package ethutil

import (
	"math/big"
	"strconv"
)

// Op codes
var OpCodes = map[string]byte{
	// 0x0 range - arithmetic ops
	"STOP": 0x00,
	"ADD":  0x01,
	"MUL":  0x02,
	"SUB":  0x03,
	"DIV":  0x04,
	"SDIV": 0x05,
	"MOD":  0x06,
	"SMOD": 0x07,
	"EXP":  0x08,
	"NEG":  0x09,
	"LT":   0x0a,
	"GT":   0x0b,
	"EQ":   0x0c,
	"NOT":  0x0d,

	// 0x10 range - bit ops
	"AND":  0x10,
	"OR":   0x11,
	"XOR":  0x12,
	"BYTE": 0x13,

	// 0x20 range - crypto
	"SHA3": 0x20,

	// 0x30 range - closure state
	"ADDRESS":      0x30,
	"BALANCE":      0x31,
	"ORIGIN":       0x32,
	"CALLER":       0x33,
	"CALLVALUE":    0x34,
	"CALLDATA":     0x35,
	"CALLDATASIZE": 0x36,
	"GASPRICE":     0x38,

	// 0x40 range - block operations
	"PREVHASH":   0x40,
	"COINBASE":   0x41,
	"TIMESTAMP":  0x42,
	"NUMBER":     0x43,
	"DIFFICULTY": 0x44,
	"GASLIMIT":   0x45,

	// 0x50 range - 'storage' and execution
	"PUSH":    0x50,
	"POP":     0x51,
	"DUP":     0x52,
	"SWAP":    0x53,
	"MLOAD":   0x54,
	"MSTORE":  0x55,
	"MSTORE8": 0x56,
	"SLOAD":   0x57,
	"SSTORE":  0x58,
	"JUMP":    0x59,
	"JUMPI":   0x5a,
	"PC":      0x5b,
	"MSIZE":   0x5c,

	// 0x60 range - closures
	"CREATE": 0x60,
	"CALL":   0x61,
	"RETURN": 0x62,

	// 0x70 range - other
	"LOG":     0x70,
	"SUICIDE": 0x7f,
}

func IsOpCode(s string) bool {
	for key, _ := range OpCodes {
		if key == s {
			return true
		}
	}
	return false
}

func CompileInstr(s interface{}) ([]byte, error) {
	switch s.(type) {
	case string:
		str := s.(string)
		isOp := IsOpCode(str)
		if isOp {
			return []byte{OpCodes[str]}, nil
		}

		num := new(big.Int)
		_, success := num.SetString(str, 0)
		// Assume regular bytes during compilation
		if !success {
			num.SetBytes([]byte(str))
		}

		return num.Bytes(), nil
	case int:
		return big.NewInt(int64(s.(int))).Bytes(), nil
	case []byte:
		return BigD(s.([]byte)).Bytes(), nil
	}

	return nil, nil
}

func Instr(instr string) (int, []string, error) {

	base := new(big.Int)
	base.SetString(instr, 0)

	args := make([]string, 7)
	for i := 0; i < 7; i++ {
		// int(int(val) / int(math.Pow(256,float64(i)))) % 256
		exp := BigPow(256, i)
		num := new(big.Int)
		num.Div(base, exp)

		args[i] = num.Mod(num, big.NewInt(256)).String()
	}
	op, _ := strconv.Atoi(args[0])

	return op, args[1:7], nil
}

// Script compilation functions
// Compiles strings to machine code
func Assemble(instructions ...interface{}) (script []string) {
	script = make([]string, len(instructions))

	for i, val := range instructions {
		instr, _ := CompileInstr(val)

		script[i] = string(instr)
	}

	return
}