Music Playlist

Example Code

<?php

class MusicPlaylist {
    private array $songs = [];
    private int $currentSongIndex = -1; // -1 indicates no song is selected initially

    /
     * Adds a song to the playlist.
     * @param string $title The title of the song.
     * @param string $artist The artist of the song.
     * @param string $album The album the song belongs to.
     * @param int $duration The duration of the song in seconds.
     */
    public function addSong(string $title, string $artist, string $album, int $duration): void
    {
        $this->songs[] = [
            'title' => $title,
            'artist' => $artist,
            'album' => $album,
            'duration' => $duration
        ];
        // If this is the first song added, set it as the current song
        if (count($this->songs) === 1) {
            $this->currentSongIndex = 0;
        }
        echo "Added: \"{$title}\" by {$artist}\n";
    }

    /
     * Removes a song from the playlist by its index.
     * @param int $index The 0-based index of the song to remove.
     */
    public function removeSong(int $index): void
    {
        if (isset($this->songs[$index])) {
            $removedSong = $this->songs[$index]['title'];
            array_splice($this->songs, $index, 1);
            echo "Removed: \"{$removedSong}\" from the playlist.\n";

            // Adjust current song index if necessary
            if ($this->currentSongIndex === $index) {
                if (!empty($this->songs)) {
                    $this->currentSongIndex = min($index, count($this->songs) - 1); // Move to next or last song
                } else {
                    $this->currentSongIndex = -1; // Playlist is empty
                }
            } elseif ($this->currentSongIndex > $index) {
                $this->currentSongIndex--; // Shift index if a song before it was removed
            }
        } else {
            echo "Error: Song at index {$index} not found.\n";
        }
    }

    /
     * Displays all songs in the playlist.
     */
    public function listSongs(): void
    {
        if (empty($this->songs)) {
            echo "Playlist is empty.\n";
            return;
        }
        echo "\n--- Current Playlist ---\n";
        foreach ($this->songs as $index => $song) {
            $isCurrent = ($index === $this->currentSongIndex) ? " (Playing)" : "";
            echo "{$index}. \"{$song['title']}\" by {$song['artist']} ({$song['duration']}s){$isCurrent}\n";
        }
        echo "-----------------------\n";
    }

    /
     * Plays the current song.
     */
    public function playCurrentSong(): void
    {
        if ($this->currentSongIndex !== -1 && isset($this->songs[$this->currentSongIndex])) {
            $song = $this->songs[$this->currentSongIndex];
            echo "Now playing: \"{$song['title']}\" by {$song['artist']}.\n";
        } else {
            echo "No song selected or playlist is empty.\n";
        }
    }

    /
     * Advances to the next song in the playlist.
     */
    public function nextSong(): void
    {
        if (empty($this->songs)) {
            echo "Playlist is empty. Cannot go to the next song.\n";
            return;
        }
        if ($this->currentSongIndex < count($this->songs) - 1) {
            $this->currentSongIndex++;
            $this->playCurrentSong();
        } else {
            echo "End of playlist. No next song.\n";
            // Option to loop back to the beginning: $this->currentSongIndex = 0; $this->playCurrentSong();
        }
    }

    /
     * Goes back to the previous song in the playlist.
     */
    public function previousSong(): void
    {
        if (empty($this->songs)) {
            echo "Playlist is empty. Cannot go to the previous song.\n";
            return;
        }
        if ($this->currentSongIndex > 0) {
            $this->currentSongIndex--;
            $this->playCurrentSong();
        } else {
            echo "Beginning of playlist. No previous song.\n";
            // Option to loop to the end: $this->currentSongIndex = count($this->songs) - 1; $this->playCurrentSong();
        }
    }

    /
     * Shuffles the songs in the playlist randomly.
     */
    public function shuffle(): void
    {
        if (empty($this->songs)) {
            echo "Playlist is empty. Nothing to shuffle.\n";
            return;
        }
        // Store the currently playing song to try and maintain its position or find it after shuffle
        $currentSong = $this->getCurrentSong();

        shuffle($this->songs);
        echo "Playlist shuffled.\n";

        // Try to find the previously current song's new index
        if ($currentSong) {
            foreach ($this->songs as $index => $song) {
                if ($song['title'] === $currentSong['title'] && $song['artist'] === $currentSong['artist']) {
                    $this->currentSongIndex = $index;
                    break;
                }
            }
        } else {
            $this->currentSongIndex = 0; // If no song was playing, default to the first after shuffle
        }
    }

    /
     * Gets the currently playing song's details.
     * @return array|null The song details or null if no song is playing.
     */
    public function getCurrentSong(): ?array
    {
        if ($this->currentSongIndex !== -1 && isset($this->songs[$this->currentSongIndex])) {
            return $this->songs[$this->currentSongIndex];
        }
        return null;
    }
}

// --- Example Usage ---
echo "=== Creating a Music Playlist ===\n";
$myPlaylist = new MusicPlaylist();

$myPlaylist->addSong("Bohemian Rhapsody", "Queen", "A Night at the Opera", 355);
$myPlaylist->addSong("Hotel California", "Eagles", "Hotel California", 390);
$myPlaylist->addSong("Stairway to Heaven", "Led Zeppelin", "Led Zeppelin IV", 482);
$myPlaylist->addSong("Smells Like Teen Spirit", "Nirvana", "Nevermind", 301);
$myPlaylist->addSong("Imagine", "John Lennon", "Imagine", 181);

$myPlaylist->listSongs();
$myPlaylist->playCurrentSong(); // Should play the first song

echo "\n=== Navigating Playlist ===\n";
$myPlaylist->nextSong(); // Play next
$myPlaylist->nextSong(); // Play next
$myPlaylist->previousSong(); // Play previous

echo "\n=== Modifying Playlist ===\n";
$myPlaylist->removeSong(1); // Remove 'Hotel California'
$myPlaylist->listSongs(); // List updated playlist
$myPlaylist->playCurrentSong(); // Show what's playing after removal

echo "\n=== Shuffling Playlist ===\n";
$myPlaylist->shuffle();
$myPlaylist->listSongs();
$myPlaylist->playCurrentSong();

echo "\n=== Edge Cases ===\n";
$emptyPlaylist = new MusicPlaylist();
$emptyPlaylist->listSongs();
$emptyPlaylist->nextSong();
$emptyPlaylist->shuffle();

?>