import type { FederatedPointerEvent } from 'pixi.js';

/** Longest gap between two presses that still reads as one double-click. */
const DOUBLE_MS = 400;
/** How far the pointer may travel between them. */
const SLOP = 6;

/** When and where a press happened. */
export interface Press {
  time: number;
  x: number;
  y: number;
}

export const pressOf = (e: FederatedPointerEvent): Press => ({
  time: e.timeStamp,
  x: e.global.x,
  y: e.global.y,
});

/** Whether `e` comes soon enough and close enough after `first` to make a double-click with it. */
export function followsPress(first: Press, e: FederatedPointerEvent): boolean {
  const gap = e.timeStamp - first.time;
  return gap >= 0 && gap <= DOUBLE_MS && Math.hypot(e.global.x - first.x, e.global.y - first.y) <= SLOP;
}

interface LastPress extends Press {
  key: unknown;
  button: number;
  count: number;
}

let last: LastPress = { key: null, button: -1, time: 0, x: 0, y: 0, count: 0 };

/**
 * Press count in a row (2 on a double-click), since Pixi leaves `detail` at 0 on `pointerdown`. `key`
 * must survive a rebuild of its widget: the first click's selection can recreate the list rows.
 */
export function pressCount(e: FederatedPointerEvent, key: unknown): number {
  const repeat = key === last.key && e.button === last.button && followsPress(last, e);
  const count = repeat ? last.count + 1 : 1;
  last = {
    ...pressOf(e),
    key,
    button: e.button,
    // A finished double-click ends the run: folding a row open and shut again is two
    // double-clicks, and the second must count as one rather than as clicks three and four.
    count: count === 2 ? 0 : count,
  };
  return count;
}