add basic keeper logic

internal/x/paychan/handler.go

@@ -5,6 +5,7 @@ import (
 	"reflect"
 )
 
+// Called when adding routes to a newly created app.
 // NewHandler returns a handler for "paychan" type messages.
 func NewHandler(k Keeper) sdk.Handler {
 	return func(ctx sdk.Context, msg sdk.Msg) sdk.Result {

internal/x/paychan/keeper.go

@@ -1,62 +1,112 @@
 package paychan
 
+import (
+	"strconv"
+)
+
 // keeper of the paychan store
 type Keeper struct {
-	storeKey   sdk.StoreKey
-	cdc        *wire.Codec // needed?
+	storeKey sdk.StoreKey
+	//cdc        *wire.Codec // needed?
 	coinKeeper bank.Keeper
 
 	// codespace
-	codespace sdk.CodespaceType // ??
+	//codespace sdk.CodespaceType // ??
 }
 
-func NewKeeper(cdc *wire.Codec, key sdk.StoreKey, ck bank.Keeper, codespace sdk.CodespaceType) Keeper {
+// Called when creating new app.
+//func NewKeeper(cdc *wire.Codec, key sdk.StoreKey, ck bank.Keeper, codespace sdk.CodespaceType) Keeper {
+func NewKeeper(key sdk.StoreKey, ck bank.Keeper) Keeper {
 	keeper := Keeper{
-		storeKey:   key,
-		cdc:        cdc,
+		storeKey: key,
+		//cdc:        cdc,
 		coinKeeper: ck,
-		codespace:  codespace,
+		//codespace:  codespace,
 	}
 	return keeper
 }
 
 // bunch of business logic ...
 
-func (keeper Keeper) GetPaychan(paychanID) Paychan {
+
+// 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
-	// unmarshall
+	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
 }
 
-func (keeer Keeper) CreatePaychan(receiver sdkAddress, amt sdk.Coins) (Paychan, sdk.Error) {
+// Create a new payment channel and lock up sender funds.
+func (keeer Keeper) CreatePaychan(sender sdk.Address, receiver sdkAddress, id integer, amt sdk.Coins) (Paychan, sdk.Error) {
 	// 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)
 
-	// validation:
-	// sender has enough coins
+	return pych, err
+
+	// TODO validation
+	// sender has enough coins - done in Subtract method
 	// receiver address exists?
 	// paychan doesn't exist already
 }
 
-func (keeper Keeper) ClosePaychan() sdk.Error {
+// 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.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)
 
-	// validation:
+
+	// TODO validation
 	// paychan exists
 	// output coins are less than paychan balance
 	// sender and receiver addresses exist?
+
+	return nil
 }
 
-func paychanKey(Paychan) {
+// 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...)
 }
 
 // maybe getAllPaychans(sender sdk.address) []Paychan

internal/x/paychan/types.go

@@ -11,6 +11,7 @@ struct Paychan {
 	balance sdk.Coins
 	sender sdk.Address
 	receiver sdk.Address
+	id integer
 }