// Copyright 2023 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package util

import (
	"bytes"
	"errors"
	"testing"

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

type readerWithError struct {
	buf *bytes.Buffer
}

func (r *readerWithError) Read(p []byte) (n int, err error) {
	if r.buf.Len() < 2 {
		return 0, errors.New("test error")
	}
	return r.buf.Read(p)
}

func TestReadWithLimit(t *testing.T) {
	bs := []byte("0123456789abcdef")

	// normal test
	for _, testCase := range []struct {
		limit    int
		expected string
	}{
		{2, "01"},
		{5, "01234"},
		{6, "012345"},
		{len(bs), "0123456789abcdef"},
		{100, "0123456789abcdef"},
	} {
		buf, err := readWithLimit(bytes.NewBuffer(bs), 5, testCase.limit)
		assert.NoError(t, err)
		assert.Equal(t, []byte(testCase.expected), buf)
	}

	// test with error
	buf, err := readWithLimit(&readerWithError{bytes.NewBuffer(bs)}, 5, 10)
	assert.NoError(t, err)
	assert.Equal(t, []byte("0123456789"), buf)

	buf, err = readWithLimit(&readerWithError{bytes.NewBuffer(bs)}, 5, 100)
	assert.ErrorContains(t, err, "test error")
	assert.Empty(t, buf)

	// test public function
	buf, err = ReadWithLimit(bytes.NewBuffer(bs), 2)
	assert.NoError(t, err)
	assert.Equal(t, []byte("01"), buf)

	buf, err = ReadWithLimit(bytes.NewBuffer(bs), 9999999)
	assert.NoError(t, err)
	assert.Equal(t, []byte("0123456789abcdef"), buf)
}