#include "koh_term.h"

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

static struct termios koh_saved;
static int koh_have_saved = 0;

int koh_term_raw(int enable) {
	if (enable) {
		if (!isatty(STDIN_FILENO)) {
			return 0;
		}
		if (tcgetattr(STDIN_FILENO, &koh_saved) != 0) {
			return 0;
		}
		koh_have_saved = 1;
		struct termios raw = koh_saved;
		/* No line buffering, no echo, no flow control, no signal keys: the
		 * view wants the bytes and has to be able to clean up after itself. */
		raw.c_lflag &= (tcflag_t) ~(ICANON | ECHO | ISIG | IEXTEN);
		raw.c_iflag &= (tcflag_t) ~(IXON | ICRNL | BRKINT | INPCK | ISTRIP);
		raw.c_cc[VMIN] = 1;
		raw.c_cc[VTIME] = 0;
		return tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == 0;
	}
	if (koh_have_saved) {
		tcsetattr(STDIN_FILENO, TCSAFLUSH, &koh_saved);
		koh_have_saved = 0;
	}
	return 1;
}

int koh_term_size(int *rows, int *cols) {
	struct winsize size;
	if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &size) == 0 && size.ws_row > 0 && size.ws_col > 0) {
		*rows = (int)size.ws_row;
		*cols = (int)size.ws_col;
		return 1;
	}
	*rows = 24;
	*cols = 80;
	return 0;
}

static int koh_poll_input(int milliseconds) {
	struct pollfd p;
	p.fd = STDIN_FILENO;
	p.events = POLLIN;
	p.revents = 0;
	return poll(&p, 1, milliseconds) > 0;
}

int koh_read_key(char *buf, int cap) {
	if (cap <= 0) {
		return 0;
	}
	ssize_t n = read(STDIN_FILENO, buf, 1);
	if (n <= 0) {
		return 0;
	}
	int total = 1;
	/* An arrow key arrives as ESC [ A, usually in one burst but not always,
	 * so give the rest of the sequence a moment to show up. */
	if (buf[0] == 0x1b) {
		if (koh_poll_input(25)) {
			ssize_t m = read(STDIN_FILENO, buf + 1, (size_t)(cap - 1));
			if (m > 0) {
				total += (int)m;
			}
		}
		return total;
	}
	/* Otherwise deliver exactly one character: the continuation bytes of a
	 * multi-byte character are gathered, but nothing else is. Two keys typed
	 * quickly, or pasted, therefore arrive as two keystrokes rather than one
	 * blob that no single key can be matched against. */
	int remaining = 0;
	unsigned char first = (unsigned char)buf[0];
	if ((first & 0xf8) == 0xf0) {
		remaining = 3;
	} else if ((first & 0xf0) == 0xe0) {
		remaining = 2;
	} else if ((first & 0xe0) == 0xc0) {
		remaining = 1;
	}
	while (remaining > 0 && total < cap) {
		if (!koh_poll_input(10)) {
			break;
		}
		ssize_t m = read(STDIN_FILENO, buf + total, 1);
		if (m <= 0) {
			break;
		}
		total += (int)m;
		remaining--;
	}
	return total;
}