// Asset-drop handlers for the timeline: drop an existing project asset at a
// placement, or upload dragged-in OS files and place them sequentially.
// Extracted verbatim from useTimelineEditing.ts to keep it under the studio
// 600-line cap.
import { useCallback, type MutableRefObject, type RefObject } from "react";
import type { TimelineElement } from "../player";
import {
  buildTimelineAssetId,
  buildTimelineAssetInsertHtml,
  buildTimelineFileDropPlacements,
  fitTimelineAssetGeometry,
  getTimelineAssetKind,
  insertTimelineAssetIntoSource,
  resolveTimelineAssetCompositionSize,
  resolveTimelineAssetSrc,
} from "../utils/timelineAssetDrop";
import { generateId } from "../utils/generateId";
import { saveProjectFilesWithHistory, type RecordEditInput } from "../utils/studioFileHistory";
import { collectHtmlIds, resolveDroppedAssetDuration } from "../utils/studioHelpers";
import { formatTimelineAttributeNumber } from "./timelineEditingHelpers";
import { readFileContent } from "./timelineTimingSync";

interface UseTimelineAssetDropOpsOptions {
  projectIdRef: MutableRefObject<string | null>;
  activeCompPath: string | null;
  timelineElements: TimelineElement[];
  showToast: (message: string, tone?: "error" | "info") => void;
  writeProjectFile: (path: string, content: string) => Promise<void>;
  recordEdit: (input: RecordEditInput) => Promise<void>;
  domEditSaveTimestampRef: MutableRefObject<number>;
  reloadPreview: () => void;
  uploadProjectFiles: (files: Iterable<File>, dir?: string) => Promise<string[]>;
  isRecordingRef?: RefObject<boolean>;
  forceReloadSdkSession?: () => void;
}

export function useTimelineAssetDropOps({
  projectIdRef,
  activeCompPath,
  timelineElements,
  showToast,
  writeProjectFile,
  recordEdit,
  domEditSaveTimestampRef,
  reloadPreview,
  uploadProjectFiles,
  isRecordingRef,
  forceReloadSdkSession,
}: UseTimelineAssetDropOpsOptions) {
  // fallow-ignore-next-line complexity
  const handleTimelineAssetDrop = useCallback(
    // fallow-ignore-next-line complexity
    async (
      assetPath: string,
      placement: Pick<TimelineElement, "start" | "track">,
      durationOverride?: number,
    ) => {
      if (isRecordingRef?.current) {
        showToast("Cannot edit timeline while recording", "error");
        return;
      }
      const pid = projectIdRef.current;
      if (!pid) throw new Error("No active project");

      const kind = getTimelineAssetKind(assetPath);
      if (!kind) {
        showToast("Only image, video, and audio assets can be dropped onto the timeline.");
        return;
      }

      const targetPath = activeCompPath || "index.html";
      try {
        const originalContent = await readFileContent(pid, targetPath);

        const normalizedStart = Number(formatTimelineAttributeNumber(placement.start));
        const duration =
          Number.isFinite(durationOverride) && durationOverride != null && durationOverride > 0
            ? durationOverride
            : await resolveDroppedAssetDuration(pid, assetPath, kind);
        const normalizedDuration = Number(formatTimelineAttributeNumber(duration));
        const newId = buildTimelineAssetId(assetPath, collectHtmlIds(originalContent));
        const resolvedAssetSrc = resolveTimelineAssetSrc(targetPath, assetPath);

        const resolvedTargetPath = targetPath || "index.html";
        const relevantElements = timelineElements.filter(
          (te) => (te.sourceFile || activeCompPath || "index.html") === resolvedTargetPath,
        );
        const newElementZIndex = Math.max(1, relevantElements.length + 1);

        const patchedContent = insertTimelineAssetIntoSource(
          originalContent,
          buildTimelineAssetInsertHtml({
            id: newId,
            hfId: `hf-${generateId()}`,
            assetPath: resolvedAssetSrc,
            kind,
            start: normalizedStart,
            duration: normalizedDuration,
            track: placement.track,
            zIndex: newElementZIndex,
            geometry: fitTimelineAssetGeometry(
              null,
              resolveTimelineAssetCompositionSize(originalContent),
            ),
          }),
        );

        domEditSaveTimestampRef.current = Date.now();
        await saveProjectFilesWithHistory({
          projectId: pid,
          label: "Add timeline asset",
          kind: "timeline",
          files: { [targetPath]: patchedContent },
          readFile: async () => originalContent,
          writeFile: writeProjectFile,
          recordEdit,
        });

        forceReloadSdkSession?.();
        reloadPreview();
      } catch (error) {
        const message =
          error instanceof Error ? error.message : "Failed to drop asset onto timeline";
        showToast(message);
      }
    },
    [
      projectIdRef,
      activeCompPath,
      recordEdit,
      showToast,
      timelineElements,
      writeProjectFile,
      domEditSaveTimestampRef,
      reloadPreview,
      isRecordingRef,
      forceReloadSdkSession,
    ],
  );

  // fallow-ignore-next-line complexity
  const handleTimelineFileDrop = useCallback(
    // fallow-ignore-next-line complexity
    async (files: File[], placement?: Pick<TimelineElement, "start" | "track">) => {
      if (isRecordingRef?.current) {
        showToast("Cannot edit timeline while recording", "error");
        return;
      }
      const pid = projectIdRef.current;
      if (!pid) return;
      const uploaded = await uploadProjectFiles(files);
      if (uploaded.length === 0) return;
      const durations: number[] = [];
      for (const assetPath of uploaded) {
        const kind = getTimelineAssetKind(assetPath);
        const duration = kind ? await resolveDroppedAssetDuration(pid, assetPath, kind) : 0;
        durations.push(Number(formatTimelineAttributeNumber(duration)));
      }
      const placements = buildTimelineFileDropPlacements(
        placement ?? { start: 0, track: 0 },
        durations,
      );
      for (const [index, assetPath] of uploaded.entries()) {
        await handleTimelineAssetDrop(
          assetPath,
          placements[index] ?? placements[0],
          durations[index],
        );
      }
    },
    [handleTimelineAssetDrop, projectIdRef, uploadProjectFiles, isRecordingRef, showToast],
  );

  return { handleTimelineAssetDrop, handleTimelineFileDrop };
}