From b76f592095c7613c7228c9f3299c2e8a8e07efbd Mon Sep 17 00:00:00 2001
From: Denis Kirillov <d.kirillov@yadro.com>
Date: Tue, 7 Nov 2023 13:57:30 +0300
Subject: [PATCH] [#48] Add commonclient package

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>
---
 commonclient/invoker.go     | 20 ++++++++++++
 commonclient/iterator.go    | 35 +++++++++++++++++++++
 commonclient/transaction.go | 63 +++++++++++++++++++++++++++++++++++++
 3 files changed, 118 insertions(+)
 create mode 100644 commonclient/invoker.go
 create mode 100644 commonclient/iterator.go
 create mode 100644 commonclient/transaction.go

diff --git a/commonclient/invoker.go b/commonclient/invoker.go
new file mode 100644
index 0000000..ff2dad0
--- /dev/null
+++ b/commonclient/invoker.go
@@ -0,0 +1,20 @@
+package commonclient
+
+import (
+	"github.com/google/uuid"
+	"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
+	"github.com/nspcc-dev/neo-go/pkg/rpcclient/invoker"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+// Invoker is a subset of methods provided by struct invoker.Invoker. The subset contains only those
+// methods that are used by ActorWrapper and clients of the contracts.
+type Invoker interface {
+	Call(contract util.Uint160, method string, params ...any) (*result.Invoke, error)
+	TraverseIterator(sessionID uuid.UUID, iterator *result.Iterator, num int) ([]stackitem.Item, error)
+	TerminateSession(sessionID uuid.UUID) error
+}
+
+// Ensure the interface is compatible with the invoker.Invoker struct.
+var _ Invoker = (*invoker.Invoker)(nil)
diff --git a/commonclient/iterator.go b/commonclient/iterator.go
new file mode 100644
index 0000000..2ff962c
--- /dev/null
+++ b/commonclient/iterator.go
@@ -0,0 +1,35 @@
+package commonclient
+
+import (
+	"fmt"
+
+	"github.com/nspcc-dev/neo-go/pkg/rpcclient/unwrap"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+// ReadIteratorItems calls method that returns iterator and traverses the iterator until all items are read into array.
+func ReadIteratorItems(inv Invoker, batchSize int, contract util.Uint160, method string, params ...any) ([]stackitem.Item, error) {
+	if batchSize <= 0 {
+		panic("batch size must be positive")
+	}
+
+	sessionID, iter, err := unwrap.SessionIterator(inv.Call(contract, method, params...))
+	if err != nil {
+		return nil, fmt.Errorf("unwrap session iterator: %w", err)
+	}
+
+	var shouldStop bool
+	res := make([]stackitem.Item, 0, len(iter.Values))
+	for !shouldStop {
+		items, err := inv.TraverseIterator(sessionID, &iter, batchSize)
+		if err != nil {
+			return nil, err
+		}
+
+		res = append(res, items...)
+		shouldStop = len(items) < batchSize
+	}
+
+	return res, nil
+}
diff --git a/commonclient/transaction.go b/commonclient/transaction.go
new file mode 100644
index 0000000..15a33aa
--- /dev/null
+++ b/commonclient/transaction.go
@@ -0,0 +1,63 @@
+package commonclient
+
+import (
+	"errors"
+
+	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
+	"github.com/nspcc-dev/neo-go/pkg/io"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
+)
+
+// Transaction allows to invoke several contract method at once.
+type Transaction struct {
+	writer   *io.BufBinWriter
+	buffer   *io.BufBinWriter
+	contract util.Uint160
+}
+
+var ErrTransactionTooLarge = errors.New("transaction/script size limit exceeded")
+
+// NewTransaction creates new transaction to accumulate contract invocations.
+func NewTransaction(contractHash util.Uint160) *Transaction {
+	return &Transaction{
+		writer:   io.NewBufBinWriter(),
+		buffer:   io.NewBufBinWriter(),
+		contract: contractHash,
+	}
+}
+
+// WrapCall accept methods and arguments to invoke.
+// Should be used with method on clients like Client.MethodNameCall.
+func (t Transaction) WrapCall(method string, args []any) error {
+	t.buffer.Reset()
+	emit.AppCall(t.buffer.BinWriter, t.contract, method, callflag.All, args...)
+
+	if t.writer.Len()+t.buffer.Len() > transaction.MaxScriptLength {
+		return ErrTransactionTooLarge
+	}
+
+	t.writer.WriteBytes(t.buffer.Bytes())
+
+	return t.writer.Err
+}
+
+// WrapCallErr accept methods, arguments and error to handle and invoke.
+// Should be used with method on clients like *CallErr.
+func (t Transaction) WrapCallErr(method string, args []any, err error) error {
+	if err != nil {
+		return err
+	}
+
+	return t.WrapCall(method, args)
+}
+
+// Bytes returns the resulting buffer and makes future writes return an error.
+func (t Transaction) Bytes() ([]byte, error) {
+	if t.writer.Len() > transaction.MaxScriptLength {
+		return nil, ErrTransactionTooLarge
+	}
+
+	return t.writer.Bytes(), nil
+}