#pragma once

#include <filesystem>
#include <string>
#include <sstream>
#include <vector>
#include <unordered_map>

namespace dumb {
	class Compiler;

	struct Token {
		enum class Type {
			KEYWORD,
			IDENTIFIER,
			OPERATOR_PLUS,
			OPERATOR_MINUS,
			OPERATOR_ASTERISK,
			OPERATOR_SLASH,
			OPERATOR_EQUALS,
			OPERATOR_DOT,
			OPERATOR_COLON,
			OPERATOR_ARROW,
			OPERATOR_DOUBLE_COLON,
			OPERATOR_AMPERSAND,
			OPERATOR_PIPE,
			INTEGER_LITERAL,
			FLOAT_LITERAL,
			STRING_LITERAL,
			SEMICOLON,
			COMMA,
			OPEN_PAREN,
			CLOSE_PAREN,
			OPEN_BRACE,
			CLOSE_BRACE,
			OPEN_BRACKET,
			CLOSE_BRACKET
		};

		static const std::vector<std::string> ReverseType;

		Type type;
		std::string data;
		size_t line;
		size_t column;

		Token(Type type, std::string data, size_t line, size_t column) : type(type), data(std::move(data)), line(line), column(column) {}
	};

	class Lexer {
		public:
			typedef std::vector<Token> TokenStream;
		private:
			Compiler& compiler;
			std::string sourceCode;
			TokenStream tokenStream;
			std::stringstream buffer;
			size_t line;
			size_t column;
			size_t pointer;

			static const std::vector<std::string> Keywords;
			static const std::unordered_map<std::string, Token::Type> Operators;

			void resetBuffer() {
				this->buffer.str("");
				this->buffer.clear();
			}

			const char& current() const {
				return this->peek(0);
			}

			const char& next() const {
				return this->peek(1);
			}

			const char& peek(size_t amount = 0) const {
				size_t address = this->pointer + amount;
				return address < this->sourceCode.size() ? this->sourceCode.at(address) : Lexer::EoF;
			}

			const char& consume() {
				const char& current = this->peek();
				this->pointer++;
				this->column++;

				return current;
			}

			static bool IsOperator(const char& car) {
				switch (car) {
					case '+':
					case '-':
					case '*':
					case '/':
					case '=':
					case ':':
					case '.':
					case '&':
					case '|':
						return true;
					default:
						return false;
				}
			}

			static bool IsKeyword(const std::string& identifier) {
				return std::any_of(Lexer::Keywords.begin(), Lexer::Keywords.end(), [&identifier](std::string keyword){
					return keyword == identifier;
				});
			}

			void readIdentifier();
			void readOperator();
			void readStringLiteral();
			void readNumber();
			void readBaseNumber();
		public:
			constexpr static char EoF = '\0';
			constexpr static char EOL = '\n';
			explicit Lexer(Compiler& compiler, std::filesystem::path sourceFile);

			const TokenStream& tokenize();
	};

}

std::ostream& operator <<(std::ostream& os, const dumb::Lexer::TokenStream& tokenStream);