chainreg+lnd: split chain control initialization

As a preparation for extracting the wallet related initialization code,
we first need to separate the purely configuration related chain control
initialization from the wallet related code. We do that by splitting the
chain control into a partial and full struct that is initialized in two
parts. This also allows us to create the wallet configuration itself
outside of the chain control package and we need to thread through fewer
parameters through the chain control config.

lnd.go

@@ -718,36 +718,59 @@ func Main(cfg *Config, lisCfg ListenerCfg, interceptor signal.Interceptor) error
 		LtcdMode:                    cfg.LtcdMode,
 		HeightHintDB:                dbs.heightHintDB,
 		ChanStateDB:                 dbs.chanStateDB.ChannelStateDB(),
-		PrivateWalletPw:             privateWalletPw,
-		PublicWalletPw:              publicWalletPw,
-		Birthday:                    walletInitParams.Birthday,
-		RecoveryWindow:              walletInitParams.RecoveryWindow,
-		Wallet:                      walletInitParams.Wallet,
 		NeutrinoCS:                  neutrinoCS,
 		ActiveNetParams:             cfg.ActiveNetParams,
 		FeeURL:                      cfg.FeeURL,
 		Dialer: func(addr string) (net.Conn, error) {
 			return cfg.net.Dial("tcp", addr, cfg.ConnectionTimeout)
 		},
-		BlockCache:    blockCache,
-		LoaderOptions: []btcwallet.LoaderOption{dbs.walletDB},
+		BlockCache: blockCache,
+	}
+
+	// Let's go ahead and create the partial chain control now that is only
+	// dependent on our configuration and doesn't require any wallet
+	// specific information.
+	partialChainControl, cleanup, err := chainreg.NewPartialChainControl(
+		chainControlCfg,
+	)
+	if cleanup != nil {
+		defer cleanup()
+	}
+	if err != nil {
+		err := fmt.Errorf("unable to create partial chain control: %v",
+			err)
+		ltndLog.Error(err)
+		return err
+	}
+
+	walletConfig := &btcwallet.Config{
+		PrivatePass:    privateWalletPw,
+		PublicPass:     publicWalletPw,
+		Birthday:       walletInitParams.Birthday,
+		RecoveryWindow: walletInitParams.RecoveryWindow,
+		NetParams:      cfg.ActiveNetParams.Params,
+		CoinType:       cfg.ActiveNetParams.CoinType,
+		Wallet:         walletInitParams.Wallet,
+		LoaderOptions:  []btcwallet.LoaderOption{dbs.walletDB},
 	}
 
 	// Parse coin selection strategy.
 	switch cfg.CoinSelectionStrategy {
 	case "largest":
-		chainControlCfg.CoinSelectionStrategy = wallet.CoinSelectionLargest
+		walletConfig.CoinSelectionStrategy = wallet.CoinSelectionLargest
 
 	case "random":
-		chainControlCfg.CoinSelectionStrategy = wallet.CoinSelectionRandom
+		walletConfig.CoinSelectionStrategy = wallet.CoinSelectionRandom
 
 	default:
 		return fmt.Errorf("unknown coin selection strategy %v",
 			cfg.CoinSelectionStrategy)
 	}
 
+	// We've created the wallet configuration now, so we can finish
+	// initializing the main chain control.
 	activeChainControl, cleanup, err := chainreg.NewChainControl(
-		chainControlCfg,
+		walletConfig, partialChainControl,
 	)
 	if cleanup != nil {
 		defer cleanup()