/*
 * Copyright (C) 1984-2012  Mark Nudelman
 * Modified for use with illumos by Garrett D'Amore.
 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information, see the README file.
 */

/*
 * Functions which manipulate the command buffer.
 * Used only by command() and related functions.
 */

#include <sys/stat.h>

#include "charset.h"
#include "cmd.h"
#include "less.h"

extern int secure;
extern int sc_width;
extern int utf_mode;

static char cmdbuf[CMDBUF_SIZE]; /* Buffer for holding a multi-char command */
static int cmd_col;             /* Current column of the cursor */
static int prompt_col;          /* Column of cursor just after prompt */
static char *cp;                /* Pointer into cmdbuf */
static int cmd_offset;          /* Index into cmdbuf of first displayed char */
static int literal;             /* Next input char should not be interpreted */
static int updown_match = -1;   /* Prefix length in up/down movement */

static int cmd_complete(int);
/*
 * These variables are statics used by cmd_complete.
 */
static int in_completion = 0;
static char *tk_text;
static char *tk_original;
static char *tk_ipoint;
static char *tk_trial;
static struct textlist tk_tlist;

static int cmd_left(void);
static int cmd_right(void);

char openquote = '"';
char closequote = '"';

/* History file */
#define HISTFILE_FIRST_LINE     ".less-history-file:"
#define HISTFILE_SEARCH_SECTION ".search"
#define HISTFILE_SHELL_SECTION  ".shell"

/*
 * A mlist structure represents a command history.
 */
struct mlist {
        struct mlist *next;
        struct mlist *prev;
        struct mlist *curr_mp;
        char *string;
        int modified;
};

/*
 * These are the various command histories that exist.
 */
struct mlist mlist_search =
        { &mlist_search,  &mlist_search,  &mlist_search,  NULL, 0 };
void * const ml_search = (void *) &mlist_search;

struct mlist mlist_examine =
        { &mlist_examine, &mlist_examine, &mlist_examine, NULL, 0 };
void * const ml_examine = (void *) &mlist_examine;

struct mlist mlist_shell =
        { &mlist_shell,   &mlist_shell,   &mlist_shell,   NULL, 0 };
void * const ml_shell = (void *) &mlist_shell;

/*
 * History for the current command.
 */
static struct mlist *curr_mlist = NULL;
static int curr_cmdflags;

static char cmd_mbc_buf[MAX_UTF_CHAR_LEN];
static int cmd_mbc_buf_len;
static int cmd_mbc_buf_index;


/*
 * Reset command buffer (to empty).
 */
void
cmd_reset(void)
{
        cp = cmdbuf;
        *cp = '\0';
        cmd_col = 0;
        cmd_offset = 0;
        literal = 0;
        cmd_mbc_buf_len = 0;
        updown_match = -1;
}

/*
 * Clear command line.
 */
void
clear_cmd(void)
{
        cmd_col = prompt_col = 0;
        cmd_mbc_buf_len = 0;
        updown_match = -1;
}

/*
 * Display an ASCII string, usually as a prompt for input,
 * into the command buffer.
 */
void
cmd_putstr(char *s)
{
        while (*s != '\0') {
                putchr(*s++);
                cmd_col++;
                prompt_col++;
        }
}

/*
 * How many characters are in the command buffer?
 */
int
len_cmdbuf(void)
{
        char *s = cmdbuf;
        char *endline = s + strlen(s);
        int len = 0;

        while (*s != '\0') {
                step_char(&s, +1, endline);
                len++;
        }
        return (len);
}

/*
 * Common part of cmd_step_right() and cmd_step_left().
 */
static char *
cmd_step_common(char *p, LWCHAR ch, int len, int *pwidth, int *bswidth)
{
        char *pr;

        if (len == 1) {
                pr = prchar((int)ch);
                if (pwidth != NULL || bswidth != NULL) {
                        int prlen = strlen(pr);
                        if (pwidth != NULL)
                                *pwidth = prlen;
                        if (bswidth != NULL)
                                *bswidth = prlen;
                }
        } else {
                pr = prutfchar(ch);
                if (pwidth != NULL || bswidth != NULL) {
                        if (is_composing_char(ch)) {
                                if (pwidth != NULL)
                                        *pwidth = 0;
                                if (bswidth != NULL)
                                        *bswidth = 0;
                        } else if (is_ubin_char(ch)) {
                                int prlen = strlen(pr);
                                if (pwidth != NULL)
                                        *pwidth = prlen;
                                if (bswidth != NULL)
                                        *bswidth = prlen;
                        } else {
                                if (pwidth != NULL)
                                        *pwidth = is_wide_char(ch) ? 2 : 1;
                                if (bswidth != NULL)
                                        *bswidth = 1;
                        }
                }
        }

        return (pr);
}

/*
 * Step a pointer one character right in the command buffer.
 */
static char *
cmd_step_right(char **pp, int *pwidth, int *bswidth)
{
        char *p = *pp;
        LWCHAR ch = step_char(pp, +1, p + strlen(p));

        return (cmd_step_common(p, ch, *pp - p, pwidth, bswidth));
}

/*
 * Step a pointer one character left in the command buffer.
 */
static char *
cmd_step_left(char **pp, int *pwidth, int *bswidth)
{
        char *p = *pp;
        LWCHAR ch = step_char(pp, -1, cmdbuf);

        return (cmd_step_common(*pp, ch, p - *pp, pwidth, bswidth));
}

/*
 * Repaint the line from cp onwards.
 * Then position the cursor just after the char old_cp (a pointer into cmdbuf).
 */
static void
cmd_repaint(char *old_cp)
{
        /*
         * Repaint the line from the current position.
         */
        clear_eol();
        while (*cp != '\0') {
                char *np = cp;
                int width;
                char *pr = cmd_step_right(&np, &width, NULL);
                if (cmd_col + width >= sc_width)
                        break;
                cp = np;
                putstr(pr);
                cmd_col += width;
        }
        while (*cp != '\0') {
                char *np = cp;
                int width;
                char *pr = cmd_step_right(&np, &width, NULL);
                if (width > 0)
                        break;
                cp = np;
                putstr(pr);
        }

        /*
         * Back up the cursor to the correct position.
         */
        while (cp > old_cp)
                cmd_left();
}

/*
 * Put the cursor at "home" (just after the prompt),
 * and set cp to the corresponding char in cmdbuf.
 */
static void
cmd_home(void)
{
        while (cmd_col > prompt_col) {
                int width, bswidth;

                cmd_step_left(&cp, &width, &bswidth);
                while (bswidth-- > 0)
                        putbs();
                cmd_col -= width;
        }

        cp = &cmdbuf[cmd_offset];
}

/*
 * Shift the cmdbuf display left a half-screen.
 */
static void
cmd_lshift(void)
{
        char *s;
        char *save_cp;
        int cols;

        /*
         * Start at the first displayed char, count how far to the
         * right we'd have to move to reach the center of the screen.
         */
        s = cmdbuf + cmd_offset;
        cols = 0;
        while (cols < (sc_width - prompt_col) / 2 && *s != '\0') {
                int width;
                cmd_step_right(&s, &width, NULL);
                cols += width;
        }
        while (*s != '\0') {
                int width;
                char *ns = s;
                cmd_step_right(&ns, &width, NULL);
                if (width > 0)
                        break;
                s = ns;
        }

        cmd_offset = s - cmdbuf;
        save_cp = cp;
        cmd_home();
        cmd_repaint(save_cp);
}

/*
 * Shift the cmdbuf display right a half-screen.
 */
static void
cmd_rshift(void)
{
        char *s;
        char *save_cp;
        int cols;

        /*
         * Start at the first displayed char, count how far to the
         * left we'd have to move to traverse a half-screen width
         * of displayed characters.
         */
        s = cmdbuf + cmd_offset;
        cols = 0;
        while (cols < (sc_width - prompt_col) / 2 && s > cmdbuf) {
                int width;
                cmd_step_left(&s, &width, NULL);
                cols += width;
        }

        cmd_offset = s - cmdbuf;
        save_cp = cp;
        cmd_home();
        cmd_repaint(save_cp);
}

/*
 * Move cursor right one character.
 */
static int
cmd_right(void)
{
        char *pr;
        char *ncp;
        int width;

        if (*cp == '\0') {
                /* Already at the end of the line. */
                return (CC_OK);
        }
        ncp = cp;
        pr = cmd_step_right(&ncp, &width, NULL);
        if (cmd_col + width >= sc_width)
                cmd_lshift();
        else if (cmd_col + width == sc_width - 1 && cp[1] != '\0')
                cmd_lshift();
        cp = ncp;
        cmd_col += width;
        putstr(pr);
        while (*cp != '\0') {
                pr = cmd_step_right(&ncp, &width, NULL);
                if (width > 0)
                        break;
                putstr(pr);
                cp = ncp;
        }
        return (CC_OK);
}

/*
 * Move cursor left one character.
 */
static int
cmd_left(void)
{
        char *ncp;
        int width, bswidth;

        if (cp <= cmdbuf) {
                /* Already at the beginning of the line */
                return (CC_OK);
        }
        ncp = cp;
        while (ncp > cmdbuf) {
                cmd_step_left(&ncp, &width, &bswidth);
                if (width > 0)
                        break;
        }
        if (cmd_col < prompt_col + width)
                cmd_rshift();
        cp = ncp;
        cmd_col -= width;
        while (bswidth-- > 0)
                putbs();
        return (CC_OK);
}

/*
 * Insert a char into the command buffer, at the current position.
 */
static int
cmd_ichar(char *cs, int clen)
{
        char *s;

        if (strlen(cmdbuf) + clen >= sizeof (cmdbuf)-1) {
                /* No room in the command buffer for another char. */
                ring_bell();
                return (CC_ERROR);
        }

        /*
         * Make room for the new character (shift the tail of the buffer right).
         */
        for (s = &cmdbuf[strlen(cmdbuf)]; s >= cp; s--)
                s[clen] = s[0];
        /*
         * Insert the character into the buffer.
         */
        for (s = cp; s < cp + clen; s++)
                *s = *cs++;
        /*
         * Reprint the tail of the line from the inserted char.
         */
        updown_match = -1;
        cmd_repaint(cp);
        cmd_right();
        return (CC_OK);
}

/*
 * Backspace in the command buffer.
 * Delete the char to the left of the cursor.
 */
static int
cmd_erase(void)
{
        char *s;
        int clen;

        if (cp == cmdbuf) {
                /*
                 * Backspace past beginning of the buffer:
                 * this usually means abort the command.
                 */
                return (CC_QUIT);
        }
        /*
         * Move cursor left (to the char being erased).
         */
        s = cp;
        cmd_left();
        clen = s - cp;

        /*
         * Remove the char from the buffer (shift the buffer left).
         */
        for (s = cp; ; s++) {
                s[0] = s[clen];
                if (s[0] == '\0')
                        break;
        }

        /*
         * Repaint the buffer after the erased char.
         */
        updown_match = -1;
        cmd_repaint(cp);

        /*
         * We say that erasing the entire command string causes us
         * to abort the current command, if CF_QUIT_ON_ERASE is set.
         */
        if ((curr_cmdflags & CF_QUIT_ON_ERASE) && cp == cmdbuf && *cp == '\0')
                return (CC_QUIT);
        return (CC_OK);
}

/*
 * Delete the char under the cursor.
 */
static int
cmd_delete(void)
{
        if (*cp == '\0') {
                /* At end of string; there is no char under the cursor. */
                return (CC_OK);
        }
        /*
         * Move right, then use cmd_erase.
         */
        cmd_right();
        cmd_erase();
        return (CC_OK);
}

/*
 * Delete the "word" to the left of the cursor.
 */
static int
cmd_werase(void)
{
        if (cp > cmdbuf && cp[-1] == ' ') {
                /*
                 * If the char left of cursor is a space,
                 * erase all the spaces left of cursor (to the first non-space).
                 */
                while (cp > cmdbuf && cp[-1] == ' ')
                        (void) cmd_erase();
        } else {
                /*
                 * If the char left of cursor is not a space,
                 * erase all the nonspaces left of cursor (the whole "word").
                 */
                while (cp > cmdbuf && cp[-1] != ' ')
                        (void) cmd_erase();
        }
        return (CC_OK);
}

/*
 * Delete the "word" under the cursor.
 */
static int
cmd_wdelete(void)
{
        if (*cp == ' ') {
                /*
                 * If the char under the cursor is a space,
                 * delete it and all the spaces right of cursor.
                 */
                while (*cp == ' ')
                        (void) cmd_delete();
        } else {
                /*
                 * If the char under the cursor is not a space,
                 * delete it and all nonspaces right of cursor (the whole word).
                 */
                while (*cp != ' ' && *cp != '\0')
                        (void) cmd_delete();
        }
        return (CC_OK);
}

/*
 * Delete all chars in the command buffer.
 */
static int
cmd_kill(void)
{
        if (cmdbuf[0] == '\0') {
                /* Buffer is already empty; abort the current command. */
                return (CC_QUIT);
        }
        cmd_offset = 0;
        cmd_home();
        *cp = '\0';
        updown_match = -1;
        cmd_repaint(cp);

        /*
         * We say that erasing the entire command string causes us
         * to abort the current command, if CF_QUIT_ON_ERASE is set.
         */
        if (curr_cmdflags & CF_QUIT_ON_ERASE)
                return (CC_QUIT);
        return (CC_OK);
}

/*
 * Select an mlist structure to be the current command history.
 */
void
set_mlist(void *mlist, int cmdflags)
{
        curr_mlist = (struct mlist *)mlist;
        curr_cmdflags = cmdflags;

        /* Make sure the next up-arrow moves to the last string in the mlist. */
        if (curr_mlist != NULL)
                curr_mlist->curr_mp = curr_mlist;
}

/*
 * Move up or down in the currently selected command history list.
 * Only consider entries whose first updown_match chars are equal to
 * cmdbuf's corresponding chars.
 */
static int
cmd_updown(int action)
{
        char *s;
        struct mlist *ml;

        if (curr_mlist == NULL) {
                /*
                 * The current command has no history list.
                 */
                ring_bell();
                return (CC_OK);
        }

        if (updown_match < 0) {
                updown_match = cp - cmdbuf;
        }

        /*
         * Find the next history entry which matches.
         */
        for (ml = curr_mlist->curr_mp; ; ) {
                ml = (action == EC_UP) ? ml->prev : ml->next;
                if (ml == curr_mlist) {
                        /*
                         * We reached the end (or beginning) of the list.
                         */
                        break;
                }
                if (strncmp(cmdbuf, ml->string, updown_match) == 0) {
                        /*
                         * This entry matches; stop here.
                         * Copy the entry into cmdbuf and echo it on the screen.
                         */
                        curr_mlist->curr_mp = ml;
                        s = ml->string;
                        if (s == NULL)
                                s = "";
                        cmd_home();
                        clear_eol();
                        strlcpy(cmdbuf, s, sizeof (cmdbuf));
                        for (cp = cmdbuf; *cp != '\0'; )
                                cmd_right();
                        return (CC_OK);
                }
        }
        /*
         * We didn't find a history entry that matches.
         */
        ring_bell();
        return (CC_OK);
}

/*
 * Add a string to a history list.
 */
void
cmd_addhist(struct mlist *mlist, const char *cmd)
{
        struct mlist *ml;

        /*
         * Don't save a trivial command.
         */
        if (strlen(cmd) == 0)
                return;

        /*
         * Save the command unless it's a duplicate of the
         * last command in the history.
         */
        ml = mlist->prev;
        if (ml == mlist || strcmp(ml->string, cmd) != 0) {
                /*
                 * Did not find command in history.
                 * Save the command and put it at the end of the history list.
                 */
                ml = ecalloc(1, sizeof (struct mlist));
                ml->string = estrdup(cmd);
                ml->next = mlist;
                ml->prev = mlist->prev;
                mlist->prev->next = ml;
                mlist->prev = ml;
        }
        /*
         * Point to the cmd just after the just-accepted command.
         * Thus, an UPARROW will always retrieve the previous command.
         */
        mlist->curr_mp = ml->next;
}

/*
 * Accept the command in the command buffer.
 * Add it to the currently selected history list.
 */
void
cmd_accept(void)
{
        /*
         * Nothing to do if there is no currently selected history list.
         */
        if (curr_mlist == NULL)
                return;
        cmd_addhist(curr_mlist, cmdbuf);
        curr_mlist->modified = 1;
}

/*
 * Try to perform a line-edit function on the command buffer,
 * using a specified char as a line-editing command.
 * Returns:
 *      CC_PASS The char does not invoke a line edit function.
 *      CC_OK   Line edit function done.
 *      CC_QUIT The char requests the current command to be aborted.
 */
static int
cmd_edit(int c)
{
        int action;
        int flags;

#define not_in_completion()     in_completion = 0

        /*
         * See if the char is indeed a line-editing command.
         */
        flags = 0;
        if (curr_mlist == NULL)
                /*
                 * No current history; don't accept history manipulation cmds.
                 */
                flags |= EC_NOHISTORY;
        if (curr_mlist == ml_search)
                /*
                 * In a search command; don't accept file-completion cmds.
                 */
                flags |= EC_NOCOMPLETE;

        action = editchar(c, flags);

        switch (action) {
        case EC_RIGHT:
                not_in_completion();
                return (cmd_right());
        case EC_LEFT:
                not_in_completion();
                return (cmd_left());
        case EC_W_RIGHT:
                not_in_completion();
                while (*cp != '\0' && *cp != ' ')
                        cmd_right();
                while (*cp == ' ')
                        cmd_right();
                return (CC_OK);
        case EC_W_LEFT:
                not_in_completion();
                while (cp > cmdbuf && cp[-1] == ' ')
                        cmd_left();
                while (cp > cmdbuf && cp[-1] != ' ')
                        cmd_left();
                return (CC_OK);
        case EC_HOME:
                not_in_completion();
                cmd_offset = 0;
                cmd_home();
                cmd_repaint(cp);
                return (CC_OK);
        case EC_END:
                not_in_completion();
                while (*cp != '\0')
                        cmd_right();
                return (CC_OK);
        case EC_INSERT:
                not_in_completion();
                return (CC_OK);
        case EC_BACKSPACE:
                not_in_completion();
                return (cmd_erase());
        case EC_LINEKILL:
                not_in_completion();
                return (cmd_kill());
        case EC_ABORT:
                not_in_completion();
                (void) cmd_kill();
                return (CC_QUIT);
        case EC_W_BACKSPACE:
                not_in_completion();
                return (cmd_werase());
        case EC_DELETE:
                not_in_completion();
                return (cmd_delete());
        case EC_W_DELETE:
                not_in_completion();
                return (cmd_wdelete());
        case EC_LITERAL:
                literal = 1;
                return (CC_OK);
        case EC_UP:
        case EC_DOWN:
                not_in_completion();
                return (cmd_updown(action));
        case EC_F_COMPLETE:
        case EC_B_COMPLETE:
        case EC_EXPAND:
                return (cmd_complete(action));
        case EC_NOACTION:
                return (CC_OK);
        default:
                not_in_completion();
                return (CC_PASS);
        }
}

/*
 * Insert a string into the command buffer, at the current position.
 */
static int
cmd_istr(char *str)
{
        char *s;
        int action;
        char *endline = str + strlen(str);

        for (s = str; *s != '\0'; ) {
                char *os = s;
                step_char(&s, +1, endline);
                action = cmd_ichar(os, s - os);
                if (action != CC_OK) {
                        ring_bell();
                        return (action);
                }
        }
        return (CC_OK);
}

/*
 * Find the beginning and end of the "current" word.
 * This is the word which the cursor (cp) is inside or at the end of.
 * Return pointer to the beginning of the word and put the
 * cursor at the end of the word.
 */
static char *
delimit_word(void)
{
        char *word;
        char *p;
        int delim_quoted = 0;
        int meta_quoted = 0;
        char *esc = get_meta_escape();
        int esclen = strlen(esc);

        /*
         * Move cursor to end of word.
         */
        if (*cp != ' ' && *cp != '\0') {
                /*
                 * Cursor is on a nonspace.
                 * Move cursor right to the next space.
                 */
                while (*cp != ' ' && *cp != '\0')
                        cmd_right();
        }

        /*
         * Find the beginning of the word which the cursor is in.
         */
        if (cp == cmdbuf)
                return (NULL);
        /*
         * If we have an unbalanced quote (that is, an open quote
         * without a corresponding close quote), we return everything
         * from the open quote, including spaces.
         */
        for (word = cmdbuf; word < cp; word++)
                if (*word != ' ')
                        break;
        if (word >= cp)
                return (cp);
        for (p = cmdbuf; p < cp; p++) {
                if (meta_quoted) {
                        meta_quoted = 0;
                } else if (esclen > 0 && p + esclen < cp &&
                    strncmp(p, esc, esclen) == 0) {
                        meta_quoted = 1;
                        p += esclen - 1;
                } else if (delim_quoted) {
                        if (*p == closequote)
                                delim_quoted = 0;
                } else { /* (!delim_quoted) */
                        if (*p == openquote)
                                delim_quoted = 1;
                        else if (*p == ' ')
                                word = p+1;
                }
        }
        return (word);
}

/*
 * Set things up to enter completion mode.
 * Expand the word under the cursor into a list of filenames
 * which start with that word, and set tk_text to that list.
 */
static void
init_compl(void)
{
        char *word;
        char c;

        free(tk_text);
        tk_text = NULL;
        /*
         * Find the original (uncompleted) word in the command buffer.
         */
        word = delimit_word();
        if (word == NULL)
                return;
        /*
         * Set the insertion point to the point in the command buffer
         * where the original (uncompleted) word now sits.
         */
        tk_ipoint = word;
        /*
         * Save the original (uncompleted) word
         */
        free(tk_original);
        tk_original = ecalloc(cp-word+1, sizeof (char));
        (void) strncpy(tk_original, word, cp-word);
        /*
         * Get the expanded filename.
         * This may result in a single filename, or
         * a blank-separated list of filenames.
         */
        c = *cp;
        *cp = '\0';
        if (*word != openquote) {
                tk_text = fcomplete(word);
        } else {
                char *qword = shell_quote(word+1);
                if (qword == NULL)
                        tk_text = fcomplete(word+1);
                else
                        tk_text = fcomplete(qword);
                free(qword);
        }
        *cp = c;
}

/*
 * Return the next word in the current completion list.
 */
static char *
next_compl(int action, char *prev)
{
        switch (action) {
        case EC_F_COMPLETE:
                return (forw_textlist(&tk_tlist, prev));
        case EC_B_COMPLETE:
                return (back_textlist(&tk_tlist, prev));
        }
        /* Cannot happen */
        return ("?");
}

/*
 * Complete the filename before (or under) the cursor.
 * cmd_complete may be called multiple times.  The global in_completion
 * remembers whether this call is the first time (create the list),
 * or a subsequent time (step thru the list).
 */
static int
cmd_complete(int action)
{
        char *s;

        if (!in_completion || action == EC_EXPAND) {
                /*
                 * Expand the word under the cursor and
                 * use the first word in the expansion
                 * (or the entire expansion if we're doing EC_EXPAND).
                 */
                init_compl();
                if (tk_text == NULL) {
                        ring_bell();
                        return (CC_OK);
                }
                if (action == EC_EXPAND) {
                        /*
                         * Use the whole list.
                         */
                        tk_trial = tk_text;
                } else {
                        /*
                         * Use the first filename in the list.
                         */
                        in_completion = 1;
                        init_textlist(&tk_tlist, tk_text);
                        tk_trial = next_compl(action, NULL);
                }
        } else {
                /*
                 * We already have a completion list.
                 * Use the next/previous filename from the list.
                 */
                tk_trial = next_compl(action, tk_trial);
        }

        /*
         * Remove the original word, or the previous trial completion.
         */
        while (cp > tk_ipoint)
                (void) cmd_erase();

        if (tk_trial == NULL) {
                /*
                 * There are no more trial completions.
                 * Insert the original (uncompleted) filename.
                 */
                in_completion = 0;
                if (cmd_istr(tk_original) != CC_OK)
                        goto fail;
        } else {
                /*
                 * Insert trial completion.
                 */
                if (cmd_istr(tk_trial) != CC_OK)
                        goto fail;
                /*
                 * If it is a directory, append a slash.
                 */
                if (is_dir(tk_trial)) {
                        if (cp > cmdbuf && cp[-1] == closequote)
                                (void) cmd_erase();
                        s = lgetenv("LESSSEPARATOR");
                        if (s == NULL)
                                s = "/";
                        if (cmd_istr(s) != CC_OK)
                                goto fail;
                }
        }

        return (CC_OK);

fail:
        in_completion = 0;
        ring_bell();
        return (CC_OK);
}

/*
 * Process a single character of a multi-character command, such as
 * a number, or the pattern of a search command.
 * Returns:
 *      CC_OK           The char was accepted.
 *      CC_QUIT         The char requests the command to be aborted.
 *      CC_ERROR        The char could not be accepted due to an error.
 */
int
cmd_char(int c)
{
        int action;
        int len;

        if (!utf_mode) {
                cmd_mbc_buf[0] = c & 0xff;
                len = 1;
        } else {
                /* Perform strict validation in all possible cases.  */
                if (cmd_mbc_buf_len == 0) {
retry:
                        cmd_mbc_buf_index = 1;
                        *cmd_mbc_buf = c & 0xff;
                        if (isascii((unsigned char)c))
                                cmd_mbc_buf_len = 1;
                        else if (IS_UTF8_LEAD(c)) {
                                cmd_mbc_buf_len = utf_len(c);
                                return (CC_OK);
                        } else {
                                /* UTF8_INVALID or stray UTF8_TRAIL */
                                ring_bell();
                                return (CC_ERROR);
                        }
                } else if (IS_UTF8_TRAIL(c)) {
                        cmd_mbc_buf[cmd_mbc_buf_index++] = c & 0xff;
                        if (cmd_mbc_buf_index < cmd_mbc_buf_len)
                                return (CC_OK);
                        if (!is_utf8_well_formed(cmd_mbc_buf)) {
                                /*
                                 * complete, but not well formed
                                 * (non-shortest form), sequence
                                 */
                                cmd_mbc_buf_len = 0;
                                ring_bell();
                                return (CC_ERROR);
                        }
                } else {
                        /* Flush incomplete (truncated) sequence.  */
                        cmd_mbc_buf_len = 0;
                        ring_bell();
                        /* Handle new char.  */
                        goto retry;
                }

                len = cmd_mbc_buf_len;
                cmd_mbc_buf_len = 0;
        }

        if (literal) {
                /*
                 * Insert the char, even if it is a line-editing char.
                 */
                literal = 0;
                return (cmd_ichar(cmd_mbc_buf, len));
        }

        /*
         * See if it is a line-editing character.
         */
        if (in_mca() && len == 1) {
                action = cmd_edit(c);
                switch (action) {
                case CC_OK:
                case CC_QUIT:
                        return (action);
                case CC_PASS:
                        break;
                }
        }

        /*
         * Insert the char into the command buffer.
         */
        return (cmd_ichar(cmd_mbc_buf, len));
}

/*
 * Return the number currently in the command buffer.
 */
off_t
cmd_int(long *frac)
{
        char *p;
        off_t n = 0;
        int err;

        for (p = cmdbuf; *p >= '0' && *p <= '9'; p++)
                n = (n * 10) + (*p - '0');
        *frac = 0;
        if (*p++ == '.') {
                *frac = getfraction(&p, NULL, &err);
                /* {{ do something if err is set? }} */
        }
        return (n);
}

/*
 * Return a pointer to the command buffer.
 */
char *
get_cmdbuf(void)
{
        return (cmdbuf);
}

/*
 * Return the last (most recent) string in the current command history.
 */
char *
cmd_lastpattern(void)
{
        if (curr_mlist == NULL)
                return (NULL);
        return (curr_mlist->curr_mp->prev->string);
}

/*
 * Get the name of the history file.
 */
static char *
histfile_name(void)
{
        char *home;
        char *name;

        /* See if filename is explicitly specified by $LESSHISTFILE. */
        name = lgetenv("LESSHISTFILE");
        if (name != NULL && *name != '\0') {
                if (strcmp(name, "-") == 0 || strcmp(name, "/dev/null") == 0)
                        /* $LESSHISTFILE == "-" means don't use history file */
                        return (NULL);
                return (estrdup(name));
        }

        /* Otherwise, file is in $HOME if enabled. */
        if (strcmp(LESSHISTFILE, "-") == 0)
                return (NULL);
        home = lgetenv("HOME");
        if (home == NULL || *home == '\0') {
                return (NULL);
        }
        return (easprintf("%s/%s", home, LESSHISTFILE));
}

/*
 * Initialize history from a .lesshist file.
 */
void
init_cmdhist(void)
{
        struct mlist *ml = NULL;
        char line[CMDBUF_SIZE];
        char *filename;
        FILE *f;
        char *p;

        if (secure)
                return;
        filename = histfile_name();
        if (filename == NULL)
                return;
        f = fopen(filename, "r");
        free(filename);
        if (f == NULL)
                return;
        if (fgets(line, sizeof (line), f) == NULL ||
            strncmp(line, HISTFILE_FIRST_LINE,
            strlen(HISTFILE_FIRST_LINE)) != 0) {
                (void) fclose(f);
                return;
        }
        while (fgets(line, sizeof (line), f) != NULL) {
                for (p = line; *p != '\0'; p++) {
                        if (*p == '\n' || *p == '\r') {
                                *p = '\0';
                                break;
                        }
                }
                if (strcmp(line, HISTFILE_SEARCH_SECTION) == 0)
                        ml = &mlist_search;
                else if (strcmp(line, HISTFILE_SHELL_SECTION) == 0) {
                        ml = &mlist_shell;
                } else if (*line == '"') {
                        if (ml != NULL)
                                cmd_addhist(ml, line+1);
                }
        }
        (void) fclose(f);
}

/*
 *
 */
static void
save_mlist(struct mlist *ml, FILE *f)
{
        int histsize = 0;
        int n;
        char *s;

        s = lgetenv("LESSHISTSIZE");
        if (s != NULL)
                histsize = atoi(s);
        if (histsize == 0)
                histsize = 100;

        ml = ml->prev;
        for (n = 0; n < histsize; n++) {
                if (ml->string == NULL)
                        break;
                ml = ml->prev;
        }
        for (ml = ml->next; ml->string != NULL; ml = ml->next)
                (void) fprintf(f, "\"%s\n", ml->string);
}

/*
 *
 */
void
save_cmdhist(void)
{
        char *filename;
        FILE *f;
        int modified = 0;
        int do_chmod = 1;
        struct stat statbuf;
        int r;

        if (secure)
                return;
        if (mlist_search.modified)
                modified = 1;
        if (mlist_shell.modified)
                modified = 1;
        if (!modified)
                return;
        filename = histfile_name();
        if (filename == NULL)
                return;
        f = fopen(filename, "w");
        free(filename);
        if (f == NULL)
                return;

        /* Make history file readable only by owner. */
        r = fstat(fileno(f), &statbuf);
        if (r == -1 || !S_ISREG(statbuf.st_mode))
                /* Don't chmod if not a regular file. */
                do_chmod = 0;
        if (do_chmod)
                (void) fchmod(fileno(f), 0600);

        (void) fprintf(f, "%s\n", HISTFILE_FIRST_LINE);

        (void) fprintf(f, "%s\n", HISTFILE_SEARCH_SECTION);
        save_mlist(&mlist_search, f);

        (void) fprintf(f, "%s\n", HISTFILE_SHELL_SECTION);
        save_mlist(&mlist_shell, f);

        (void) fclose(f);
}