#include "slang-token-reader.h"

namespace Slang {
namespace Misc {

    enum class TokenizeErrorType
    {
        InvalidCharacter, InvalidEscapeSequence
    };

    enum class State
    {
        Start, Identifier, Operator, Int, Hex, Fixed, Double, Char, String, MultiComment, SingleComment
    };

    enum class LexDerivative
    {
        None, Line, File
    };

    inline bool IsLetter(char ch)
    {
        return ((ch >= 'a' && ch <= 'z') ||
            (ch >= 'A' && ch <= 'Z') || ch == '_');
    }

    inline bool IsDigit(char ch)
    {
        return ch >= '0' && ch <= '9';
    }

    inline bool IsPunctuation(char ch)
    {
        return  ch == '+' || ch == '-' || ch == '*' || ch == '/' || ch == '%' ||
            ch == '!' || ch == '^' || ch == '&' || ch == '(' || ch == ')' ||
            ch == '=' || ch == '{' || ch == '}' || ch == '[' || ch == ']' ||
            ch == '|' || ch == ';' || ch == ',' || ch == '.' || ch == '<' ||
            ch == '>' || ch == '~' || ch == '@' || ch == ':' || ch == '?' || ch == '#';
    }

    inline bool IsWhiteSpace(char ch)
    {
        return (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r' || ch == '\v');
    }

    void ParseOperators(const String & str, List<Token> & tokens, TokenFlags& tokenFlags, int line, int col, int startPos, String fileName)
    {
        Index pos = 0;
        while (pos < str.getLength())
        {
            wchar_t curChar = str[pos];
            wchar_t nextChar = (pos < str.getLength() - 1) ? str[pos + 1] : '\0';
            wchar_t nextNextChar = (pos < str.getLength() - 2) ? str[pos + 2] : '\0';
            auto InsertToken = [&](TokenType type, const String & ct)
            {
                tokens.add(Token(type, ct, line, int(col + pos), int(pos + startPos), fileName, tokenFlags));
                tokenFlags = 0;
            };
            switch (curChar)
            {
            case '+':
                if (nextChar == '+')
                {
                    InsertToken(TokenType::OpInc, "++");
                    pos += 2;
                }
                else if (nextChar == '=')
                {
                    InsertToken(TokenType::OpAddAssign, "+=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpAdd, "+");
                    pos++;
                }
                break;
            case '-':
                if (nextChar == '-')
                {
                    InsertToken(TokenType::OpDec, "--");
                    pos += 2;
                }
                else if (nextChar == '=')
                {
                    InsertToken(TokenType::OpSubAssign, "-=");
                    pos += 2;
                }
                else if (nextChar == '>')
                {
                    InsertToken(TokenType::RightArrow, "->");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpSub, "-");
                    pos++;
                }
                break;
            case '*':
                if (nextChar == '=')
                {
                    InsertToken(TokenType::OpMulAssign, "*=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpMul, "*");
                    pos++;
                }
                break;
            case '/':
                if (nextChar == '=')
                {
                    InsertToken(TokenType::OpDivAssign, "/=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpDiv, "/");
                    pos++;
                }
                break;
            case '%':
                if (nextChar == '=')
                {
                    InsertToken(TokenType::OpModAssign, "%=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpMod, "%");
                    pos++;
                }
                break;
            case '|':
                if (nextChar == '|')
                {
                    InsertToken(TokenType::OpOr, "||");
                    pos += 2;
                }
                else if (nextChar == '=')
                {
                    InsertToken(TokenType::OpOrAssign, "|=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpBitOr, "|");
                    pos++;
                }
                break;
            case '&':
                if (nextChar == '&')
                {
                    InsertToken(TokenType::OpAnd, "&&");
                    pos += 2;
                }
                else if (nextChar == '=')
                {
                    InsertToken(TokenType::OpAndAssign, "&=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpBitAnd, "&");
                    pos++;
                }
                break;
            case '^':
                if (nextChar == '=')
                {
                    InsertToken(TokenType::OpXorAssign, "^=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpBitXor, "^");
                    pos++;
                }
                break;
            case '>':
                if (nextChar == '>')
                {
                    if (nextNextChar == '=')
                    {
                        InsertToken(TokenType::OpShrAssign, ">>=");
                        pos += 3;
                    }
                    else
                    {
                        InsertToken(TokenType::OpRsh, ">>");
                        pos += 2;
                    }
                }
                else if (nextChar == '=')
                {
                    InsertToken(TokenType::OpGeq, ">=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpGreater, ">");
                    pos++;
                }
                break;
            case '<':
                if (nextChar == '<')
                {
                    if (nextNextChar == '=')
                    {
                        InsertToken(TokenType::OpShlAssign, "<<=");
                        pos += 3;
                    }
                    else
                    {
                        InsertToken(TokenType::OpLsh, "<<");
                        pos += 2;
                    }
                }
                else if (nextChar == '=')
                {
                    InsertToken(TokenType::OpLeq, "<=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpLess, "<");
                    pos++;
                }
                break;
            case '=':
                if (nextChar == '=')
                {
                    InsertToken(TokenType::OpEql, "==");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpAssign, "=");
                    pos++;
                }
                break;
            case '!':
                if (nextChar == '=')
                {
                    InsertToken(TokenType::OpNeq, "!=");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::OpNot, "!");
                    pos++;
                }
                break;
            case '?':
                InsertToken(TokenType::QuestionMark, "?");
                pos++;
                break;
            case '@':
                InsertToken(TokenType::At, "@");
                pos++;
                break;
            case '#':
                if (nextChar == '#')
                {
                    InsertToken(TokenType::PoundPound, "##");
                    pos += 2;
                }
                else
                {
                    InsertToken(TokenType::Pound, "#");
                    pos++;
                }
                pos++;
                break;
            case ':':
                InsertToken(TokenType::Colon, ":");
                pos++;
                break;
            case '~':
                InsertToken(TokenType::OpBitNot, "~");
                pos++;
                break;
            case ';':
                InsertToken(TokenType::Semicolon, ";");
                pos++;
                break;
            case ',':
                InsertToken(TokenType::Comma, ",");
                pos++;
                break;
            case '.':
                InsertToken(TokenType::Dot, ".");
                pos++;
                break;
            case '{':
                InsertToken(TokenType::LBrace, "{");
                pos++;
                break;
            case '}':
                InsertToken(TokenType::RBrace, "}");
                pos++;
                break;
            case '[':
                InsertToken(TokenType::LBracket, "[");
                pos++;
                break;
            case ']':
                InsertToken(TokenType::RBracket, "]");
                pos++;
                break;
            case '(':
                InsertToken(TokenType::LParent, "(");
                pos++;
                break;
            case ')':
                InsertToken(TokenType::RParent, ")");
                pos++;
                break;
            }
        }
    }

    List<Token> TokenizeText(const String & fileName, const String & text)
    {
        Index lastPos = 0, pos = 0;
        int line = 1, col = 0;
        String file = fileName;
        State state = State::Start;
        StringBuilder tokenBuilder;
        int tokenLine, tokenCol;
        List<Token> tokenList;
        LexDerivative derivative = LexDerivative::None;
        TokenFlags tokenFlags = TokenFlag::AtStartOfLine;
        auto InsertToken = [&](TokenType type)
        {
            derivative = LexDerivative::None;
            tokenList.add(Token(type, tokenBuilder.toString(), tokenLine, tokenCol, int(pos), file, tokenFlags));
            tokenFlags = 0;
            tokenBuilder.clear();
        };
        auto ProcessTransferChar = [&](char nextChar)
        {
            switch (nextChar)
            {
            case '\\':
            case '\"':
            case '\'':
                tokenBuilder.append(nextChar);
                break;
            case 't':
                tokenBuilder.append('\t');
                break;
            case 's':
                tokenBuilder.append(' ');
                break;
            case 'n':
                tokenBuilder.append('\n');
                break;
            case 'r':
                tokenBuilder.append('\r');
                break;
            case 'b':
                tokenBuilder.append('\b');
                break;
            }
        };
        while (pos <= text.getLength())
        {
            char curChar = (pos < text.getLength() ? text[pos] : ' ');
            char nextChar = (pos < text.getLength() - 1) ? text[pos + 1] : '\0';
            if (lastPos != pos)
            {
                if (curChar == '\n')
                {
                    line++;
                    col = 0;
                }
                else
                    col++;
                lastPos = pos;
            }

            switch (state)
            {
            case State::Start:
                if (IsLetter(curChar))
                {
                    state = State::Identifier;
                    tokenLine = line;
                    tokenCol = col;
                }
                else if (IsDigit(curChar))
                {
                    state = State::Int;
                    tokenLine = line;
                    tokenCol = col;
                }
                else if (curChar == '\'')
                {
                    state = State::Char;
                    pos++;
                    tokenLine = line;
                    tokenCol = col;
                }
                else if (curChar == '"')
                {
                    state = State::String;
                    pos++;
                    tokenLine = line;
                    tokenCol = col;
                }
                else if (curChar == '\r' || curChar == '\n')
                {
                    tokenFlags |= TokenFlag::AtStartOfLine | TokenFlag::AfterWhitespace;
                    pos++;
                }
                else if (curChar == ' ' || curChar == '\t' || curChar == '\xC2' || curChar == '\xA0') // -62/-96:non-break space
                {
                    tokenFlags |= TokenFlag::AfterWhitespace;
                    pos++;
                }
                else if (curChar == '/' && nextChar == '/')
                {
                    state = State::SingleComment;
                    pos += 2;
                }
                else if (curChar == '/' && nextChar == '*')
                {
                    pos += 2;
                    state = State::MultiComment;
                }
                else if (curChar == '.' && IsDigit(nextChar))
                {
                    tokenBuilder.append("0.");
                    state = State::Fixed;
                    pos++;
                }
                else if (IsPunctuation(curChar))
                {
                    state = State::Operator;
                    tokenLine = line;
                    tokenCol = col;
                }
                else
                {
                    pos++;
                }
                break;
            case State::Identifier:
                if (IsLetter(curChar) || IsDigit(curChar))
                {
                    tokenBuilder.append(curChar);
                    pos++;
                }
                else
                {
                    auto tokenStr = tokenBuilder.toString();
#if 0
                    if (tokenStr == "#line_reset#")
                    {
                        line = 0;
                        col = 0;
                        tokenBuilder.clear();
                    }
                    else if (tokenStr == "#line")
                    {
                        derivative = LexDerivative::Line;
                        tokenBuilder.clear();
                    }
                    else if (tokenStr == "#file")
                    {
                        derivative = LexDerivative::File;
                        tokenBuilder.clear();
                        line = 0;
                        col = 0;
                    }
                    else
#endif
                        InsertToken(TokenType::Identifier);
                    state = State::Start;
                }
                break;
            case State::Operator:
                if (IsPunctuation(curChar) && !((curChar == '/' && nextChar == '/') || (curChar == '/' && nextChar == '*')))
                {
                    tokenBuilder.append(curChar);
                    pos++;
                }
                else
                {
                    //do token analyze
                    ParseOperators(tokenBuilder.toString(), tokenList, tokenFlags, tokenLine, tokenCol, (int)(pos - tokenBuilder.getLength()), file);
                    tokenBuilder.clear();
                    state = State::Start;
                }
                break;
            case State::Int:
                if (IsDigit(curChar))
                {
                    tokenBuilder.append(curChar);
                    pos++;
                }
                else if (curChar == '.')
                {
                    state = State::Fixed;
                    tokenBuilder.append(curChar);
                    pos++;
                }
                else if (curChar == 'e' || curChar == 'E')
                {
                    state = State::Double;
                    tokenBuilder.append(curChar);
                    if (nextChar == '-' || nextChar == '+')
                    {
                        tokenBuilder.append(nextChar);
                        pos++;
                    }
                    pos++;
                }
                else if (curChar == 'x')
                {
                    state = State::Hex;
                    tokenBuilder.append(curChar);
                    pos++;
                }
                else if (curChar == 'u')
                {
                    pos++;
                    tokenBuilder.append(curChar);
                    InsertToken(TokenType::IntLiteral);
                    state = State::Start;
                }
                else
                {
                    if (derivative == LexDerivative::Line)
                    {
                        derivative = LexDerivative::None;
                        line = stringToInt(tokenBuilder.toString()) - 1;
                        col = 0;
                        tokenBuilder.clear();
                    }
                    else
                    {
                        InsertToken(TokenType::IntLiteral);
                    }
                    state = State::Start;
                }
                break;
            case State::Hex:
                if (IsDigit(curChar) || (curChar >= 'a' && curChar <= 'f') || (curChar >= 'A' && curChar <= 'F'))
                {
                    tokenBuilder.append(curChar);
                    pos++;
                }
                else
                {
                    InsertToken(TokenType::IntLiteral);
                    state = State::Start;
                }
                break;
            case State::Fixed:
                if (IsDigit(curChar))
                {
                    tokenBuilder.append(curChar);
                    pos++;
                }
                else if (curChar == 'e' || curChar == 'E')
                {
                    state = State::Double;
                    tokenBuilder.append(curChar);
                    if (nextChar == '-' || nextChar == '+')
                    {
                        tokenBuilder.append(nextChar);
                        pos++;
                    }
                    pos++;
                }
                else
                {
                    if (curChar == 'f')
                        pos++;
                    InsertToken(TokenType::DoubleLiteral);
                    state = State::Start;
                }
                break;
            case State::Double:
                if (IsDigit(curChar))
                {
                    tokenBuilder.append(curChar);
                    pos++;
                }
                else
                {
                    if (curChar == 'f')
                        pos++;
                    InsertToken(TokenType::DoubleLiteral);
                    state = State::Start;
                }
                break;
            case State::String:
                if (curChar != '"')
                {
                    if (curChar == '\\')
                    {
                        ProcessTransferChar(nextChar);
                        pos++;
                    }
                    else
                        tokenBuilder.append(curChar);
                }
                else
                {
                    if (derivative == LexDerivative::File)
                    {
                        derivative = LexDerivative::None;
                        file = tokenBuilder.toString();
                        tokenBuilder.clear();
                    }
                    else
                    {
                        InsertToken(TokenType::StringLiteral);
                    }
                    state = State::Start;
                }
                pos++;
                break;
            case State::Char:
                if (curChar != '\'')
                {
                    if (curChar == '\\')
                    {
                        ProcessTransferChar(nextChar);
                        pos++;
                    }
                    else
                        tokenBuilder.append(curChar);
                }
                else
                {
                    InsertToken(TokenType::CharLiteral);
                    state = State::Start;
                }
                pos++;
                break;
            case State::SingleComment:
                if (curChar == '\n')
                {
                    state = State::Start;
                    tokenFlags |= TokenFlag::AtStartOfLine | TokenFlag::AfterWhitespace;
                }
                pos++;
                break;
            case State::MultiComment:
                if (curChar == '*' && nextChar == '/')
                {
                    state = State::Start;
                    tokenFlags |= TokenFlag::AfterWhitespace;
                    pos += 2;
                }
                else
                    pos++;
                break;
            }
        }
        return tokenList;
    }
    List<Token> TokenizeText(const String & text)
    {
        return TokenizeText("", text);
    }

    TokenReader::TokenReader(String text)
    {
        this->tokens = TokenizeText("", text);
        tokenPtr = 0;
    }

} // namespace Misc
} // namespace Slang