#pragma once

#include <LX_Parser.h>

namespace PashaBibko::LXC::Parser
{
    class ParserContext final
    {
        public:
            // Sets the information of the context //
            ParserContext(const Lexer::LexerOutput& inputTokens) :
                input(inputTokens), length(inputTokens.size()), index(0)
            {}

            // Returns a pointer to the token x-distance away (default 1) //
            inline const Lexer::Token* Peek(size_t peekDistance = 1) const
            {
                // Checks if at the end of the tokens before fetching to stop errors //
                size_t peekIndex = index + peekDistance;
                if (peekIndex >= length)
                    return nullptr;

                return &input[peekIndex];
            }

            // Returns a pointer to the current token //
            inline const Lexer::Token* At() const { return Peek(0); }

            // Advances x-distance in the tokens (default 1) //
            inline const Lexer::Token* Advance(size_t distance = 1)
            {
                // Adds the distance and checks if in bounds to stop read errors //
                index += distance;
                if (index >= length)
                    return nullptr;

                return &input[index];
            }

            // Checks if the tokens are the correct types //
            inline bool Expect(const std::span<const Lexer::Token::TokenType>& tokens) const
            {
                for (int i = 0; i < tokens.size(); i++)
                {
                    const Lexer::Token* current = Peek(i);
                    if (!current || current->type != tokens[i])
                        return false;
                }

                return true;
            }

            // Is the current index in bounds //
            inline bool InBounds() const { return index < length; }

            // Output //
            std::vector<FunctionAST> output;

        private:
            size_t index;

            const Lexer::LexerOutput& input;
            const size_t length;
    };
}