sitegen/framework/lib/async.ts

const five_minutes = 5 * 60 * 1000;

interface QueueOptions<T, R> {
  name: string;
  fn: (item: T, spin: Spinner) => Promise<R>;
  getItemText?: (item: T) => string;
  maxJobs?: number;
  passive?: boolean;
}

// Process multiple items in parallel, queue up as many.
export class Queue<T, R> {
  #name: string;
  #fn: (item: T, spin: Spinner) => Promise<R>;
  #maxJobs: number;
  #getItemText: (item: T) => string;
  #passive: boolean;

  #active: Spinner[] = [];
  #queue: Array<[T] | [T, (result: R) => void, (err: unknown) => void]> = [];

  #cachedProgress: Progress<{ active: Spinner[] }> | null = null;
  #done: number = 0;
  #total: number = 0;
  #onComplete: (() => void) | null = null;
  #estimate: number | null = null;
  #errors: unknown[] = [];

  constructor(options: QueueOptions<T, R>) {
    this.#name = options.name;
    this.#fn = options.fn;
    this.#maxJobs = options.maxJobs ?? 5;
    this.#getItemText = options.getItemText ?? defaultGetItemText;
    this.#passive = options.passive ?? false;
  }

  cancel() {
    const bar = this.#cachedProgress;
    bar?.stop();
    this.#queue = [];
  }

  get bar() {
    const cached = this.#cachedProgress;
    if (!cached) {
      const bar = this.#cachedProgress = new Progress({
        spinner: null,
        text: ({ active }) => {
          const now = performance.now();
          let text = `[${this.#done}/${this.#total}] ${this.#name}`;
          let n = 0;
          for (const item of active) {
            let itemText = "- " + item.format(now);
            text += `\n` +
              itemText.slice(0, Math.max(0, process.stdout.columns - 1));
            if (n > 10) {
              text += `\n  ... + ${active.length - n} more`;
              break;
            }
            n++;
          }
          return text;
        },
        props: {
          active: [] as Spinner[],
        },
      });
      bar.value = 0;
      return bar;
    }
    return cached;
  }

  addReturn(args: T) {
    this.#total += 1;
    this.updateTotal();
    if (this.#active.length >= this.#maxJobs) {
      const { promise, resolve, reject } = Promise.withResolvers<R>();
      this.#queue.push([args, resolve, reject]);
      return promise;
    }
    return this.#run(args);
  }

  add(args: T) {
    return this.addReturn(args).then(() => {}, () => {});
  }

  addMany(items: T[]) {
    this.#total += items.length;
    this.updateTotal();

    const runNowCount = this.#maxJobs - this.#active.length;
    const runNow = items.slice(0, runNowCount);
    const runLater = items.slice(runNowCount);
    this.#queue.push(...runLater.reverse().map<[T]>((x) => [x]));
    runNow.map((item) => this.#run(item).catch(() => {}));
  }

  async #run(args: T): Promise<R> {
    const bar = this.bar;
    const itemText = this.#getItemText(args);
    const spinner = new Spinner(itemText);
    spinner.stop();
    (spinner as any).redraw = () => (bar as any).redraw();
    const active = this.#active;
    try {
      active.unshift(spinner);
      bar.props = { active };
      // console.log(this.#name + ": " + itemText);
      const result = await this.#fn(args, spinner);
      this.#done++;
      return result;
    } catch (err) {
      if (err && typeof err === "object") {
        (err as any).job = itemText;
      }
      this.#errors.push(err);
      console.error(util.inspect(err, false, Infinity, true));
      throw err;
    } finally {
      active.splice(active.indexOf(spinner), 1);
      bar.props = { active };
      bar.value = this.#done;

      // Process next item
      const next = this.#queue.shift();
      if (next) {
        const args = next[0];
        this.#run(args)
          .then((result) => next[1]?.(result))
          .catch((err) => next[2]?.(err));
      } else if (this.#active.length === 0) {
        if (this.#passive) {
          this.bar.stop();
          this.#cachedProgress = null;
        }
        this.#onComplete?.();
      }
    }
  }

  updateTotal() {
    const bar = this.bar;
    bar.total = Math.max(this.#total, this.#estimate ?? 0);
  }

  set estimate(e: number) {
    this.#estimate = e;
    if (this.#cachedProgress) {
      this.updateTotal();
    }
  }

  async done(o?: { method: "success" | "stop" }) {
    if (this.#active.length === 0) {
      this.#end(o);
      return;
    }

    const { promise, resolve } = Promise.withResolvers<void>();
    this.#onComplete = resolve;
    await promise;
    this.#end(o);
  }

  #end(
    { method = this.#passive ? "stop" : "success" }: {
      method?: "success" | "stop";
    } = {},
  ) {
    const bar = this.#cachedProgress;
    if (this.#errors.length > 0) {
      if (bar) bar.stop();
      throw new AggregateError(
        this.#errors,
        this.#errors.length + " jobs failed in '" + this.#name + "'",
      );
    }

    if (bar) bar[method]();
  }

  get active(): boolean {
    return this.#active.length !== 0;
  }

  [Symbol.dispose]() {
    if (this.active) {
      this.cancel();
    }
  }
}

const cwd = process.cwd();
function defaultGetItemText(item: unknown) {
  let itemText = "";
  if (typeof item === "string") {
    itemText = item;
  } else if (typeof item === "object" && item !== null) {
    const { path, label, id } = item as any;
    itemText = label ?? path ?? id ?? JSON.stringify(item);
  } else {
    itemText = JSON.stringify(item);
  }

  if (itemText.startsWith(cwd)) {
    itemText = path.relative(cwd, itemText);
  }
  return itemText;
}

export class OnceMap<T> {
  private ongoing = new Map<string, Promise<T>>();

  get(key: string, compute: () => Promise<T>) {
    if (this.ongoing.has(key)) {
      return this.ongoing.get(key)!;
    }

    const result = compute();
    this.ongoing.set(key, result);
    return result;
  }
}

interface ARCEValue<T> {
  value: T;
  [Symbol.dispose]: () => void;
}

export function RefCountedExpirable<T>(
  init: () => Promise<T>,
  deinit: (value: T) => void,
  expire: number = five_minutes,
): () => Promise<ARCEValue<T>> {
  let refs = 0;
  let item: ARCEValue<T> | null = null;
  let loading: Promise<ARCEValue<T>> | null = null;
  let timer: ReturnType<typeof setTimeout> | null = null;

  function deref() {
    ASSERT(item !== null);
    if (--refs !== 0) return;
    ASSERT(timer === null);
    timer = setTimeout(() => {
      ASSERT(refs === 0);
      ASSERT(loading === null);
      ASSERT(item !== null);
      deinit(item.value);
      item = null;
      timer = null;
    }, expire);
  }

  return async function () {
    if (timer !== null) {
      clearTimeout(timer);
      timer = null;
    }
    if (item !== null) {
      refs++;
      return item;
    }
    if (loading !== null) {
      refs++;
      return loading;
    }
    const p = Promise.withResolvers<ARCEValue<T>>();
    loading = p.promise;
    try {
      const value = await init();
      item = { value, [Symbol.dispose]: deref };
      refs++;
      p.resolve(item);
      return item;
    } catch (e) {
      p.reject(e);
      throw e;
    } finally {
      loading = null;
    }
  };
}

export function once<T>(fn: () => Promise<T>): () => Promise<T> {
  let result: T | Promise<T> | null = null;
  return async () => {
    if (result) return result;
    result = await fn();
    return result;
  };
}

import { Progress } from "@paperclover/console/Progress";
import { Spinner } from "@paperclover/console/Spinner";
import * as path from "node:path";
import process from "node:process";
import * as util from "node:util";