#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <unistd.h>

#include "serial.h"
#include "simulation.h"

static int serial_fd;
static bool serial_initialised = false;

void serial_init(void)
{
	struct termios options;

	// hack to get argv and argc
	extern char ** environ;
	int argc = 1;
        char **argv = environ - 3;

        while((int)*argv != argc)
        {
                ++argc;
                --argv;
        }
	argv++;

	sim_assert(argc >= 2, "please specify a serial port device name");

	sim_info("opening serial port %s", argv[1]);
	serial_fd = open(argv[1], O_RDWR | O_NOCTTY | O_NDELAY);
	sim_assert(serial_fd != -1, "couldn't open serial port");
	sim_assert(isatty(serial_fd), "not a TTY");

	sim_info("configuring port");
	// Get the current options for the port
	if (tcgetattr(serial_fd, &options) != 0)
	{
		sim_error("tcgetattr");
	}

	// Set the baud rates
	cfsetispeed(&options, B115200);
	cfsetospeed(&options, B115200);

	// Enable the receiver and set local mode
	options.c_cflag |= (CLOCAL | CREAD);

	options.c_cflag &= ~PARENB;
	options.c_cflag &= ~CSTOPB;
	options.c_cflag &= ~CSIZE;
	options.c_cflag |= CS8;

	// Set the new options for the port
	if (tcsetattr(serial_fd, TCSANOW, &options) != 0)
	{
		sim_error("tcsetattr");
	}

	// flush tx and rx buffers
	tcflush(serial_fd, TCIOFLUSH);

	serial_initialised = true;
}

// return number of characters in the receive buffer
uint8_t serial_rxchars(void)
{
	int rx_chars_nb;
	sim_assert(serial_initialised, "serial interface not initialised");
	ioctl(serial_fd, FIONREAD, &rx_chars_nb);
	return rx_chars_nb;
}

// read one character
uint8_t serial_popchar(void)
{
	uint8_t c;
	ssize_t count;

	sim_assert(serial_initialised, "serial interface not initialised");
	sim_assert(serial_rxchars() > 0, "no chars to read");
	count = read(serial_fd, &c, 1);
	sim_assert(count == 1, "no character in serial RX buffer");
	return c;
}

// send one character
void serial_writechar(uint8_t data)
{
	ssize_t count;
	sim_assert(serial_initialised, "serial interface not initialised");
	putchar(data);
	count = write(serial_fd, &data, 1);
	sim_assert(count == 1, "could not write to serial port");
}

// read/write many characters
void serial_writestr(uint8_t *data)
{
	ssize_t count;
	const char *str = (char *)data;
	sim_assert(serial_initialised, "serial interface not initialised");
	puts(str);
	count = write(serial_fd, str, strlen(str));
	sim_assert(count == strlen(str), "could not write to serial port");
}

// write from flash
void serial_writestr_P(PGM_P data)
{
	serial_writestr((uint8_t *)data);
}