package ioutil

import (
	"io"
	"sync"
)

// PipeWriter is similar to io.PipeWriter with wait group
type PipeWriter struct {
	*io.PipeWriter
	once sync.Once
	done func()
}

// CloseWithError close with supplied error the writer end.
func (w *PipeWriter) CloseWithError(err error) error {
	err = w.PipeWriter.CloseWithError(err)
	w.once.Do(func() {
		w.done()
	})
	return err
}

	// This will also flush the ring buffer if used.
	err := b.iow.Close()

	// Wait for all data to be written before returning else it causes race conditions.
	// Race condition is because of io.PipeWriter implementation. i.e consider the following
	// sequent of operations:
	// 1) pipe.Write()
	// 2) pipe.Close()
	// Now pipe.Close() can return before the data is read on the other end of the pipe and written to the disk

	opts Options

	// f is the currently open file used for appends.
	// Writes to f are only synchronized once Close() is called,
	// or when files are being rotated.
	f *os.File

	pw *xioutil.PipeWriter
	pr *xioutil.PipeReader
}

// Write writes p into the current file, rotating if necessary.
// Write is non-blocking, if the writer's queue is not full.
// Write is blocking otherwise.

		err = w.err
	default:
		err = w.w.Close()
	}
	for i := range w.buffer {
		delete(w.buffer, i)
	}
	w.wg.Wait()
	return err
}

type writerAt struct {
	w      *io.PipeWriter
	r      *io.PipeReader
	wg     *sync.WaitGroup
	buffer map[int64][]byte
	err    error

	nextOffset int64
	m          sync.Mutex
}

	"sync"
	"testing"
	"time"
)

func TestRingBuffer_interface(t *testing.T) {
	rb := New(1)
	var _ io.Writer = rb
	var _ io.Reader = rb
	// var _ io.StringWriter = rb
	var _ io.ByteReader = rb
	var _ io.ByteWriter = rb
}

func TestRingBuffer_Write(t *testing.T) {
	rb := New(64)

	// check empty or full
	if !rb.IsEmpty() {
		t.Fatalf("expect IsEmpty is true but got false")
	}
	if rb.IsFull() {