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event.go
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event.go
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// Copyright © 2023 Ory Corp
// SPDX-License-Identifier: Apache-2.0
package watcherx
import (
"bytes"
"encoding/json"
"fmt"
"io"
"github.com/pkg/errors"
)
type (
Event interface {
// MarshalJSON is required to work multiple times
json.Marshaler
Reader() io.Reader
Source() string
String() string
setSource(string)
}
source string
ErrorEvent struct {
error
source
}
ChangeEvent struct {
data []byte
source
}
RemoveEvent struct {
source
}
serialEventType string
serialEvent struct {
Type serialEventType `json:"type"`
Data []byte `json:"data"`
Source source `json:"source"`
}
)
const (
serialTypeChange serialEventType = "change"
serialTypeRemove serialEventType = "remove"
serialTypeError serialEventType = "error"
)
var errUnknownEvent = errors.New("unknown event type")
func (e *ErrorEvent) Reader() io.Reader {
return bytes.NewBufferString(e.Error())
}
func (e *ErrorEvent) MarshalJSON() ([]byte, error) {
return json.Marshal(serialEvent{
Type: serialTypeError,
Data: []byte(e.Error()),
Source: e.source,
})
}
func (e *ErrorEvent) String() string {
return fmt.Sprintf("error: %+v; source: %s", e.error, e.source)
}
func (e source) Source() string {
return string(e)
}
func (e *source) setSource(nsrc string) {
*e = source(nsrc)
}
func (e *ChangeEvent) Reader() io.Reader {
return bytes.NewBuffer(e.data)
}
func (e *ChangeEvent) MarshalJSON() ([]byte, error) {
return json.Marshal(serialEvent{
Type: serialTypeChange,
Data: e.data,
Source: e.source,
})
}
func (e *ChangeEvent) String() string {
return fmt.Sprintf("data: %s; source: %s", e.data, e.source)
}
func (e *RemoveEvent) Reader() io.Reader {
return nil
}
func (e *RemoveEvent) MarshalJSON() ([]byte, error) {
return json.Marshal(serialEvent{
Type: serialTypeRemove,
Source: e.source,
})
}
func (e *RemoveEvent) String() string {
return fmt.Sprintf("removed source: %s", e.source)
}
func unmarshalEvent(data []byte) (Event, error) {
var serialEvent serialEvent
if err := json.Unmarshal(data, &serialEvent); err != nil {
return nil, errors.WithStack(err)
}
switch serialEvent.Type {
case serialTypeRemove:
return &RemoveEvent{
source: serialEvent.Source,
}, nil
case serialTypeChange:
return &ChangeEvent{
data: serialEvent.Data,
source: serialEvent.Source,
}, nil
case serialTypeError:
return &ErrorEvent{
error: errors.New(string(serialEvent.Data)),
source: serialEvent.Source,
}, nil
}
return nil, errUnknownEvent
}