import { html } from "htm";
import * as React from "preact";

/** @typedef {({children, classes}:{children:preact.VNode, classes:string|null})=>preact.VNode} BasicElement */
/** @typedef {{Open:boolean, Done:boolean}} Stage*/
/** @typedef {[set:Stage, get:React.StateUpdater<Stage>]} Binding */

const BranchContext = React.createContext(
  /** @type Binding */ ([{ Open: false, Done: true }, (_n) => {}]),
);

/** @type BasicElement */
export const Branch = (props) => {
  /** @type Binding */ const stage = React.useState(
    /** @type Stage */ ({ Open: false, Done: true }),
  );
  /** @type Binding */ const stageParent = React.useContext(BranchContext);

  React.useEffect(() => {
    const [{ Open, Done }, Shut] = stageParent;
    if (!Open && Done) {
      Shut({ Open: false, Done: true });
    }
  }, [stageParent]);

  return React.createElement(BranchContext.Provider, {
    value: stage,
    children: props.children,
  });
};

/** @type BasicElement */
export const Button = (props) => {
  /** @type Binding */
  const [stageGet, stageSet] = React.useContext(BranchContext);

  const handler = () => {
    const value = { Open: !stageGet.Open, Done: false };
    stageSet(value);
    console.log(value);
  };

  return html`<button onClick=${handler} class=${props.classes}>stage: ${
    JSON.stringify(stageGet)
  }
  ${props.children}
  </button>`;
};

/** @type BasicElement */
export const Menu = (props) => {
  const [stageGet, stageSet] = React.useContext(BranchContext);
  const refElement = React.useRef(null);
  const refCollapser = React.useRef(null);

  React.useEffect(() => {
    refCollapser.current = Collapser(refElement.current);
  }, []);

  React.useEffect(() => {
    refCollapser.current(
      stageGet.Open,
      stageGet.Open == false && stageGet.Done ? 0 : 600,
      () => stageSet({ ...stageGet, Done: true }),
    );
  }, [stageGet.Open]);

  return html`
  <div ref=${refElement} class=${props.classes}>
    ${props.children}
  </div>
  `;
};

/** @typedef {(Open:boolean)=>void} UserDone */
/** @typedef {(inOpen:boolean, inMilliseconds:number, inUserDone:UserDone)=>void} Toggler */
/** @type {(inElement:HTMLElement)=>Toggler} */
const Collapser = (inElement) => {
  console.log("Collapser initialized");

  /** @type UserDone */
  let userDone = () => {};
  const collapse = inElement;
  /** @type {(inEvent:TransitionEvent)=>void} */
  const done = (inEvent) => {
    if (inEvent.propertyName == "height" && inEvent.target == collapse) {
      inEvent.stopPropagation();
      if (collapse.clientHeight > 0) {
        collapse.style.height = "auto";
        collapse.style.overflow = "visible";
        userDone(true);
      } else {
        userDone(false);
      }
    }
  };
  /** @type Toggler */
  const show = (inOpen, inMs, inDone) => {
    collapse.removeEventListener("transitionend", done);
    userDone = inDone;
    collapse.addEventListener("transitionend", done);

    collapse.style.height = collapse.clientHeight + "px";
    collapse.style.overflow = "hidden";
    collapse.style.transition = "none";
    requestAnimationFrame(() => {
      collapse.style.height = `${inOpen ? collapse.scrollHeight : 0}px`;
      collapse.style.transition = `height ${inMs / 1000}s`;
    });
  };
  return show;
};