import { mulberry32 } from './mulberry32'

// Cumulative reach at a playback round, shared by the panel stats and the
// reach chart so both always agree with the network picture.
export function reachedCountAtRound(reachedAtRound: number[], round: number): number {
  return reachedAtRound.filter((reachedAt) => reachedAt >= 0 && reachedAt <= round).length
}

// During playback, dots of the current round do not appear at once: each
// node gets a deterministic random moment inside the first APPEAR_WINDOW
// of the round interval (the rest of the interval is its fade). The same
// jitter drives the dot's animation-delay and the live counter, so the
// percentage ticks up exactly as dots start appearing.

export const APPEAR_WINDOW = 0.7

export function appearanceJitter(nodeIndex: number): number {
  return mulberry32(nodeIndex * 7919 + 17)()
}

// Reach as displayed mid-transition: every earlier round fully, plus the
// current round's nodes whose appearance moment has passed. With
// roundProgress = 1 this equals reachedCountAtRound.
export function reachedCountDisplayed(
  reachedAtRound: number[],
  round: number,
  roundProgress: number,
): number {
  let displayed = 0
  reachedAtRound.forEach((reachedAt, nodeIndex) => {
    if (reachedAt < 0 || reachedAt > round) return
    if (reachedAt < round || roundProgress >= appearanceJitter(nodeIndex) * APPEAR_WINDOW) {
      displayed += 1
    }
  })
  return displayed
}