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dwelling-radio/internal/radio/playlist.go

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package radio
import (
"os"
"strings"
"sync"
"github.com/pkg/errors"
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)
// Playlist holds a list of paths to a song files.
type Playlist struct {
sync.Mutex
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filePath string
playlist []string
cur int
repeat bool
}
// NewPlaylist returns an instance of a Playlist struct with a loaded playlist.
// Returns an error if failed to load a playlist file.
func NewPlaylist(filePath string, repeat bool) (*Playlist, error) {
p := &Playlist{filePath: filePath, repeat: repeat}
return p, p.load()
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}
// Next returns the next song to play. Returns an empty string if repeat is
// false and the end of a playlist was reached.
func (p *Playlist) Next() (song string) {
p.Lock()
defer p.Unlock()
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if p.cur == len(p.playlist) {
// If the end of a playlist was reached and repeat is set to true,
// then go back to the head of it, thus repeating it. Return an empty
// string otherwise.
if p.repeat {
p.cur = 0
} else {
return ""
}
}
song = p.playlist[p.cur]
p.cur++
return
}
// Load reads a playlist file.
func (p *Playlist) load() error {
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data, err := os.ReadFile(p.filePath)
if err != nil {
return errors.Wrap(err, "cannot open a playlist file")
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}
if len(data) == 0 {
return errors.New("a playlist file is empty. Did not update")
}
p.Lock()
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p.playlist = strings.Split(string(data), "\n")
p.cur = 0
p.Unlock()
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return nil
}
func (p *Playlist) Reload() error {
return p.load()
}