refactor: add MigrateHandler to allow reuse migrate genesis related f…

…unction (backport cosmos#17296) (cosmos#17301)

Co-authored-by: mmsqe <mavis@crypto.com>
Co-authored-by: Julien Robert <julien@rbrt.fr>

CHANGELOG.md

@@ -38,6 +38,11 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
 
+### Improvements
+
+* (x/genutil) [#17296](https://github.com/cosmos/cosmos-sdk/pull/17296) Add `MigrateHandler` to allow reuse migrate genesis related function.
+    * In v0.46, v0.47 this function is additive to the `genesis migrate` command. However in v0.50+, adding custom migrations to the `genesis migrate` command is directly possible.
+
 ## [v0.46.14](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.46.14) - 2023-07-17
 
 ### Features

x/genutil/client/cli/migrate.go

@@ -73,9 +73,20 @@ func MigrateHandler(cmd *cobra.Command, args []string, migrations types.Migratio
 			" upgrade guide at %s.\n", chainUpgradeGuide)
 	}
 
-	var initialState types.AppMap
-	if err := json.Unmarshal(appGenesis.AppState, &initialState); err != nil {
-		return fmt.Errorf("failed to JSON unmarshal initial genesis state: %w", err)
+// MigrateGenesisCmd returns a command to execute genesis state migration.
+func MigrateGenesisCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "migrate [target-version] [genesis-file]",
+		Short: "Migrate genesis to a specified target version",
+		Long: fmt.Sprintf(`Migrate the source genesis into the target version and print to STDOUT.
+
+Example:
+$ %s migrate v0.36 /path/to/genesis.json --chain-id=cosmoshub-3 --genesis-time=2019-04-22T17:00:00Z
+`, version.AppName),
+		Args: cobra.ExactArgs(2),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return MigrateHandler(cmd, args, migrationMap)
+		},
 	}
 
 	newGenState, err := migrationFunc(initialState, clientCtx)
@@ -122,3 +133,75 @@ func MigrateHandler(cmd *cobra.Command, args []string, migrations types.Migratio
 
 	return nil
 }
+
+// MigrateHandler handles the migration command with a migration map as input,
+// returning an error upon failure.
+func MigrateHandler(cmd *cobra.Command, args []string, migrations types.MigrationMap) error {
+	clientCtx := client.GetClientContextFromCmd(cmd)
+
+	var err error
+
+	target := args[0]
+	importGenesis := args[1]
+
+	genDoc, err := validateGenDoc(importGenesis)
+	if err != nil {
+		return err
+	}
+
+	// Since some default values are valid values, we just print to
+	// make sure the user didn't forget to update these values.
+	if genDoc.ConsensusParams.Evidence.MaxBytes == 0 {
+		fmt.Printf("Warning: consensus_params.evidence.max_bytes is set to 0. If this is"+
+			" deliberate, feel free to ignore this warning. If not, please have a look at the chain"+
+			" upgrade guide at %s.\n", chainUpgradeGuide)
+	}
+
+	var initialState types.AppMap
+	if err := json.Unmarshal(genDoc.AppState, &initialState); err != nil {
+		return errors.Wrap(err, "failed to JSON unmarshal initial genesis state")
+	}
+
+	migrationFunc := GetMigrationCallback(target)
+	if migrationFunc == nil {
+		return fmt.Errorf("unknown migration function for version: %s", target)
+	}
+
+	// TODO: handler error from migrationFunc call
+	newGenState := migrationFunc(initialState, clientCtx)
+
+	genDoc.AppState, err = json.Marshal(newGenState)
+	if err != nil {
+		return errors.Wrap(err, "failed to JSON marshal migrated genesis state")
+	}
+
+	genesisTime, _ := cmd.Flags().GetString(flagGenesisTime)
+	if genesisTime != "" {
+		var t time.Time
+
+		err := t.UnmarshalText([]byte(genesisTime))
+		if err != nil {
+			return errors.Wrap(err, "failed to unmarshal genesis time")
+		}
+
+		genDoc.GenesisTime = t
+	}
+
+	chainID, _ := cmd.Flags().GetString(flags.FlagChainID)
+	if chainID != "" {
+		genDoc.ChainID = chainID
+	}
+
+	bz, err := tmjson.Marshal(genDoc)
+	if err != nil {
+		return errors.Wrap(err, "failed to marshal genesis doc")
+	}
+
+	sortedBz, err := sdk.SortJSON(bz)
+	if err != nil {
+		return errors.Wrap(err, "failed to sort JSON genesis doc")
+	}
+
+	cmd.Println(string(sortedBz))
+	return nil
+}