#pragma once

namespace eth
{

// TODO: Update comments.

/// Virtual machine bytecode instruction.
enum class Instruction: uint8_t
{
	STOP = 0x00,		///< halts execution
	ADD,				///< Rx Ry Rz - sets Rz <- Rx + Ry mod 2^256
	SUB,				///< Rx Ry Rz - sets Rz <- Rx - Ry mod 2^256
	MUL,				///< Rx Ry Rz - sets Rz <- Rx * Ry mod 2^256
	DIV,				///< Rx Ry Rz - sets Rz <- floor(Rx / Ry)
	SDIV,				///< Rx Ry Rz - like DIV, except it treats values above 2^255 as negative (ie. 2^256 - x -> -x)
	MOD,				///< Rx Ry Rz - sets Rz <- Rx mod Ry
	SMOD,				///< Rx Ry Rz - like MOD, but for signed values just like SDIV (using Python's convention with negative numbers)
	EXP,				///< Rx Ry Rz - sets Rz <- Rx ^ Ry mod 2^256
	NEG,				///< Rx Ry - sets Ry <- 2^256 - Rx
	LT,					///< Rx Ry Rz - sets Rz <- 1 if Rx < Ry else 0
	LE,					///< Rx Ry Rz - sets Rz <- 1 if Rx <= Ry else 0
	GT,					///< Rx Ry Rz - sets Rz <- 1 if Rx > Ry else 0
	GE,					///< Rx Ry Rz - sets Rz <- 1 if Rx >= Ry else 0
	EQ,					///< Rx Ry Rz - sets Rz <- 1 if Rx = Ry else 0
	NOT,				///< Rx Ry - sets Ry <- 1 if Rx = 0 else 0
	MYADDRESS = 0x10,	///< Rx - sets Rx to the contract's own address
	TXSENDER,			///< pushes the transaction sender
	TXVALUE	,			///< pushes the transaction value
	TXFEE,				///< pushes the transaction fee
	TXDATAN,			///< pushes the number of data items
	TXDATA,				///< pops one item and pushes data item S[-1], or zero if index out of range
	BLK_PREVHASH,		///< pushes the hash of the previous block (NOT the current one since that's impossible!)
	BLK_COINBASE,		///< pushes the coinbase of the current block
	BLK_TIMESTAMP,		///< pushes the timestamp of the current block
	BLK_NUMBER,			///< pushes the current block number
	BLK_DIFFICULTY,		///< pushes the difficulty of the current block
	SHA256 = 0x20,		///< sets Ry <- SHA256(Rx)
	RIPEMD160,			///< Rx Ry - sets Ry <- RIPEMD160(Rx)
	ECMUL,				///< Rx Ry Rz Ra Rb - sets (Ra, Rb) = Rz * (Rx, Ry) in secp256k1, using (0,0) for the point at infinity
	ECADD,				///< Rx Ry Rz Ra Rb Rc - sets (Rb, Rc) = (Rx, Ry) + (Ra, Rb)
	ECSIGN,				///< Rx Ry Rz Ra Rb - sets(Rz, Ra, Rb)as the(r,s,prefix)values of an Electrum-style RFC6979 deterministic signature ofRxwith private keyRy`
	ECRECOVER,			///< Rx Ry Rz Ra Rb Rc - sets(Rb, Rc)as the public key from the signature(Ry, Rz, Ra)of the message hashRx`
	ECVALID,			///< Rx Ry Rz Ra Rb Rc - sets(Rb, Rc)as the public key from the signature(Ry, Rz, Ra)of the message hashRx`
	PUSH = 0x30,
	POP,
	DUP,
	DUPN,
	SWAP,
	SWAPN,
	LOAD,
	STORE,
	JMP = 0x40,			///< Rx - sets the index pointer to the value at Rx
	JMPI,				///< Rx Ry - if Rx != 0, sets the index pointer to Ry
	IND,				///< pushes the index pointer.
	EXTRO = 0x50,		///< Rx Ry Rz - looks at the contract at address Rx and its memory state Ry, and outputs the result to Rz
	BALANCE,			///< Rx - returns the ether balance of address Rx
	MKTX = 0x60,		///< Rx Ry Rz Rw Rv - sends Ry ether to Rx plus Rz fee with Rw data items starting from memory index Rv (and then reading to (Rv + 1), (Rv + 2) etc). Note that if Rx = 0 then this creates a new contract.
	SUICIDE = 0xff		///< Rx - destroys the contract and clears all memory, sending the entire balance plus the negative fee from clearing memory minus TXFEE to the address
};

}