#include <zephyr/sys/atomic.h>

#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(modem_at_shell, CONFIG_MODEM_LOG_LEVEL);

#define AT_SHELL_MODEM_NODE DT_ALIAS(modem)
#define AT_SHELL_PIPELINK_NAME _CONCAT(user_pipe_, CONFIG_MODEM_AT_SHELL_USER_PIPE)

#define AT_SHELL_STATE_ATTACHED_BIT       0
#define AT_SHELL_STATE_SCRIPT_RUNNING_BIT 1

MODEM_PIPELINK_DT_DECLARE(AT_SHELL_MODEM_NODE, AT_SHELL_PIPELINK_NAME);

static struct modem_pipelink *at_shell_pipelink =
	MODEM_PIPELINK_DT_GET(AT_SHELL_MODEM_NODE, AT_SHELL_PIPELINK_NAME);

static struct modem_chat at_shell_chat;
static uint8_t at_shell_chat_receive_buf[CONFIG_MODEM_AT_SHELL_CHAT_RECEIVE_BUF_SIZE];
static uint8_t *at_shell_chat_argv_buf[2];
static uint8_t at_shell_request_buf[CONFIG_MODEM_AT_SHELL_COMMAND_MAX_SIZE];
static struct modem_chat_script_chat at_shell_script_chat[1];
static struct modem_chat_match at_shell_script_chat_matches[2];
static uint8_t at_shell_match_buf[CONFIG_MODEM_AT_SHELL_RESPONSE_MAX_SIZE];
static const struct shell *at_shell_active_shell;
static struct k_work at_shell_open_pipe_work;
static struct k_work at_shell_attach_chat_work;
static struct k_work at_shell_release_chat_work;
static atomic_t at_shell_state;

static void at_shell_print_any_match(struct modem_chat *chat, char **argv, uint16_t argc,
				     void *user_data)
{
	if (at_shell_active_shell == NULL) {
		return;
	}

	if (argc != 2) {
		return;
	}

	shell_print(at_shell_active_shell, "%s", argv[1]);
}

static void at_shell_print_match(struct modem_chat *chat, char **argv, uint16_t argc,
				 void *user_data)
{
	if (at_shell_active_shell == NULL) {
		return;
	}

	if (argc != 1) {
		return;
	}

	shell_print(at_shell_active_shell, "%s", argv[0]);
}

MODEM_CHAT_MATCHES_DEFINE(
	at_shell_abort_matches,
	MODEM_CHAT_MATCH("ERROR", "", at_shell_print_match),
);

static void at_shell_script_callback(struct modem_chat *chat,
				     enum modem_chat_script_result result,
				     void *user_data)
{
	atomic_clear_bit(&at_shell_state, AT_SHELL_STATE_SCRIPT_RUNNING_BIT);
}

MODEM_CHAT_SCRIPT_DEFINE(
	at_shell_script,
	at_shell_script_chat,
	at_shell_abort_matches,
	at_shell_script_callback,
	CONFIG_MODEM_AT_SHELL_RESPONSE_TIMEOUT_S
);

static void at_shell_pipe_callback(struct modem_pipe *pipe,
				   enum modem_pipe_event event,
				   void *user_data)
{
	ARG_UNUSED(user_data);

	switch (event) {
	case MODEM_PIPE_EVENT_OPENED:
		LOG_INF("pipe opened");
		k_work_submit(&at_shell_attach_chat_work);
		break;

	default:
		break;
	}
}

void at_shell_pipelink_callback(struct modem_pipelink *link,
				enum modem_pipelink_event event,
				void *user_data)
{
	ARG_UNUSED(user_data);

	switch (event) {
	case MODEM_PIPELINK_EVENT_CONNECTED:
		LOG_INF("pipe connected");
		k_work_submit(&at_shell_open_pipe_work);
		break;

	case MODEM_PIPELINK_EVENT_DISCONNECTED:
		LOG_INF("pipe disconnected");
		k_work_submit(&at_shell_release_chat_work);
		break;

	default:
		break;
	}
}

static void at_shell_open_pipe_handler(struct k_work *work)
{
	ARG_UNUSED(work);

	LOG_INF("opening pipe");

	modem_pipe_attach(modem_pipelink_get_pipe(at_shell_pipelink),
			  at_shell_pipe_callback,
			  NULL);

	modem_pipe_open_async(modem_pipelink_get_pipe(at_shell_pipelink));
}

static void at_shell_attach_chat_handler(struct k_work *work)
{
	ARG_UNUSED(work);

	modem_chat_attach(&at_shell_chat, modem_pipelink_get_pipe(at_shell_pipelink));
	atomic_set_bit(&at_shell_state, AT_SHELL_STATE_ATTACHED_BIT);
	LOG_INF("chat attached");
}

static void at_shell_release_chat_handler(struct k_work *work)
{
	ARG_UNUSED(work);

	modem_chat_release(&at_shell_chat);
	atomic_clear_bit(&at_shell_state, AT_SHELL_STATE_ATTACHED_BIT);
	LOG_INF("chat released");
}

static void at_shell_init_work(void)
{
	k_work_init(&at_shell_open_pipe_work, at_shell_open_pipe_handler);
	k_work_init(&at_shell_attach_chat_work, at_shell_attach_chat_handler);
	k_work_init(&at_shell_release_chat_work, at_shell_release_chat_handler);
}

static void at_shell_init_chat(void)
{
	const struct modem_chat_config at_shell_chat_config = {
		.receive_buf = at_shell_chat_receive_buf,
		.receive_buf_size = sizeof(at_shell_chat_receive_buf),
		.delimiter = "\r",
		.delimiter_size = sizeof("\r") - 1,
		.filter = "\n",
		.filter_size = sizeof("\n") - 1,
		.argv = at_shell_chat_argv_buf,
		.argv_size = ARRAY_SIZE(at_shell_chat_argv_buf),
	};

	modem_chat_init(&at_shell_chat, &at_shell_chat_config);
}

static void at_shell_init_script_chat(void)
{
	/* Match anything except the expected response without progressing script */
	modem_chat_match_init(&at_shell_script_chat_matches[0]);
	modem_chat_match_set_match(&at_shell_script_chat_matches[0], "");
	modem_chat_match_set_separators(&at_shell_script_chat_matches[0], "");
	modem_chat_match_set_callback(&at_shell_script_chat_matches[0], at_shell_print_any_match);
	modem_chat_match_set_partial(&at_shell_script_chat_matches[0], true);
	modem_chat_match_enable_wildcards(&at_shell_script_chat_matches[0], false);

	/* Match the expected response and terminate script */
	modem_chat_match_init(&at_shell_script_chat_matches[1]);
	modem_chat_match_set_match(&at_shell_script_chat_matches[1], "");
	modem_chat_match_set_separators(&at_shell_script_chat_matches[1], "");
	modem_chat_match_set_callback(&at_shell_script_chat_matches[1], at_shell_print_match);
	modem_chat_match_set_partial(&at_shell_script_chat_matches[1], false);
	modem_chat_match_enable_wildcards(&at_shell_script_chat_matches[1], false);

	modem_chat_script_chat_init(at_shell_script_chat);
	modem_chat_script_chat_set_response_matches(at_shell_script_chat,
						    at_shell_script_chat_matches,
						    ARRAY_SIZE(at_shell_script_chat_matches));
	modem_chat_script_chat_set_timeout(at_shell_script_chat,
					   CONFIG_MODEM_AT_SHELL_RESPONSE_TIMEOUT_S);
}

static void at_shell_init_pipelink(void)
{
	modem_pipelink_attach(at_shell_pipelink, at_shell_pipelink_callback, NULL);
}

static int at_shell_init(void)
{
	at_shell_init_work();
	at_shell_init_chat();
	at_shell_init_script_chat();
	at_shell_init_pipelink();
	return 0;
}

SYS_INIT(at_shell_init, POST_KERNEL, 99);

static int at_shell_cmd_handler(const struct shell *sh, size_t argc, char **argv)
{
	int ret;

	if (argc < 2) {
		return -EINVAL;
	}

	if (!atomic_test_bit(&at_shell_state, AT_SHELL_STATE_ATTACHED_BIT)) {
		shell_error(sh, "modem is not ready");
		return -EPERM;
	}

	if (atomic_test_and_set_bit(&at_shell_state, AT_SHELL_STATE_SCRIPT_RUNNING_BIT)) {
		shell_error(sh, "script is already running");
		return -EBUSY;
	}

	strncpy(at_shell_request_buf, argv[1], sizeof(at_shell_request_buf) - 1);
	ret = modem_chat_script_chat_set_request(at_shell_script_chat, at_shell_request_buf);
	if (ret < 0) {
		return -EINVAL;
	}

	if (argc == 3) {
		strncpy(at_shell_match_buf, argv[2], sizeof(at_shell_match_buf) - 1);
	} else {
		strncpy(at_shell_match_buf, "OK", sizeof(at_shell_match_buf) - 1);
	}

	ret = modem_chat_match_set_match(&at_shell_script_chat_matches[1], at_shell_match_buf);
	if (ret < 0) {
		return -EINVAL;
	}

	at_shell_active_shell = sh;

	ret = modem_chat_run_script_async(&at_shell_chat, &at_shell_script);
	if (ret < 0) {
		shell_error(sh, "failed to start script");
		atomic_clear_bit(&at_shell_state, AT_SHELL_STATE_SCRIPT_RUNNING_BIT);
	}

	return ret;
}

SHELL_STATIC_SUBCMD_SET_CREATE(modem_sub_cmds,
	SHELL_CMD_ARG(at, NULL, "at <command> <response>", at_shell_cmd_handler, 1, 2),
	SHELL_SUBCMD_SET_END
);

SHELL_CMD_REGISTER(modem, &modem_sub_cmds, "Modem commands", NULL);