/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) 2008 Rob Landley <rob@landley.net>
 * Copyright (C) 2008 Denys Vlasenko <vda.linux@googlemail.com>
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */
#include "libbb.h"

int64_t FAST_FUNC read_key(int fd, char *buffer, int timeout)
{
        struct pollfd pfd;
        const char *seq;
        int n;

        /* Known escape sequences for cursor and function keys */
        static const char esccmds[] ALIGN1 = {
                'O','A'        |0x80,KEYCODE_UP      ,
                'O','B'        |0x80,KEYCODE_DOWN    ,
                'O','C'        |0x80,KEYCODE_RIGHT   ,
                'O','D'        |0x80,KEYCODE_LEFT    ,
                'O','H'        |0x80,KEYCODE_HOME    ,
                'O','F'        |0x80,KEYCODE_END     ,
#if 0
                'O','P'        |0x80,KEYCODE_FUN1    ,
                /* [ESC] ESC O [2] P - [Alt-][Shift-]F1 */
                /* ESC [ O 1 ; 2 P - Shift-F1 */
                /* ESC [ O 1 ; 3 P - Alt-F1 */
                /* ESC [ O 1 ; 4 P - Alt-Shift-F1 */
                /* ESC [ O 1 ; 5 P - Ctrl-F1 */
                /* ESC [ O 1 ; 6 P - Ctrl-Shift-F1 */
                'O','Q'        |0x80,KEYCODE_FUN2    ,
                'O','R'        |0x80,KEYCODE_FUN3    ,
                'O','S'        |0x80,KEYCODE_FUN4    ,
#endif
                '[','A'        |0x80,KEYCODE_UP      ,
                '[','B'        |0x80,KEYCODE_DOWN    ,
                '[','C'        |0x80,KEYCODE_RIGHT   ,
                '[','D'        |0x80,KEYCODE_LEFT    ,
                /* ESC [ 1 ; 2 x, where x = A/B/C/D: Shift-<arrow> */
                /* ESC [ 1 ; 3 x, where x = A/B/C/D: Alt-<arrow> */
                /* ESC [ 1 ; 4 x, where x = A/B/C/D: Alt-Shift-<arrow> */
                /* ESC [ 1 ; 5 x, where x = A/B/C/D: Ctrl-<arrow> - implemented below */
                /* ESC [ 1 ; 6 x, where x = A/B/C/D: Ctrl-Shift-<arrow> */
                '[','H'        |0x80,KEYCODE_HOME    , /* xterm */
                /* [ESC] ESC [ [2] H - [Alt-][Shift-]Home */
                '[','F'        |0x80,KEYCODE_END     , /* xterm */
                '[','1','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
                '[','2','~'    |0x80,KEYCODE_INSERT  ,
                /* ESC [ 2 ; 3 ~ - Alt-Insert */
                '[','3','~'    |0x80,KEYCODE_DELETE  ,
                /* [ESC] ESC [ 3 [;2] ~ - [Alt-][Shift-]Delete */
                /* ESC [ 3 ; 3 ~ - Alt-Delete */
                /* ESC [ 3 ; 5 ~ - Ctrl-Delete */
                '[','4','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
                '[','5','~'    |0x80,KEYCODE_PAGEUP  ,
                /* ESC [ 5 ; 3 ~ - Alt-PgUp */
                /* ESC [ 5 ; 5 ~ - Ctrl-PgUp */
                /* ESC [ 5 ; 7 ~ - Ctrl-Alt-PgUp */
                '[','6','~'    |0x80,KEYCODE_PAGEDOWN,
                '[','7','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
                '[','8','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
#if 0
                '[','1','1','~'|0x80,KEYCODE_FUN1    ,
                '[','1','2','~'|0x80,KEYCODE_FUN2    ,
                '[','1','3','~'|0x80,KEYCODE_FUN3    ,
                '[','1','4','~'|0x80,KEYCODE_FUN4    ,
                '[','1','5','~'|0x80,KEYCODE_FUN5    ,
                /* [ESC] ESC [ 1 5 [;2] ~ - [Alt-][Shift-]F5 */
                '[','1','7','~'|0x80,KEYCODE_FUN6    ,
                '[','1','8','~'|0x80,KEYCODE_FUN7    ,
                '[','1','9','~'|0x80,KEYCODE_FUN8    ,
                '[','2','0','~'|0x80,KEYCODE_FUN9    ,
                '[','2','1','~'|0x80,KEYCODE_FUN10   ,
                '[','2','3','~'|0x80,KEYCODE_FUN11   ,
                '[','2','4','~'|0x80,KEYCODE_FUN12   ,
                /* ESC [ 2 4 ; 2 ~ - Shift-F12 */
                /* ESC [ 2 4 ; 3 ~ - Alt-F12 */
                /* ESC [ 2 4 ; 4 ~ - Alt-Shift-F12 */
                /* ESC [ 2 4 ; 5 ~ - Ctrl-F12 */
                /* ESC [ 2 4 ; 6 ~ - Ctrl-Shift-F12 */
#endif
                /* '[','1',';','5','A' |0x80,KEYCODE_CTRL_UP   , - unused */
                /* '[','1',';','5','B' |0x80,KEYCODE_CTRL_DOWN , - unused */
                '[','1',';','5','C' |0x80,KEYCODE_CTRL_RIGHT,
                '[','1',';','5','D' |0x80,KEYCODE_CTRL_LEFT ,
                0
                /* ESC [ Z - Shift-Tab */
        };

        pfd.fd = fd;
        pfd.events = POLLIN;

        buffer++; /* saved chars counter is in buffer[-1] now */

 start_over:
        errno = 0;
        n = (unsigned char)buffer[-1];
        if (n == 0) {
                /* If no data, wait for input.
                 * If requested, wait TIMEOUT ms. TIMEOUT = -1 is useful
                 * if fd can be in non-blocking mode.
                 */
                if (timeout >= -1) {
                        if (safe_poll(&pfd, 1, timeout) == 0) {
                                /* Timed out */
                                errno = EAGAIN;
                                return -1;
                        }
                }
                /* It is tempting to read more than one byte here,
                 * but it breaks pasting. Example: at shell prompt,
                 * user presses "c","a","t" and then pastes "\nline\n".
                 * When we were reading 3 bytes here, we were eating
                 * "li" too, and cat was getting wrong input.
                 */
                n = safe_read(fd, buffer, 1);
                if (n <= 0)
                        return -1;
        }

        {
                unsigned char c = buffer[0];
                n--;
                if (n)
                        memmove(buffer, buffer + 1, n);
                /* Only ESC starts ESC sequences */
                if (c != 27) {
                        buffer[-1] = n;
                        return c;
                }
        }

        /* Loop through known ESC sequences */
        seq = esccmds;
        while (*seq != '\0') {
                /* n - position in sequence we did not read yet */
                int i = 0; /* position in sequence to compare */

                /* Loop through chars in this sequence */
                while (1) {
                        /* So far escape sequence matched up to [i-1] */
                        if (n <= i) {
                                /* Need more chars, read another one if it wouldn't block.
                                 * Note that escape sequences come in as a unit,
                                 * so if we block for long it's not really an escape sequence.
                                 * Timeout is needed to reconnect escape sequences
                                 * split up by transmission over a serial console. */
                                if (safe_poll(&pfd, 1, 50) == 0) {
                                        /* No more data!
                                         * Array is sorted from shortest to longest,
                                         * we can't match anything later in array -
                                         * anything later is longer than this seq.
                                         * Break out of both loops. */
                                        goto got_all;
                                }
                                errno = 0;
                                if (safe_read(fd, buffer + n, 1) <= 0) {
                                        /* If EAGAIN, then fd is O_NONBLOCK and poll lied:
                                         * in fact, there is no data. */
                                        if (errno != EAGAIN) {
                                                /* otherwise: it's EOF/error */
                                                buffer[-1] = 0;
                                                return -1;
                                        }
                                        goto got_all;
                                }
                                n++;
                        }
                        if (buffer[i] != (seq[i] & 0x7f)) {
                                /* This seq doesn't match, go to next */
                                seq += i;
                                /* Forward to last char */
                                while (!(*seq & 0x80))
                                        seq++;
                                /* Skip it and the keycode which follows */
                                seq += 2;
                                break;
                        }
                        if (seq[i] & 0x80) {
                                /* Entire seq matched */
                                n = 0;
                                /* n -= i; memmove(...);
                                 * would be more correct,
                                 * but we never read ahead that much,
                                 * and n == i here. */
                                buffer[-1] = 0;
                                return (signed char)seq[i+1];
                        }
                        i++;
                }
        }
        /* We did not find matching sequence.
         * We possibly read and stored more input in buffer[] by now.
         * n = bytes read. Try to read more until we time out.
         */
        while (n < KEYCODE_BUFFER_SIZE-1) { /* 1 for count byte at buffer[-1] */
                if (safe_poll(&pfd, 1, 50) == 0) {
                        /* No more data! */
                        break;
                }
                errno = 0;
                if (safe_read(fd, buffer + n, 1) <= 0) {
                        /* If EAGAIN, then fd is O_NONBLOCK and poll lied:
                         * in fact, there is no data. */
                        if (errno != EAGAIN) {
                                /* otherwise: it's EOF/error */
                                buffer[-1] = 0;
                                return -1;
                        }
                        break;
                }
                n++;
                /* Try to decipher "ESC [ NNN ; NNN R" sequence */
                if ((ENABLE_FEATURE_EDITING_ASK_TERMINAL || ENABLE_FEATURE_VI_ASK_TERMINAL)
                 && n >= 5
                 && buffer[0] == '['
                 && buffer[n-1] == 'R'
                 && isdigit(buffer[1])
                ) {
                        char *end;
                        unsigned long row, col;

                        row = strtoul(buffer + 1, &end, 10);
                        if (*end != ';' || !isdigit(end[1]))
                                continue;
                        col = strtoul(end + 1, &end, 10);
                        if (*end != 'R')
                                continue;
                        if (row < 1 || col < 1 || (row | col) > 0x7fff)
                                continue;

                        buffer[-1] = 0;
                        /* Pack into "1 <row15bits> <col16bits>" 32-bit sequence */
                        col |= (((-1 << 15) | row) << 16);
                        /* Return it in high-order word */
                        return ((int64_t) col << 32) | (uint32_t)KEYCODE_CURSOR_POS;
                }
        }
 got_all:

        if (n <= 1) {
                /* Alt-x is usually returned as ESC x.
                 * Report ESC, x is remembered for the next call.
                 */
                buffer[-1] = n;
                return 27;
        }

        /* We were doing "buffer[-1] = n; return c;" here, but this results
         * in unknown key sequences being interpreted as ESC + garbage.
         * This was not useful. Pretend there was no key pressed,
         * go and wait for a new keypress:
         */
        buffer[-1] = 0;
        goto start_over;
}

void FAST_FUNC read_key_ungets(char *buffer, const char *str, unsigned len)
{
        unsigned cur_len = (unsigned char)buffer[0];
        if (len > KEYCODE_BUFFER_SIZE-1 - cur_len)
                len = KEYCODE_BUFFER_SIZE-1 - cur_len;
        memcpy(buffer + 1 + cur_len, str, len);
        buffer[0] += len;
}