/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <paths.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
/*
 * Editline and history functions (and glue).
 */
#include "alias.h"
#include "exec.h"
#include "shell.h"
#include "parser.h"
#include "var.h"
#include "options.h"
#include "main.h"
#include "output.h"
#include "mystring.h"
#include "builtins.h"
#ifndef NO_HISTORY
#include "myhistedit.h"
#include "error.h"
#include "eval.h"
#include "memalloc.h"

#define MAXHISTLOOPS    4       /* max recursions through fc */
#define DEFEDITOR       "ed"    /* default editor *should* be $EDITOR */

History *hist;  /* history cookie */
EditLine *el;   /* editline cookie */
int displayhist;
static int savehist;
static FILE *el_in, *el_out;
static bool in_command_completion;

static char *fc_replace(const char *, char *, char *);
static int not_fcnumber(const char *);
static int str_to_event(const char *, int);
static int comparator(const void *, const void *, void *);
static char **sh_matches(const char *, int, int);
static const char *append_char_function(const char *);
static unsigned char sh_complete(EditLine *, int);

static const char *
get_histfile(void)
{
        const char *histfile;

        /* don't try to save if the history size is 0 */
        if (hist == NULL || !strcmp(histsizeval(), "0"))
                return (NULL);
        histfile = expandstr("${HISTFILE-${HOME-}/.sh_history}");

        if (histfile[0] == '\0')
                return (NULL);
        return (histfile);
}

void
histsave(void)
{
        HistEvent he;
        char *histtmpname = NULL;
        const char *histfile;
        int fd;
        FILE *f;

        if (!savehist || (histfile = get_histfile()) == NULL)
                return;
        INTOFF;
        asprintf(&histtmpname, "%s.XXXXXXXXXX", histfile);
        if (histtmpname == NULL) {
                INTON;
                return;
        }
        fd = mkstemp(histtmpname);
        if (fd == -1 || (f = fdopen(fd, "w")) == NULL) {
                free(histtmpname);
                INTON;
                return;
        }
        if (history(hist, &he, H_SAVE_FP, f) < 1 ||
            rename(histtmpname, histfile) == -1)
                unlink(histtmpname);
        fclose(f);
        free(histtmpname);
        INTON;

}

void
histload(void)
{
        const char *histfile;
        HistEvent he;

        if ((histfile = get_histfile()) == NULL)
                return;
        errno = 0;
        if (history(hist, &he, H_LOAD, histfile) != -1 || errno == ENOENT)
                savehist = 1;
}

/*
 * Set history and editing status.  Called whenever the status may
 * have changed (figures out what to do).
 */
void
histedit(void)
{

#define editing (Eflag || Vflag)

        if (iflag) {
                if (!hist) {
                        /*
                         * turn history on
                         */
                        INTOFF;
                        hist = history_init();
                        INTON;

                        if (hist != NULL)
                                sethistsize(histsizeval());
                        else
                                out2fmt_flush("sh: can't initialize history\n");
                }
                if (editing && !el && isatty(0)) { /* && isatty(2) ??? */
                        /*
                         * turn editing on
                         */
                        char *term;

                        INTOFF;
                        if (el_in == NULL)
                                el_in = fdopen(0, "r");
                        if (el_out == NULL)
                                el_out = fdopen(2, "w");
                        if (el_in == NULL || el_out == NULL)
                                goto bad;
                        term = lookupvar("TERM");
                        if (term)
                                setenv("TERM", term, 1);
                        else
                                unsetenv("TERM");
                        el = el_init(arg0, el_in, el_out, el_out);
                        if (el != NULL) {
                                if (hist)
                                        el_set(el, EL_HIST, history, hist);
                                el_set(el, EL_PROMPT_ESC, getprompt, '\001');
                                el_set(el, EL_ADDFN, "sh-complete",
                                    "Filename completion",
                                    sh_complete);
                        } else {
bad:
                                out2fmt_flush("sh: can't initialize editing\n");
                        }
                        INTON;
                } else if (!editing && el) {
                        INTOFF;
                        el_end(el);
                        el = NULL;
                        INTON;
                }
                if (el) {
                        if (Vflag)
                                el_set(el, EL_EDITOR, "vi");
                        else if (Eflag) {
                                el_set(el, EL_EDITOR, "emacs");
                        }
                        el_set(el, EL_BIND, "^I", "sh-complete", NULL);
                        el_source(el, NULL);
                }
        } else {
                INTOFF;
                if (el) {       /* no editing if not interactive */
                        el_end(el);
                        el = NULL;
                }
                if (hist) {
                        history_end(hist);
                        hist = NULL;
                }
                INTON;
        }
}


void
sethistsize(const char *hs)
{
        int histsize;
        HistEvent he;

        if (hist != NULL) {
                if (hs == NULL || !is_number(hs))
                        histsize = 100;
                else
                        histsize = atoi(hs);
                history(hist, &he, H_SETSIZE, histsize);
                history(hist, &he, H_SETUNIQUE, 1);
        }
}

void
setterm(const char *term)
{
        if (rootshell && el != NULL && term != NULL)
                el_set(el, EL_TERMINAL, term);
}

int
histcmd(int argc, char **argv __unused)
{
        const char *editor = NULL;
        HistEvent he;
        int lflg = 0, nflg = 0, rflg = 0, sflg = 0;
        int i, retval;
        const char *firststr, *laststr;
        int first, last, direction;
        char *pat = NULL, *repl = NULL;
        static int active = 0;
        struct jmploc jmploc;
        struct jmploc *savehandler;
        char editfilestr[PATH_MAX];
        char *volatile editfile;
        FILE *efp = NULL;
        int oldhistnum;

        if (hist == NULL)
                error("history not active");

        if (argc == 1)
                error("missing history argument");

        while (not_fcnumber(*argptr))
                do {
                        switch (nextopt("e:lnrs")) {
                        case 'e':
                                editor = shoptarg;
                                break;
                        case 'l':
                                lflg = 1;
                                break;
                        case 'n':
                                nflg = 1;
                                break;
                        case 'r':
                                rflg = 1;
                                break;
                        case 's':
                                sflg = 1;
                                break;
                        case '\0':
                                goto operands;
                        }
                } while (nextopt_optptr != NULL);
operands:
        savehandler = handler;
        /*
         * If executing...
         */
        if (lflg == 0 || editor || sflg) {
                lflg = 0;       /* ignore */
                editfile = NULL;
                /*
                 * Catch interrupts to reset active counter and
                 * cleanup temp files.
                 */
                if (setjmp(jmploc.loc)) {
                        active = 0;
                        if (editfile)
                                unlink(editfile);
                        handler = savehandler;
                        longjmp(handler->loc, 1);
                }
                handler = &jmploc;
                if (++active > MAXHISTLOOPS) {
                        active = 0;
                        displayhist = 0;
                        error("called recursively too many times");
                }
                /*
                 * Set editor.
                 */
                if (sflg == 0) {
                        if (editor == NULL &&
                            (editor = bltinlookup("FCEDIT", 1)) == NULL &&
                            (editor = bltinlookup("EDITOR", 1)) == NULL)
                                editor = DEFEDITOR;
                        if (editor[0] == '-' && editor[1] == '\0') {
                                sflg = 1;       /* no edit */
                                editor = NULL;
                        }
                }
        }

        /*
         * If executing, parse [old=new] now
         */
        if (lflg == 0 && *argptr != NULL &&
             ((repl = strchr(*argptr, '=')) != NULL)) {
                pat = *argptr;
                *repl++ = '\0';
                argptr++;
        }
        /*
         * determine [first] and [last]
         */
        if (*argptr == NULL) {
                firststr = lflg ? "-16" : "-1";
                laststr = "-1";
        } else if (argptr[1] == NULL) {
                firststr = argptr[0];
                laststr = lflg ? "-1" : argptr[0];
        } else if (argptr[2] == NULL) {
                firststr = argptr[0];
                laststr = argptr[1];
        } else
                error("too many arguments");
        /*
         * Turn into event numbers.
         */
        first = str_to_event(firststr, 0);
        last = str_to_event(laststr, 1);

        if (rflg) {
                i = last;
                last = first;
                first = i;
        }
        /*
         * XXX - this should not depend on the event numbers
         * always increasing.  Add sequence numbers or offset
         * to the history element in next (diskbased) release.
         */
        direction = first < last ? H_PREV : H_NEXT;

        /*
         * If editing, grab a temp file.
         */
        if (editor) {
                int fd;
                INTOFF;         /* easier */
                sprintf(editfilestr, "%s/_shXXXXXX", _PATH_TMP);
                if ((fd = mkstemp(editfilestr)) < 0)
                        error("can't create temporary file %s", editfile);
                editfile = editfilestr;
                if ((efp = fdopen(fd, "w")) == NULL) {
                        close(fd);
                        error("Out of space");
                }
        }

        /*
         * Loop through selected history events.  If listing or executing,
         * do it now.  Otherwise, put into temp file and call the editor
         * after.
         *
         * The history interface needs rethinking, as the following
         * convolutions will demonstrate.
         */
        history(hist, &he, H_FIRST);
        retval = history(hist, &he, H_NEXT_EVENT, first);
        for (;retval != -1; retval = history(hist, &he, direction)) {
                if (lflg) {
                        if (!nflg)
                                out1fmt("%5d ", he.num);
                        out1str(he.str);
                } else {
                        const char *s = pat ?
                           fc_replace(he.str, pat, repl) : he.str;

                        if (sflg) {
                                if (displayhist) {
                                        out2str(s);
                                        flushout(out2);
                                }
                                evalstring(s, 0);
                                if (displayhist && hist) {
                                        /*
                                         *  XXX what about recursive and
                                         *  relative histnums.
                                         */
                                        oldhistnum = he.num;
                                        history(hist, &he, H_ENTER, s);
                                        /*
                                         * XXX H_ENTER moves the internal
                                         * cursor, set it back to the current
                                         * entry.
                                         */
                                        history(hist, &he,
                                            H_NEXT_EVENT, oldhistnum);
                                }
                        } else
                                fputs(s, efp);
                }
                /*
                 * At end?  (if we were to lose last, we'd sure be
                 * messed up).
                 */
                if (he.num == last)
                        break;
        }
        if (editor) {
                char *editcmd;

                fclose(efp);
                INTON;
                editcmd = stalloc(strlen(editor) + strlen(editfile) + 2);
                sprintf(editcmd, "%s %s", editor, editfile);
                evalstring(editcmd, 0); /* XXX - should use no JC command */
                readcmdfile(editfile, 0 /* verify */);  /* XXX - should read back - quick tst */
                unlink(editfile);
        }

        if (lflg == 0 && active > 0)
                --active;
        if (displayhist)
                displayhist = 0;
        handler = savehandler;
        return 0;
}

static char *
fc_replace(const char *s, char *p, char *r)
{
        char *dest;
        int plen = strlen(p);

        STARTSTACKSTR(dest);
        while (*s) {
                if (*s == *p && strncmp(s, p, plen) == 0) {
                        STPUTS(r, dest);
                        s += plen;
                        *p = '\0';      /* so no more matches */
                } else
                        STPUTC(*s++, dest);
        }
        STPUTC('\0', dest);
        dest = grabstackstr(dest);

        return (dest);
}

static int
not_fcnumber(const char *s)
{
        if (s == NULL)
                return (0);
        if (*s == '-')
                s++;
        return (!is_number(s));
}

static int
str_to_event(const char *str, int last)
{
        HistEvent he;
        const char *s = str;
        int relative = 0;
        int i, retval;

        retval = history(hist, &he, H_FIRST);
        switch (*s) {
        case '-':
                relative = 1;
                /*FALLTHROUGH*/
        case '+':
                s++;
        }
        if (is_number(s)) {
                i = atoi(s);
                if (relative) {
                        while (retval != -1 && i--) {
                                retval = history(hist, &he, H_NEXT);
                        }
                        if (retval == -1)
                                retval = history(hist, &he, H_LAST);
                } else {
                        retval = history(hist, &he, H_NEXT_EVENT, i);
                        if (retval == -1) {
                                /*
                                 * the notion of first and last is
                                 * backwards to that of the history package
                                 */
                                retval = history(hist, &he, last ? H_FIRST : H_LAST);
                        }
                }
                if (retval == -1)
                        error("history number %s not found (internal error)",
                               str);
        } else {
                /*
                 * pattern
                 */
                retval = history(hist, &he, H_PREV_STR, str);
                if (retval == -1)
                        error("history pattern not found: %s", str);
        }
        return (he.num);
}

int
bindcmd(int argc, char **argv)
{
        int ret;
        FILE *old;
        FILE *out;

        if (el == NULL)
                error("line editing is disabled");

        INTOFF;

        out = out1fp();
        if (out == NULL)
                error("Out of space");

        el_get(el, EL_GETFP, 1, &old);
        el_set(el, EL_SETFP, 1, out);

        ret = el_parse(el, argc, __DECONST(const char **, argv));

        el_set(el, EL_SETFP, 1, old);

        fclose(out);

        if (argc > 1 && argv[1][0] == '-' &&
            memchr("ve", argv[1][1], 2) != NULL) {
                Vflag = argv[1][1] == 'v';
                Eflag = !Vflag;
                histedit();
        }

        INTON;

        return ret;
}

/*
 * Comparator function for qsort(). The use of curpos here is to skip
 * characters that we already know to compare equal (common prefix).
 */
static int
comparator(const void *a, const void *b, void *thunk)
{
        size_t curpos = (intptr_t)thunk;

        return (strcmp(*(char *const *)a + curpos,
                *(char *const *)b + curpos));
}

static char
**add_match(char **matches, size_t i, size_t *size, char *match_copy)
{
        if (match_copy == NULL)
                return (NULL);
        matches[i] = match_copy;
        if (i >= *size - 1) {
                *size *= 2;
                matches = reallocarray(matches, *size, sizeof(matches[0]));
        }

        return (matches);
}

/*
 * This function is passed to libedit's fn_complete2(). The library will use
 * it instead of its standard function that finds matching files in current
 * directory. If we're at the start of the line, we want to look for
 * available commands from all paths in $PATH.
 */
static char
**sh_matches(const char *text, int start, int end)
{
        char *free_path = NULL, *path;
        const char *dirname;
        char **matches = NULL, **rmatches;
        size_t i = 0, size = 16, uniq;
        size_t curpos = end - start, lcstring = -1;
        struct cmdentry e;

        in_command_completion = false;
        if (start > 0 || memchr("/.~", text[0], 3) != NULL)
                return (NULL);
        in_command_completion = true;
        if ((free_path = path = strdup(pathval())) == NULL)
                goto out;
        if ((matches = malloc(size * sizeof(matches[0]))) == NULL)
                goto out;
        while ((dirname = strsep(&path, ":")) != NULL) {
                struct dirent *entry;
                DIR *dir;
                int dfd;

                dir = opendir(dirname[0] == '\0' ? "." : dirname);
                if (dir == NULL)
                        continue;
                if ((dfd = dirfd(dir)) == -1) {
                        closedir(dir);
                        continue;
                }
                while ((entry = readdir(dir)) != NULL) {
                        struct stat statb;

                        if (strncmp(entry->d_name, text, curpos) != 0)
                                continue;
                        if (entry->d_type == DT_UNKNOWN || entry->d_type == DT_LNK) {
                                if (fstatat(dfd, entry->d_name, &statb, 0) == -1)
                                        continue;
                                if (!S_ISREG(statb.st_mode))
                                        continue;
                        } else if (entry->d_type != DT_REG)
                                continue;
                        rmatches = add_match(matches, ++i, &size,
                                strdup(entry->d_name));
                        if (rmatches == NULL) {
                                closedir(dir);
                                goto out;
                        }
                        matches = rmatches;
                }
                closedir(dir);
        }
        for (const unsigned char *bp = builtincmd; *bp != 0; bp += 2 + bp[0]) {
                if (curpos > bp[0] || memcmp(bp + 2, text, curpos) != 0)
                        continue;
                rmatches = add_match(matches, ++i, &size, strndup(bp + 2, bp[0]));
                if (rmatches == NULL)
                        goto out;
                matches = rmatches;
        }
        for (const struct alias *ap = NULL; (ap = iteralias(ap)) != NULL;) {
                if (strncmp(ap->name, text, curpos) != 0)
                        continue;
                rmatches = add_match(matches, ++i, &size, strdup(ap->name));
                if (rmatches == NULL)
                        goto out;
                matches = rmatches;
        }
        for (const void *a = NULL; (a = itercmd(a, &e)) != NULL;) {
                if (e.cmdtype != CMDFUNCTION)
                        continue;
                if (strncmp(e.cmdname, text, curpos) != 0)
                        continue;
                rmatches = add_match(matches, ++i, &size, strdup(e.cmdname));
                if (rmatches == NULL)
                        goto out;
                matches = rmatches;
        }
out:
        free(free_path);
        if (i == 0) {
                free(matches);
                return (NULL);
        }
        uniq = 1;
        if (i > 1) {
                qsort_s(matches + 1, i, sizeof(matches[0]), comparator,
                        (void *)(intptr_t)curpos);
                for (size_t k = 2; k <= i; k++) {
                        const char *l = matches[uniq] + curpos;
                        const char *r = matches[k] + curpos;
                        size_t common = 0;

                        while (*l != '\0' && *r != '\0' && *l == *r)
                                (void)l++, r++, common++;
                        if (common < lcstring)
                                lcstring = common;
                        if (*l == *r)
                                free(matches[k]);
                        else
                                matches[++uniq] = matches[k];
                }
        }
        matches[uniq + 1] = NULL;
        /*
         * matches[0] is special: it's not a real matching file name but
         * a common prefix for all matching names. It can't be null, unlike
         * any other element of the array. When strings matches[0] and
         * matches[1] compare equal and matches[2] is null that means to
         * libedit that there is only a single match. It will then replace
         * user input with possibly escaped string in matches[0] which is the
         * reason to copy the full name of the only match.
         */
        if (uniq == 1)
                matches[0] = strdup(matches[1]);
        else if (lcstring != (size_t)-1)
                matches[0] = strndup(matches[1], curpos + lcstring);
        else
                matches[0] = strdup(text);
        if (matches[0] == NULL) {
                for (size_t k = 1; k <= uniq; k++)
                        free(matches[k]);
                free(matches);
                return (NULL);
        }
        return (matches);
}

/*
 * If we don't specify this function as app_func in the call to fn_complete2,
 * libedit will use the default one, which adds a " " to plain files and
 * a "/" to directories regardless of whether it's a command name or a plain
 * path (relative or absolute). We never want to add "/" to commands.
 *
 * For example, after I did "mkdir rmdir", "rmdi" would be autocompleted to
 * "rmdir/" instead of "rmdir ".
 */
static const char *
append_char_function(const char *name)
{
        struct stat stbuf;
        char *expname = name[0] == '~' ? fn_tilde_expand(name) : NULL;
        const char *rs;

        if (!in_command_completion &&
            stat(expname ? expname : name, &stbuf) == 0 &&
            S_ISDIR(stbuf.st_mode))
                rs = "/";
        else
                rs = " ";
        free(expname);
        return (rs);
}

/*
 * This is passed to el_set(el, EL_ADDFN, ...) so that it's possible to
 * bind a key (tab by default) to execute the function.
 */
unsigned char
sh_complete(EditLine *sel, int ch __unused)
{
        return (unsigned char)fn_complete2(sel, NULL, sh_matches,
                L" \t\n\"\\'`@$><=;|&{(", NULL, append_char_function,
                (size_t)100, NULL, &((int) {0}), NULL, NULL, FN_QUOTE_MATCH);
}

#else
#include "error.h"

int
histcmd(int argc __unused, char **argv __unused)
{

        error("not compiled with history support");
        /*NOTREACHED*/
        return (0);
}

int
bindcmd(int argc __unused, char **argv __unused)
{

        error("not compiled with line editing support");
        return (0);
}
#endif