import type { PointerEvent as ReactPointerEvent, RefObject } from 'react';
import { useCallback, useEffect, useMemo, useRef, useState } from 'react';

import { hasReadableAssetSource } from '../../services/assetReadUrlService';
import type { AssetMarqueeState, EditorAsset } from './ImageCanvasEditorTypes';

const ASSET_ITEM_SELECTOR = '[data-asset-id]';
const ASSET_MARQUEE_BLOCKED_TARGET_SELECTOR =
  'button, input, textarea, select, [data-asset-id]';

type ClientRectLike = Pick<DOMRect, 'bottom' | 'left' | 'right' | 'top'>;

type ClientPoint = {
  clientX: number;
  clientY: number;
};

type ScrollContainerLike = Pick<HTMLElement, 'scrollLeft' | 'scrollTop'>;

type AssetHitTarget = {
  assetId: string;
  rect: ClientRectLike;
};

export type AssetSelectionInteraction = {
  visibleAssetIds: string[];
  shiftKey?: boolean;
};

type AssetSelectionState = {
  selectedAssetIds: Set<string>;
  anchorAssetId: string | null;
};

export function isSelectableAsset(asset: EditorAsset) {
  return (
    asset.sourceKind === 'uploaded' &&
    asset.uploadStatus !== 'uploading' &&
    asset.uploadStatus !== 'failed' &&
    hasReadableAssetSource(asset.src, asset.objectKey)
  );
}

export function getSelectableAssets(assets: EditorAsset[]) {
  return assets.filter(isSelectableAsset);
}

export function countHiddenSelectedAssets(
  selectedAssetIds: Set<string>,
  visibleAssetIds: string[],
) {
  const visibleIds = new Set(visibleAssetIds);
  return [...selectedAssetIds].filter((assetId) => !visibleIds.has(assetId))
    .length;
}

function doRectsIntersect(rect: ClientRectLike, selectionRect: ClientRectLike) {
  return (
    rect.left <= selectionRect.right &&
    rect.right >= selectionRect.left &&
    rect.top <= selectionRect.bottom &&
    rect.bottom >= selectionRect.top
  );
}

function shouldStartAssetMarquee({
  isAssetSelectionMode,
  button,
  isBlockedTarget,
}: {
  isAssetSelectionMode: boolean;
  button: number;
  isBlockedTarget: boolean;
}) {
  return isAssetSelectionMode && button === 0 && !isBlockedTarget;
}

export function createAssetMarqueeFromPointer({
  pointerId,
  point,
  containerRect,
  container,
}: {
  pointerId: number;
  point: ClientPoint;
  containerRect: Pick<DOMRect, 'left' | 'top'> | null | undefined;
  container?: ScrollContainerLike | null;
}): AssetMarqueeState {
  const startX =
    point.clientX - (containerRect?.left ?? 0) + (container?.scrollLeft ?? 0);
  const startY =
    point.clientY - (containerRect?.top ?? 0) + (container?.scrollTop ?? 0);
  return {
    pointerId,
    startX,
    startY,
    currentX: startX,
    currentY: startY,
  };
}

export function moveAssetMarqueeToPointer({
  marquee,
  point,
  containerRect,
  container,
}: {
  marquee: AssetMarqueeState;
  point: ClientPoint;
  containerRect: Pick<DOMRect, 'left' | 'top'> | null | undefined;
  container?: ScrollContainerLike | null;
}) {
  return {
    ...marquee,
    currentX:
      point.clientX - (containerRect?.left ?? 0) + (container?.scrollLeft ?? 0),
    currentY:
      point.clientY - (containerRect?.top ?? 0) + (container?.scrollTop ?? 0),
  };
}

export function createAssetMarqueeSelectionRect({
  marquee,
  point,
  containerRect,
  container,
}: {
  marquee: AssetMarqueeState;
  point: ClientPoint;
  containerRect: Pick<DOMRect, 'left' | 'top'> | null | undefined;
  container?: ScrollContainerLike | null;
}): ClientRectLike {
  const startClientX =
    (containerRect?.left ?? 0) + marquee.startX - (container?.scrollLeft ?? 0);
  const startClientY =
    (containerRect?.top ?? 0) + marquee.startY - (container?.scrollTop ?? 0);
  return {
    left: Math.min(startClientX, point.clientX),
    right: Math.max(startClientX, point.clientX),
    top: Math.min(startClientY, point.clientY),
    bottom: Math.max(startClientY, point.clientY),
  };
}

export function selectUploadedAssetsInRect({
  assets,
  assetTargets,
  selectionRect,
}: {
  assets: EditorAsset[];
  assetTargets: AssetHitTarget[];
  selectionRect: ClientRectLike;
}) {
  const uploadedAssetIds = new Set(
    getSelectableAssets(assets).map((asset) => asset.id),
  );
  return new Set(
    assetTargets
      .filter(
        (target) =>
          uploadedAssetIds.has(target.assetId) &&
          doRectsIntersect(target.rect, selectionRect),
      )
      .map((target) => target.assetId),
  );
}

function createEmptyAssetSelection(): AssetSelectionState {
  return {
    selectedAssetIds: new Set(),
    anchorAssetId: null,
  };
}

function readAssetHitTargets(listElement: ParentNode | null) {
  return [
    ...(listElement?.querySelectorAll<HTMLElement>(ASSET_ITEM_SELECTOR) ?? []),
  ].flatMap((element) => {
    const assetId = element.dataset.assetId;
    return assetId
      ? [
          {
            assetId,
            rect: element.getBoundingClientRect(),
          },
        ]
      : [];
  });
}

function dedupeAssetIds(assetIds: string[]) {
  return Array.from(new Set(assetIds));
}

function toggleAssetId(selectedAssetIds: Set<string>, assetId: string) {
  const nextIds = new Set(selectedAssetIds);
  if (nextIds.has(assetId)) {
    nextIds.delete(assetId);
  } else {
    nextIds.add(assetId);
  }
  return nextIds;
}

function reconcileAssetSelection(
  selection: AssetSelectionState,
  selectableAssetIds: string[],
) {
  const selectableIds = new Set(selectableAssetIds);
  const selectedAssetIds = new Set(
    [...selection.selectedAssetIds].filter((assetId) =>
      selectableIds.has(assetId),
    ),
  );
  const anchorAssetId =
    selection.anchorAssetId && selectableIds.has(selection.anchorAssetId)
      ? selection.anchorAssetId
      : null;
  if (
    anchorAssetId === selection.anchorAssetId &&
    selectedAssetIds.size === selection.selectedAssetIds.size
  ) {
    return selection;
  }
  return { selectedAssetIds, anchorAssetId };
}

function resolveAssetSelection(
  selection: AssetSelectionState,
  targetAssetId: string,
  interaction: AssetSelectionInteraction,
) {
  const orderedAssetIds = dedupeAssetIds(interaction.visibleAssetIds);
  const targetIndex = orderedAssetIds.indexOf(targetAssetId);
  if (targetIndex < 0) {
    return selection;
  }

  const anchorIndex = selection.anchorAssetId
    ? orderedAssetIds.indexOf(selection.anchorAssetId)
    : -1;
  if (interaction.shiftKey && anchorIndex >= 0) {
    const rangeStart = Math.min(anchorIndex, targetIndex);
    const rangeEnd = Math.max(anchorIndex, targetIndex);
    return {
      selectedAssetIds: new Set([
        ...selection.selectedAssetIds,
        ...orderedAssetIds.slice(rangeStart, rangeEnd + 1),
      ]),
      anchorAssetId: selection.anchorAssetId,
    };
  }

  return {
    selectedAssetIds: toggleAssetId(selection.selectedAssetIds, targetAssetId),
    anchorAssetId: targetAssetId,
  };
}

function toggleVisibleAssetIds(
  selectedAssetIds: Set<string>,
  visibleAssetIds: string[],
) {
  const orderedAssetIds = dedupeAssetIds(visibleAssetIds);
  const allVisibleAssetsSelected =
    orderedAssetIds.length > 0 &&
    orderedAssetIds.every((assetId) => selectedAssetIds.has(assetId));
  if (allVisibleAssetsSelected) {
    const visibleIds = new Set(orderedAssetIds);
    return new Set(
      [...selectedAssetIds].filter((assetId) => !visibleIds.has(assetId)),
    );
  }
  return new Set([...selectedAssetIds, ...orderedAssetIds]);
}

export function useImageCanvasAssetSelection({
  assetListRef,
  assets,
  onOpenSelectionMode,
}: {
  assetListRef: RefObject<HTMLDivElement | null>;
  assets: EditorAsset[];
  onOpenSelectionMode?: () => void;
}) {
  const [isAssetSelectionMode, setIsAssetSelectionMode] = useState(false);
  const [assetSelection, setAssetSelection] = useState<AssetSelectionState>(
    createEmptyAssetSelection,
  );
  const [assetMarquee, setAssetMarquee] = useState<AssetMarqueeState | null>(
    null,
  );
  const marqueeBaseSelectionRef = useRef<Set<string>>(new Set());
  const selectableAssets = useMemo(() => getSelectableAssets(assets), [assets]);
  const selectableAssetIds = useMemo(
    () => selectableAssets.map((asset) => asset.id),
    [selectableAssets],
  );
  const selectedAssets = useMemo(
    () =>
      assets.filter((asset) => assetSelection.selectedAssetIds.has(asset.id)),
    [assetSelection.selectedAssetIds, assets],
  );

  useEffect(() => {
    if (!isAssetSelectionMode) {
      return;
    }
    setAssetSelection((currentSelection) =>
      reconcileAssetSelection(currentSelection, selectableAssetIds),
    );
  }, [isAssetSelectionMode, selectableAssetIds]);

  const clearAssetSelection = useCallback(() => {
    setAssetSelection(createEmptyAssetSelection());
    marqueeBaseSelectionRef.current = new Set();
    setAssetMarquee(null);
  }, []);

  const openAssetSelectionMode = useCallback(() => {
    clearAssetSelection();
    onOpenSelectionMode?.();
    setIsAssetSelectionMode(true);
  }, [clearAssetSelection, onOpenSelectionMode]);

  const closeAssetSelectionMode = useCallback(() => {
    setIsAssetSelectionMode(false);
    clearAssetSelection();
  }, [clearAssetSelection]);

  const toggleAssetSelected = useCallback(
    (assetId: string, interaction: AssetSelectionInteraction) => {
      setAssetSelection((currentSelection) =>
        resolveAssetSelection(currentSelection, assetId, interaction),
      );
    },
    [],
  );

  const toggleAllAssetsSelected = useCallback((visibleAssetIds: string[]) => {
    setAssetSelection((currentSelection) => ({
      selectedAssetIds: toggleVisibleAssetIds(
        currentSelection.selectedAssetIds,
        visibleAssetIds,
      ),
      anchorAssetId: null,
    }));
  }, []);

  const updateAssetSelectionFromMarquee = useCallback(
    (selectionRect: {
      left: number;
      right: number;
      top: number;
      bottom: number;
    }) => {
      // TODO(性能问题): pointermove 会读取全部素材布局并更新 React state；后续需在保留滚动框选、末帧提交和取消回滚语义的前提下，用内容坐标缓存与 rAF 合帧优化。
      const marqueeSelection = selectUploadedAssetsInRect({
        assets,
        assetTargets: readAssetHitTargets(assetListRef.current),
        selectionRect,
      });
      setAssetSelection({
        selectedAssetIds: new Set([
          ...marqueeBaseSelectionRef.current,
          ...marqueeSelection,
        ]),
        anchorAssetId: null,
      });
    },
    [assetListRef, assets],
  );

  const handleAssetMarqueePointerDown = useCallback(
    (event: ReactPointerEvent<HTMLDivElement>) => {
      const target = event.target as HTMLElement;
      if (
        event.pointerType === 'touch' ||
        !shouldStartAssetMarquee({
          isAssetSelectionMode,
          button: event.button,
          isBlockedTarget: Boolean(
            target.closest(ASSET_MARQUEE_BLOCKED_TARGET_SELECTOR),
          ),
        })
      ) {
        return;
      }
      event.preventDefault();
      const container = assetListRef.current;
      container?.setPointerCapture?.(event.pointerId);
      setAssetMarquee(
        createAssetMarqueeFromPointer({
          pointerId: event.pointerId,
          point: event,
          containerRect: container?.getBoundingClientRect(),
          container,
        }),
      );
      marqueeBaseSelectionRef.current =
        event.ctrlKey || event.metaKey
          ? new Set(assetSelection.selectedAssetIds)
          : new Set();
      setAssetSelection({
        selectedAssetIds: new Set(marqueeBaseSelectionRef.current),
        anchorAssetId: null,
      });
    },
    [assetListRef, assetSelection.selectedAssetIds, isAssetSelectionMode],
  );

  const handleAssetMarqueePointerMove = useCallback(
    (event: ReactPointerEvent<HTMLDivElement>) => {
      if (!assetMarquee || assetMarquee.pointerId !== event.pointerId) {
        return;
      }
      event.preventDefault();
      const container = assetListRef.current;
      const containerRect = container?.getBoundingClientRect();
      setAssetMarquee((currentMarquee) =>
        currentMarquee
          ? moveAssetMarqueeToPointer({
              marquee: currentMarquee,
              point: event,
              containerRect,
              container,
            })
          : null,
      );
      updateAssetSelectionFromMarquee(
        createAssetMarqueeSelectionRect({
          marquee: assetMarquee,
          point: event,
          containerRect,
          container,
        }),
      );
    },
    [assetListRef, assetMarquee, updateAssetSelectionFromMarquee],
  );

  const handleAssetMarqueePointerUp = useCallback(
    (event: ReactPointerEvent<HTMLDivElement>) => {
      if (!assetMarquee || assetMarquee.pointerId !== event.pointerId) {
        return;
      }
      event.preventDefault();
      const container = assetListRef.current;
      updateAssetSelectionFromMarquee(
        createAssetMarqueeSelectionRect({
          marquee: assetMarquee,
          point: event,
          containerRect: container?.getBoundingClientRect(),
          container,
        }),
      );
      if (assetListRef.current?.hasPointerCapture?.(event.pointerId)) {
        assetListRef.current.releasePointerCapture?.(event.pointerId);
      }
      setAssetMarquee(null);
    },
    [assetListRef, assetMarquee, updateAssetSelectionFromMarquee],
  );

  const handleAssetMarqueePointerCancel = useCallback(
    (event: ReactPointerEvent<HTMLDivElement>) => {
      if (!assetMarquee || assetMarquee.pointerId !== event.pointerId) {
        return;
      }
      if (assetListRef.current?.hasPointerCapture?.(event.pointerId)) {
        assetListRef.current.releasePointerCapture?.(event.pointerId);
      }
      setAssetSelection({
        selectedAssetIds: new Set(marqueeBaseSelectionRef.current),
        anchorAssetId: null,
      });
      setAssetMarquee(null);
    },
    [assetListRef, assetMarquee],
  );

  const handleAssetMarqueeLostPointerCapture = useCallback(
    (event: ReactPointerEvent<HTMLDivElement>) => {
      setAssetMarquee((currentMarquee) =>
        currentMarquee?.pointerId === event.pointerId ? null : currentMarquee,
      );
    },
    [],
  );

  return {
    selectableAssets,
    selectedAssets,
    selectedAssetIds: assetSelection.selectedAssetIds,
    isAssetSelectionMode,
    assetMarquee,
    clearAssetSelection,
    openAssetSelectionMode,
    closeAssetSelectionMode,
    toggleAssetSelected,
    toggleAllAssetsSelected,
    handleAssetMarqueePointerDown,
    handleAssetMarqueePointerMove,
    handleAssetMarqueePointerUp,
    handleAssetMarqueePointerCancel,
    handleAssetMarqueeLostPointerCapture,
  };
}