package httputils

import (
	"io"
	"os"
	"time"
)

type Stream interface {
	io.Reader
	io.Closer
}

type SeekableStream interface {
	Stream
	io.Seeker
}

type DefinedStream interface {
	SeekableStream
	Size() int64
	ModTime() time.Time
}

type FileStream struct {
	file    *os.File
	size    int64
	modTime time.Time
}

const modTimeFormat = "Mon, 02 Jan 2006 15:04:05 GMT"

func (fs *FileStream) Read(p []byte) (n int, err error) {
	return fs.file.Read(p)
}

func (fs *FileStream) Seek(offset int64, whence int) (int64, error) {
	return fs.file.Seek(offset, whence)
}

func (fs *FileStream) Close() error {
	return fs.file.Close()
}

func (fs *FileStream) Size() int64 {
	return fs.size
}

func (fs *FileStream) ModTime() time.Time {
	return fs.modTime
}

func NewStreamFromFile(file *os.File) DefinedStream {
	if file == nil {
		return nil
	}

	fstat, err := file.Stat()
	if err != nil {
		return nil
	}

	return &FileStream{
		file:    file,
		size:    fstat.Size(),
		modTime: fstat.ModTime(),
	}
}