#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "options.h"
#include "baud.h"
#include "debug.h"

/**
 * Read data from a slow device
 *
 * return 1 when a complete NULL terminated line has been read
 *
 * return 0 when a partial line has been read and appended to the
 *		 buffer at @offset
 *
 * return negative on error
 */
static int read_log_line(int infd, char *buf, size_t bufsize, int *offset)
{
	int ret;
	int i;

	ret = read(infd, buf + *offset, bufsize - *offset - 1);
	if (ret < 0) {
		pr_err("read: %m\n");
		return -1;
	}

	if (ret == 0) {
		pr_err("Read EOF, stopping\n");
		return -1;
	}
	buf[*offset + ret] = 0;

	for (i = 0; i < ret; i++) {
		if (buf[i + *offset] == '\n' ||
		    buf[i + *offset] == '\r') {
			/*
			 * Got a complete line when there is a newline
			 * at the end. Remove the newline and possible
			 * other junk, such as '\r'
			 */
			buf[i + *offset] = 0;
			*offset = 0;

			return 1;
		}

		/*
		 * Fixme! Nothing guarantees that there isn't actually
		 * more data (a part of a new log entry perhaps) after
		 * the newline. So in rare cases (we are prevented
		 * from reading the serial line in very long time) we
		 * might lose data from the stream..
		 */
	}

	*offset += ret;
	return 0;
}

static int read_data(int infd, int outfd)
{
	struct epoll_event ev;
	int epoll_fd;
	int ret;
	char buf[256];
	int offset;

	epoll_fd = epoll_create(1);
	if (epoll_fd < 0) {
		pr_err("Failed to create epoll socket: %m\n");
		return -1;
	}

	ev.events = EPOLLIN;
	ev.data.fd = infd;
	if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, infd, &ev) == -1) {
		pr_err("epoll_ctl: %m\n");
		return 1;
	}

	while (1) {
		ret = epoll_wait(epoll_fd, &ev, 1, -1);
		if (ret == 0)
			continue;

		if (ret < 0) {
			pr_err("epoll: %m\n");
			return -1;
		}

		ret = read_log_line(infd, buf, sizeof(buf), &offset);
		if (ret < 0)
			return ret;

		if (ret == 0)
			continue;

		if (outfd) {
			char newline = '\n';
			ret = write(outfd, buf, strlen(buf));
			if (read < 0) {
				pr_err("write: %m\n");
				break;
			}
			ret = write(outfd, &newline, 1);
			if (read < 0) {
				pr_err("write: %m\n");
				break;
			}
		}

		pr_info("%s\n", buf);
	}

	return 0;
}

int main(int argc, char *argv[])
{
	struct plotter_options options;
	int fd, baud, ret = 0, out_fd = 0;

	if (read_args(argc, argv, &options))
		return 1;

	baud = options.baud_rate;
	fd = open_at_baud(options.device_path, &baud);
	if (fd < 0)
		return 1;

	if (baud != options.baud_rate) {
		pr_err("Failed to set baudrate to %d, only got %d\n",
			options.baud_rate, baud);
		ret = 1;
		goto out;
	}

	if (options.output_path) {
		pr_debug("Opening %s for writing the log file\n",
			options.output_path);

		out_fd = open(options.output_path,
			O_CREAT | O_APPEND | O_WRONLY, 0664);
		if (out_fd < 0) {
			pr_err("Failed to open file %s for writing: %m\n",
				options.output_path);
			ret = 1;
			goto out;
		}
	}

	read_data(fd, out_fd);

out:
	close(fd);
	return ret;
}