import type { ImageDocument } from "@core/document";
import type { Layer } from "@core/layer";
import type { SelectionState } from "@editor/state";

export type SelectionSummary =
  | { type: "none" }
  | { type: "artboard"; name: string; layerCount: number }
  | { type: "layer"; name: string; layer: Layer }
  | { type: "multi-layer"; count: number; layers: Layer[] };

export function getSelectionSummary(document: ImageDocument, selection: SelectionState): SelectionSummary {
  const selectedLayers = selection.layerIds.flatMap((layerId) => {
    const layer = findLayer(document.artboards.flatMap((artboard) => artboard.layers), layerId);
    return layer ? [layer] : [];
  });

  if (selectedLayers.length === 1 && selectedLayers[0]) {
    return { type: "layer", name: selectedLayers[0].name, layer: selectedLayers[0] };
  }

  if (selectedLayers.length > 1) {
    return { type: "multi-layer", count: selectedLayers.length, layers: selectedLayers };
  }

  if (selection.artboardId) {
    const artboard = document.artboards.find((candidate) => candidate.id === selection.artboardId);
    if (artboard) return { type: "artboard", name: artboard.name, layerCount: artboard.layers.length };
  }

  return { type: "none" };
}

function findLayer(layers: Layer[], layerId: string): Layer | undefined {
  for (const layer of layers) {
    if (layer.id === layerId) return layer;
    if (layer.type === "group") {
      const child = findLayer(layer.children, layerId);
      if (child) return child;
    }
  }

  return undefined;
}