/*
 * Author: Sven Gothel <sgothel@jausoft.com>
 * Copyright (c) 2008-2010 Bjoern Hoehrmann <bjoern@hoehrmann.de> (see details below)
 * Copyright (c) 2020 Gothel Software e.K.
 * Copyright (c) 2020 ZAFENA AB
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include "direct_bt/dfa_utf8_decode.hpp"

std::string dfa_utf8_decode(const uint8_t *buffer, const size_t buffer_size) {
    uint32_t codepoint;
    uint32_t state = DFA_UTF8_ACCEPT;
    size_t byte_count;
    const uint8_t *ibuffer = buffer;

    for( byte_count = 0; byte_count < buffer_size && *ibuffer; byte_count++ ) {
        if ( DFA_UTF8_REJECT == dfa_utf8_decode(state, codepoint, *ibuffer++) ) {
            break; // not a valid byte for a utf8 stream, end here!
        } // else DFA_UTF8_ACCEPT -> valid_utf8_chars++
    }
    if( 0 < byte_count ) {
        return std::string( (const char*)buffer, byte_count );
    }
    return std::string();
}

/************************************************************************/
/************************************************************************/
/************************************************************************/

/**
 * Copyright (c) 2008-2010 Bjoern Hoehrmann <bjoern@hoehrmann.de>
 * See http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute,
 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

static const uint8_t dfa_utf8d[] = {
    // The first part of the table maps bytes to character classes that
    // to reduce the size of the transition table and create bitmasks.
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,  9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
    7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
    8,8,2,2,2,2,2,2,2,2,2,2,2,2,2,2,  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
    10,3,3,3,3,3,3,3,3,3,3,3,3,4,3,3, 11,6,6,6,5,8,8,8,8,8,8,8,8,8,8,8,

    // The second part is a transition table that maps a combination
    // of a state of the automaton and a character class to a state.
    0,12,24,36,60,96,84,12,12,12,48,72, 12,12,12,12,12,12,12,12,12,12,12,12,
    12, 0,12,12,12,12,12, 0,12, 0,12,12, 12,24,12,12,12,12,12,24,12,24,12,12,
    12,12,12,12,12,12,12,24,12,12,12,12, 12,24,12,12,12,12,12,12,12,24,12,12,
    12,12,12,12,12,12,12,36,12,36,12,12, 12,36,12,12,12,12,12,36,12,36,12,12,
    12,36,12,12,12,12,12,12,12,12,12,12,
};

uint32_t dfa_utf8_decode(uint32_t & state, uint32_t & codep, const uint32_t byte_value) {
  const uint32_t type = dfa_utf8d[byte_value];

  codep = (state != DFA_UTF8_ACCEPT) ?
    (byte_value & 0x3fu) | (codep << 6) :
    (0xff >> type) & (byte_value);

  state = dfa_utf8d[256 + state + type];
  return state;
}