0g-chain/internal/x/paychan/keeper.go
2018-07-09 19:46:51 +01:00

113 lines
3.2 KiB
Go

package paychan
import (
"strconv"
)
// keeper of the paychan store
type Keeper struct {
storeKey sdk.StoreKey
//cdc *wire.Codec // needed?
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(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, 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)
return pych, err
// TODO validation
// sender has enough coins - done in Subtract method
// receiver address exists?
// paychan doesn't exist already
}
// 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)
// TODO validation
// paychan exists
// output coins are less than paychan balance
// sender and receiver addresses exist?
return 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...)
}
// maybe getAllPaychans(sender sdk.address) []Paychan