mirror of
https://github.com/nspcc-dev/neo-go.git
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279 lines
7.5 KiB
Go
279 lines
7.5 KiB
Go
package tokensale
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import (
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"github.com/nspcc-dev/neo-go/pkg/interop"
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"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
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"github.com/nspcc-dev/neo-go/pkg/interop/storage"
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"github.com/nspcc-dev/neo-go/pkg/interop/util"
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)
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const (
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decimals = 8
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multiplier = decimals * 10
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)
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var (
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owner = util.FromAddress("NbrUYaZgyhSkNoRo9ugRyEMdUZxrhkNaWB")
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trigger byte
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token TokenConfig
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ctx storage.Context
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)
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// TokenConfig holds information about the token we want to use for the sale.
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type TokenConfig struct {
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// Name of the token.
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Name string
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// 3 letter abbreviation of the token.
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Symbol string
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// How decimals this token will have.
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Decimals int
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// Address of the token owner. This is the Uint160 hash.
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Owner []byte
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// The total amount of tokens created. Notice that we need to multiply the
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// amount by 100000000. (10^8)
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TotalSupply int
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// Initial amount is number of tokens that are available for the token sale.
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InitialAmount int
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// How many NEO will be worth 1 token. For example:
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// Lets say 1 euro per token, where 1 NEO is 60 euro. This means buyers
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// will get (60 * 10^8) tokens for 1 NEO.
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AmountPerNEO int
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// How many Gas will be worth 1 token. This is the same calculation as
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// for the AmountPerNEO, except Gas price will have a different value.
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AmountPerGas int
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// The maximum amount you can mint in the limited round. For example:
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// 500 NEO/buyer * 60 tokens/NEO * 10^8
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MaxExchangeLimitRound int
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// When to start the token sale.
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SaleStart int
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// When to end the initial limited round if there is one. For example:
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// SaleStart + 10000
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LimitRoundEnd int
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// The prefix used to store how many tokens there are in circulation.
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CirculationKey []byte
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// The prefix used to store how many tokens there are in the limited round.
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LimitRoundKey []byte
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// The prefix used to store the addresses that are registered with KYC.
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KYCKey []byte
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}
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// newTokenConfig returns the initialized TokenConfig.
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func newTokenConfig() TokenConfig {
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return TokenConfig{
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Name: "My awesome token",
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Symbol: "MAT",
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Decimals: decimals,
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Owner: owner,
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TotalSupply: 10000000 * multiplier,
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InitialAmount: 5000000 * multiplier,
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AmountPerNEO: 60 * multiplier,
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AmountPerGas: 40 * multiplier,
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MaxExchangeLimitRound: 500 * 60 * multiplier,
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SaleStart: 75500,
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LimitRoundEnd: 75500 + 10000,
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CirculationKey: []byte("in_circulation"),
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LimitRoundKey: []byte("r1"),
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KYCKey: []byte("kyc_ok"),
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}
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}
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// getIntFromDB is a helper that checks for nil result of storage.Get and returns
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// zero as the default value.
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func getIntFromDB(ctx storage.Context, key []byte) int {
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var res int
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val := storage.Get(ctx, key)
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if val != nil {
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res = val.(int)
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}
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return res
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}
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// InCirculation returns the amount of total tokens that are in circulation.
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func InCirculation() int {
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return getIntFromDB(ctx, token.CirculationKey)
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}
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// addToCirculation sets the given amount as "in circulation" in the storage.
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func addToCirculation(amount int) bool {
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if amount < 0 {
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return false
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}
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supply := getIntFromDB(ctx, token.CirculationKey)
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supply += amount
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if supply > token.TotalSupply {
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return false
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}
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storage.Put(ctx, token.CirculationKey, supply)
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return true
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}
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// AvailableAmount returns the total amount of available tokens left
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// to be distributed.
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func AvailableAmount() int {
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inCirc := getIntFromDB(ctx, token.CirculationKey)
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return token.TotalSupply - inCirc
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}
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// init initializes runtime trigger, TokenConfig and storage context before any
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// other contract method is called
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func init() {
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trigger = runtime.GetTrigger()
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token = newTokenConfig()
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ctx = storage.GetContext()
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}
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// checkOwnerWitness is a helper function which checks whether the invoker is the
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// owner of the contract.
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func checkOwnerWitness() bool {
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// This is used to verify if a transfer of system assets (NEO and Gas)
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// involving this contract's address can proceed.
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if trigger == runtime.Application {
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// Check if the invoker is the owner of the contract.
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return runtime.CheckWitness(token.Owner)
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}
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return false
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}
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// Decimals returns the token decimals
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func Decimals() int {
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if trigger != runtime.Application {
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panic("invalid trigger")
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}
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return token.Decimals
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}
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// Symbol returns the token symbol
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func Symbol() string {
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if trigger != runtime.Application {
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panic("invalid trigger")
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}
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return token.Symbol
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}
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// TotalSupply returns the token total supply value
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func TotalSupply() int {
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if trigger != runtime.Application {
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panic("invalid trigger")
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}
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return getIntFromDB(ctx, token.CirculationKey)
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}
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// BalanceOf returns the amount of token on the specified address
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func BalanceOf(holder interop.Hash160) int {
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if trigger != runtime.Application {
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panic("invalid trigger")
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}
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return getIntFromDB(ctx, holder)
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}
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// Transfer transfers specified amount of token from one user to another
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func Transfer(from, to interop.Hash160, amount int, _ interface{}) bool {
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if trigger != runtime.Application {
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return false
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}
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if amount <= 0 || len(to) != 20 || !runtime.CheckWitness(from) {
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return false
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}
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amountFrom := getIntFromDB(ctx, from)
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if amountFrom < amount {
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return false
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}
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if amountFrom == amount {
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storage.Delete(ctx, from)
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} else {
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diff := amountFrom - amount
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storage.Put(ctx, from, diff)
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}
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amountTo := getIntFromDB(ctx, to)
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totalAmountTo := amountTo + amount
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if totalAmountTo != 0 {
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storage.Put(ctx, to, totalAmountTo)
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}
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return true
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}
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// TransferFrom transfers specified amount of token from one user to another.
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// It differs from Transfer in that it use allowance value to store the amount
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// of token available to transfer.
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func TransferFrom(from, to []byte, amount int) bool {
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if trigger != runtime.Application {
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return false
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}
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if amount <= 0 {
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return false
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}
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availableKey := append(from, to...)
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if len(availableKey) != 40 {
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return false
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}
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availableTo := getIntFromDB(ctx, availableKey)
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if availableTo < amount {
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return false
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}
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fromBalance := getIntFromDB(ctx, from)
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if fromBalance < amount {
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return false
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}
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toBalance := getIntFromDB(ctx, to)
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newFromBalance := fromBalance - amount
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newToBalance := toBalance + amount
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storage.Put(ctx, to, newToBalance)
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storage.Put(ctx, from, newFromBalance)
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newAllowance := availableTo - amount
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if newAllowance == 0 {
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storage.Delete(ctx, availableKey)
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} else {
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storage.Put(ctx, availableKey, newAllowance)
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}
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return true
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}
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// Approve stores token transfer data if the owner has enough token to send.
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func Approve(owner, spender []byte, amount int) bool {
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if !checkOwnerWitness() || amount < 0 {
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return false
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}
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if len(spender) != 20 {
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return false
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}
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toSpend := getIntFromDB(ctx, owner)
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if toSpend < amount {
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return false
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}
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approvalKey := append(owner, spender...)
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if amount == 0 {
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storage.Delete(ctx, approvalKey)
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} else {
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storage.Put(ctx, approvalKey, amount)
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}
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return true
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}
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// Allowance returns allowance value for specified sender and receiver.
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func Allowance(from, to []byte) interface{} {
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if trigger != runtime.Application {
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return false
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}
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key := append(from, to...)
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return getIntFromDB(ctx, key)
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}
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// Mint initial supply of tokens
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func Mint(to []byte) bool {
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if trigger != runtime.Application {
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return false
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}
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if !checkOwnerWitness() {
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return false
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}
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minted := storage.Get(ctx, []byte("minted"))
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if minted != nil && minted.(bool) == true {
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return false
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}
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storage.Put(ctx, to, token.TotalSupply)
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storage.Put(ctx, []byte("minted"), true)
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addToCirculation(token.TotalSupply)
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return true
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}
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