#pragma once
#include <string>
#include <set>
#include <vector>
#include <memory>
#include <optional>
#include <charconv>
#include <concepts>

#include "molasses/lexer.h"

namespace molasses {
	struct type {
		[[nodiscard]] virtual std::string name() const = 0;
		[[nodiscard]] virtual size_t byte_size() const = 0;
	};
	
	inline auto operator<=>(const type& lhs, const type& rhs) {
		return lhs.name() <=> rhs.name();
	}
	
	struct primitive_type : public type {
		std::string _name;
		size_t _byte_size;
		
		primitive_type(std::string name, size_t byte_size)
		: _name(std::forward<std::string>(name))
		, _byte_size(byte_size)
		{}
		
		[[nodiscard]] std::string name() const final {
			return _name;
		}
		[[nodiscard]] size_t byte_size() const final {
			return _byte_size;
		};
	};
	
	struct parser_context;
	
	struct operation {
		[[nodiscard]] virtual std::string name() const = 0;
		[[nodiscard]] virtual std::vector<std::string> argument_types() const = 0;
		[[nodiscard]] virtual std::vector<std::string> return_types() const = 0;
        [[nodiscard]] virtual std::vector<std::string> generate(const parser_context&, const lexed_output& lexer_data) const = 0;
        [[nodiscard]] virtual std::vector<std::string> emit(const parser_context&) const = 0;
	};
	
	struct primitive_operation : public operation {
		std::string _name;
		std::vector<std::string> _args;
		std::vector<std::string> _rets;
		std::vector<std::string> _instructions;
		
		primitive_operation(std::string name, std::vector<std::string> args, std::vector<std::string> rets, std::vector<std::string> body)
			: _name(std::forward<std::string>(name))
			, _args(std::forward<std::vector<std::string>>(args))
            , _rets(std::forward<std::vector<std::string>>(rets))
            , _instructions(std::forward<std::vector<std::string>>(body))
		{}
		
		[[nodiscard]] std::string name() const final {
			return _name;
		}
		[[nodiscard]] std::vector<std::string> argument_types() const final {
			return _args;
		}
		[[nodiscard]] std::vector<std::string> return_types() const final {
			return _rets;
		}
        [[nodiscard]] std::vector<std::string> generate(const parser_context&, const lexed_output& lexer_data) const final {
            return {};
        }
        [[nodiscard]] std::vector<std::string> emit(const parser_context&) const final {
            return _instructions;
        }
	};
	
	struct procedure_operation : public operation {
		std::string _name;
		std::vector<std::string> _args;
		std::vector<std::string> _rets;
		std::vector<symbol> _body;
		
		procedure_operation(std::string name, std::vector<std::string> args, std::vector<std::string> rets, std::vector<symbol> body)
			: _name(std::forward<std::string>(name))
			, _args(std::forward<std::vector<std::string>>(args))
			, _rets(std::forward<std::vector<std::string>>(rets))
			, _body(std::forward<std::vector<symbol>>(body))
		{}
		
		[[nodiscard]] std::string name() const final {
			return _name;
		}
		[[nodiscard]] std::vector<std::string> argument_types() const final {
			return _args;
		}
		[[nodiscard]] std::vector<std::string> return_types() const final {
			return _rets;
		}
        [[nodiscard]] std::vector<std::string> generate(const parser_context&, const lexed_output& lexer_data) const final;
        [[nodiscard]] std::vector<std::string> emit(const parser_context&) const final;
	};
	
	inline auto operator<=>(const operation& lhs, const operation& rhs) {
		return lhs.name() <=> rhs.name();
	}
	
	struct TypeInputError : std::runtime_error {
		TypeInputError() : std::runtime_error("Bad type provided") {}
		// TODO: Better error message
	};
	struct ValueMissingError : std::runtime_error {
		ValueMissingError() : std::runtime_error("Expected value, none provided") {}
		// TODO: Better error message
	};
	struct ProcedureStackError : std::runtime_error {
		ProcedureStackError() : std::runtime_error("Expected the stack to look like the return stack upon completion") {}
		// TODO: Better error message
	};
	struct UnexpectedTokenError : std::runtime_error {
		UnexpectedTokenError() : std::runtime_error("An unexpected token has been encountered") {}
		// TODO: Better error message
	};
    struct ExpectingTokenError : std::runtime_error {
        ExpectingTokenError() : std::runtime_error("An expected token has not been encountered before the end of the input") {}
        // TODO: Better error message
    };
    struct UnknownTokenError : std::runtime_error {
        UnknownTokenError() : std::runtime_error("An unknown token has not been encountered") {}
        // TODO: Better error message
    };
	
	std::vector<std::string> operator>>(std::vector<std::string> current_stack, const operation& next_op);
	
	std::optional<int32_t> try_parse_int32(const std::string& str);
	
	struct parser_context {
		std::vector<std::shared_ptr<type>> types;
		std::vector<std::shared_ptr<operation>> operations;
		
		[[nodiscard]] std::shared_ptr<type> lookup_type(const std::string&) const;
		[[nodiscard]] std::shared_ptr<operation> lookup_operation(const std::string&) const;
	};
	
	parser_context parse(parser_context, const lexed_output&);

    parser_context register_integers(parser_context);
    parser_context register_i32_operations(parser_context);
	
	bool type_check(const parser_context&, const lexed_output&, const std::vector<symbol>&, std::vector<std::string> execution_input, const std::vector<std::string>& execution_output);
}