/*
 * Copyright (C) 2016 Mark Roszko <mark.roszko@gmail.com>
 * Copyright (C) 2016 QiEDA Developers
 *
 * 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 2 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 "sexpr/sexpr_parser.h"
#include "sexpr/sexpr_exception.h"
#include <cctype>
#include <iterator>
#include <stdexcept>
#include <stdlib.h>     /* strtod */

#include <fstream>
#include <streambuf>

namespace SEXPR
{
    const std::string PARSER::whitespaceCharacters = " \t\n\r\b\f\v";

    PARSER::PARSER() : m_lineNumber(0), m_lineOffset(0)
    {
    }

    PARSER::~PARSER()
    {
    }

    SEXPR* PARSER::Parse(const std::string &aString) 
    {
        std::string::const_iterator it = aString.begin();
        return parseString(aString, it);
    }

    SEXPR* PARSER::ParseFromFile(const std::string &aFileName)
    {
        std::string str = GetFileContents(aFileName);

        std::string::const_iterator it = str.begin();
        return parseString(str, it);
    }

    std::string PARSER::GetFileContents(const std::string &aFileName)
    {
        std::ifstream file(aFileName.c_str(), std::ios::binary);
        std::string str;

        // Faster than automatic allocation
        file.seekg(0, std::ios::end);

        auto length = file.tellg();
        if (length < 0)
        {
            throw PARSE_EXCEPTION("Error occurred attempting to read in file");
        }

        str.resize(static_cast<size_t>(length));
        file.seekg(0, std::ios::beg);

        file.read(&str[0], str.length());

        return str;
    }

    SEXPR* PARSER::parseString(const std::string& aString, std::string::const_iterator& it)
    {
        std::string::const_iterator eit = aString.end();
        for (; it != aString.end(); ++it)
        {
            if (*it == '\n')
            {
                m_lineNumber++;
                m_lineOffset = 0;
            }

            if (whitespaceCharacters.find(*it) != std::string::npos)
                continue;

            if (*it == '(')
            {
                std::advance(it, 1);

                SEXPR_LIST* list = new SEXPR_LIST(m_lineNumber);
                while (it != aString.end() && *it != ')')
                {
                    if (whitespaceCharacters.find(*it) != std::string::npos)
                    {
                        std::advance(it, 1);
                        continue;
                    }

                    SEXPR* item = parseString(aString, it);
                    list->AddChild(item);
                }

                if (it != aString.end())
                {
                    std::advance(it, 1);
                }

                return list;
            }
            else if (*it == ')')
            {
                return NULL;
            }
            else if (*it == '"')
            {
                size_t startPos = std::distance(aString.begin(), it) + 1;
                size_t closingPos = aString.find_first_of('"', startPos);

                if (closingPos != std::string::npos)
                {
                    SEXPR_STRING* str = new SEXPR_STRING(aString.substr(startPos, closingPos - startPos),m_lineNumber);
                    std::advance(it, closingPos - startPos + 2);

                    return str;
                }
                else
                {
                    throw PARSE_EXCEPTION("missing closing quote");
                }
            }
            else
            {
                size_t startPos = std::distance(aString.begin(), it);
                size_t closingPos = aString.find_first_of(whitespaceCharacters+"()", startPos);

                std::string tmp = aString.substr(startPos, closingPos - startPos);


                if (closingPos != std::string::npos)
                {
                    if (tmp.find_first_not_of("0123456789.") == std::string::npos ||
                        (tmp.size() > 1 && tmp[0] == '-' && tmp.find_first_not_of("0123456789.",1) == std::string::npos)
                        )
                    {
                        SEXPR* res;
                        if (tmp.find('.') != std::string::npos)
                        {
                            res = new SEXPR_DOUBLE(strtod(tmp.c_str(), NULL), m_lineNumber);
                            //floating point type
                        }
                        else
                        {
                            res = new SEXPR_INTEGER(strtoll(tmp.c_str(), NULL, 0), m_lineNumber);
                        }
                        std::advance(it, closingPos - startPos);
                        return res;
                    }
                    else
                    {
                        SEXPR_SYMBOL* str = new SEXPR_SYMBOL(tmp, m_lineNumber);
                        std::advance(it, closingPos - startPos);

                        return str;
                    }
                }
                else
                {
                    throw PARSE_EXCEPTION("format error");
                }
            }
        }

        return NULL;
    }
}