ERC20 token bridging (withdrawal flow) (#1259)

* Extract common code for withdraw and deposit commands

* Refactor deposit and withdraw commands, introduce exit command (draft)

* Mark json rpc flags optional and rely on default values

* Withdrawal workflow implemented

* Cleanups

* Remove child-token flag

* E2E build fix

* Document bridge exit command

* Refactor flags in bridge subcommands

* Remove AdminAddr from manifest file

* Update polybft readme

* Update README.md

Remove child-token flag from deposit-erc20 command example.

* Fix receivers addresses

* Code cleanup and wrapping up

* Generate missing bindings

* Remove json rpc unused flag name

* Introduce L2StateSyncedEvent and utilize it

* Remove outdated comment

command/bridge/README.md

@@ -2,13 +2,42 @@
 
 This is a helper command, which allows sending deposits from root to child chain and make withdrawals from child chain to root chain.
 
-## Deposit
-This is a helper command which bridges assets from rootchain to the child chain (allows depositing)
+## Deposit ERC20
+This is a helper command which deposits ERC20 tokens from the root chain to the child chain
 
 ```bash
-$ polygon-edge bridge deposit 
-    --depositor-key <hex_encoded_depositor_private_key>
-    --token <token_type>
+$ polygon-edge bridge deposit-erc20
+    --sender-key <hex_encoded_depositor_private_key>
     --receivers <receivers_addresses>
     --amounts <amounts>
-```
+    --root-token <root_erc20_token_address>
+    --root-predicate <root_erc20_predicate_address>
+    --json-rpc <root_chain_json_rpc_endpoint>
+```
+
+## Withdraw ERC20
+This is a helper command which withdraws ERC20 tokens from the child chain to the root chain
+
+```bash
+$ polygon-edge bridge withdraw-erc20
+    --sender-key <hex_encoded_withdraw_sender_private_key>
+    --receivers <receivers_addresses>
+    --amounts <amounts>
+    --child-predicate <rchild_erc20_predicate_address>
+    [--child-token <child_erc20_token_address>]
+    --json-rpc <child_chain_json_rpc_endpoint>
+```
+
+## Exit
+This is a helper command which qeuries child chain for exit event proof and sends an exit transaction to ExitHelper smart contract.
+
+```bash
+$ polygon-edge bridge exit
+    --sender-key <hex_encoded_withdraw_sender_private_key>
+    --exit-helper <exit_helper_address>
+    --event-id <exit_event_id>
+    --epoch <epoch_in_which_exit_event_got_processed>
+    --checkpoint-block <epoch_in_which_exit_event_got_processed>
+    --root-json-rpc <root_chain_json_rpc_endpoint>
+    --child-json-rpc <child_chain_json_rpc_endpoint>
+```

command/bridge/bridge.go

@@ -1,8 +1,10 @@
 package bridge
 
 import (
-	"github.com/0xPolygon/polygon-edge/command/bridge/deposit"
 	"github.com/spf13/cobra"
+
+	"github.com/0xPolygon/polygon-edge/command/bridge/deposit"
+	"github.com/0xPolygon/polygon-edge/command/bridge/withdraw"
 )
 
 // GetCommand creates "bridge" helper command
@@ -21,5 +23,9 @@ func registerSubcommands(baseCmd *cobra.Command) {
 	baseCmd.AddCommand(
 		// bridge deposit
 		deposit.GetCommand(),
+		// bridge withdraw
+		withdraw.GetWithdrawCommand(),
+		// bridge exit
+		withdraw.GetExitCommand(),
 	)
 }

command/bridge/common/bridge_erc20_params.go

@@ -0,0 +1,29 @@
+package common
+
+import (
+	"errors"
+)
+
+const (
+	SenderKeyFlag = "sender-key"
+	ReceiversFlag = "receivers"
+	AmountsFlag   = "amounts"
+)
+
+var (
+	errInconsistentAccounts = errors.New("receivers and amounts must be equal length")
+)
+
+type ERC20BridgeParams struct {
+	TxnSenderKey string
+	Receivers    []string
+	Amounts      []string
+}
+
+func (bp *ERC20BridgeParams) ValidateFlags() error {
+	if len(bp.Receivers) != len(bp.Amounts) {
+		return errInconsistentAccounts
+	}
+
+	return nil
+}