/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
 *
 *   Permission is hereby granted, free of charge, to any person
 *   obtaining a copy of this software and associated documentation
 *   files (the "Software"), to deal in the Software without
 *   restriction, including without limitation the rights to use,
 *   copy, modify, merge, publish, distribute, sublicense, and/or
 *   sell copies of the Software, and to permit persons to whom
 *   the Software is furnished to do so, subject to the following
 *   conditions:
 *
 *   The above copyright notice and this permission notice shall
 *   be included in all copies or substantial portions of the Software.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 *   OTHER DEALINGS IN THE SOFTWARE.
 *
 * ----------------------------------------------------------------------- */

/*
 * get_key.c
 *
 * Get a single key, and try to pick apart function key codes.
 * This doesn't decode anywhere close to all possiblities, but
 * hopefully is enough to be useful.
 */

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <sys/times.h>
#include <getkey.h>
#include <libutil.h>

struct keycode {
    int code;
    int seqlen;
    const unsigned char *seq;
};

#define CODE(x,y) { x, (sizeof y)-1, (const unsigned char *)(y) }

static const struct keycode keycodes[] = {
    /* First, the BIOS combined codes */
    CODE(KEY_F1, "\0\x3B"),
    CODE(KEY_F2, "\0\x3C"),
    CODE(KEY_F3, "\0\x3D"),
    CODE(KEY_F4, "\0\x3E"),
    CODE(KEY_F5, "\0\x3F"),
    CODE(KEY_F6, "\0\x40"),
    CODE(KEY_F7, "\0\x41"),
    CODE(KEY_F8, "\0\x42"),
    CODE(KEY_F9, "\0\x43"),
    CODE(KEY_F10, "\0\x44"),
    CODE(KEY_F11, "\0\x85"),
    CODE(KEY_F12, "\0\x86"),

    CODE(KEY_UP, "\0\x48"),
    CODE(KEY_DOWN, "\0\x50"),
    CODE(KEY_LEFT, "\0\x4B"),
    CODE(KEY_RIGHT, "\0\x4D"),
    CODE(KEY_PGUP, "\0\x49"),
    CODE(KEY_PGDN, "\0\x51"),
    CODE(KEY_HOME, "\0\x47"),
    CODE(KEY_END, "\0\x4F"),
    CODE(KEY_INSERT, "\0\x52"),
    CODE(KEY_DELETE, "\0\x53"),

    /* Now, VT/xterm/Linux codes */
    CODE(KEY_F1, "\033[[A"),
    CODE(KEY_F1, "\033OP"),
    CODE(KEY_F2, "\033[[B"),
    CODE(KEY_F2, "\033OQ"),
    CODE(KEY_F3, "\033[[C"),
    CODE(KEY_F3, "\033OR"),
    CODE(KEY_F4, "\033[[D"),
    CODE(KEY_F4, "\033OS"),
    CODE(KEY_F5, "\033[[E"),
    CODE(KEY_F5, "\033[15~"),
    CODE(KEY_F6, "\033[17~"),
    CODE(KEY_F7, "\033[18~"),
    CODE(KEY_F8, "\033[19~"),
    CODE(KEY_F9, "\033[20~"),
    CODE(KEY_F10, "\033[21~"),
    CODE(KEY_F11, "\033[23~"),
    CODE(KEY_F12, "\033[24~"),

    CODE(KEY_UP, "\033[A"),
    CODE(KEY_DOWN, "\033[B"),
    CODE(KEY_LEFT, "\033[D"),
    CODE(KEY_RIGHT, "\033[C"),
    CODE(KEY_PGUP, "\033[5~"),
    CODE(KEY_PGUP, "\033[V"),
    CODE(KEY_PGDN, "\033[6~"),
    CODE(KEY_PGDN, "\033[U"),
    CODE(KEY_HOME, "\033[1~"),
    CODE(KEY_HOME, "\033[H"),
    CODE(KEY_END, "\033[4~"),
    CODE(KEY_END, "\033[F"),
    CODE(KEY_END, "\033OF"),
    CODE(KEY_INSERT, "\033[2~"),
    CODE(KEY_INSERT, "\033[@"),
    CODE(KEY_DELETE, "\033[3~"),
};

#define NCODES ((int)(sizeof keycodes/sizeof(struct keycode)))

#define KEY_TIMEOUT ((CLK_TCK+9)/10)

/*
 * Attempt to decode the key sequence in 'buffer'.
 *
 * On success (the data in 'buffer' matches a key code) put the
 * corresponding key code in 'code' and return 0. Return 1 if 'buffer'
 * partially matches a key code, i.e. we need more data before we can
 * make an unambiguous match. Return -1 if the buffer does not contain
 * a key code.
 */
int get_key_decode(char *buffer, int nc, int *code)
{
    const struct keycode *kc;
    int i, rv;

    rv = -1;
    for (i = 0, kc = keycodes; i < NCODES; i++, kc++) {
	if (nc == kc->seqlen && !memcmp(buffer, kc->seq, nc)) {
	    *code = kc->code;
	    rv = 0;
	    break;
	} else if (nc < kc->seqlen && !memcmp(buffer, kc->seq, nc)) {
	    rv = 1;
	    break;
	}
    }

    return rv;
}

int get_key(FILE * f, clock_t timeout)
{
    char buffer[KEY_MAXLEN];
    int nc, rv;
    int another;
    char ch;
    clock_t start;
    int code;

    /* We typically start in the middle of a clock tick */
    if (timeout)
	timeout++;

    nc = 0;
    start = times(NULL);
    do {
	rv = read(fileno(f), &ch, 1);
	if (rv == 0 || (rv == -1 && errno == EAGAIN)) {
	    clock_t lateness = times(NULL) - start;
	    if (nc && lateness > 1 + KEY_TIMEOUT) {
		if (nc == 1)
		    return (unsigned char)buffer[0];	/* timeout */
		else if (timeout && lateness > timeout)
		    return KEY_NONE;
	    } else if (!nc && timeout && lateness > timeout)
		return KEY_NONE;	/* timeout before sequence */

	    do_idle();

	    another = 1;
	    continue;
	}

	start = times(NULL);

	buffer[nc++] = ch;

	another = 0;
	rv = get_key_decode(buffer, nc, &code);
	if (!rv)
		return code;
	else if (rv == 1)
		another = 1;

    } while (another);

    /* We got an unrecognized sequence; return the first character */
    /* We really should remember this and return subsequent characters later */
    return (unsigned char)buffer[0];
}
