#include "hecl/Frontend.hpp"

namespace hecl::Frontend
{

int Scanner::_read()
{
    if (m_sourceIt == m_source.end())
        return -1;
    return *m_sourceIt++;
}

bool Scanner::read()
{
    if (ch == EOF)
        return false;
    if (ch == LF)
    {
        lastLine = std::move(currentLine);
        currentLine = std::string();
    }
    int c = _read();
    ch = char(c);
    if (ch == LF)
    {
        loc.line++;
        lfcol = loc.col;
        loc.col = 0;
    }
    else if (c != EOF)
    {
        currentLine += ch;
        loc.col++;
    }
    return c != EOF;
}

Token Scanner::next()
{
    if (ch == EOF)
        return Token(Token::Kind::Eof, loc);

    char c = ch;
    int tline = loc.line;
    int tcol = loc.col;
    int tlfcol = lfcol;
    read();

    // skip comments and newlines
    while (c != EOF && (c == COMMENT || isspace(c)))
    {
        if (c == COMMENT)
        {
            while (c != LF && c != EOF)
            {
                tline = loc.line;
                tcol = loc.col;
                tlfcol = lfcol;
                c = ch;
                read();
            }
        }
        while (c != EOF && isspace(c))
        {
            if (c == LF)
                return Token(Token::Kind::Lf, {tline - 1, tlfcol + 1});
            tline = loc.line;
            tcol = loc.col;
            tlfcol = lfcol;
            c = ch;
            read();
        }
    }

    Token::Kind kind = CharToTokenKind(c);
    if (kind != Token::Kind::None)
        return Token(kind, {tline, tcol});

    if (ch == EOF)
        return Token(Token::Kind::Eof, {tline, tcol});

    // ident or number
    if (isDigit(c))
    {
        std::string buf;
        buf += c;
        while (isDigit(ch))
        {
            buf += ch;
            read();
        }
        if (ch == '.')
        { // float
            buf += ch;
            read();
            while (isDigit(ch))
            {
                buf += ch;
                read();
            }
        }
        return Token(Token::Kind::Number, std::move(buf), {tline, tcol});
    }

    if (isStartIdent(c))
    {
        std::string buf;
        buf += c;
        while (isMidIdent(ch))
        {
            buf += ch;
            read();
        }
        return Token(Token::Kind::Ident, std::move(buf), {tline, tcol});
    }

    error({tline, tcol}, "unexpected character '%c' (X'%02X')", chr(c), int(c));

    return Token(Token::Kind::None, {tline, tcol});
}

}