import { TimelineBounds } from './types';
import { state } from './state';

const formatTime = (seconds: number): string => {
  if (!Number.isFinite(seconds) || seconds < 0) return '00:00';
  const mins = Math.floor(seconds / 60);
  const secs = Math.floor(seconds % 60);
  return `${mins.toString().padStart(2, '0')}:${secs.toString().padStart(2, '0')}`;
};

let cachedBounds: TimelineBounds = { start: 0, end: 0, duration: 0 };

export const timelineBounds = (): TimelineBounds => {
  const duration =
    Number.isFinite(state.video.duration) && state.video.duration > 0 ? state.video.duration : 0;
  let start = 0;
  if (state.video.seekable.length > 0) {
    const seekableStart = state.video.seekable.start(0);
    if (Number.isFinite(seekableStart) && seekableStart > 0) start = seekableStart;
  }
  if (duration > start) {
    return { start, end: duration, duration: duration - start };
  }
  if (state.video.seekable.length > 0) {
    const seekableEnd = state.video.seekable.end(state.video.seekable.length - 1);
    if (Number.isFinite(seekableEnd) && seekableEnd > start) {
      return { start, end: seekableEnd, duration: seekableEnd - start };
    }
  }
  return { start: 0, end: duration, duration };
};

export const invalidateBounds = (): void => {
  cachedBounds = timelineBounds();
};

export const getBounds = (): TimelineBounds => cachedBounds;

export const displayTimeFromAbsolute = (absoluteTime: number): number => {
  const b = getBounds();
  if (!Number.isFinite(absoluteTime) || b.duration <= 0) return 0;
  return Math.max(b.start, Math.min(b.end, absoluteTime)) - b.start;
};

export const absoluteTimeFromDisplay = (displayTime: number): number => {
  const b = getBounds();
  if (!Number.isFinite(displayTime) || b.duration <= 0) return 0;
  return b.start + Math.max(0, Math.min(b.duration, displayTime));
};

export const absoluteTimeFromRatio = (ratio: number): number => {
  const b = getBounds();
  if (!Number.isFinite(ratio) || b.duration <= 0) return 0;
  return b.start + Math.max(0, Math.min(1, ratio)) * b.duration;
};

export const getBufferedEnd = (): number => {
  const currentTime = state.video.currentTime;
  let end = 0;
  for (let i = 0; i < state.video.buffered.length; i++) {
    if (
      state.video.buffered.start(i) <= currentTime &&
      state.video.buffered.end(i) >= currentTime
    ) {
      end = state.video.buffered.end(i);
      break;
    }
  }
  if (end === 0) {
    for (let i = 0; i < state.video.buffered.length; i++) {
      if (state.video.buffered.end(i) > currentTime) {
        end = Math.max(end, state.video.buffered.end(i));
      }
    }
  }
  return end;
};

export const updateTimeline = (currentTime: number): void => {
  const { progress, scrubber, timeDisplay, durationDisplay, buffered } = state;
  const b = getBounds();

  if (b.duration <= 0) {
    progress.style.width = '0%';
    buffered.style.width = '0%';
    scrubber.style.left = '0%';
    timeDisplay.textContent = '00:00';
    durationDisplay.textContent = '00:00';
    return;
  }

  const pct = (displayTimeFromAbsolute(currentTime) / b.duration) * 100;
  progress.style.width = `${pct}%`;
  scrubber.style.left = `${pct}%`;
  timeDisplay.textContent = formatTime(displayTimeFromAbsolute(currentTime));
  durationDisplay.textContent = formatTime(b.duration);

  const bufferedEnd = getBufferedEnd();
  const bufferedPct = (displayTimeFromAbsolute(bufferedEnd) / b.duration) * 100;
  buffered.style.width = `${bufferedPct}%`;
};