package logger

import (
	"errors"
	"io"
	"strings"
	"testing"

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

type errReader struct{}

func (errReader) Read(_ []byte) (n int, err error) {
	return 0, errors.New("test error")
}

func TestLoggerPeek(t *testing.T) {
	cases := []struct {
		body    string
		n       int64
		excerpt string
		hasMore bool
	}{
		{"", -1, "", false},
		{"", 0, "", false},
		{"", 1024, "", false},
		{"123456", -1, "", true},
		{"123456", 0, "", true},
		{"123456", 4, "1234", true},
		{"123456", 5, "12345", true},
		{"123456", 6, "123456", false},
		{"123456", 7, "123456", false},
	}

	for _, c := range cases {
		r, excerpt, hasMore, err := peek(strings.NewReader(c.body), c.n)
		if !assert.NoError(t, err) {
			continue
		}

		body, err := io.ReadAll(r)
		if !assert.NoError(t, err) {
			continue
		}

		assert.Equal(t, c.body, string(body))
		assert.Equal(t, c.excerpt, excerpt)
		assert.Equal(t, c.hasMore, hasMore)
	}

	_, _, _, err := peek(errReader{}, 1024)
	assert.Error(t, err)
}