// Copyright 2019 The Gorilla WebSocket Authors. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

package websocket

import (

	"io"

	"strings"

)

// JoinMessages concatenates received messages to create a single io.Reader.

// The string term is appended to each message. The returned reader does not

// support concurrent calls to the Read method.

func JoinMessages(c *Conn, term string) io.Reader {

	return &joinReader{c: c, term: term}

}

type joinReader struct {

	c    *Conn

	term string

	r    io.Reader

}

func (r *joinReader) Read(p []byte) (int, error) {

	if r.r == nil {

		var err error

		_, r.r, err = r.c.NextReader()

		if err != nil {

			return 0, err

		}

		if r.term != "" {

			r.r = io.MultiReader(r.r, strings.NewReader(r.term))

		}

	}

	n, err := r.r.Read(p)

	if err == io.EOF {

		err = nil

		r.r = nil

	}

	return n, err

}