OpenCut/apps/web/src/lib/timeline/track-utils.ts

import type {
  TrackType,
  TimelineTrack,
  ElementType,
  VideoTrack,
  AudioTrack,
  StickerTrack,
  TextTrack,
} from "@/types/timeline";
import {
  TRACK_COLORS,
  TRACK_HEIGHTS,
  TRACK_GAP,
} from "@/constants/timeline-constants";
import { generateUUID } from "@/lib/utils";

export function canTracktHaveAudio(
  track: TimelineTrack,
): track is VideoTrack | AudioTrack {
  return track.type === "audio" || track.type === "video";
}

export function canTrackBeHidden(
  track: TimelineTrack,
): track is VideoTrack | TextTrack | StickerTrack {
  return track.type !== "audio";
}

export function getTrackColor({ type }: { type: TrackType }) {
  return TRACK_COLORS[type];
}

export function getTrackClasses({ type }: { type: TrackType }) {
  const colors = TRACK_COLORS[type];
  return `${colors.background}`.trim();
}

export function getTrackHeight({ type }: { type: TrackType }): number {
  return TRACK_HEIGHTS[type];
}

export function getCumulativeHeightBefore({
  tracks,
  trackIndex,
}: {
  tracks: Array<{ type: TrackType }>;
  trackIndex: number;
}): number {
  return tracks
    .slice(0, trackIndex)
    .reduce(
      (sum, track) => sum + getTrackHeight({ type: track.type }) + TRACK_GAP,
      0,
    );
}

export function getTotalTracksHeight({
  tracks,
}: {
  tracks: Array<{ type: TrackType }>;
}): number {
  const tracksHeight = tracks.reduce(
    (sum, track) => sum + getTrackHeight({ type: track.type }),
    0,
  );
  const gapsHeight = Math.max(0, tracks.length - 1) * TRACK_GAP;
  return tracksHeight + gapsHeight;
}

export function buildEmptyTrack({
  id,
  type,
  name,
}: {
  id: string;
  type: TrackType;
  name?: string;
}): TimelineTrack {
  const trackName =
    name ??
    (type === "video"
      ? "Video track"
      : type === "text"
        ? "Text track"
        : type === "audio"
          ? "Audio track"
          : type === "sticker"
            ? "Sticker track"
            : "Track");

  switch (type) {
    case "video":
      return {
        id,
        name: trackName,
        type: "video",
        elements: [],
        hidden: false,
        muted: false,
        isMain: false,
      };
    case "text":
      return {
        id,
        name: trackName,
        type: "text",
        elements: [],
        hidden: false,
      };
    case "sticker":
      return {
        id,
        name: trackName,
        type: "sticker",
        elements: [],
        hidden: false,
      };
    case "audio":
      return {
        id,
        name: trackName,
        type: "audio",
        elements: [],
        muted: false,
      };
    default:
      throw new Error(`Unsupported track type: ${type}`);
  }
}

export function getDefaultInsertIndexForTrack({
  tracks,
  trackType,
}: {
  tracks: TimelineTrack[];
  trackType: TrackType;
}): number {
  if (trackType === "audio") {
    return tracks.length;
  }

  const mainTrackIndex = tracks.findIndex((track) => isMainTrack(track));
  if (mainTrackIndex >= 0) {
    return mainTrackIndex;
  }

  const firstAudioTrackIndex = tracks.findIndex(
    (track) => track.type === "audio",
  );
  if (firstAudioTrackIndex >= 0) {
    return firstAudioTrackIndex;
  }

  return tracks.length;
}

export function getHighestInsertIndexForTrack({
  tracks,
  trackType,
}: {
  tracks: TimelineTrack[];
  trackType: TrackType;
}): number {
  const mainTrackIndex = tracks.findIndex((track) => isMainTrack(track));

  if (trackType === "audio") {
    return mainTrackIndex >= 0 ? mainTrackIndex + 1 : tracks.length;
  }

  return 0;
}

export function isMainTrack(track: TimelineTrack): track is VideoTrack {
  return track.type === "video" && track.isMain === true;
}

export function getMainTrack({
  tracks,
}: {
  tracks: TimelineTrack[];
}): TimelineTrack | null {
  return tracks.find((track) => isMainTrack(track)) ?? null;
}

export function ensureMainTrack({
  tracks,
}: {
  tracks: TimelineTrack[];
}): TimelineTrack[] {
  const hasMainTrack = tracks.some((track) => isMainTrack(track));

  if (!hasMainTrack) {
    const mainTrack: TimelineTrack = {
      id: generateUUID(),
      name: "Main Track",
      type: "video",
      elements: [],
      muted: false,
      isMain: true,
      hidden: false,
    };
    return [mainTrack, ...tracks];
  }

  return tracks;
}

export function canElementGoOnTrack({
  elementType,
  trackType,
}: {
  elementType: ElementType;
  trackType: TrackType;
}): boolean {
  if (elementType === "text") return trackType === "text";
  if (elementType === "audio") return trackType === "audio";
  if (elementType === "sticker") return trackType === "sticker";
  if (elementType === "video" || elementType === "image") {
    return trackType === "video";
  }
  return false;
}

export function validateElementTrackCompatibility({
  element,
  track,
}: {
  element: { type: ElementType };
  track: { type: TrackType };
}): { isValid: boolean; errorMessage?: string } {
  const isValid = canElementGoOnTrack({
    elementType: element.type,
    trackType: track.type,
  });

  if (!isValid) {
    return {
      isValid: false,
      errorMessage: `${element.type} elements cannot be placed on ${track.type} tracks`,
    };
  }

  return { isValid: true };
}