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command.go
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command.go
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// Copyright (c) 2021 - The Event Horizon authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package json
import (
"context"
"encoding/json"
"fmt"
eh "github.com/2908755265/eventhorizon"
)
// CommandCodec is a codec for marshaling and unmarshaling commands
// to and from bytes in JSON format.
type CommandCodec struct{}
// MarshalCommand marshals a command into bytes in JSON format.
func (_ CommandCodec) MarshalCommand(ctx context.Context, cmd eh.Command) ([]byte, error) {
c := command{
CommandType: cmd.CommandType(),
Context: eh.MarshalContext(ctx),
}
var err error
if c.Command, err = json.Marshal(cmd); err != nil {
return nil, fmt.Errorf("could not marshal command data: %w", err)
}
b, err := json.Marshal(c)
if err != nil {
return nil, fmt.Errorf("could not marshal command: %w", err)
}
return b, nil
}
// UnmarshalCommand unmarshals a command from bytes in JSON format.
func (_ CommandCodec) UnmarshalCommand(ctx context.Context, b []byte) (eh.Command, context.Context, error) {
var c command
if err := json.Unmarshal(b, &c); err != nil {
return nil, nil, fmt.Errorf("could not unmarshal command: %w", err)
}
cmd, err := eh.CreateCommand(c.CommandType)
if err != nil {
return nil, nil, fmt.Errorf("could not create command: %w", err)
}
if err := json.Unmarshal(c.Command, &cmd); err != nil {
return nil, nil, fmt.Errorf("could not unmarshal command data: %w", err)
}
ctx = eh.UnmarshalContext(ctx, c.Context)
return cmd, ctx, nil
}
// command is the internal structure used on the wire only.
type command struct {
CommandType eh.CommandType `json:"command_type"`
Command json.RawMessage `json:"command"`
Context map[string]interface{} `json:"context"`
}