#pragma once

#include <exception>
#include <memory>
#include <string>
#include <typeinfo>
#include <typeindex>

class bad_cast : public std::exception {
	std::string why;
public:
	bad_cast( const std::type_index& f, const std::type_index& t ) : std::exception() {
		why = std::string{"bad cast of "} + f.name() + " to " + t.name();
	}

	~bad_cast() override = default;
	
	const char* what() const noexcept override { return why.c_str(); }
};

template<typename T>
std::type_index class_of() { return { typeid(T) }; }

class object {
public:
	std::type_index get_class() const { return { typeid(*this) }; }

	template<typename T>
	T& as() {
		std::type_index from = get_class(), to = class_of<T>();
		if ( from != to ) throw bad_cast{ from, to };
		return reinterpret_cast<T&>(*this);
	}

	template<typename T>
	const T& as() const {
		std::type_index from = get_class(), to = class_of<T>();
		if ( from != to ) throw bad_cast{ from, to };
		return reinterpret_cast<const T&>(*this);
	}

	virtual std::unique_ptr<object> new_inst() const = 0;
	
	virtual std::unique_ptr<object> new_copy() const = 0;
	
	virtual object& operator= (const object&) = 0;
	
	virtual ~object() = default;
};

template<typename T>
T* as_subclass_of( object* o ) {
	T* r = dynamic_cast<T*>( o );
	if ( r == nullptr ) throw bad_cast{ o->get_class(), class_of<T>() };
	return r;
}

template<typename T>
const T* as_subclass_of( const object* o ) {
	const T* r = dynamic_cast<const T*>( o );
	if ( r == nullptr ) throw bad_cast{ o->get_class(), class_of<T>() };
	return r;
}

class ordered : public object {
public:
	virtual int cmp(const ordered&) const = 0;

	bool operator< (const ordered& that) const { return cmp(that) < 0; }

	bool operator<= ( const ordered& that ) const { return cmp(that) <= 0; }

	bool operator== ( const ordered& that ) const { return cmp(that) == 0; }

	bool operator!= ( const ordered& that ) const { return cmp(that) != 0; }

	bool operator> ( const ordered& that ) const { return cmp(that) > 0; }

	bool operator>= ( const ordered& that ) const { return cmp(that) >= 0; }
};

class boolean : public ordered {
private:
	bool x;

public:
	boolean() = default;

	boolean(bool x) : x(x) {}

	std::unique_ptr<object> new_inst() const override { return std::make_unique<boolean>(); }
	
	std::unique_ptr<object> new_copy() const override { return std::make_unique<boolean>(*this); }

	boolean& operator= (const boolean& that) {
		x = that.x;
		return *this;	
	}

	object& operator= (const object& that) override {
		std::type_index from = that.get_class(), to = get_class();
		if ( from != to ) throw bad_cast{ from, to };
		return *this = static_cast<const boolean&>(that);
	}

	~boolean() override = default;

	int cmp(const boolean& that) const { return x == that.x ? 0 : x == false ? -1 : 1; }

	// bool operator< (const boolean& that) const { return x < that.x; }

	// bool operator== (const boolean& that) const { return x == that.x; }

	int cmp(const ordered& that) const override {
		std::type_index from = that.get_class(), to = get_class();
		if ( from != to ) throw bad_cast{ from, to };
		return cmp( static_cast<const boolean&>(that) );
	}
};

class character : public ordered {
private:
	char x;

public:
	character() = default;

	character(char x) : x(x) {}

	std::unique_ptr<object> new_inst() const override { return std::make_unique<character>(); }
	
	std::unique_ptr<object> new_copy() const override { return std::make_unique<character>(*this); }

	character& operator= (const character& that) {
		x = that.x;
		return *this;	
	}

	object& operator= (const object& that) override {
		std::type_index from = that.get_class(), to = get_class();
		if ( from != to ) throw bad_cast{ from, to };
		return *this = static_cast<const character&>(that);
	}

	~character() override = default;

	int cmp(const character& that) const { return x == that.x ? 0 : x < that.x ? -1 : 1; }

	// bool operator< (const character& that) const { return x < that.x; }

	// bool operator== (const character& that) const { return x == that.x; }

	int cmp(const ordered& that) const override {
		std::type_index from = that.get_class(), to = get_class();
		if ( from != to ) throw bad_cast{ from, to };
		return cmp( static_cast<const character&>(that) );
	}
};

class integer : public ordered {
private:
	int x;

public:
	integer() = default;

	integer(int x) : x(x) {}

	std::unique_ptr<object> new_inst() const override { return std::make_unique<integer>(); }
	
	std::unique_ptr<object> new_copy() const override { return std::make_unique<integer>(*this); }

	integer& operator= (const integer& that) {
		x = that.x;
		return *this;	
	}

	object& operator= (const object& that) override {
		std::type_index from = that.get_class(), to = get_class();
		if ( from != to ) throw bad_cast{ from, to };
		return *this = static_cast<const integer&>(that);
	}

	~integer() override = default;

	int cmp(const integer& that) const { return x == that.x ? 0 : x < that.x ? -1 : 1; }

	// bool operator< (const integer& that) const { return x < that.x; }

	// bool operator== (const integer& that) const { return x == that.x; }

	int cmp(const ordered& that) const override {
		std::type_index from = that.get_class(), to = get_class();
		if ( from != to ) throw bad_cast{ from, to };
		return cmp( static_cast<const integer&>(that) );
	}
};

class pair : public ordered {
private:
	std::unique_ptr<object> x;
	std::unique_ptr<object> y;

public:
	pair() = default;

	pair(std::unique_ptr<object>&& x, std::unique_ptr<object>&& y)
		: x(std::move(x)), y(std::move(y)) {}
	
	std::unique_ptr<object> new_inst() const override { return std::make_unique<pair>(); }

	std::unique_ptr<object> new_copy() const override {
		return std::make_unique<pair>(x->new_copy(), y->new_copy());
	}

	pair& operator= (const pair& that) {
		x = that.x->new_copy();
		y = that.y->new_copy();
		return *this;
	}

	object& operator= (const object& that) override {
		std::type_index from = that.get_class(), to = get_class();
		if ( from != to ) throw bad_cast{ from, to };
		return *this = static_cast<const pair&>(that);
	}

	~pair() override = default;

	int cmp(const pair& that) const {
		const ordered* a = as_subclass_of<ordered>( x.get() );
		const ordered* b = as_subclass_of<ordered>( that.x.get() );
		int c = a->cmp( *b );
		if ( c != 0 ) return c;
		a = as_subclass_of<ordered>( y.get() );
		b = as_subclass_of<ordered>( that.y.get() );
		return a->cmp( *b );
	}

	// bool operator< (const pair& that) const { return cmp(that) < 0; }

	// bool operator== ( const pair& that) const { return cmp(that) == 0; }

	int cmp(const ordered& that) const override {
		std::type_index from = that.get_class(), to = get_class();
		if ( from != to ) throw bad_cast{ from, to };
		return cmp( static_cast<const pair&>(that) );
	}
};