/* =========================================================================
 * Freetype GL - A C OpenGL Freetype engine
 * Platform:    Any
 * WWW:         https://github.com/rougier/freetype-gl
 * -------------------------------------------------------------------------
 * Copyright 2011,2012 Nicolas P. Rougier. All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY NICOLAS P. ROUGIER ''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 NICOLAS P. ROUGIER 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.
 *
 * The views and conclusions contained in the software and documentation are
 * those of the authors and should not be interpreted as representing official
 * policies, either expressed or implied, of Nicolas P. Rougier.
 * ========================================================================= */

#include <string.h>
#include "utf8-utils.h"

// ----------------------------------------------------- utf8_surrogate_len ---
size_t
utf8_surrogate_len( const char* character )
{
    size_t result = 0;
    char test_char;

    if (!character)
        return 0;

    test_char = character[0];

    if ((test_char & 0x80) == 0)
        return 1;

    while (test_char & 0x80)
    {
        test_char <<= 1;
        result++;
    }

    return result;
}

// ------------------------------------------------------------ utf8_strlen ---
size_t
utf8_strlen( const char* string )
{
    const char* ptr = string;
    size_t result = 0;

    while (*ptr)
    {
        ptr += utf8_surrogate_len(ptr);
        result++;
    }

    return result;
}

uint32_t
utf8_to_utf32( const char * character )
{
    uint32_t result = -1;

    if( !character )
    {
        return result;
    }

    if( ( character[0] & 0x80 ) == 0x0 )
    {
        result = character[0];
    }

    if( ( character[0] & 0xC0 ) == 0xC0 )
    {
        result = ( ( character[0] & 0x3F ) << 6 ) | ( character[1] & 0x3F );
    }

    if( ( character[0] & 0xE0 ) == 0xE0 )
    {
        result = ( ( character[0] & 0x1F ) << ( 6 + 6 ) ) | ( ( character[1] & 0x3F ) << 6 ) | ( character[2] & 0x3F );
    }

    if( ( character[0] & 0xF0 ) == 0xF0 )
    {
        result = ( ( character[0] & 0x0F ) << ( 6 + 6 + 6 ) ) | ( ( character[1] & 0x3F ) << ( 6 + 6 ) ) | ( ( character[2] & 0x3F ) << 6 ) | ( character[3] & 0x3F );
    }

    if( ( character[0] & 0xF8 ) == 0xF8 )
    {
        result = ( ( character[0] & 0x07 ) << ( 6 + 6 + 6 + 6 ) ) | ( ( character[1] & 0x3F ) << ( 6 + 6 + 6 ) ) | ( ( character[2] & 0x3F ) << ( 6 + 6 ) ) | ( ( character[3] & 0x3F ) << 6 ) | ( character[4] & 0x3F );
    }

    return result;
}