/**
 * Gesture-begin functions: startGroupDrag and startGesture.
 * These are pure "start a new gesture" operations — no draft rect updates.
 */
import { type DomEditSelection } from "./domEditing";
import {
  createManualOffsetDragMember,
  restoreManualOffsetDragMembers,
  type ManualOffsetDragMember,
} from "./manualOffsetDrag";
import {
  beginStudioManualEditGesture,
  captureStudioBoxSize,
  captureStudioPathOffset,
  captureStudioRotation,
  readStudioBoxSize,
  readStudioRotation,
} from "./manualEdits";
import {
  type OverlayRect,
  filterNestedDomEditGroupItems,
  selectionCacheKey,
} from "./domEditOverlayGeometry";
import { type GestureKind, type GestureState } from "./domEditOverlayGestures";
import type { UseDomEditOverlayGesturesOptions } from "./useDomEditOverlayGestures";

export function startGroupDrag(
  e: React.PointerEvent<HTMLElement>,
  opts: UseDomEditOverlayGesturesOptions,
): boolean {
  const items = opts.groupOverlayItemsRef.current;
  if (items.length <= 1) return false;

  const blockedSelection = items.find(
    (item) => !item.selection.capabilities.canApplyManualOffset,
  )?.selection;
  if (blockedSelection) {
    e.preventDefault();
    e.stopPropagation();
    opts.onBlockedMoveRef.current(blockedSelection);
    return false;
  }

  opts.onManualDragStartRef.current?.();
  const dragItems = filterNestedDomEditGroupItems(items);
  const members: ManualOffsetDragMember[] = [];
  for (const item of dragItems) {
    const result = createManualOffsetDragMember({
      key: item.key,
      selection: item.selection,
      element: item.element,
      rect: item.rect,
    });
    if (!result.ok) {
      restoreManualOffsetDragMembers(members);
      e.preventDefault();
      e.stopPropagation();
      opts.onBlockedMoveRef.current(result.selection);
      return false;
    }
    members.push(result.member);
  }

  e.preventDefault();
  e.stopPropagation();
  e.currentTarget.setPointerCapture(e.pointerId);
  opts.rafPausedRef.current = true;
  opts.groupGestureRef.current = {
    startX: e.clientX,
    startY: e.clientY,
    originItems: items,
    members,
  };
  return true;
}

export function startGesture(
  kind: GestureKind,
  e: React.PointerEvent<HTMLElement>,
  opts: UseDomEditOverlayGesturesOptions,
  options?: { selection?: DomEditSelection; rect?: OverlayRect | null },
): boolean {
  const sel = options?.selection ?? opts.selectionRef.current;
  const rect = options?.rect ?? opts.overlayRectRef.current;
  const box = opts.boxRef.current;
  const overlayEl = opts.overlayRef.current;
  if (!sel || !rect) return false;
  if (kind !== "drag" && !box) return false;
  const mode: GestureState["mode"] =
    kind === "rotate" ? "rotation" : kind === "drag" ? "path-offset" : "box-size";
  if (kind === "drag" && !sel.capabilities.canApplyManualOffset) return false;
  if (kind === "resize" && !sel.capabilities.canApplyManualSize) return false;
  if (kind === "rotate" && !sel.capabilities.canApplyManualRotation) return false;
  if (kind === "resize" && (!Number.isFinite(rect.width) || !Number.isFinite(rect.height)))
    return false;

  const size = readStudioBoxSize(sel.element);
  const rotation = readStudioRotation(sel.element);
  const actualWidth = size.width > 0 ? size.width : rect.width / rect.editScaleX;
  const actualHeight = size.height > 0 ? size.height : rect.height / rect.editScaleY;
  let initialPathOffset = captureStudioPathOffset(sel.element);
  let manualEditDragToken: string | undefined;
  let pathOffsetMember: ManualOffsetDragMember | undefined;

  if (kind === "drag") {
    opts.onManualDragStartRef.current?.();
    const result = createManualOffsetDragMember({
      key: selectionCacheKey(sel),
      selection: sel,
      element: sel.element,
      rect,
    });
    if (!result.ok) {
      opts.onBlockedMoveRef.current(result.selection);
      return false;
    }
    pathOffsetMember = result.member;
    initialPathOffset = result.member.initialPathOffset;
    manualEditDragToken = result.member.gestureToken;
  } else {
    manualEditDragToken = beginStudioManualEditGesture(sel.element);
  }

  const overlayBounds = overlayEl?.getBoundingClientRect();
  const centerX = (overlayBounds?.left ?? 0) + rect.left + rect.width / 2;
  const centerY = (overlayBounds?.top ?? 0) + rect.top + rect.height / 2;
  e.preventDefault();
  e.stopPropagation();
  e.currentTarget.setPointerCapture(e.pointerId);
  opts.rafPausedRef.current = true;
  opts.gestureRef.current = {
    kind,
    mode,
    selection: sel,
    startX: e.clientX,
    startY: e.clientY,
    centerX,
    centerY,
    initialPathOffset,
    initialRotation: captureStudioRotation(sel.element),
    initialBoxSize: captureStudioBoxSize(sel.element),
    pathOffsetMember,
    originLeft: rect.left,
    originTop: rect.top,
    originWidth: rect.width,
    originHeight: rect.height,
    actualWidth,
    actualHeight,
    actualRotation: rotation.angle,
    editScaleX: rect.editScaleX,
    editScaleY: rect.editScaleY,
    manualEditDragToken,
  };
  return true;
}
