#include "jsonsax.hpp"

#include <assert.h>

#define CASE_IS_SPACE \

	case ' ':		  \

case '\n':			  \

case '\t':			  \

case '\r'

#define CASE_IS_DIGIT \

	case '0':		  \

case '1':			  \

case '2':			  \

case '3':			  \

case '4':			  \

case '5':			  \

case '6':			  \

case '7':			  \

case '8':			  \

case '9'

JSLXParser::JSLXParser(IJSLXBackend* pBackend)

    : m_pBackend(pBackend)

{}

bool JSLXParser::Parse()

{

    return GetNextChar() && ParseValue();

}

bool JSLXParser::_GetNextChar()

{

    if (!m_pBackend->Eof())

    {

        m_lastChar = m_pBackend->GetChar();

        return true;

    }

    return false;

}

bool JSLXParser::TrimWhiteSpace()

{

    do

    {

        switch(m_lastChar)

        {

        CASE_IS_SPACE:

            break;

        default:

            return true;

        }

    }

    while(_GetNextChar());

    return false;

}

bool JSLXParser::GetNextChar(bool trim /* = true */)

{

    if (trim)

    {

        return _GetNextChar() && TrimWhiteSpace();

    }

    return _GetNextChar();

}

bool JSLXParser::ParseValue()

{

    switch(m_lastChar)

    {

    case '[':

        return ParseArray();

    case '{':

        return ParseObject();

    case '"':

        return ParseString();

    case '-':

    CASE_IS_DIGIT:

        return ParseNumber();

    case 'n':

        return ParseNull();

    case 't':

        return ParseTrue();

    case 'f':

        return ParseFalse();

    default:

        return false;

    }

}

bool JSLXParser::ParseObject()

{

    assert(m_lastChar == '{');

    m_pBackend->OnStartObject();

    GetNextChar();

    while(ParsePair())

    {

        switch(m_lastChar)

        {

        case ',':

            GetNextChar();

            break;

        case '}':

            m_pBackend->OnStopObject();

            GetNextChar();

            return true;

        default:

            m_pBackend->OnError("ParseObject: invalid char");

            return false;

        }

    }

    if (m_lastChar != '}')

    {

        m_pBackend->OnError("ParseObject: invalid char");

        return false;

    }

    m_pBackend->OnStopObject();

    GetNextChar();

    return true;

}

bool JSLXParser::ParsePair()

{

    if (m_lastChar != '"')

    {

        m_pBackend->OnError("ParsePair: Invalid Key");

        return false;

    }

    if (!ParseString())

    {

        m_pBackend->OnError("ParsePair: Invalid Key");

        return false;

    }

    if (m_lastChar != ':')

    {

        m_pBackend->OnError("ParsePair: Missing pair separator");

        return false;

    }

    if (!GetNextChar())

    {

        m_pBackend->OnError("ParsePair: Missing value");

        return false;

    }

    return ParseValue();

}

bool JSLXParser::ParseArray()

{

    assert(m_lastChar == '[');

    if (!GetNextChar()) return false;

    while(ParseValue())

    {

        switch(m_lastChar)

        {

        case ',':

            GetNextChar();

            break;

        case ']':

            m_pBackend->OnStopArray();

            GetNextChar();

            return true;

        default:

            m_pBackend->OnError("ParseArray: Missing seperator in array");

            return false;

        }

    }

    if (m_lastChar != ']')

    {

        m_pBackend->OnError("ParseArray: Bad value in array");

        return false;

    }

    m_pBackend->OnStopArray();

    GetNextChar();

    return true;

}

bool JSLXParser::ParseString()

{

    assert(m_lastChar == '"');

    m_pBackend->OnStartString();

    while(GetNextChar())

    {

        switch(m_lastChar)

        {

        case '\\':

            GetNextChar();

            break;

        case '"':

            m_pBackend->OnStopString();

            GetNextChar();

            return true;

        }

    }

    return false;

}

bool JSLXParser::ParseNumber()

{

    assert(m_lastChar == '-' ||

        m_lastChar == '0' ||

        m_lastChar == '1' ||

        m_lastChar == '2' ||

        m_lastChar == '3' ||

        m_lastChar == '4' ||

        m_lastChar == '5' ||

        m_lastChar == '6' ||

        m_lastChar == '7' ||

        m_lastChar == '8' ||

        m_lastChar == '9');

    m_pBackend->OnStartNumber();

    while(GetNextChar())

    {

        switch(m_lastChar)

        {

            // TODO: lookup for correct number format.

        case 'e':

        case '-':

        case '.':

        CASE_IS_DIGIT:

            break;

        default:

            m_pBackend->OnStopNumber();

            return true;

        }

    }

    return true;

}

bool JSLXParser::ParseNull()

{

    if (ParseConstant("null"))

    {

        m_pBackend->OnNull();

        return true;

    }

    return false;

}

bool JSLXParser::ParseTrue()

{

    if (ParseConstant("true"))

    {

        m_pBackend->OnTrue();

        return true;

    }

    return false;

}

bool JSLXParser::ParseFalse()

{

    if (ParseConstant("false"))

    {

        m_pBackend->OnFalse();

        return true;

    }

    return false;

}

bool JSLXParser::ParseConstant(const char* constant)

{

    assert(m_lastChar == constant[0]);

    ++constant;

    while(GetNextChar())

    {

        if (*constant == '\0')

            return true;

        if (*constant != m_lastChar)

            return false;

        constant++;

    }

    return *constant == '\0';

}

#undef CASE_IS_DIGIT

#undef CASE_IS_SPACE