/* ask - a simple command line asker
 * Copyright 2019 Bruce Hill
 * Released under the MIT License (see LICENSE for details)
 * Usage: ask [-q|--quickpick] [-p|--password] [-v|--version] [-h|--help] [--initial=initial] [prompt [options...]]
 *    --password: password mode
 *    --quickpick: quickpick mode (exit when only one option remains)
 *    --version: print version and exit
 *    --help: print usage and exit
 *    --initial: initial value to pre-populate user input
 */
#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"

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

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

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

/* Return length of the longest substring of patt[p:] that occurs within
 * str[s:], while still leaving enough space for the rest of `patt` to occur
 * within the rest of `str`. If there is no valid solution, return -1.
 */
static int lcs(const char *str, const char *patt, int slen, int plen, int s, int p, int *cache)
{
    if (!patt[p]) return 0;
    if (!str[s]) return -1;
    if (cache[s*plen + p]) return cache[s*plen + p];
    if (!EQ(str[s], patt[p])) return lcs(str, patt, slen, plen, s+1, p, cache);
    // Run starting here
    int run = 1;
    while (str[s+run] && patt[p+run] && EQ(str[s+run], patt[p+run])
           && lcs(str, patt, slen, plen, s+run, p+run, cache) >= 0) {
        ++run;
    }
    if (run == 0) run = -1;
    cache[s*plen + p] = run;
    return run;
}

static int matches(const char *str, const char *patt)
{
    while (*patt) {
        while (!EQ(*str, *patt)) {
            if (!*str) return 0;
            ++str;
        }
        ++str;
        ++patt;
    }
    return 1;
}

static void draw_line(FILE *out, const char *line, const char *patt, int cursor)
{
    size_t linelen = strlen(line), patlen = strlen(patt);
    int dim = 0;
    int p = 0;
    int run = 0;
    int *cache = calloc((linelen+1)*(patlen+1), sizeof(int));
    if (cursor >= (int)patlen)
        fputs("\0337", out);
    for (int i = 0; i < (int)linelen; i++) {
        if (EQ(patt[p], line[i]) &&
            run + lcs(line,patt,(int)linelen,(int)patlen,i,p,cache)
            >= lcs(line,patt,(int)linelen,(int)patlen,i+1,p,cache)) {
            if (dim) {
                fputs("\033[22m", out);
                dim = 0;
            }
            fputc(patt[p], out);
            ++run;
            ++p;
            if (cursor == p)
                fputs("\0337", out);
        } else {
            run = 0;
            if (!dim) {
                fputs("\033[2m", out);
                dim = 1;
            }
            fputc(line[i], out);
        }
    }
    fputs("\0338", out);
}

/*
 * A basic fuzzy matcher and line inputter
 */
static char *get_input(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);
    }

    int start = 0;
    // 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);
        }
        case_sensitive = 0;
        for (const char *p = buf; *p; ++p)
            case_sensitive |= ('A' <= *p && *p <= 'Z');

        int ncandidates = 0;
        picked = NULL;
        for (int i = 0; i < nopts; i++) {
            int j = (start + i) % nopts;
            if (matches(opts[j], buf)) {
                ++ncandidates;
                if (!picked) {
                    picked = opts[j];
                    start = j;
                }
            }
        }

        if (quickpick && ncandidates == 1 && picked)
            goto finished;

        if (password) {
            if (picked) fputs("\033[0;32m", out);
            else if (nopts > 0) fputs("\033[0;31m", out);
            else fputs("\033[0;2m", out);
            fputc((PASSWORD)[strlen(buf) % strlen(PASSWORD)], out);
            fputs("\033[0m", out);
        } else {
            if (picked) {
                draw_line(out, picked, buf, b);
            } else {
                if (nopts > 0)
                    fprintf(out, "\033[0;31m%s\033[0m", buf);
                else
                    fprintf(out, "\033[0m%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);
                buf = NULL;
                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 (picked) {
                    for (int i = 1; i < nopts; i++) {
                        int j = (start + i) % nopts;
                        if (matches(opts[j], buf)) {
                            start = j;
                            break;
                        }
                    }
                }
                break;
            case KEY_CTRL_P:
                if (picked) {
                    for (int i = nopts-1; i > 0; i--) {
                        int j = (start + i) % nopts;
                        if (matches(opts[j], buf)) {
                            start = j;
                            break;
                        }
                    }
                }
                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 (b < len)
                        memmove(buf+b+1, buf+b, (size_t)(len-b+1));
                    buf[b++] = (char)key;
                    buf[++len] = 0;
                }
                break;
        }
    }
  finished:
    if (picked) picked = memcheck(strdup(picked));
    else picked = buf;
    return picked;
}

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 (argv[a][0] == '-' && argv[a][1] != '-') {
            for (char *p = &argv[a][1]; *p; p++) {
                switch (*p) {
                    case 'p': password = 1; break;
                    case 'q': quickpick = 1; break;
                    case 'h': goto help_flag;
                    case 'v': goto version_flag;
                }
            }
        } else if (strncmp(argv[a], "--initial=", strlen("--initial=")) == 0) {
            initial = &argv[a][strlen("--initial=")];
        } else if (strcmp(argv[a], "--password") == 0) {
            password = 1;
        } else if (strcmp(argv[a], "--quickpick") == 0) {
            quickpick = 1;
        } else if (strcmp(argv[a], "--help") == 0) {
          help_flag:
            printf("ask - A simple command line input tool.\n"
                   "Usage: ask [-q|--quickpick] [-p|--password] [-v|--version] [-h|--help] [--initial=initial] [prompt [options...]]\n");
            return 0;
        } else if (strcmp(argv[a], "--version") == 0) {
          version_flag:
            printf("ask v0.1\n");
            return 0;
        } else break;
        ++a;
    }
    if (!prompt && a < argc) prompt = argv[a++];
    if (!prompt) prompt = "> ";

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

    char *output = get_input(tty_in, tty_out, prompt, initial, nlines, lines);

    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);
    free(output);

    // This doesn't free the memory in lines, but it doesn't need to because
    // the program is exiting
    return 0;
}
// vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1