Funkin/source/funkin/play/song/SongDataUtils.hx

package funkin.play.song;

using Lambda;

class SongDataUtils {
    /**
     * Given an array of SongNoteData objects, return a new array of SongNoteData objects
     * whose timestamps are shifted by the given amount.
     * 
     * @param notes The notes to modify.
     * @param offset The time difference to apply in milliseconds.
     */
    public static function offsetSongNoteData(notes:Array<SongNoteData>, offset:Int):Array<SongNoteData> {
        return notes.map(function(note:SongNoteData):SongNoteData {
            return new SongNoteData(note.time + offset, note.data, note.length, note.kind);
        });
    }

    /**
     * Remove a certain subset of notes from an array of SongNoteData objects.
     * 
     * @param notes The array of notes to be subtracted from.
     * @param subtrahend The notes to remove from the `notes` array. Yes, subtrahend is a real word.
     */
    public static function subtractNotes(notes:Array<SongNoteData>, subtrahend:Array<SongNoteData>) {
        if (notes.length == 0 || subtrahend.length == 0)
            return notes;

        if (subtrahend.length == 1)
            return notes.remove(subtrahend[0]);

        return notes.filter(function(note:SongNoteData):Bool {
            // SongNoteData's == operation has been overridden so that this will work.
            return !subtrahend.has(note);
        });
    }

    /**
     * Remove a certain subset of events from an array of SongEventData objects.
     * 
     * @param events The array of events to be subtracted from.
     * @param subtrahend The events to remove from the `events` array. Yes, subtrahend is a real word.
     */
     public static function subtractEvents(events:Array<SongEventData>, subtrahend:Array<SongEventData>) {
        if (events.length == 0 || subtrahend.length == 0)
            return events;

        if (subtrahend.length == 1)
            return events.remove(subtrahend[0]);

        return events.filter(function(event:SongEventData):Bool {
            // SongEventData's == operation has been overridden so that this will work.
            return !subtrahend.has(event);
        });
    }

    /**
     * Prepare an array of notes to be used as the clipboard data.
     * 
     * Offset the provided array of notes such that the first note is at 0 milliseconds.
     */
    public static function buildClipboard(notes:Array<SongNoteData>):Array<SongNoteData> {
        return offsetSongNoteData(notes, -notes[0].time);
    }
}