/*Copyright (C) 2010  Armin Preiml

This program 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.

This program 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 <iostream>
#include <vector>
#include <iconv.h>
#include <errno.h>

string convertToUTF8(string input)
{
    string output = "";

    //create convert description
    iconv_t cd = iconv_open("UTF-8", "ISO-8859-1");

    if (cd == (iconv_t)-1)  //error handling
    {
        cerr << "Convert to UTF-8 failed: ";

        switch (errno)      //detailed error messages (maybe it contains too much detail :)
        {
            case EMFILE:
            cerr << "{OPEN_MAX} files descriptors are currently open in the calling process.\n";
            case ENFILE:
            cerr << "Too many files are currently open in the system. \n";
            case ENOMEM:
            cerr << "Insufficient storage space is available. \n";
            case EINVAL:
            cerr << "The conversion specified by fromcode and tocode is not supported by the implementation. \n";

            default:
            cerr << "WTF?\n";
        }

    }
    else
    {
        const size_t inputSize = input.size();

        if (inputSize)  //input is not empty
        {
            //convert function doesn't accept const char *, therefore copy content into an char *
            vector<char> inputBuffer(input.begin(), input.end());
            char *inputBufferBegin = &inputBuffer[0];

            size_t inputBytesLeft = inputSize;  //bytes to convert

            static const size_t outputSize = 1000;
            size_t outputBytesLeft;

            char outputBuffer[outputSize];
            char *outputBufferBegin;

            while (inputBytesLeft > 0 )
            {
                outputBytesLeft = outputSize;
                outputBufferBegin = outputBuffer;

                if (iconv(cd, &inputBufferBegin, &inputBytesLeft, &outputBufferBegin, &outputBytesLeft) == (size_t)-1)
                {
                    switch (errno) {
                    case E2BIG: //outputBuffer is full
                        output += string(outputBuffer, outputSize);
                        break;

                    case EILSEQ:
                        cerr << "Invalid multibyte sequence.\n";
                        break;
                    case EINVAL:
                        cerr << "Incomplete multibyte sequence.\n";
                        break;

                    default:
                        cerr << "DUNNO\n";
                    }

                }
            }

            //read only relevant bytes from outputBuffer
            output += string(outputBuffer, outputSize - outputBytesLeft);

        }

    }

    iconv_close (cd);

    return output;
}