PackageManager/Client/Filesystem/FileObject.go

package Filesystem

import (
	"bytes"
	"crypto/sha1"
	"encoding/gob"
	"encoding/hex"
	"errors"
	"fmt"
	"hash"
	"io"
	"os"
	"path/filepath"
)

var (
	// TODO: Where do I put this
	Data string
)

type Package struct {
	Name    string
	Version string
}

type FileObject struct {
	FileMode os.FileMode
	Size     int64
	Package  Package
	Ref      string
	Sha1     []byte
}

type ByName []Package

func (f FileObject) IsLink() bool {
	return f.FileMode&os.ModeSymlink != 0
}

func (f FileObject) objFile() string {
	return filepath.Join(f.objDir(), hex.EncodeToString(f.Sha1))
}

func (f FileObject) objDir() string {
	return filepath.Join(Data, hex.EncodeToString(f.Sha1[:2]))
}

func (f FileObject) Reset(dst string) error {
	var e error

	if f.IsLink() {
		_, e = os.Lstat(dst)
		if !os.IsNotExist(e) {
			e = os.Remove(dst)
			if e != nil {
				return e
			}
		}

		e = os.Symlink(f.Ref, dst)
		if e != nil {
			return e
		}

		return nil
	}

	f.cp(f.objFile(), dst)
	e = os.Chmod(dst, f.FileMode)
	if e != nil {
		return e
	}

	return nil
}

func (f FileObject) Stov(src string) error {
	var e error

	if f.IsLink() {
		return nil
	}

	e = os.MkdirAll(f.objDir(), 0744)
	if e != nil {
		return e
	}

	f.cp(src, f.objFile())
	return nil
}

func (f FileObject) cp(src string, dst string) error {
	var (
		srcFile, dstFile *os.File
		e                error
	)

	fmt.Println("cp ", src, dst)

	srcFile, e = os.Open(src)
	if e != nil {
		return e
	}
	defer srcFile.Close()

	dstFile, e = os.Create(dst)
	if e != nil {
		return e
	}
	defer dstFile.Close()

	_, e = io.Copy(dstFile, srcFile)
	if e != nil {
		return e
	}

	return dstFile.Sync()
}

func (f FileObject) IsDifferent(fn FileObject) error {
	if f.FileMode != fn.FileMode {
		return errors.New("Mode does not match")
	}

	if f.IsLink() {
		if f.Ref != fn.Ref {
			return errors.New("Ref does not match")
		}
		return nil
	}

	if f.Size != fn.Size {
		return errors.New("Size does not match")
	}

	if bytes.Compare(f.Sha1, fn.Sha1) != 0 {
		return errors.New("Sha1 does not match")
	}

	return nil
}

func CreateFileObject(f string) (FileObject, error) {
	var (
		sha1Hash hash.Hash = sha1.New()
		fo       FileObject
		fi       os.FileInfo
		file     *os.File
		e        error
	)

	fi, e = os.Lstat(f)
	if e != nil {
		return fo, e
	}

	fo = FileObject{
		FileMode: fi.Mode(),
		Size:     fi.Size(),
	}

	if fo.IsLink() {
		fo.Ref, e = os.Readlink(f)
		if e != nil {
			return fo, e
		}
		return fo, nil

	}

	file, e = os.Open(f)
	if e != nil {
		return fo, e
	}
	defer file.Close()

	io.Copy(sha1Hash, file)
	fo.Sha1 = sha1Hash.Sum(nil)

	return fo, nil
}

func (f FileObject) ToBytes() ([]byte, error) {
	var (
		encoder *gob.Encoder
		buf     bytes.Buffer
		e       error
	)

	encoder = gob.NewEncoder(&buf)
	e = encoder.Encode(f)
	return buf.Bytes(), e
}

func FromBytes(v []byte) (FileObject, error) {
	var (
		buf     *bytes.Buffer
		decoder *gob.Decoder
		fo      FileObject
		e       error
	)

	buf = bytes.NewBuffer(v)

	decoder = gob.NewDecoder(buf)

	e = decoder.Decode(&fo)
	if e != nil {
		return fo, e
	}

	return fo, nil
}