#pragma once
#include <charconv>
#include <concepts>
#include <functional>
#include <memory>
#include <optional>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <variant>
#include <vector>

#include "molasses/lexer.h"


enum class architecture_t {
	x86_64_linux,
	x86_linux
};

#if defined(__x86_64__) && __linux__
constexpr architecture_t architecture = architecture_t::x86_64_linux;
constexpr size_t architecture_ptr_size = 8;
#elif defined(__i386) || defined(__i386__) || defined(i386) && __linux__
constexpr architecture_t architecture = architecture_t::x86_linux;
constexpr size_t architecture_ptr_size = 4;
#endif

namespace molasses {
    namespace details {
        template<typename ...RestT>
        std::string concatenate_builder_impl(std::stringstream& stream)
            requires (sizeof...(RestT) == 0)
        {
            return stream.str();
        }
        template<typename FirstT, typename ...RestT>
        std::string concatenate_builder_impl(std::stringstream& stream, FirstT first, RestT... rest) {
            stream << first;
            return concatenate_builder_impl(stream, rest...);
        }
        template<typename ...RestT>
        std::string concatenate_builder(RestT... rest) {
            std::stringstream stream{};
            return concatenate_builder_impl(stream, rest...);
        }
    }

	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 ptr_type{
        void* ptr;
        std::shared_ptr<type> pointed;
    };

    using stack_element = std::variant<int32_t, int64_t, ptr_type>;

    using interpreter_stack = std::stack<stack_element>;

    struct generate_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;
        virtual void execute(const generate_context&, interpreter_stack&) 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;
        std::function<void(const generate_context&, interpreter_stack&)> _executable;
		
		primitive_operation(std::string name, std::vector<std::string> args, std::vector<std::string> rets, std::vector<std::string> body, std::function<void(const generate_context&,interpreter_stack&)> executable)
			: _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))
            , _executable(std::move(executable))
		{}
		
		[[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;
        }

        void execute(const generate_context& ctx, interpreter_stack& stack) const override {
            _executable(ctx, stack);
        };
	};
	
	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;
        void execute(const generate_context&, interpreter_stack&) const final;
	};
	
	inline auto operator<=>(const operation& lhs, const operation& rhs) {
		return lhs.name() <=> rhs.name();
	}

    struct parser_error : public std::runtime_error {
        explicit parser_error(const std::string& str) : std::runtime_error(str) {}
    };
	
	struct type_input_error : public parser_error {
		type_input_error() : parser_error("Bad type provided") {}
		// TODO: Better error message
	};
	struct value_missing_error : public parser_error {
		value_missing_error() : parser_error("Expected value, none provided") {}
		// TODO: Better error message
	};
	struct procedure_stack_error : public parser_error {
		procedure_stack_error() : parser_error("Expected the stack to look like the return stack upon completion\n") {}
		// TODO: Better error message
	};
	struct unexpected_token_error : public parser_error {
		unexpected_token_error(const symbol& sym, const std::string& found, const std::string& expected)
        : parser_error (
          details::concatenate_builder(
            "Unexpected token encountered\n",
            "\tAt ", sym.file_name,":",sym.line,":",sym.column,"\n",
            "\tExpected ", expected, "\n",
            "\tFound ", found, "\n"
          )
        ) {}
	};
    struct expecting_token_error : public parser_error {
        expecting_token_error(const std::string& expected, const std::string& context)
        : parser_error(
          details::concatenate_builder(
            "An expected token has not been encountered before the end of the input\n",
            "\tExpected ", expected,"\n",
            "\t", context,"\n"
          )
        )
        {}
        // TODO: Better error message
    };
	struct unknown_token_error : public parser_error {
		explicit unknown_token_error(const symbol& sym) : parser_error(details::concatenate_builder("An unknown token has been encountered\n", "\tAt ", sym.file_name,":",sym.line,":",sym.column,"\n")) {}
		// TODO: Better error message
	};
	struct type_expected_with_modifier_error : public parser_error {
		type_expected_with_modifier_error() : parser_error("A type is expected before a modifier") {}
		// 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;
        std::vector<std::shared_ptr<procedure_operation>> procedures;
		
        [[nodiscard]] std::shared_ptr<type> lookup_type(const std::string&) const;
        [[nodiscard]] std::shared_ptr<operation> lookup_operation(const std::string&) const;
    };

    struct generate_context {
        lexed_output lexer;
        parser_context parser;
        std::vector<std::shared_ptr<procedure_operation>> procedures;
    };
	
    generate_context parse(parser_context, const lexed_output&);
    std::vector<std::string> generate(const generate_context&);

    parser_context register_integers(parser_context);

    template<architecture_t Arch = architecture>
    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);
}