make payments

nitro/wallet/balances.nim

@@ -0,0 +1,42 @@
+import std/tables
+import std/sequtils
+import ../basics
+import ../protocol
+
+include questionable/errorban
+
+type
+  Balances* = OrderedTable[Destination, UInt256]
+
+func `balances`*(outcome: Outcome, asset: EthAddress): ?Balances =
+  for assetOutcome in seq[AssetOutcome](outcome):
+    if assetOutcome.assetHolder == asset:
+      if assetOutcome.kind == allocationType:
+        let allocation = assetOutcome.allocation
+        let items = seq[AllocationItem](allocation)
+        return items.toOrderedTable.some
+  Balances.none
+
+func `update`*(outcome: var Outcome, asset: EthAddress, table: Balances) =
+  for assetOutcome in seq[AssetOutcome](outcome).mitems:
+    if assetOutcome.assetHolder == asset:
+      if assetOutcome.kind == allocationType:
+        assetOutcome.allocation = Allocation(toSeq(table.pairs))
+
+func move*(balances: var Balances,
+           source: Destination,
+           destination: Destination,
+           amount: UInt256): ?!void =
+  try:
+    if balances[source] < amount:
+      return void.failure "insufficient funds"
+
+    balances[source] -= amount
+    if (balances.contains(destination)):
+      balances[destination] += amount
+    else:
+      balances[destination] = amount
+
+    ok()
+  except KeyError:
+    void.failure "no funds"

nitro/wallet/signedstate.nim

@@ -6,7 +6,8 @@ include questionable/errorban
 type
   SignedState* = object
     state*: State
-    signatures*: seq[(EthAddress, Signature)]
+    signatures*: Signatures
+  Signatures* = seq[(EthAddress, Signature)]
 
 func hasParticipant*(signed: SignedState, participant: EthAddress): bool =
   signed.state.channel.participants.contains(participant)

nitro/wallet/wallet.nim

@@ -4,18 +4,23 @@ import ../keys
 import ../protocol
 import ./signedstate
 import ./ledger
+import ./balances
 
 include questionable/errorban
 
 export basics
 export keys
 export signedstate
+export balances
 
 type
   Wallet* = object
     key: PrivateKey
     channels: Table[ChannelId, SignedState]
   ChannelId* = Destination
+  Payment* = tuple
+    destination: Destination
+    amount: UInt256
 
 func init*(_: type Wallet, key: PrivateKey): Wallet =
   result.key = key
@@ -23,8 +28,8 @@ func init*(_: type Wallet, key: PrivateKey): Wallet =
 func address*(wallet: Wallet): EthAddress =
   wallet.key.toPublicKey.toAddress
 
-func `[]`*(wallet: Wallet, channel: ChannelId): ?SignedState =
-  wallet.channels[channel].catch.option
+func destination*(wallet: Wallet): Destination =
+  wallet.address.toDestination
 
 func sign(wallet: Wallet, state: SignedState): SignedState =
   var signed = state
@@ -37,6 +42,11 @@ func createChannel(wallet: var Wallet, state: SignedState): ChannelId =
   wallet.channels[id] = signed
   id
 
+func updateChannel(wallet: var Wallet, state: SignedState) =
+  let signed = wallet.sign(state)
+  let id = getChannelId(signed.state.channel)
+  wallet.channels[id] = signed
+
 func openLedgerChannel*(wallet: var Wallet,
                         hub: EthAddress,
                         chainId: UInt256,
@@ -54,3 +64,68 @@ func acceptChannel*(wallet: var Wallet, signed: SignedState): ?!ChannelId =
     return ChannelId.failure "incorrect signatures"
 
   wallet.createChannel(signed).success
+
+func state*(wallet: Wallet, channel: ChannelId): ?State =
+  try:
+    wallet.channels[channel].state.some
+  except KeyError:
+    State.none
+
+func signatures*(wallet: Wallet, channel: ChannelId): ?Signatures =
+  try:
+    wallet.channels[channel].signatures.some
+  except KeyError:
+    Signatures.none
+
+func signature*(wallet: Wallet,
+                channel: ChannelId,
+                address: EthAddress): ?Signature =
+  if signatures =? wallet.signatures(channel):
+    for (signer, signature) in signatures:
+      if signer == address:
+        return signature.some
+  Signature.none
+
+func balance*(wallet: Wallet,
+              channel: ChannelId,
+              asset: EthAddress,
+              destination: Destination): UInt256 =
+  if state =? wallet.state(channel):
+    if balances =? state.outcome.balances(asset):
+      try:
+        return balances[destination]
+      except KeyError:
+        return 0.u256
+  0.u256
+
+func balance*(wallet: Wallet,
+              channel: ChannelId,
+              asset: EthAddress,
+              address: EthAddress): UInt256 =
+  wallet.balance(channel, asset, address.toDestination)
+
+func pay*(wallet: var Wallet,
+          channel: ChannelId,
+          asset: EthAddress,
+          receiver: Destination,
+          amount: UInt256): ?!void =
+  if var state =? wallet.state(channel):
+    if var balances =? state.outcome.balances(asset):
+      ?balances.move(wallet.destination, receiver, amount)
+      try:
+        state.outcome.update(asset, balances)
+        wallet.updateChannel(SignedState(state: state))
+        ok()
+      except KeyError as error:
+        void.failure error
+    else:
+      void.failure "asset not found"
+  else:
+    void.failure "channel not found"
+
+func pay*(wallet: var Wallet,
+          channel: ChannelId,
+          asset: EthAddress,
+          receiver: EthAddress,
+          amount: UInt256): ?!void =
+  wallet.pay(channel, asset, receiver.toDestination, amount)

tests/nitro/testWallet.nim

@@ -2,7 +2,7 @@ import ./basics
 
 suite "wallet":
 
-  test "wallet can be created from private key":
+  test "wallet is created from private key":
     let key = PrivateKey.random()
     let wallet = Wallet.init(key)
     check wallet.address == key.toPublicKey.toAddress
@@ -24,24 +24,23 @@ suite "wallet: opening ledger channel":
     channel = wallet.openLedgerChannel(hub, chainId, nonce, asset, amount)
 
   test "sets correct channel definition":
-    let definition = wallet[channel].get.state.channel
+    let definition = wallet.state(channel).get.channel
     check definition.chainId == chainId
     check definition.nonce == nonce
     check definition.participants == @[wallet.address, hub]
 
   test "provides correct outcome":
-    let outcome = wallet[channel].get.state.outcome
-    let destination = wallet.address.toDestination
-    check outcome == Outcome.init(asset, {destination: amount})
+    let outcome = wallet.state(channel).get.outcome
+    check outcome == Outcome.init(asset, {wallet.destination: amount})
 
   test "signs the state":
-    let state = wallet[channel].get.state
-    let signatures = wallet[channel].get.signatures
+    let state = wallet.state(channel).get
+    let signatures = wallet.signatures(channel).get
     check signatures == @{wallet.address: key.sign(state)}
 
   test "sets app definition and app data to zero":
-    check wallet[channel].get.state.appDefinition == EthAddress.zero
-    check wallet[channel].get.state.appData.len == 0
+    check wallet.state(channel).get.appDefinition == EthAddress.zero
+    check wallet.state(channel).get.appData.len == 0
 
 suite "wallet: accepting incoming channel":
 
@@ -56,12 +55,12 @@ suite "wallet: accepting incoming channel":
 
   test "returns the new channel id":
     let channel = wallet.acceptChannel(signed).get
-    check wallet[channel].get.state == signed.state
+    check wallet.state(channel).get == signed.state
 
   test "signs the channel state":
     let channel = wallet.acceptChannel(signed).get
     let expectedSignatures = @{wallet.address: key.sign(signed.state)}
-    check wallet[channel].get.signatures == expectedSignatures
+    check wallet.signatures(channel).get == expectedSignatures
 
   test "fails when wallet address is not a participant":
     let wrongParticipants = seq[EthAddress].example
@@ -75,3 +74,59 @@ suite "wallet: accepting incoming channel":
     signed.state.channel.participants &= @[otherWallet.address]
     signed.signatures = @{wrongAddress: otherKey.sign(signed.state)}
     check wallet.acceptChannel(signed).isErr
+
+suite "wallet: making payments":
+
+  let key = PrivateKey.random()
+  let asset = EthAddress.example
+  let hub = EthAddress.example
+  let chainId = UInt256.example
+  let nonce = UInt48.example
+
+  var wallet: Wallet
+  var channel: ChannelId
+
+  test "paying updates the channel state":
+    wallet = Wallet.init(key)
+    let me = wallet.address
+    channel = wallet.openLedgerChannel(hub, chainId, nonce, asset, 100.u256)
+
+    check wallet.pay(channel, asset, hub, 1.u256).isOk
+    check wallet.balance(channel, asset, me) == 99.u256
+    check wallet.balance(channel, asset, hub) == 1.u256
+
+    check wallet.pay(channel, asset, hub, 2.u256).isOk
+    check wallet.balance(channel, asset, me) == 97.u256
+    check wallet.balance(channel, asset, hub) == 3.u256
+
+  test "paying updates signatures":
+    wallet = Wallet.init(key)
+    channel = wallet.openLedgerChannel(hub, chainId, nonce, asset, 100.u256)
+    check wallet.pay(channel, asset, hub, 1.u256).isOk
+    let expectedSignature = key.sign(wallet.state(channel).get)
+    check wallet.signature(channel, wallet.address) == expectedSignature.some
+
+  test "payment fails when channel not found":
+    wallet = Wallet.init(key)
+    check wallet.pay(channel, asset, hub, 1.u256).isErr
+
+  test "payment fails when asset not found":
+    wallet = Wallet.init(key)
+    var state = State.example
+    state.channel.participants &= wallet.address
+    channel = wallet.acceptChannel(SignedState(state: state)).get
+    check wallet.pay(channel, asset, hub, 1.u256).isErr
+
+  test "payment fails when payer has no allocation":
+    wallet = Wallet.init(key)
+    var state: State
+    state.channel = ChannelDefinition(participants: @[wallet.address])
+    state.outcome = Outcome.init(asset, @[])
+    channel = wallet.acceptChannel(SignedState(state: state)).get
+    check wallet.pay(channel, asset, hub, 1.u256).isErr
+
+  test "payment fails when payer has insufficient funds":
+    wallet = Wallet.init(key)
+    channel = wallet.openLedgerChannel(hub, chainId, nonce, asset, 1.u256)
+    check wallet.pay(channel, asset, hub, 1.u256).isOk
+    check wallet.pay(channel, asset, hub, 1.u256).isErr