package cache

import (
	"bytes"
	"io"
	"os"
)

type Blob interface {
	io.ReaderAt
	io.Closer
	Size() int64
}

type byteBlob struct {
	buf *bytes.Reader
}

func NewByteBlob(b []byte) Blob {
	return &byteBlob{buf: bytes.NewReader(b)}
}

func (blob *byteBlob) ReadAt(p []byte, off int64) (n int, err error) {
	return blob.buf.ReadAt(p, off)
}

func (blob *byteBlob) Size() int64 {
	return blob.buf.Size()
}

func (blob *byteBlob) Close() error {
	return nil
}

type fileBlob struct {
	buf *os.File
}

func NewFileBlob(f *os.File) Blob {
	return &fileBlob{buf: f}
}

func (blob *fileBlob) ReadAt(p []byte, off int64) (n int, err error) {
	return blob.buf.ReadAt(p, off)
}

func (blob *fileBlob) Size() int64 {
	if i, err := blob.buf.Stat(); err != nil {
		return i.Size()
	}
	return 0
}

func (blob *fileBlob) Close() error {
	return nil
}