/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2013 poljar (Damir Jelić) <poljarinho@gmail.com>
 * Copyright (C) 2013 Martin Ling <martin-sigrok@earth.li>
 *
 * 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 "libsigrok.h"
#include "libsigrok-internal.h"

#include <glib.h>
#include <string.h>

#define LOG_PREFIX "scpi_serial"

#define BUFFER_SIZE 1024

struct scpi_serial {
	struct sr_serial_dev_inst *serial;
	char buffer[BUFFER_SIZE];
	size_t count;
	size_t read;
};

static int scpi_serial_dev_inst_new(void *priv, const char *resource,
		char **params, const char *serialcomm)
{
	struct scpi_serial *sscpi = priv;

	(void)params;

	if (!(sscpi->serial = sr_serial_dev_inst_new(resource, serialcomm)))
		return SR_ERR;

	return SR_OK;
}

static int scpi_serial_open(void *priv)
{
	struct scpi_serial *sscpi = priv;
	struct sr_serial_dev_inst *serial = sscpi->serial;

	if (serial_open(serial, SERIAL_RDWR | SERIAL_NONBLOCK) != SR_OK)
		return SR_ERR;

	if (serial_flush(serial) != SR_OK)
		return SR_ERR;

	sscpi->count = 0;
	sscpi->read = 0;

	return SR_OK;
}

static int scpi_serial_source_add(void *priv, int events, int timeout,
			sr_receive_data_callback_t cb, void *cb_data)
{
	struct scpi_serial *sscpi = priv;
	struct sr_serial_dev_inst *serial = sscpi->serial;

	return serial_source_add(serial, events, timeout, cb, cb_data);
}

static int scpi_serial_source_remove(void *priv)
{
	struct scpi_serial *sscpi = priv;
	struct sr_serial_dev_inst *serial = sscpi->serial;

	return serial_source_remove(serial);
}

static int scpi_serial_send(void *priv, const char *command)
{
	int len, result, written;
	gchar *terminated_command;
	struct scpi_serial *sscpi = priv;
	struct sr_serial_dev_inst *serial = sscpi->serial;

	terminated_command = g_strconcat(command, "\n", NULL);
	len = strlen(terminated_command);
	written = 0;
	while (written < len) {
		result = serial_write(serial, terminated_command + written, len - written);
		if (result < 0) {
			sr_err("Error while sending SCPI command: '%s'.", command);
			g_free(terminated_command);
			return SR_ERR;
		}
		written += result;
	}

	g_free(terminated_command);

	sr_spew("Successfully sent SCPI command: '%s'.", command);

	return SR_OK;
}

static int scpi_serial_read_begin(void *priv)
{
	(void) priv;

	return SR_OK;
}

static int scpi_serial_read_data(void *priv, char *buf, int maxlen)
{
	struct scpi_serial *sscpi = priv;
	int len, ret;

	len = BUFFER_SIZE - sscpi->count;

	/* Try to read new data into the buffer if there is space. */
	if (len > 0) {
		ret = serial_read(sscpi->serial, sscpi->buffer + sscpi->read,
				BUFFER_SIZE - sscpi->count);

		if (ret < 0)
			return ret;

		sscpi->count += ret;

		if (ret > 0)
			sr_spew("Read %d bytes into buffer.", ret);
	}

	/* Return as many bytes as possible from buffer, excluding any trailing newline. */
	if (sscpi->read < sscpi->count) {
		len = sscpi->count - sscpi->read;
		if (len > maxlen)
			len = maxlen;
		if (sscpi->buffer[sscpi->read + len - 1] == '\n')
			len--;
		sr_spew("Returning %d bytes from buffer.", len);
		memcpy(buf, sscpi->buffer + sscpi->read, len);
		sscpi->read += len;
		if (sscpi->read == BUFFER_SIZE) {
			sr_spew("Resetting buffer.");
			sscpi->count = 0;
			sscpi->read = 0;
		}
		return len;
	}

	return 0;
}

static int scpi_serial_read_complete(void *priv)
{
	struct scpi_serial *sscpi = priv;

	/* If the next character is a newline, discard it and report complete. */
	if (sscpi->read < sscpi->count && sscpi->buffer[sscpi->read] == '\n') {
		sscpi->read++;
		return 1;
	} else {
		return 0;
	}
}

static int scpi_serial_close(void *priv)
{
	struct scpi_serial *sscpi = priv;

	return serial_close(sscpi->serial);
}

static void scpi_serial_free(void *priv)
{
	struct scpi_serial *sscpi = priv;

	sr_serial_dev_inst_free(sscpi->serial);
}

SR_PRIV const struct sr_scpi_dev_inst scpi_serial_dev = {
	.name          = "serial",
	.prefix        = "",
	.priv_size     = sizeof(struct scpi_serial),
	.dev_inst_new  = scpi_serial_dev_inst_new,
	.open          = scpi_serial_open,
	.source_add    = scpi_serial_source_add,
	.source_remove = scpi_serial_source_remove,
	.send          = scpi_serial_send,
	.read_begin    = scpi_serial_read_begin,
	.read_data     = scpi_serial_read_data,
	.read_complete = scpi_serial_read_complete,
	.close         = scpi_serial_close,
	.free          = scpi_serial_free,
};