neo-go/examples/timer/timer.go

package timer

import (
	"github.com/nspcc-dev/neo-go/pkg/interop"
	"github.com/nspcc-dev/neo-go/pkg/interop/binary"
	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
	"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
	"github.com/nspcc-dev/neo-go/pkg/interop/storage"
	"github.com/nspcc-dev/neo-go/pkg/interop/util"
)

const defaultTicks = 3
const mgmtKey = "mgmt"

var (
	// ctx holds storage context for contract methods
	ctx storage.Context
	// Check if the invoker of the contract is the specified owner
	owner = util.FromAddress("NULwe3UAHckN2fzNdcVg31tDiaYtMDwANt")
	// ticksKey is a storage key for ticks counter
	ticksKey = []byte("ticks")
)

func init() {
	ctx = storage.GetContext()
}

func _deploy(_ interface{}, isUpdate bool) {
	if isUpdate {
		ticksLeft := storage.Get(ctx, ticksKey).(int) + 1
		storage.Put(ctx, ticksKey, ticksLeft)
		runtime.Log("One more tick is added.")
		return
	}
	sh := runtime.GetCallingScriptHash()
	storage.Put(ctx, mgmtKey, sh)
	storage.Put(ctx, ticksKey, defaultTicks)
	i := binary.Itoa(defaultTicks, 10)
	runtime.Log("Timer set to " + i + " ticks.")
}

// Migrate migrates the contract.
func Migrate(script []byte, manifest []byte) bool {
	if !runtime.CheckWitness(owner) {
		runtime.Log("Only owner is allowed to update the contract.")
		return false
	}
	mgmt := storage.Get(ctx, mgmtKey).(interop.Hash160)
	contract.Call(mgmt, "update", contract.All, script, manifest)
	runtime.Log("Contract updated.")
	return true
}

// Tick decrement ticks count and checks whether the timer is fired.
func Tick() bool {
	runtime.Log("Tick-tock.")
	ticksLeft := storage.Get(ctx, ticksKey)
	ticksLeft = ticksLeft.(int) - 1
	if ticksLeft == 0 {
		runtime.Log("Fired!")
		return contract.Call(runtime.GetExecutingScriptHash(), "selfDestroy", contract.All).(bool)
	}
	storage.Put(ctx, ticksKey, ticksLeft)
	i := binary.Itoa(ticksLeft.(int), 10)
	runtime.Log(i + " ticks left.")
	return true
}

// SelfDestroy destroys the contract.
func SelfDestroy() bool {
	if !(runtime.CheckWitness(owner) || runtime.CheckWitness(runtime.GetExecutingScriptHash())) {
		runtime.Log("Only owner or the contract itself are allowed to destroy the contract.")
		return false
	}
	mgmt := storage.Get(ctx, mgmtKey).(interop.Hash160)
	contract.Call(mgmt, "destroy", contract.All)
	runtime.Log("Destroyed.")
	return true
}