package tokensale import ( "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 ( decimals = 8 multiplier = decimals * 10 ) var ( owner = util.FromAddress("NULwe3UAHckN2fzNdcVg31tDiaYtMDwANt") trigger byte token TokenConfig ctx storage.Context ) // TokenConfig holds information about the token we want to use for the sale. type TokenConfig struct { // Name of the token. Name string // 3 letter abbreviation of the token. Symbol string // How decimals this token will have. Decimals int // Address of the token owner. This is the Uint160 hash. Owner []byte // The total amount of tokens created. Notice that we need to multiply the // amount by 100000000. (10^8) TotalSupply int // Initial amount is number of tokens that are available for the token sale. InitialAmount int // How many NEO will be worth 1 token. For example: // Lets say 1 euro per token, where 1 NEO is 60 euro. This means buyers // will get (60 * 10^8) tokens for 1 NEO. AmountPerNEO int // How many Gas will be worth 1 token. This is the same calculation as // for the AmountPerNEO, except Gas price will have a different value. AmountPerGas int // The maximum amount you can mint in the limited round. For example: // 500 NEO/buyer * 60 tokens/NEO * 10^8 MaxExchangeLimitRound int // When to start the token sale. SaleStart int // When to end the initial limited round if there is one. For example: // SaleStart + 10000 LimitRoundEnd int // The prefix used to store how many tokens there are in circulation. CirculationKey []byte // The prefix used to store how many tokens there are in the limited round. LimitRoundKey []byte // The prefix used to store the addresses that are registered with KYC. KYCKey []byte } // newTokenConfig returns the initialized TokenConfig. func newTokenConfig() TokenConfig { return TokenConfig{ Name: "My awesome token", Symbol: "MAT", Decimals: decimals, Owner: owner, TotalSupply: 10000000 * multiplier, InitialAmount: 5000000 * multiplier, AmountPerNEO: 60 * multiplier, AmountPerGas: 40 * multiplier, MaxExchangeLimitRound: 500 * 60 * multiplier, SaleStart: 75500, LimitRoundEnd: 75500 + 10000, CirculationKey: []byte("in_circulation"), LimitRoundKey: []byte("r1"), KYCKey: []byte("kyc_ok"), } } // getIntFromDB is a helper that checks for nil result of storage.Get and returns // zero as the default value. func getIntFromDB(ctx storage.Context, key []byte) int { var res int val := storage.Get(ctx, key) if val != nil { res = val.(int) } return res } // InCirculation returns the amount of total tokens that are in circulation. func InCirculation() int { return getIntFromDB(ctx, token.CirculationKey) } // addToCirculation sets the given amount as "in circulation" in the storage. func addToCirculation(amount int) bool { if amount < 0 { return false } supply := getIntFromDB(ctx, token.CirculationKey) supply += amount if supply > token.TotalSupply { return false } storage.Put(ctx, token.CirculationKey, supply) return true } // AvailableAmount returns the total amount of available tokens left // to be distributed. func AvailableAmount() int { inCirc := getIntFromDB(ctx, token.CirculationKey) return token.TotalSupply - inCirc } // init initializes runtime trigger, TokenConfig and storage context before any // other contract method is called func init() { trigger = runtime.GetTrigger() token = newTokenConfig() ctx = storage.GetContext() } // checkOwnerWitness is a helper function which checks whether the invoker is the // owner of the contract. func checkOwnerWitness() bool { // This is used to verify if a transfer of system assets (NEO and Gas) // involving this contract's address can proceed. if trigger == runtime.Application { // Check if the invoker is the owner of the contract. return runtime.CheckWitness(token.Owner) } return false } // Decimals returns the token decimals func Decimals() interface{} { if trigger != runtime.Application { return false } return token.Decimals } // Symbol returns the token symbol func Symbol() interface{} { if trigger != runtime.Application { return false } return token.Symbol } // TotalSupply returns the token total supply value func TotalSupply() interface{} { if trigger != runtime.Application { return false } return getIntFromDB(ctx, token.CirculationKey) } // BalanceOf returns the amount of token on the specified address func BalanceOf(holder []byte) interface{} { if trigger != runtime.Application { return false } return getIntFromDB(ctx, holder) } // Transfer transfers specified amount of token from one user to another func Transfer(from, to []byte, amount int) bool { if trigger != runtime.Application { return false } if amount <= 0 || len(to) != 20 || !runtime.CheckWitness(from) { return false } amountFrom := getIntFromDB(ctx, from) if amountFrom < amount { return false } if amountFrom == amount { storage.Delete(ctx, from) } else { diff := amountFrom - amount storage.Put(ctx, from, diff) } amountTo := getIntFromDB(ctx, to) totalAmountTo := amountTo + amount storage.Put(ctx, to, totalAmountTo) return true } // TransferFrom transfers specified amount of token from one user to another. // It differs from Transfer in that it use allowance value to store the amount // of token available to transfer. func TransferFrom(from, to []byte, amount int) bool { if trigger != runtime.Application { return false } if amount <= 0 { return false } availableKey := append(from, to...) if len(availableKey) != 40 { return false } availableTo := getIntFromDB(ctx, availableKey) if availableTo < amount { return false } fromBalance := getIntFromDB(ctx, from) if fromBalance < amount { return false } toBalance := getIntFromDB(ctx, to) newFromBalance := fromBalance - amount newToBalance := toBalance + amount storage.Put(ctx, to, newToBalance) storage.Put(ctx, from, newFromBalance) newAllowance := availableTo - amount if newAllowance == 0 { storage.Delete(ctx, availableKey) } else { storage.Put(ctx, availableKey, newAllowance) } return true } // Approve stores token transfer data if the owner has enough token to send. func Approve(owner, spender []byte, amount int) bool { if !checkOwnerWitness() || amount < 0 { return false } if len(spender) != 20 { return false } toSpend := getIntFromDB(ctx, owner) if toSpend < amount { return false } approvalKey := append(owner, spender...) if amount == 0 { storage.Delete(ctx, approvalKey) } else { storage.Put(ctx, approvalKey, amount) } return true } // Allowance returns allowance value for specified sender and receiver. func Allowance(from, to []byte) interface{} { if trigger != runtime.Application { return false } key := append(from, to...) return getIntFromDB(ctx, key) } // Mint initial supply of tokens func Mint(to []byte) bool { if trigger != runtime.Application { return false } if !checkOwnerWitness() { return false } minted := storage.Get(ctx, []byte("minted")) if minted != nil && minted.(bool) == true { return false } storage.Put(ctx, to, token.TotalSupply) storage.Put(ctx, []byte("minted"), true) addToCirculation(token.TotalSupply) return true }