package paychan import ( "strconv" sdk "github.com/cosmos/cosmos-sdk/types" "github.com/cosmos/cosmos-sdk/wire" ) // keeper of the paychan store type Keeper struct { storeKey sdk.StoreKey cdc *wire.Codec // needed to serialize objects before putting them in the store coinKeeper bank.Keeper // codespace //codespace sdk.CodespaceType // ?? } // Called when creating new app. //func NewKeeper(cdc *wire.Codec, key sdk.StoreKey, ck bank.Keeper, codespace sdk.CodespaceType) Keeper { func NewKeeper(cdc *wire.Codec, key sdk.StoreKey, ck bank.Keeper) Keeper { keeper := Keeper{ storeKey: key, cdc: cdc, coinKeeper: ck, //codespace: codespace, } return keeper } // bunch of business logic ... // Reteive a payment channel struct from the blockchain store. // They are indexed by a concatenation of sender address, receiver address, and an integer. func (keeper Keeper) GetPaychan(ctx sdk.Context, sender sdk.Address, receiver sdk.Address, id integer) (Paychan, bool) { // Return error as second argument instead of bool? var pych Paychan // load from DB store := ctx.KVStore(k.storeKey) bz := store.Get(paychanKey(sender, receiver, id)) if bz == nil { return pych, false } // unmarshal k.cdc.MustUnmarshalBinary(bz, &pych) // return return pych, true } // Store payment channel struct in blockchain store. func (keeper Keeper) setPaychan(pych Paychan) sdk.Error { store := ctx.KVStore(k.storeKey) // marshal bz := k.cdc.MustMarshalBinary(pych) // write to db pychKey := paychanKey(pych.sender, pych.receiver, pych.id) store.Set(pychKey, bz) // TODO handler errors } // Create a new payment channel and lock up sender funds. func (keeer Keeper) CreatePaychan(sender sdk.Address, receiver sdkAddress, amt sdk.Coins) (sdk.Tags, sdk.Error) { // Calculate next id (num existing paychans plus 1) id := len(keeper.GetPaychans(sender, receiver)) + 1 // subtract coins from sender k.coinKeeper.SubtractCoins(ctx, sender, amt) // create new Paychan struct (create ID) pych := Paychan{sender, receiver, id, balance: amt} // save to db err := k.setPaychan(pych) // TODO validation // sender has enough coins - done in Subtract method // receiver address exists? // paychan doesn't exist already tags := sdk.NewTags() return tags, err } // Close a payment channel and distribute funds to participants. func (keeper Keeper) ClosePaychan(sender sdk.Address, receiver sdk.Address, id integer, receiverAmt sdk.Coins) (sdk.Tags, sdk.Error) { pych := GetPaychan(ctx, sender, receiver, id) // compute coin distribution senderAmt = pych.balance.Minus(receiverAmt) // Minus sdk.Coins method // add coins to sender k.coinKeeper.AddCoins(ctx, sender, senderAmt) // add coins to receiver k.coinKeeper.AddCoins(ctx, receiver, receiverAmt) // delete paychan from db pychKey := paychanKey(pych.sender, pych.receiver, pych.id) store.Delete(pychKey) // TODO validation // paychan exists // output coins are less than paychan balance // sender and receiver addresses exist? //sdk.NewTags( // "action", []byte("channel closure"), // "receiver", receiver.Bytes(), // "sender", sender.Bytes(), // "id", ??) tags := sdk.NewTags() return tags, nil } // Creates a key to reference a paychan in the blockchain store. func paychanKey(sender sdk.Address, receiver sdk.Address, id integer) []byte { //sdk.Address is just a slice of bytes under a different name //convert id to string then to byte slice idAsBytes := []byte(strconv.Itoa(id)) // concat sender and receiver and integer ID return append(sender.Bytes(), receiver.Bytes()..., idAsBytes...) } // Get all paychans between a given sender and receiver. func (keeper Keeper) GetPaychans(sender sdk.Address, receiver sdk.Address) []Paychan { var paychans []Paychan // TODO Implement this return paychans } // maybe getAllPaychans(sender sdk.address) []Paychan