// SPDX-License-Identifier: MIT

#ifndef RGBDS_ASM_RPN_HPP
#define RGBDS_ASM_RPN_HPP

#include <stdint.h>
#include <string>
#include <vector>

#include "either.hpp"
#include "linkdefs.hpp"

struct Symbol;

struct Expression {
	Either<
	    int32_t,    // If the expression's value is known, it's here
	    std::string // Why the expression is not known, if it isn't
	    >
	    data = 0;
	bool isSymbol = false; // Whether the expression represents a symbol suitable for const diffing
	std::vector<uint8_t> rpn{}; // Bytes serializing the RPN expression
	uint32_t rpnPatchSize = 0;  // Size the expression will take in the object file

	Expression() = default;
	Expression(Expression &&) = default;
#ifdef _MSC_VER
	// MSVC and WinFlexBison won't build without this...
	Expression(Expression const &) = default;
#endif

	Expression &operator=(Expression &&) = default;

	bool isKnown() const { return data.holds<int32_t>(); }
	int32_t value() const { return data.get<int32_t>(); }

	int32_t getConstVal() const;
	Symbol const *symbolOf() const;
	bool isDiffConstant(Symbol const *symName) const;

	void makeNumber(uint32_t value);
	void makeSymbol(std::string const &symName);
	void makeBankSymbol(std::string const &symName);
	void makeBankSection(std::string const &sectName);
	void makeSizeOfSection(std::string const &sectName);
	void makeStartOfSection(std::string const &sectName);
	void makeSizeOfSectionType(SectionType type);
	void makeStartOfSectionType(SectionType type);
	void makeUnaryOp(RPNCommand op, Expression &&src);
	void makeBinaryOp(RPNCommand op, Expression &&src1, Expression const &src2);

	bool makeCheckHRAM();
	void makeCheckRST();

	void checkNBit(uint8_t n) const;

private:
	void clear();
	uint8_t *reserveSpace(uint32_t size);
	uint8_t *reserveSpace(uint32_t size, uint32_t patchSize);
};

bool checkNBit(int32_t v, uint8_t n, char const *name);

#endif // RGBDS_ASM_RPN_HPP