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// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you 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 streaming

import (
	"math/rand"
	"strings"
	"testing"

	"github.com/stretchr/testify/assert"
)

func TestResetableLimitedReader(t *testing.T) {
	maxReadBuffer := 400

	t.Run("WhenMaxReadIsReachedInMultipleRead", func(t *testing.T) {
		r := strings.NewReader(randomString(maxReadBuffer * 2))
		m := NewResetableLimitedReader(r, uint64(maxReadBuffer))
		toRead := make([]byte, maxReadBuffer)
		_, err := m.Read(toRead)
		assert.NoError(t, err)
		toRead = make([]byte, 300)
		_, err = m.Read(toRead)
		assert.Equal(t, ErrMaxReadBuffer, err)
	})

	t.Run("WhenMaxReadIsNotReached", func(t *testing.T) {
		r := strings.NewReader(randomString(maxReadBuffer * 2))
		m := NewResetableLimitedReader(r, uint64(maxReadBuffer))
		toRead := make([]byte, maxReadBuffer)
		_, err := m.Read(toRead)
		assert.NoError(t, err)
	})

	t.Run("WhenResetIsCalled", func(t *testing.T) {
		r := strings.NewReader(randomString(maxReadBuffer * 2))
		m := NewResetableLimitedReader(r, uint64(maxReadBuffer))
		toRead := make([]byte, maxReadBuffer)
		_, err := m.Read(toRead)
		assert.NoError(t, err)
		m.Reset()
		toRead = make([]byte, 300)
		_, err = m.Read(toRead)
		assert.NoError(t, err)
	})
}

func randomString(l int) string {
	charsets := []byte("abcdefghijklmnopqrstuvwzyzABCDEFGHIJKLMNOPQRSTUVWZYZ0123456789")
	message := make([]byte, l)
	for i := range message {
		message[i] = charsets[rand.Intn(len(charsets))]
	}
	return string(message)
}
