import { commandIds } from "@commands/ids";
import type { Dispatch } from "@commands/dispatcher";
import type { ImageDocument } from "@core/document";
import type { Layer } from "@core/layer";
import { resolveTransformTargetBounds } from "@editor/transform-targets";
import type { ViewportState } from "@editor/state";
import type { PointerInputEvent } from "./pointer";

export function handleArtboardSelection(options: {
  event: PointerInputEvent;
  document: ImageDocument;
  viewport: ViewportState;
  dispatch: Dispatch;
}): boolean {
  if (options.event.pointerType !== "mouse" || (options.event.buttons & 1) !== 1) return false;

  const point = viewportPointToDocumentPoint(options.event.position, options.viewport);
  const layerHit = findTopmostLayerAtPoint(options.document, point);
  if (layerHit) {
    options.dispatch(commandIds.selectionSet, { artboardId: layerHit.artboardId, layerIds: [layerHit.layerId] });
    return true;
  }

  const artboard = [...options.document.artboards].reverse().find((candidate) => {
    const bounds = candidate.bounds;
    return point.x >= bounds.x && point.x <= bounds.x + bounds.w && point.y >= bounds.y && point.y <= bounds.y + bounds.h;
  });

  if (!artboard) {
    options.dispatch(commandIds.selectionClear, undefined);
    return true;
  }

  options.dispatch(commandIds.selectionSet, { artboardId: artboard.id, layerIds: [] });
  return true;
}

function findTopmostLayerAtPoint(document: ImageDocument, point: { x: number; y: number }) {
  for (const artboard of [...document.artboards].reverse()) {
    const layerId = findTopmostLayerInTreeAtPoint(document, [...artboard.layers].reverse(), point);
    if (layerId) return { artboardId: artboard.id, layerId };
  }

  return undefined;
}

function findTopmostLayerInTreeAtPoint(document: ImageDocument, layers: Layer[], point: { x: number; y: number }): string | undefined {
  for (const layer of layers) {
    if (layer.type === "group") {
      const childId = findTopmostLayerInTreeAtPoint(document, [...layer.children].reverse(), point);
      if (childId) return childId;
    }

    const bounds = resolveTransformTargetBounds(document, { type: "layer", id: layer.id });
    if (bounds && point.x >= bounds.x && point.x <= bounds.x + bounds.w && point.y >= bounds.y && point.y <= bounds.y + bounds.h) {
      return layer.id;
    }
  }

  return undefined;
}

function viewportPointToDocumentPoint(point: PointerInputEvent["position"], viewport: ViewportState) {
  return {
    x: viewport.center.x + (point.x - viewport.size.w / 2) / viewport.zoom,
    y: viewport.center.y + (point.y - viewport.size.h / 2) / viewport.zoom,
  };
}