/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2013 Matthias Heidbrink <m-sigrok@heidbrink.biz>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <string.h>
#include "protocol.h"

/* Serial communication parameters for Metrahit 1x/2x with 'RS232' adaptor */
#define SERIALCOMM_1X_RS232 "8228/6n1/dtr=1/rts=1/flow=0" /* =8192, closer with divider */
#define SERIALCOMM_2X_RS232 "9600/6n1/dtr=1/rts=1/flow=0"
#define VENDOR_GMC "Gossen Metrawatt"

SR_PRIV struct sr_dev_driver gmc_mh_1x_2x_rs232_driver_info;
static struct sr_dev_driver *di = &gmc_mh_1x_2x_rs232_driver_info;

static const int32_t hwopts[] = {
	SR_CONF_CONN,
	SR_CONF_SERIALCOMM,
};

static const int32_t hwcaps[] = {
	SR_CONF_MULTIMETER,
	SR_CONF_LIMIT_SAMPLES,
	SR_CONF_LIMIT_MSEC,
	SR_CONF_CONTINUOUS,
};

static int init(struct sr_context *sr_ctx)
{
	return std_init(sr_ctx, di, LOG_PREFIX);
}

/**
 * Read single byte from serial port.
 *
 * @retval -1 Timeout or error.
 * @retval other Byte.
 */
static int read_byte(struct sr_serial_dev_inst *serial, gint64 timeout)
{
	uint8_t result = 0;
	int rc = 0;

	for (;;) {
		rc = serial_read(serial, &result, 1);
		if (rc == 1) {
			sr_spew("read: 0x%02x/%d", result, result);
			return result;
		}
		if (g_get_monotonic_time() > timeout)
			return -1;
		g_usleep(2000);
	}
}

/**
 * Try to detect GMC 1x/2x multimeter model in send mode for max. 1 second.
 *
 * @param serial Configured, open serial port.
 *
 * @retval NULL Detection failed.
 * @retval other Model code.
 */
static enum model scan_model_sm(struct sr_serial_dev_inst *serial)
{
	int byte, bytecnt, cnt;
	enum model model;
	gint64 timeout_us;

	model = METRAHIT_NONE;
	timeout_us = g_get_monotonic_time() + 1 * 1000 * 1000;

	/*
	 * Try to find message consisting of device code and several
	 * (at least 4) data bytes.
	 */
	for (bytecnt = 0; bytecnt < 100; bytecnt++) {
		byte = read_byte(serial, timeout_us);
		if ((byte == -1) || (timeout_us < g_get_monotonic_time()))
			break;
		if ((byte & MSGID_MASK) == MSGID_INF) {
			if (!(model = gmc_decode_model_sm(byte & MSGC_MASK)))
				break;
			/* Now expect (at least) 4 data bytes. */
			for (cnt = 0; cnt < 4; cnt++) {
				byte = read_byte(serial, timeout_us);
				if ((byte == -1) ||
					((byte & MSGID_MASK) != MSGID_DATA))
				{
					model = METRAHIT_NONE;
					bytecnt = 100;
					break;
				}
			}
			break;
		}
	}

	return model;
}

/**
 * Scan for Metrahit 1x and Metrahit 2x in send mode using Gossen Metrawatt
 * 'RS232' interface.
 *
 * The older 1x models use 8192 baud and the newer 2x 9600 baud.
 * The DMM usually sends up to about 20 messages per second. However, depending
 * on configuration and measurement mode the intervals can be much larger and
 * then the detection might not work.
 */
static GSList *scan(GSList *options)
{
	struct sr_dev_inst *sdi;
	struct drv_context *drvc;
	struct dev_context *devc;
	struct sr_config *src;
	struct sr_probe *probe;
	struct sr_serial_dev_inst *serial;
	GSList *l, *devices;
	const char *conn, *serialcomm;
	enum model model;
	gboolean serialcomm_given;

	devices = NULL;
	drvc = di->priv;
	drvc->instances = NULL;
	conn = serialcomm = NULL;
	model = METRAHIT_NONE;
	serialcomm_given = FALSE;

	sr_spew("scan() called!");

	for (l = options; l; l = l->next) {
		src = l->data;
		switch (src->key) {
		case SR_CONF_CONN:
			conn = g_variant_get_string(src->data, NULL);
			break;
		case SR_CONF_SERIALCOMM:
			serialcomm = g_variant_get_string(src->data, NULL);
			serialcomm_given = TRUE;
			break;
		}
	}
	if (!conn)
		return NULL;
	if (!serialcomm)
		serialcomm = SERIALCOMM_2X_RS232;

	if (!(serial = sr_serial_dev_inst_new(conn, serialcomm)))
		return NULL;

	if (serial_open(serial, SERIAL_RDWR | SERIAL_NONBLOCK) != SR_OK) {
		sr_serial_dev_inst_free(serial);
		return NULL;
	}

	serial_flush(serial);

	model = scan_model_sm(serial);

	/*
	 * If detection failed and no user-supplied parameters,
	 * try second baud rate.
	 */
	if ((model == METRAHIT_NONE) && !serialcomm_given) {
		serialcomm = SERIALCOMM_1X_RS232;
		g_free(serial->serialcomm);
		serial->serialcomm = g_strdup(serialcomm);
		if (serial_set_paramstr(serial, serialcomm) == SR_OK) {
			serial_flush(serial);
			model = scan_model_sm(serial);
		}
	}

	if (model != METRAHIT_NONE) {
		sr_spew("%s %s detected!", VENDOR_GMC, gmc_model_str(model));
		if (!(sdi = sr_dev_inst_new(0, SR_ST_INACTIVE, VENDOR_GMC,
				gmc_model_str(model), "")))
			return NULL;
		if (!(devc = g_try_malloc0(sizeof(struct dev_context)))) {
			sr_err("Device context malloc failed.");
			return NULL;
		}
		devc->model = model;
		devc->limit_samples = 0;
		devc->limit_msec = 0;
		devc->num_samples = 0;
		devc->elapsed_msec = g_timer_new();
		devc->settings_ok = FALSE;

		sdi->conn = serial;
		sdi->priv = devc;
		sdi->driver = di;
		if (!(probe = sr_probe_new(0, SR_PROBE_ANALOG, TRUE, "P1")))
			return NULL;
		sdi->probes = g_slist_append(sdi->probes, probe);
		drvc->instances = g_slist_append(drvc->instances, sdi);
		devices = g_slist_append(devices, sdi);
	}

	return devices;
}

static GSList *dev_list(void)
{
	return ((struct drv_context *)(di->priv))->instances;
}

static int dev_clear(void)
{
	return std_dev_clear(di, NULL);
}

static int dev_close(struct sr_dev_inst *sdi)
{
	struct dev_context *devc;

	std_serial_dev_close(sdi);

	sdi->status = SR_ST_INACTIVE;

	/* Free dynamically allocated resources. */
	if ((devc = sdi->priv) && devc->elapsed_msec) {
		g_timer_destroy(devc->elapsed_msec);
		devc->elapsed_msec = NULL;
		devc->model = METRAHIT_NONE;
	}

	return SR_OK;
}

static int cleanup(void)
{
	return dev_clear();
}

/** TODO */
static int config_get(int key, GVariant **data, const struct sr_dev_inst *sdi,
		const struct sr_probe_group *probe_group)
{
	int ret;

	(void)sdi;
	(void)data;
	(void)probe_group;

	ret = SR_OK;
	switch (key) {
	/* TODO */
	default:
		return SR_ERR_NA;
	}

	return ret;
}

static int config_set(int key, GVariant *data, const struct sr_dev_inst *sdi,
		const struct sr_probe_group *probe_group)
{
	struct dev_context *devc;

	(void)probe_group;

	if (sdi->status != SR_ST_ACTIVE)
		return SR_ERR_DEV_CLOSED;

	if (!(devc = sdi->priv)) {
		sr_err("sdi->priv was NULL.");
		return SR_ERR_BUG;
	}

	switch (key) {
	case SR_CONF_LIMIT_MSEC:
		if (g_variant_get_uint64(data) == 0) {
			sr_err("LIMIT_MSEC can't be 0.");
			return SR_ERR;
		}
		devc->limit_msec = g_variant_get_uint64(data);
		sr_dbg("Setting time limit to %" PRIu64 "ms.",
		       devc->limit_msec);
		break;
	case SR_CONF_LIMIT_SAMPLES:
		devc->limit_samples = g_variant_get_uint64(data);
		sr_dbg("Setting sample limit to %" PRIu64 ".",
		       devc->limit_samples);
		break;
	default:
		return SR_ERR_NA;
	}

	return SR_OK;
}

static int config_list(int key, GVariant **data, const struct sr_dev_inst *sdi,
		const struct sr_probe_group *probe_group)
{
	(void)sdi;
	(void)probe_group;

	switch (key) {
	case SR_CONF_SCAN_OPTIONS:
		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_INT32,
				hwopts, ARRAY_SIZE(hwopts), sizeof(int32_t));
		break;
	case SR_CONF_DEVICE_OPTIONS:
		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_INT32,
				hwcaps, ARRAY_SIZE(hwcaps), sizeof(int32_t));
		break;
	default:
		return SR_ERR_NA;
	}

	return SR_OK;
}

static int dev_acquisition_start(const struct sr_dev_inst *sdi, void *cb_data)
{
	struct dev_context *devc;
	struct sr_serial_dev_inst *serial;

	if (!sdi || !cb_data || !(devc = sdi->priv))
		return SR_ERR_BUG;

	if (sdi->status != SR_ST_ACTIVE)
		return SR_ERR_DEV_CLOSED;

	devc->cb_data = cb_data;
	devc->settings_ok = FALSE;
	devc->buflen = 0;

	/* Send header packet to the session bus. */
	std_session_send_df_header(cb_data, LOG_PREFIX);

	/* Start timer, if required. */
	if (devc->limit_msec)
		g_timer_start(devc->elapsed_msec);

	/* Poll every 40ms, or whenever some data comes in. */
	serial = sdi->conn;
	serial_source_add(serial, G_IO_IN, 40, gmc_mh_1x_2x_receive_data,
		(void *)sdi);

	return SR_OK;
}

static int dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data)
{
	struct dev_context *devc;

	/* Stop timer, if required. */
	if (sdi && (devc = sdi->priv) && devc->limit_msec)
		g_timer_stop(devc->elapsed_msec);

	return std_serial_dev_acquisition_stop(sdi, cb_data, dev_close,
			sdi->conn, LOG_PREFIX);
}

SR_PRIV struct sr_dev_driver gmc_mh_1x_2x_rs232_driver_info = {
	.name = "gmc-mh-1x-2x-rs232",
	.longname = "Gossen Metrawatt Metrahit 1x/2x, 'RS232' interface",
	.api_version = 1,
	.init = init,
	.cleanup = cleanup,
	.scan = scan,
	.dev_list = dev_list,
	.dev_clear = dev_clear,
	.config_get = config_get,
	.config_set = config_set,
	.config_list = config_list,
	.dev_open = std_serial_dev_open,
	.dev_close = dev_close,
	.dev_acquisition_start = dev_acquisition_start,
	.dev_acquisition_stop = dev_acquisition_stop,
	.priv = NULL,
};