feat: InitChainer auto stakes uniformly to validators at genesis (#26)

Stake automatically 50% of balance for accounts that have more than 25
$GOVGEN at genesis initialization. The resulting stake distribution will
provide approximately the same voting power to all genesis validators.
Accounts will automatically stake to 5 validators if balance is less
than 500 $GOVGEN, 10 validators if balance is less than 10000 $GOVGEN
and 20 validators if more, uniformly.

---------

Co-authored-by: Giuseppe Natale <[email protected]>

CHANGELOG.md

@@ -20,5 +20,7 @@
   ([#13](https://github.com/atomone-hub/govgen/pull/13)).
 * Adapt voting period to proposal type.
   ([#16](https://github.com/atomone-hub/govgen/pull/16)).
+* `InitChainer` auto stakes uniformly to validators at genesis
+  ([#26](https://github.com/atomone-hub/govgen/pull/26)).
 
 ### STATE BREAKING

README.md

@@ -14,3 +14,5 @@ The following modifications have been made to the Cosmos Hub software to create
     7. Removed ability for validators to vote on proposals with delegations, they can only use their own stake
     8. Removed community spend proposal
     9. Allowed setting different voting periods for different proposal types
+   10. Stake automatically 50% of balance for accounts that have more than 25 $GOVGEN at genesis initialization. The resulting stake distribution will provide approximately the same voting power to all genesis validators. Accounts will automatically stake to 5 validators if balance is less than 500 $GOVGEN, 10 validators if balance is less than 10000 $GOVGEN and 20 validators if more, uniformly.
+

app/app.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"sort"
 
 	"github.com/gorilla/mux"
 	"github.com/rakyll/statik/fs"
@@ -15,6 +16,7 @@ import (
 	"github.com/tendermint/tendermint/libs/log"
 	tmos "github.com/tendermint/tendermint/libs/os"
 	dbm "github.com/tendermint/tm-db"
+	"golang.org/x/exp/slices"
 
 	// unnamed import of statik for swagger UI support
 	_ "github.com/cosmos/cosmos-sdk/client/docs/statik"
@@ -37,6 +39,7 @@ import (
 	authrest "github.com/cosmos/cosmos-sdk/x/auth/client/rest"
 	authtx "github.com/cosmos/cosmos-sdk/x/auth/tx"
 	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
+	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
 	"github.com/cosmos/cosmos-sdk/x/crisis"
 	stakingtypes "github.com/cosmos/cosmos-sdk/x/staking/types"
 	upgradetypes "github.com/cosmos/cosmos-sdk/x/upgrade/types"
@@ -241,7 +244,87 @@ func (app *GovGenApp) InitChainer(ctx sdk.Context, req abci.RequestInitChain) ab
 
 	app.UpgradeKeeper.SetModuleVersionMap(ctx, app.mm.GetVersionMap())
 
-	return app.mm.InitGenesis(ctx, app.appCodec, genesisState)
+	res := app.mm.InitGenesis(ctx, app.appCodec, genesisState)
+
+	// auto stake genesis accounts
+	app.setInitialStakingDistribution(ctx, genesisState)
+
+	return res
+}
+
+// setInitialStakingDistribution auto stakes genesis accounts in a fairly
+// distributed manner.
+func (app *GovGenApp) setInitialStakingDistribution(ctx sdk.Context, genesisState GenesisState) {
+	var bankState banktypes.GenesisState
+	app.appCodec.MustUnmarshalJSON(genesisState[banktypes.ModuleName], &bankState)
+	// Sort balances in descending order
+	sort.Slice(bankState.Balances, func(i, j int) bool {
+		return bankState.Balances[i].Coins.IsAllGT(bankState.Balances[j].Coins)
+	})
+
+	var (
+		minTokens      = sdk.NewInt(25_000_000)
+		powerReduction = app.StakingKeeper.PowerReduction(ctx)
+	)
+	// Extend validator to track delegations
+	type validator struct {
+		stakingtypes.Validator
+		totalDelegations int64
+	}
+	var validators []*validator
+	for _, val := range app.StakingKeeper.GetAllValidators(ctx) {
+		validators = append(validators, &validator{
+			Validator: val,
+		})
+	}
+	if len(validators) == 0 {
+		return
+	}
+	for _, balance := range bankState.Balances {
+		tokens := balance.Coins.AmountOf("ugovgen")
+		if tokens.LTE(minTokens) {
+			// Don't stake when tokens <= minToken
+			continue
+		}
+		// Take 50% of the balance for staking
+		stake := tokens.QuoRaw(2)
+
+		// Determine the number of validators that will receive a delegation
+		var splitStake sdk.Int
+		switch {
+		case stake.LT(sdk.NewInt(500_000_000)):
+			splitStake = stake.QuoRaw(5)
+		case stake.LT(sdk.NewInt(10_000_000_000)):
+			splitStake = stake.QuoRaw(10)
+		default:
+			splitStake = stake.QuoRaw(20)
+		}
+
+		// Delegation loop for each selected validator
+		for ; stake.GTE(powerReduction); stake = stake.Sub(splitStake) {
+			bondAmt := sdk.MinInt(stake, splitStake)
+			// Delegate to validator which has the less delegations
+			validator := slices.MinFunc(validators, func(val1, val2 *validator) int {
+				return int(val1.totalDelegations - val2.totalDelegations)
+			})
+			if _, err := app.StakingKeeper.Delegate(
+				ctx,
+				balance.GetAddress(),
+				bondAmt,
+				stakingtypes.Unbonded,
+				validator.Validator,
+				true,
+			); err != nil {
+				panic(err)
+			}
+
+			// track delegation for the sake of the algorithm
+			validator.totalDelegations += bondAmt.Int64()
+
+			// reload validator to avoid power index problem
+			validator.Validator, _ = app.StakingKeeper.GetValidator(ctx, validator.GetOperator())
+		}
+	}
 }
 
 // LoadHeight loads a particular height

x/gov/module_test.go

@@ -19,7 +19,8 @@ func TestItCreatesModuleAccountOnInitBlock(t *testing.T) {
 
 	app.InitChain(
 		abcitypes.RequestInitChain{
-			AppStateBytes: []byte("{}"),
+			// bank module must be present because of app.setInitialStakingDistribution
+			AppStateBytes: []byte(`{"bank":{}}`),
 			ChainId:       "test-chain-id",
 		},
 	)