0g-chain/internal/x/paychan/keeper.go
2018-07-15 12:41:55 +01:00

193 lines
5.9 KiB
Go

package paychan
import (
"strconv"
sdk "github.com/cosmos/cosmos-sdk/types"
"github.com/cosmos/cosmos-sdk/wire"
"github.com/cosmos/cosmos-sdk/x/bank"
)
// keeper of the paychan store
// Handles validation internally. Does not rely on calling code to do validation.
// Aim to keep public methids safe, private ones not necessaily.
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 (k Keeper) GetPaychan(ctx sdk.Context, sender sdk.Address, receiver sdk.Address, id int64) (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 (k Keeper) setPaychan(ctx sdk.Context, pych Paychan) {
store := ctx.KVStore(k.storeKey)
// marshal
bz := k.cdc.MustMarshalBinary(pych) // panics if something goes wrong
// write to db
pychKey := paychanKey(pych.Sender, pych.Receiver, pych.Id)
store.Set(pychKey, bz) // panics if something goes wrong
}
// Create a new payment channel and lock up sender funds.
func (k Keeper) CreatePaychan(ctx sdk.Context, sender sdk.Address, receiver sdk.Address, amount sdk.Coins) (sdk.Tags, sdk.Error) {
// TODO move validation somewhere nicer
// args present
if len(sender) == 0 {
return nil, sdk.ErrInvalidAddress(sender.String())
}
if len(receiver) == 0 {
return nil, sdk.ErrInvalidAddress(receiver.String())
}
if len(amount) == 0 {
return nil, sdk.ErrInvalidCoins(amount.String())
}
// Check if coins are sorted, non zero, positive
if !amount.IsValid() {
return nil, sdk.ErrInvalidCoins(amount.String())
}
if !amount.IsPositive() {
return nil, sdk.ErrInvalidCoins(amount.String())
}
// sender should exist already as they had to sign.
// receiver address exists. am is the account mapper in the coin keeper.
// TODO automatically create account if not present?
// TODO remove as account mapper not available to this pkg
//if k.coinKeeper.am.GetAccount(ctx, receiver) == nil {
// return nil, sdk.ErrUnknownAddress(receiver.String())
//}
// sender has enough coins - done in Subtract method
// TODO check if sender and receiver different?
// Calculate next id (just num of existing paychans - zero indexed)
id := int64(len(k.GetPaychans(sender, receiver)))
// subtract coins from sender
_, tags, err := k.coinKeeper.SubtractCoins(ctx, sender, amount)
if err != nil {
return nil, err
}
// create new Paychan struct
pych := Paychan{
Sender: sender,
Receiver: receiver,
Id: id,
Balance: amount,
}
// save to db
k.setPaychan(ctx, pych)
// TODO create tags
//tags := sdk.NewTags()
return tags, err
}
// Close a payment channel and distribute funds to participants.
func (k Keeper) ClosePaychan(ctx sdk.Context, sender sdk.Address, receiver sdk.Address, id int64, receiverAmount sdk.Coins) (sdk.Tags, sdk.Error) {
if len(sender) == 0 {
return nil, sdk.ErrInvalidAddress(sender.String())
}
if len(receiver) == 0 {
return nil, sdk.ErrInvalidAddress(receiver.String())
}
if len(receiverAmount) == 0 {
return nil, sdk.ErrInvalidCoins(receiverAmount.String())
}
// check id ≥ 0
if id < 0 {
return nil, sdk.ErrInvalidAddress(strconv.Itoa(int(id))) // TODO implement custom errors
}
// Check if coins are sorted, non zero, non negative
if !receiverAmount.IsValid() {
return nil, sdk.ErrInvalidCoins(receiverAmount.String())
}
if !receiverAmount.IsPositive() {
return nil, sdk.ErrInvalidCoins(receiverAmount.String())
}
store := ctx.KVStore(k.storeKey)
pych, exists := k.GetPaychan(ctx, sender, receiver, id)
if !exists {
return nil, sdk.ErrUnknownAddress("paychan not found") // TODO implement custom errors
}
// compute coin distribution
senderAmount := pych.Balance.Minus(receiverAmount) // Minus sdk.Coins method
// check that receiverAmt not greater than paychan balance
if !senderAmount.IsNotNegative() {
return nil, sdk.ErrInsufficientFunds(pych.Balance.String())
}
// add coins to sender
// creating account if it doesn't exist
k.coinKeeper.AddCoins(ctx, sender, senderAmount)
// add coins to receiver
k.coinKeeper.AddCoins(ctx, receiver, receiverAmount)
// delete paychan from db
pychKey := paychanKey(pych.Sender, pych.Receiver, pych.Id)
store.Delete(pychKey)
// TODO create tags
//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 int64) []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(int(id)))
// concat sender and receiver and integer ID
key := append(sender.Bytes(), receiver.Bytes()...)
key = append(key, idAsBytes...)
return key
}
// Get all paychans between a given sender and receiver.
func (k Keeper) GetPaychans(sender sdk.Address, receiver sdk.Address) []Paychan {
var paychans []Paychan
// TODO Implement this
return paychans
}
// maybe getAllPaychans(sender sdk.address) []Paychan