/****************************************************************************
 Copyright (c) 2020-2021 Simdsoft Limited.

 https://simdsoft.com
 
 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.
 ****************************************************************************/
#ifndef SIMDSOFT_FAST_CSV_HPP
#define SIMDSOFT_FAST_CSV_HPP

#include <type_traits>

/* The usage of fastl::fast_csv_parse_line
std::string buffer = read_file("xxx.csv");
const char* cursor = buffer.c_str();
while(*cursor) {
   cursor = fastl::fast_csv_parse_line(cursor, [&](const char* v_start, const char* v_end) {
       // do somethings, store or parse the column value
       // std::string value(v_start, v_end);
   });
}
*/

namespace xsbase
{
    /*
    * The common xsv fwd, the delimiter could be any other
    */
    template <int _Delimiter, typename _CStr, typename _Fty> inline _CStr fast_xsv_parse_line(_CStr s, _Fty&& op);

    /*
     * op prototype: op(const char* v_start, const char* v_end)
     */
    template <typename _CStr, typename _Fty> inline _CStr fast_csv_parse_line(_CStr s, _Fty&& op)
    {
        return fast_xsv_parse_line<(int)','>(s, std::forward<_Fty>(op));
    }

    /*
     * op prototype: op(const char* v_start, const char* v_end)
     */
    template <int _Delimiter, typename _CStr, typename _Fty> inline _CStr fast_xsv_parse_line(_CStr s, _Fty&& op)
    {
        // FSM
        enum
        {
            normal, // new field
            quote_field,
            quote_field_try_end,
            quote_field_end,
        } state;

        state = normal;

        _CStr _Start = s; // the start of every string
        _CStr _Ptr = s; // source string iterator
        _CStr _Quote = nullptr;
        int skipCRLF = 1;

    _L_loop:
        {
            switch ((int)*_Ptr)
            {
            case _Delimiter:
                switch (state)
                {
                case normal:
                    if (_Start <= _Ptr)
                        op(_Start, _Ptr);
                    _Start = _Ptr + 1;
                    break;
                case quote_field_try_end:
                    if (_Start < _Ptr)
                        op(_Start, _Ptr - 1);
                case quote_field_end:
                    state = normal;
                    _Start = _Ptr + 1; // skip the field end '\"'
                    break;
                default:; // quote_field, do nothing
                }

                break;
            case (int)'\"':
                switch (state)
                {
                case normal:
                    state = quote_field;
                    ++_Start; // skip left '\"'
                    break;
                case quote_field: // field end by right '\"'
                    _Quote = _Ptr;
                    state = quote_field_try_end; // delay 1 loop to detect whether is a
                                                  // inner quote, not end for field
                    break;
                case quote_field_try_end:
                    if (_Ptr - _Quote > 1)
                    {
                        state = quote_field_end;
                        op(_Start, _Ptr);
                    }
                    else
                    {
                        state = quote_field;
                    }
                    break;
                default:;
                }
                break;
            case (int)'\r':
                skipCRLF = 2;
            case (int)'\n':
                if (quote_field == state)
                {
                    skipCRLF = 0;
                    break;
                }
            case (int)'\0':
                switch (state)
                {
                case normal:
                    if (_Start <= _Ptr)
                        op(_Start, _Ptr);
                    break;
                case quote_field_try_end:
                    if (_Start < _Ptr)
                        op(_Start, _Ptr - 1);
                    break;
                default:; // other state, do nothing, quote_field, invalid csv format
                }
                goto _L_end;
            }
            ++_Ptr;

            goto _L_loop;
        }

    _L_end:
        return _Ptr + skipCRLF; // pointer to next line or after of
                                // null-termainted-charactor
    }
}

#endif