/*
 * 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.
 */

/*
 * Routines to convert text in various ways.  Used by search.
 */

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

extern int utf_mode;

/*
 * Get the length of a buffer needed to convert a string.
 */
int
cvt_length(int len)
{
        if (utf_mode)
                /*
                 * Just copying a string in UTF-8 mode can cause it to grow
                 * in length.
                 * Four output bytes for one input byte is the worst case.
                 */
                len *= 4;
        return (len + 1);
}

/*
 * Allocate a chpos array for use by cvt_text.
 */
int *
cvt_alloc_chpos(int len)
{
        int i;
        int *chpos = ecalloc(sizeof (int), len);
        /* Initialize all entries to an invalid position. */
        for (i = 0; i < len; i++)
                chpos[i] = -1;
        return (chpos);
}

/*
 * Convert text.  Perform the transformations specified by ops.
 * Returns converted text in odst.  The original offset of each
 * odst character (when it was in osrc) is returned in the chpos array.
 */
void
cvt_text(char *odst, char *osrc, int *chpos, int *lenp, int ops)
{
        char *dst;
        char *edst = odst;
        char *src;
        char *src_end;
        wchar_t ch;
        int len;

        if (lenp != NULL)
                src_end = osrc + *lenp;
        else
                src_end = osrc + strlen(osrc);

        for (src = osrc, dst = odst; src < src_end; ) {
                int src_pos = src - osrc;
                int dst_pos = dst - odst;
                if ((len = mbtowc(&ch, src, src_end - src)) < 1)
                        ch = L'\0';
                if ((ops & CVT_BS) && ch == '\b' && dst > odst) {
                        src++;
                        /* Delete backspace and preceding char. */
                        do {
                                dst--;
                        } while (dst > odst && IS_UTF8_TRAIL(*dst));
                } else if ((ops & CVT_ANSI) && ch == ESC) {
                        /* Skip to end of ANSI escape sequence. */
                        src++;  /* skip the CSI start char */
                        while (src < src_end)
                                if (!is_ansi_middle(*src++))
                                        break;
                } else if (len < 1) {
                        *dst++ = *src++;
                        if (chpos != NULL)
                                chpos[dst_pos] = src_pos;
                } else {
                        src += len;
                        /* Just copy the char to the destination buffer. */
                        if ((ops & CVT_TO_LC) && iswupper(ch))
                                ch = towlower(ch);
                        dst += wctomb(dst, ch);
                        /* Record the original position of the char. */
                        if (chpos != NULL)
                                chpos[dst_pos] = src_pos;
                }
                if (dst > edst)
                        edst = dst;
        }
        if ((ops & CVT_CRLF) && edst > odst && edst[-1] == '\r')
                edst--;
        *edst = '\0';
        if (lenp != NULL)
                *lenp = edst - odst;
}