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db.go
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db.go
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// Copyright (c) 2016, Ben Morgan. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
package lackey
import (
"errors"
"fmt"
"os"
"path/filepath"
"github.com/facebookgo/symwalk"
"github.com/goulash/audio"
_ "github.com/cassava/lackey/audio/mp3"
"github.com/cassava/lackey/filetype"
_ "github.com/goulash/audio/flac"
)
var Skip = errors.New("skip the directory or remaining files in directory")
// Entry and EntryType {{{
type EntryType int
const (
DirEntry EntryType = 1 << iota
FileEntry
MusicEntry
IgnoreEntry
ErrorEntry EntryType = 0
)
type Entry struct {
db *Database // pointer to database (root)
parent *Entry
children []*Entry
path string // path relative to database root
fi os.FileInfo
typ EntryType // entry type (dir|file|music)
bytes int64 // cumulative size of entry
codec audio.Codec
data interface{} // any extra data stored with this entry
}
func (e *Entry) Key() string {
return e.path
}
func (e *Entry) FileInfo() os.FileInfo {
return e.fi
}
func (e *Entry) IsExists() bool {
return e != nil && e.fi != nil
}
func (e *Entry) IsDir() bool {
return e.typ == DirEntry
}
func (e *Entry) IsMusic() bool {
return e.typ == MusicEntry
}
func (e *Entry) IsIgnored() bool {
return e.typ == IgnoreEntry
}
func (e *Entry) Parent() *Entry {
return e.parent
}
func (e *Entry) Children() []*Entry {
return e.children
}
// Care should be taken with when Data is called, as the first call may involve
// reading the metadata of the associated file.
func (e *Entry) Data() interface{} {
if e.data != nil {
return e.data
}
// Get this data in a lazy fashion
if e.typ == MusicEntry {
abs := filepath.Join(e.db.Path(), e.path)
m, err := audio.ReadMetadata(abs)
if err != nil {
e.data = err
return e.data
}
e.data = m
}
return e.data
}
func (e *Entry) Encoding() audio.Codec {
return e.codec
}
func (e *Entry) Metadata() audio.Metadata {
md, ok := e.Data().(audio.Metadata)
if !ok {
fmt.Fprintf(os.Stderr, "Error: %s: %v\n", e.Key(), e.Data())
return nil
}
return md
}
func (e *Entry) Walk(fn func(e *Entry) error) error {
if e.IsDir() {
err := fn(e)
if err != nil {
if err == Skip {
return nil
}
return err
}
for _, c := range e.children {
err = c.Walk(fn)
if err != nil {
if err == Skip {
return nil
}
return err
}
}
return nil
} else {
return fn(e)
}
}
// Size returns the size of the entry in bytes.
// A directory's size is the size of all its children.
func (e *Entry) Size() int64 {
return e.bytes
}
func (e *Entry) Type() EntryType {
return e.typ
}
func (e *Entry) Filename() string {
return filepath.Base(e.path)
}
func (e *Entry) FilenameExt() (base string, ext string) {
name := filepath.Base(e.path)
ext = filepath.Ext(e.path)
base = name[:len(name)-len(ext)]
return base, ext
}
func (e *Entry) RelPath() string {
return e.path
}
func (e *Entry) AbsPath() string {
return filepath.Join(e.db.Path(), e.path)
}
func (e *Entry) RootPath() string {
return e.db.Path()
}
// }}}
// Database {{{
type Database struct {
path string
root *Entry
entries map[string]*Entry
// Options
ignoreHidden bool
followSymlinks bool
walker func(string, filepath.WalkFunc) error
}
func (db *Database) Path() string {
return db.path
}
func (db *Database) Size() int64 {
return db.root.Size()
}
func (db *Database) Root() *Entry {
return db.root
}
// Get returns the entry that has the given key, or nil.
func (db *Database) Get(key string) *Entry {
return db.entries[key]
}
func (db *Database) Set(key string, e *Entry) {
db.entries[key] = e
}
func (db *Database) Walk(fn func(e *Entry) error) error {
return db.root.Walk(fn)
}
// init populates the entry with all the relevant informations.
// It is expected that e.parent and e.db are already set.
func (e *Entry) init(path string, fi os.FileInfo, err error) {
defer e.db.Set(path, e)
root := e.db.Path()
abs := filepath.Join(root, path)
e.path = path
e.fi = fi
if err != nil {
e.typ = ErrorEntry
e.data = err
return
}
if fi.IsDir() {
e.typ = DirEntry
e.db.walker(abs, func(path string, fi os.FileInfo, err error) error {
if path == abs {
return nil
}
// Ignore hidden files if requested
if e.db.ignoreHidden && filepath.HasPrefix(filepath.Base(path), ".") {
return nil
}
path, _ = filepath.Rel(root, path)
v := &Entry{
db: e.db,
parent: e,
}
v.init(path, fi, err)
e.children = append(e.children, v)
e.bytes += v.bytes
// filepath.Walk should not recurse, because v.init does that already.
if fi != nil && fi.IsDir() {
return filepath.SkipDir
}
return nil
})
return
}
e.bytes = fi.Size()
e.codec, err = audio.Identify(abs)
if e.codec == audio.Unknown {
ft := filetype.Identify(abs)
if ft == filetype.Text || ft == filetype.Image {
e.typ = FileEntry
} else {
e.typ = IgnoreEntry
}
e.data = err
} else {
e.typ = MusicEntry
// We don't set e.data now, rather when Data is called.
}
}
type LibraryReader struct {
FollowSymlinks bool
IgnoreHidden bool
}
func (r LibraryReader) ReadLibrary(path string) (*Database, error) {
abs, err := filepath.Abs(path)
if err != nil {
return nil, err
}
fi, err := os.Stat(path)
if err != nil {
return nil, err
}
if !fi.IsDir() {
return nil, errors.New("library path must be a directory")
}
db := &Database{
path: abs,
entries: make(map[string]*Entry),
followSymlinks: r.FollowSymlinks,
ignoreHidden: r.IgnoreHidden,
walker: filepath.Walk,
}
if r.FollowSymlinks {
db.walker = symwalk.Walk
}
db.root = &Entry{db: db}
db.root.init(".", fi, nil)
return db, nil
}
// ReadLibrary reads a library using the recommended options, namely:
//
// FollowSymlinks = true
// IgnoreHidden = true
func ReadLibrary(path string) (*Database, error) {
r := LibraryReader{
FollowSymlinks: true,
IgnoreHidden: true,
}
return r.ReadLibrary(path)
}
// }}}