package wsjson

import (

"context"

"encoding/json"

"golang.org/x/xerrors"

"github.com/coder/websocket"

)

type Encoder[T any] struct {

conn *websocket.Conn

typ websocket.MessageType

}

func (e *Encoder[T]) Encode(v T) error {

w, err := e.conn.Writer(context.Background(), e.typ)

if err != nil {

return xerrors.Errorf("get websocket writer: %w", err)

}

defer w.Close()

j := json.NewEncoder(w)

err = j.Encode(v)

if err != nil {

return xerrors.Errorf("encode json: %w", err)

}

return nil

}

// nolint: revive // complains that Decoder has the same function name

func (e *Encoder[T]) Close(c websocket.StatusCode) error {

return e.conn.Close(c, "")

}

// NewEncoder creates a JSON-over websocket encoder for the type T, which must be JSON-serializable.

// You may then call Encode() to send objects over the websocket. Creating an Encoder closes the

// websocket for reading, turning it into a unidirectional write stream of JSON-encoded objects.

func NewEncoder[T any](conn *websocket.Conn, typ websocket.MessageType) *Encoder[T] {

// Here we close the websocket for reading, so that the websocket library will handle pings and

// close frames.

_ = conn.CloseRead(context.Background())

return &Encoder[T]{conn: conn, typ: typ}

}