import { atom } from 'jotai';
import type { TUploadContent } from '../utils/matrix';

/**
 * [cinny-desktop #10] Every in-flight upload across all rooms, so the desktop
 * taskbar can show one combined progress bar. Written by `createUploadAtom`
 * (state/upload.ts) as its uploads start, progress, finish or fail.
 */
export type UploadProgressEntry = {
  loaded: number;
  total: number;
  failed: boolean;
  /** ms timestamp of the last change; stale entries are ignored. */
  updatedAt: number;
};

export const uploadProgressAtom = atom(new Map<TUploadContent, UploadProgressEntry>());

export type TaskbarProgress =
  | { status: 'none' }
  | { status: 'indeterminate' }
  | { status: 'normal'; progress: number }
  | { status: 'error'; progress: number };

/** An upload with no update for this long is treated as abandoned. */
export const UPLOAD_STALE_MS = 2 * 60_000;

/**
 * Combine every upload into one taskbar state: the byte-weighted percentage
 * while anything is uploading (indeterminate while no size is known yet), red
 * when an upload failed and nothing else is running, nothing otherwise.
 */
export const aggregateUploadProgress = (
  entries: Iterable<UploadProgressEntry>,
  now: number,
): TaskbarProgress => {
  let loaded = 0;
  let total = 0;
  let active = 0;
  let failed = 0;
  let failedLoaded = 0;
  let failedTotal = 0;
  Array.from(entries).forEach((e) => {
    if (now - e.updatedAt > UPLOAD_STALE_MS) return;
    if (e.failed) {
      failed += 1;
      failedLoaded += e.loaded;
      failedTotal += e.total;
      return;
    }
    active += 1;
    loaded += Math.min(e.loaded, e.total);
    total += e.total;
  });
  if (active > 0) {
    if (total <= 0) return { status: 'indeterminate' };
    return { status: 'normal', progress: Math.min(100, Math.floor((loaded / total) * 100)) };
  }
  if (failed > 0) {
    return {
      status: 'error',
      progress:
        failedTotal > 0 ? Math.min(100, Math.floor((failedLoaded / failedTotal) * 100)) : 100,
    };
  }
  return { status: 'none' };
};