#ifndef MALACHSCRIPT_LEXER_HPP
#define MALACHSCRIPT_LEXER_HPP

#include <string_view>
#include "../../Diagnostics/Diagnostics.hpp"
#include "../../Utils/MemoryPool.hpp"
#include "LexToken.hpp"

namespace MalachScript::Parser {
    class Lexer {
    public:
        Lexer(const char8_t* scriptName, const char8_t* script, Diagnostics::Diagnostics* diag)
            : Lexer(std::u8string_view(scriptName), std::u8string_view(script), diag) {}
        Lexer(std::u8string_view scriptName, std::u8string_view script, Diagnostics::Diagnostics* diag)
            : _scriptName(scriptName), _script(script), _scriptLength(script.size()), _diagnostics(diag) {}
        const LexToken* Lex();

    private:
        std::u8string_view _scriptName;
        std::u8string_view _script;
        size_t _position = -1;
        size_t _scriptLength;
        Diagnostics::Diagnostics* _diagnostics;

        Utils::MemoryPool<2048, 1024> _allocator;

        inline char8_t Consume() {
            if (++_position >= _scriptLength) {
                return '\0';
            }
            return _script[_position];
        }

        inline void Progress(size_t steps = 1) { _position += steps; }

        inline char8_t Peek(size_t offset = 1) {
            auto pos = _position + offset;
            if (pos >= _scriptLength) {
                return '\0';
            }
            return _script[pos];
        }

        LexToken* LexNext();
        LexToken* LexNumerical(char8_t);
        LexToken* LexDecimal(uint64_t initial);
        IntegerLiteral* LexHexadecimal();
        IntegerLiteral* LexOctal();
        IntegerLiteral* LexBinary();

        StringLiteral* LexString(char8_t opening, bool heredoc);
        LexToken* LexKeywordOrIdentifier();

        static bool IsAlphaNumericalOrUnderscore(char8_t c);

        template <class T, class... parameters> inline T* Create(parameters... args) {
            return _allocator.Create<T>(args...);
        }

        inline void LogError(Diagnostics::DiagnosticType type, TextSpan span) {
            _diagnostics->LogError(type, _scriptName, span);
        }
    };
}

#endif // MALACHSCRIPT_LEXER_HPP