package sendaround

import (
	"io"
	"net/http"
	"os"
	"path/filepath"
)

func normalizeFilePath(filePath string) string {
	return filepath.ToSlash(filePath)
}

type RemoteFile interface {
	FileName() string
	Length() uint64
	MimeType() string
}

type File interface {
	RemoteFile
	getReader() io.ReadSeeker
}

type fileRemote struct {
	fileName string
	length   uint64
	mimeType string
}

func (f *fileRemote) FileName() string {
	return f.fileName
}

func (f *fileRemote) Length() uint64 {
	return f.length
}

func (f *fileRemote) MimeType() string {
	return f.mimeType
}

type file struct {
	io.ReadSeeker

	fileName string
	length   uint64
	mimeType string
}

func (f *file) FileName() string {
	return f.fileName
}

func (f *file) Length() uint64 {
	return f.length
}

func (f *file) MimeType() string {
	return f.mimeType
}

func (f *file) getReader() io.ReadSeeker {
	return f.ReadSeeker
}

func FileFromFilesystem(f *os.File, newFileName string) (data File, err error) {
	retval := new(file)
	retval.ReadSeeker = f

	if len(newFileName) > 0 {
		retval.fileName = newFileName
	} else {
		retval.fileName = filepath.Base(f.Name())
	}

	retval.fileName = normalizeFilePath(retval.fileName)

	fi, err := f.Stat()
	if err != nil {
		return
	}
	retval.length = uint64(fi.Size())

	// Only the first 512 bytes are used to sniff the content type.
	buf := make([]byte, 512)
	_, err = f.Read(buf)
	if err != nil {
		return
	}
	f.Seek(0, os.SEEK_SET)
	retval.mimeType = http.DetectContentType(buf)

	data = retval
	return
}

func FileFromReader(fileName string, length uint64, mimeType string, r io.ReadSeeker) (data File) {
	if len(mimeType) <= 0 {
		mimeType = "application/octet-stream"
	}

	return &file{
		ReadSeeker: r,
		fileName:   normalizeFilePath(fileName),
		length:     length,
		mimeType:   mimeType,
	}
}