ask/ask.c

/* ask - a simple command line asker
 * Copyright 2019 Bruce Hill
 * Released under the MIT License (see LICENSE for details)
 * Usage: ask [-p | --password] [-q | --quickpick] [prompt [initial value]]
 *    -p: password mode
 *    -q: quickpick mode (exit when only one option remains)
 */
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <termios.h>
#include <unistd.h>

#include "bterm.h"

static int password = 0, quickpick = 0, case_sensitive = 0, to_skip = 0;

#define LOWERCASE(c) ('A' <= (c) && (c) <= 'Z' ? ((c) + 'a' - 'A') : (c))
#define EQ(a, b) (case_sensitive ? (a) == (b) : LOWERCASE(a) == LOWERCASE(b))

static inline void *memcheck(void *p)
{
    if (!p) {
        fprintf(stderr, "Memory allocation failure\n");
        exit(1);
    }
    return p;
}

static int score(const char *str, const char *patt)
{
    if (!patt[0]) return 0;
    int score = 0;
    const char *sp = str, *pp = patt;
    while (*sp && !EQ(*sp, *pp)) ++sp;
    while (*sp && *pp && EQ(*sp, *pp)) {
        ++score;
        ++sp;
        ++pp;
    }
    for (; *pp; ++sp, ++pp) {
        while (*sp && !EQ(*sp, *pp)) ++sp;
        if (!*sp) return 0;
    }
    if (*pp && !*sp) return 0;
    return score;
}

static void draw_line(FILE *out, const char *line, const char *hl, const char *cur)
{
    int dim = 0, backtrack = 0;
    for (const char *pl = line, *phl = hl; *pl; pl++) {
        if (phl >= cur) ++backtrack;
        if (case_sensitive ? *pl == *phl : LOWERCASE(*pl) == LOWERCASE(*phl)) {
            ++phl;
            if (dim) {
                fputs("\033[22m", out);
                dim = 0;
            }
        } else if (!dim) {
            fputs("\033[2m", out);
            dim = 1;
        }
        fputc(*pl, out);
    }
    if (backtrack)
        fprintf(out, "\033[%dD", backtrack);
}

/*
 * A basic fuzzly matcher
 */
static char *fzline(FILE *in, FILE *out, const char *prompt, const char *initial, int nopts, char **opts)
{
    size_t cap = initial ? strlen(initial) + 100 : 100;
    char *buf = memcheck(calloc(cap, 1));
    char *picked = NULL;
    int b = 0, len = 0;
    if (initial) {
        if (!strcpy(buf, initial)) return NULL;
        len = (int)strlen(initial);
        b = len;
        fputs(initial, out);
    }

    // Show cursor and set to blinking line:
    while (1) {
        fputs("\033[G\033[K\033[0m", out);
        if (prompt) {
            fputs("\033[1G\033[K\033[37;1m", out);
            fputs(prompt, out);
            fputs("\033[0m", out);
        }
        picked = NULL;
        case_sensitive = 0;
        for (const char *p = buf; *p; ++p)
            case_sensitive |= ('A' <= *p && *p <= 'Z');

        int ncandidates = 0;
        for (int i = 0; i < nopts; i++)
            ncandidates += score(opts[i], buf) > 0;

        int bestscore = 0;
        char *best = NULL;
        int skipped = 0;
        for (int i = 0; i < nopts; i++) {
            int s = score(opts[i], buf);
            if (s && skipped < to_skip) {
                ++skipped;
                continue;
            }
            if (s > bestscore) {
                best = opts[i];
                bestscore = s;
            }
        }
        if (quickpick && ncandidates == 1 && best)
            return best;

        picked = best;
        if (best) {
            draw_line(out, best, buf, &buf[b]);
        } else {
            fprintf(out, "\033[0;31m%s\033[0m", buf);
            if (b < (int)strlen(buf))
                fprintf(out, "\033[%dD", (int)strlen(buf) - b);
        }
        fflush(out);
        int key;
      skip_redraw:
        key = bgetkey(in, NULL, NULL, -1);
        switch (key) {
            case -1: case -2: case -3: goto skip_redraw;
            case '\r':
                // TODO: support backslash-enter
                goto finished;
            case KEY_CTRL_C: case KEY_ESC:
                free(buf);
                picked = NULL;
                goto finished;
            case KEY_CTRL_A:
                if (b > 0) b = 0;
                break;
            case KEY_CTRL_E:
                if (b < len) b = len;
                break;
            case KEY_CTRL_U: {
                int to_clear = b;
                if (to_clear) {
                    memmove(buf, buf+b, (size_t)(len-b));
                    buf[len -= b] = 0;
                    b = 0;
                }
                break;
            }
            case KEY_CTRL_K:
                if (b < len)
                    buf[len = b] = 0;
                break;
            case KEY_CTRL_N:
                if (ncandidates)
                    to_skip = (to_skip + 1) % ncandidates;
                break;
            case KEY_CTRL_P:
                if (ncandidates)
                    to_skip = (to_skip + ncandidates - 1) % ncandidates;
                break;
            case KEY_BACKSPACE: case KEY_BACKSPACE2:
                if (b > 0) {
                    --b;
                    memmove(buf+b, buf+b+1, (size_t)(len-b));
                    buf[--len] = 0;
                }
                break;
            case KEY_DELETE: case KEY_CTRL_D:
                if (b < len) {
                    memmove(buf+b, buf+b+1, (size_t)(len-b));
                    buf[--len] = 0;
                }
                break;
            case KEY_ARROW_LEFT: case KEY_CTRL_B:
                if (b > 0) --b;
                break;
            case KEY_ARROW_RIGHT: case KEY_CTRL_F:
                if (b < len) ++b;
                break;
            default:
                if (' ' <= key && key <= '~') {
                    if (len + 1 >= (int)cap) {
                        buf = memcheck(realloc(buf, (cap += 100)));
                        if (!buf) goto finished;
                    }
                    if (b < len)
                        memmove(buf+b+1, buf+b, (size_t)(len-b+1));
                    buf[b++] = (char)key;
                    buf[++len] = 0;
                }
                break;
        }
    }
  finished:
    return picked;
}

/**
 * A basic readline implementation. No history, but all the normal editing
 * key bindings like Ctrl-U to clear to the beginning of the line, backspace,
 * arrow keys, etc.
 *
 * Takes an input file and output file, and an optional prompt and returns
 * a malloc'd string containing the user's input or NULL if an error occurred
 * or if the user hit Escape or Ctrl-c.
 */
static char *breadline(FILE *in, FILE *out, const char *prompt, const char *initial)
{
    size_t cap = initial ? strlen(initial) + 100 : 100;
    char *buf = calloc(cap, 1);
    if (!buf) return NULL;
    int i = 0, len = 0;
    if (prompt) {
        fputs("\033[1G\033[K\033[37;1m", out);
        fputs(prompt, out);
        fputs("\033[0m", out);
    }
    if (initial) {
        strcpy(buf, initial);
        len = (int)strlen(initial);
        i = len;
        fputs(initial, out);
    }
    // Show cursor
    fputs("\033[?25h", out);
    while (1) {
        fflush(out);
        int key = bgetkey(in, NULL, NULL, -1);
        switch (key) {
            case -1: case -2: case -3: continue;
            case '\r':
                // TODO: support backslash-enter
                goto finished;
            case KEY_CTRL_C: case KEY_ESC:
                free(buf);
                buf = NULL;
                goto finished;
            case KEY_CTRL_A:
                if (i > 0) {
                    fprintf(out, "\033[%dD", i);
                    i = 0;
                }
                break;
            case KEY_CTRL_E:
                if (i < len) {
                    fprintf(out, "\033[%dC", len-i);
                    i = len;
                }
                break;
            case KEY_CTRL_U: {
                int to_clear = i;
                if (to_clear) {
                    memmove(buf, buf+i, (size_t)(len-i));
                    buf[len -= i] = 0;
                    i = 0;
                    fprintf(out, "\033[%dD\033[K", to_clear);
                    if (len > 0)
                        fprintf(out, "%s\033[%dD", buf, len);
                }
                break;
            }
            case KEY_CTRL_K:
                if (i < len) {
                    buf[len = i] = 0;
                    fputs("\033[K", out);
                }
                break;
            case KEY_BACKSPACE: case KEY_BACKSPACE2:
                if (i > 0) {
                    --i;
                    memmove(buf+i, buf+i+1, (size_t)(len-i));
                    buf[--len] = 0;
                    if (i == len) fputs("\033[D \033[D", out);
                    else fprintf(out, "\033[D%s\033[K\033[%dD", buf+i, len-i);
                }
                break;
            case KEY_DELETE: case KEY_CTRL_D:
                if (i < len) {
                    memmove(buf+i, buf+i+1, (size_t)(len-i));
                    buf[--len] = 0;
                    if (i == len) fputs(" \033[D", out);
                    else fprintf(out, "%s\033[K\033[%dD", buf+i, len-i);
                }
                break;
            case KEY_ARROW_LEFT: case KEY_CTRL_B:
                if (i > 0) {
                    --i;
                    fputs("\033[D", out);
                }
                break;
            case KEY_ARROW_RIGHT: case KEY_CTRL_F:
                if (i < len) {
                    ++i;
                    fputs("\033[C", out);
                }
                break;
            default:
                if (' ' <= key && key <= '~') {
                    if (len + 1 >= (int)cap) {
                        cap += 100;
                        buf = realloc(buf, cap);
                        if (!buf) goto finished;
                    }
                    if (i < len)
                        memmove(buf+i+1, buf+i, (size_t)(len-i+1));
                    buf[i++] = (char)key;
                    buf[++len] = 0;
                    if (i == len)
                        fputc(key, out);
                    else
                        fprintf(out, "%c%s\033[%dD", (char)key, buf+i, len-i);
                }
                break;
        }
    }
  finished:
    // Reset cursor to block
    fputs("\033[1G\033[1 q\033[2K", out);
    return buf;
}

int main(int argc, char *argv[])
{
    FILE *tty_in = fopen("/dev/tty", "r");
    FILE *tty_out = fopen("/dev/tty", "w");
    struct termios orig_termios, bb_termios;
    tcgetattr(fileno(tty_out), &orig_termios);
    cfmakeraw(&bb_termios);
    if (tcsetattr(fileno(tty_out), TCSAFLUSH, &bb_termios) == -1)
        return 1;

    char *prompt = NULL, *initial = NULL;
    char **lines = NULL;
    size_t linescap = 0, linecap = 0;
    int nlines = 0;
    char *line = NULL;
    struct pollfd pfd = {STDIN_FILENO, POLLIN, 0};
    if (poll(&pfd, 1, 50) > 0) {
        while ((getline(&line, &linecap, stdin)) >= 0) {
            if ((size_t)nlines >= linescap)
                lines = memcheck(realloc(lines, (linescap += 100)*sizeof(char*)));
            if (!line[0]) continue;
            if (line[strlen(line)-1] == '\n')
                line[strlen(line)-1] = '\0';
            lines[nlines++] = memcheck(strdup(line));
        }
    }
    int a = 1;
    while (a < argc) {
        if (strcmp(argv[a], "-p") == 0 || strcmp(argv[a], "--password") == 0) {
            password = 1;
        } else if (strcmp(argv[a], "-q") == 0 || strcmp(argv[a], "--quickpick") == 0) {
            quickpick = 1;
        } else break;
        ++a;
    }
    if (!prompt && a < argc) prompt = argv[a++];
    if (!initial && a < argc) initial = argv[a++];

    while (a < argc) {
        if ((size_t)nlines >= linescap)
            lines = memcheck(realloc(lines, (linescap += 100)*sizeof(char*)));
        lines[nlines++] = argv[a++];
    }

    char *output = nlines > 0
        ? fzline(tty_in, tty_out, prompt, initial, nlines, lines)
        : breadline(tty_in, tty_out, prompt, initial);

    fputs("\033[G\033[K\033[0m", tty_out);
    fflush(tty_out);
    tcsetattr(fileno(tty_out), TCSAFLUSH, &orig_termios);
    fclose(tty_out);
    tty_out = NULL;
    fclose(tty_in);
    tty_in = NULL;

    if (!output) return 1;

    puts(output);
    return 0;
}
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