import { onMounted, onUnmounted, type Ref } from "vue";
import type { ProjectFile } from "../../domain/project";
import type { Node } from "../../domain/phy";
import { fitViewport, zoomAround } from "./viewport";
import { localBounds } from "./logic";

type Options = {
  project: () => ProjectFile;
  svg: Ref<SVGSVGElement | undefined>;
  size: Ref<{ w: number; h: number }>;
  zoom: Ref<number>;
  pan: Ref<{ x: number; y: number }>;
  selected: Ref<string[]>;
  variants: Ref<Record<string, string>>;
  node: (id: string) => Node | undefined;
};

export function usePhyViewport(options: Options) {
  let observer: ResizeObserver | null = null;

  function fit() {
    const bounds = localBounds(options.project().phy.root, options.variants.value);
    const viewport = fitViewport(bounds, options.size.value.w, options.size.value.h);
    options.zoom.value = viewport.zoom;
    options.pan.value = viewport.pan;
  }

  function fitSelected() {
    const nodes = options.selected.value
      .map((id) => options.node(id))
      .filter((node): node is Node => node !== undefined);
    if (!nodes.length) return;
    const bounds = localBounds(nodes, options.variants.value);
    const viewport = fitViewport(bounds, options.size.value.w, options.size.value.h);
    options.zoom.value = viewport.zoom;
    options.pan.value = viewport.pan;
  }

  function localPoint(element: SVGSVGElement | SVGGElement, x: number, y: number) {
    const transform = element.getScreenCTM();
    if (!transform) return { x: 0, y: 0 };
    const point = new DOMPoint(x, y).matrixTransform(transform.inverse());
    return { x: point.x, y: point.y };
  }

  function wheel(event: WheelEvent) {
    const svg = options.svg.value;
    if (!svg) return;
    const point = localPoint(svg, event.clientX, event.clientY);
    const viewport = zoomAround(
      point,
      { zoom: options.zoom.value, pan: options.pan.value },
      Math.exp(-event.deltaY * 0.001),
    );
    options.zoom.value = viewport.zoom;
    options.pan.value = viewport.pan;
  }

  onMounted(() => {
    if (!options.svg.value) return;
    // viewBox はSVG自身の大きさに合わせる。ペインにはツールバーも入り、折り返すと高さがずれる
    observer = new ResizeObserver((entries) => {
      const rect = entries[0]!.contentRect;
      options.size.value = { w: rect.width, h: rect.height };
      fit();
    });
    observer.observe(options.svg.value);
    fit();
  });
  onUnmounted(() => observer?.disconnect());

  return { fit, fitSelected, localPoint, wheel };
}