/* $Id: utf8.c,v 1.3 2013/06/09 20:11:30 steffen Exp $ */
/* utf8.c
 * Copyright (C) Steffen Pohle 2013 <steffen@gulpe.de>
 *
 * spOSMroute is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * spOSMroute is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */


#include <stdlib.h>
#include <strings.h>
#include "system.h"
#include "utf8.h"


/*
 * 84218421 84218421 84218421 84218421
 * -----------------------------------
 * 00000000 00000000 00000000 0aaaaaaa = FF FF FF 80 > 0
 * 00000000 00000000 00000bbb bbaaaaaa = FF FF F8 00 > 1
 * 00000000 00000000 ccccbbbb bbaaaaaa = FF FF 00 00 > 2
 * 00000000 000dddcc ccccbbbb bbaaaaaa = FF E0 00 00 > 3
 * 000000ee ddddddcc ccccbbbb bbaaaaaa = FC 00 00 00 > 4
 * 0feeeeee ddddddcc ccccbbbb bbaaaaaa               > 5
 */


void u8_encode (char *dest, uint32_t key) {
	uint8_t maskor = 0;
	uint8_t maskand = 0;
	int blocks = 0;

	if  ((key & 0xFFFFFF80) == 0) {
		blocks = 0;
		maskand = 0x7F;
		maskor = 0x00;
	}
	else if ((key & 0xFFFFF800) == 0) {
		blocks = 1;
		maskand = 0x1F;
		maskor = 0xC0;
	}
	else if ((key & 0xFFFF0000) == 0) {
		blocks = 2;
		maskand = 0x0F;
		maskor = 0xE0;
	}
	else if ((key & 0xFFE00000) == 0) {
		blocks = 3;
		maskand = 0x07;
		maskor = 0xF0;
	}
	else if ((key & 0xFC000000) == 0) {
		blocks = 4;
		maskand = 0x03;
		maskor = 0xF8;
	}
	else {
		blocks = 5;
		maskand = 0x01;
		maskor = 0xFC;
	}

	dest[blocks+1] = 0;
	while (blocks>0) {
		dest[blocks] = (uint8_t)((key & 0x3F) | 0x80);
		key = key >> 6;
		blocks--;
	}

	*dest = (key & maskand) | maskor;
};



uint32_t u8_decode (char *str, int *charsize) {
	uint32_t chr = 0;
	int block = 0;
	uint8_t c = 0;

	/* check how many elements */
	c = *str;
	if ((c &  0x80) == 0) {
		block = 0;
		chr = c;
	}
	else if ((c & 0xE0) == 0xC0) {		// (str[0] & 111x xxxx) == 110x xxxx
		block = 1;
		chr = c & 0x1F;
	}
	else if ((c & 0xF0) == 0xE0) {		// (str[0] & 1111 xxxx) == 1110 xxxx
		block = 2;
		chr = c & 0x0F;
	}
	else if ((c & 0xF8) == 0xF0) {		// (str[0] & 1111 1xxx) == 1111 0xxx
		block = 3;
		chr = c & 0x07;
	}
	else if ((c & 0xFC) == 0xF8) {		// (str[0] & 1111 11xx) == 1111 10xx
		block = 4;
		chr = c & 0x03;
	}
	else if ((c & 0xFE) == 0xFC) {		// (str[0] & 1111 111x) == 1111 110x
		block = 5;
		chr = c & 0x01;
	}
	else {
		/* error: no valid code */
		if (charsize != NULL) *charsize = 0;
		return 0;
	}

	if (charsize != NULL) *charsize = block+1;	/* return size in bytes for utf8 char */
	str++;

	for (;block > 0; block--) {
		c = *str;
		if ((c & 0xC0) != 0X80) {
			/* error: no valid code */
			*charsize = 0;
			return 0;
		}
		chr <<= 6;
		chr |= (c & 0x3F);
		str++;
	}

	return chr;
};


/* return the size in chars not in bytes. */
int u8_strlen (char *str) {
	int cnt, i, j;
	int bytelen = strlen (str);

	for (cnt = 0, i = 0; i < bytelen;) {
		if (u8_decode (str+i, &j) == 0) {
			d_printf ("u8_strlen: something went wrong. str:%s i:%d  str+i:%s", str, i, str+i);
			return 0;
		}
		cnt++;
		i += j;
	}

	return cnt;
};


void u8_strcpy (char *dest, char *src, int pos, int len) {
	int curpos = 0;
	int size = 0;

	while (*src != 0 && curpos < pos+len) {
		u8_decode (src, &size);
		if (curpos >= pos) {
			memcpy (dest, src, size);
			dest += size;
		}
		curpos++;
		src += size;
	}
	*dest = 0;
};


void u8_strncat (char *dest, int size, char *src) {
	int len;
	len = strlen (src)+1;

	if (len + strlen(dest) > size)
		len = size - strlen(dest) - 1;
	memcpy (dest+strlen(dest), src, len);
	dest[size-1] = 0;
};


void u8_strdel (char *str, int start, int len) {
	int curpos = 0;
	char *nstr = str;
	int slen = u8_strlen (str);
	int size = 0;
	int clen = strlen (str);

	while (*nstr != 0 && curpos < slen) {
		u8_decode (nstr, &size);
		if (curpos >= start && curpos < start+len)	memmove (nstr, nstr+size, clen-(nstr-str));
		else nstr += size;
		curpos++;
	}
	*nstr = 0;
};


void u8_strninsert (char *str, int size, char *text, int pos) {
	char *nstr = str;
	int curpos = 0;
	int chrsize = 0;
	int len = u8_strlen (str);
	int clen = strlen (str);

	while (curpos <= len && curpos <= pos) { // no need to move
		if (curpos == pos) {
			int cnt = strlen (text);

			if (nstr-str + cnt >= size) {
				memcpy (nstr, text, size-(nstr-str)-1);
				str[size-1] = 0;
				break;
			}
			else if (clen + strlen(text) >= size) {	// need to move only part
				memmove (nstr+cnt, nstr, size-(nstr-str)-strlen(text));
				str[size-1] = 0;
			}
			else { 	// no overrun
				memmove (nstr+cnt, nstr, clen-(nstr-str));
				str[clen+cnt] = 0;
			}
			memcpy (nstr, text, strlen(text));

			break;
		}
		u8_decode (nstr, &chrsize);
		curpos++;
		nstr += chrsize;
	}
};