Add total and available delegation limits info to staker.

internal/graphql/schema/bundle.go

@@ -1,6 +1,6 @@
 package gqlschema
 
-// Auto generated GraphQL schema bundle; created 2020-05-01 00:34
+// Auto generated GraphQL schema bundle; created 2020-05-02 10:50
 const schema = `
 # StakerInfo represents extended staker information from smart contract.
 type StakerInfo {
@@ -118,7 +118,7 @@ type EstimatedRewards {
     currentRewardRateYearly: Int!
 
     """
-    Total amount of staked FTM tokens used for the calculation.
+    Total amount of staked FTM tokens used for the calculation in WEI units.
     The estimation uses total staked amount, not the effective amount provided
     by the last epoch. The effective amount does include current undelegations and also
     skips offline self-stakings and flagged stakings.
@@ -314,6 +314,18 @@ type Staker {
     "Amount of tokens delegated to the staker."
     delegatedMe: BigInt
 
+    """
+    Maximum total amount of tokens allowed to be delegated to the staker.
+    This value depends on the amount of self staked tokens.
+    """
+    totalDelegatedLimit: BigInt!
+
+    """
+    Maximum amount of tokens allowed to be delegated to the staker on a new delegation.
+    This value depends on the amount of self staked tokens.
+    """
+    delegatedLimit: BigInt!
+
     "Is this a validator record."
     isValidator: Boolean!
 
@@ -520,7 +532,7 @@ type Query {
     price(to:String!):Price!
 
     """
-    Get calculated staking rewards for an account or given staking amount.
+    Get calculated staking rewards for an account or given staking amount in FTM tokens.
     At least one of the address and amount parameters must be provided.
     If you provide both, the address takes precedence and the amount is ignored.
     """

internal/graphql/schema/definition/types/staker.graphql

@@ -12,9 +12,21 @@ type Staker {
     "Amount of own staked tokens in WEI."
     stake: BigInt
 
-    "Amount of tokens delegated to the staker."
+    "Amount of tokens delegated to the staker in WEI."
     delegatedMe: BigInt
 
+    """
+    Maximum total amount of tokens allowed to be delegated to the staker in WEI.
+    This value depends on the amount of self staked tokens.
+    """
+    totalDelegatedLimit: BigInt!
+
+    """
+    Maximum amount of tokens allowed to be delegated to the staker on a new delegation in WEI.
+    This value depends on the amount of self staked tokens.
+    """
+    delegatedLimit: BigInt!
+
     "Is this a validator record."
     isValidator: Boolean!
 

internal/repository/rpc/sfc.go

@@ -131,8 +131,17 @@ func (ftm *FtmBridge) stakerUpdateFromSfc(staker *types.Staker) error {
 		staker.Stake = (*hexutil.Big)(si.StakeAmount)
 		staker.Status = hexutil.Uint64(si.Status.Uint64())
 
-		// recalculate the total stake
-		staker.TotalStake = (*hexutil.Big)(big.NewInt(0).Add(si.DelegatedMe, si.StakeAmount))
+		if staker.Stake != nil && staker.DelegatedMe != nil {
+			// recalculate the total stake
+			staker.TotalStake = (*hexutil.Big)(big.NewInt(0).Add(si.DelegatedMe, si.StakeAmount))
+
+			// calculate delegation limit
+			staker.TotalDelegatedLimit = ftm.maxDelegatedLimit(staker.Stake, contract)
+
+			// calculate available limit for staking
+			val := new(big.Int).Sub((*big.Int)(&staker.TotalDelegatedLimit), (*big.Int)(staker.DelegatedMe))
+			staker.DelegatedLimit = (hexutil.Big)(*val)
+		}
 	} else {
 		// log issue
 		ftm.log.Debug("staker info update from SFC failed, no data received")
@@ -142,6 +151,32 @@ func (ftm *FtmBridge) stakerUpdateFromSfc(staker *types.Staker) error {
 	return nil
 }
 
+// maxDelegatedLimit calculate maximum amount of tokens allowed to be delegated to a staker.
+func (ftm *FtmBridge) maxDelegatedLimit(staked *hexutil.Big, contract *SfcContract) hexutil.Big {
+	// if we don't know the staked amount, return zero
+	if staked == nil {
+		return (hexutil.Big)(*hexutil.MustDecodeBig("0x0"))
+	}
+
+	// ratio unit is used to calculate the value (1.000.000)
+	// please note this formula is taken from SFC contract and can change
+	ratioUnit := hexutil.MustDecodeBig("0xF4240")
+
+	// get delegation ration
+	ratio, err := contract.MaxDelegatedRatio(nil)
+	if err != nil {
+		ftm.log.Errorf("can not get the delegation ratio; %s", err.Error())
+		return (hexutil.Big)(*hexutil.MustDecodeBig("0x0"))
+	}
+
+	// calculate the delegation limit temp value
+	temp := new(big.Int).Mul((*big.Int)(staked), ratio)
+
+	// adjust to percent
+	value := new(big.Int).Div(temp, ratioUnit)
+	return (hexutil.Big)(*value)
+}
+
 // Staker extract a staker information by numeric id.
 func (ftm *FtmBridge) Staker(id hexutil.Uint64) (*types.Staker, error) {
 	// keep track of the operation

internal/types/staker.go

@@ -32,6 +32,10 @@ type Staker struct {
 	ClaimedRewards           *hexutil.Big   `json:"claimedRewards"`
 	DelegationClaimedRewards *hexutil.Big   `json:"delegatorsClaimedRewards"`
 	Status                   hexutil.Uint64 `json:"status"`
+
+	/* delegation limits */
+	TotalDelegatedLimit hexutil.Big
+	DelegatedLimit      hexutil.Big
 }
 
 // StakerInfo holds extended staker information.