import { getJob, getReadInfo, refreshReadInfo } from "#lib/api/endpoints.js";
import type { ReadInfo } from "#lib/api/types.js";
import { accounts } from "#lib/stores/accounts.svelte.js";

const POLL_INTERVAL = 1000;
const POLL_MAX = 20;

export interface ReadEntry {
  fetching: boolean;
  info: ReadInfo;
}

function delay(ms: number): Promise<void> {
  return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
}

async function waitForJob(jobId: number) {
  for (let attempt = 0; attempt < POLL_MAX; attempt += 1) {
    // biome-ignore lint/performance/noAwaitInLoops: polling waits between tries on purpose
    await delay(POLL_INTERVAL);
    const job = await getJob(jobId);
    if (job.status !== "pending" && job.status !== "running") {
      return;
    }
  }
}

function createReads() {
  let entries = $state<Record<string, ReadEntry>>({});
  const inflight = new Set<string>();

  function key(chatId: number, messageId: number): string {
    return `${accounts.selectedId}:${chatId}:${messageId}`;
  }

  async function load(entryKey: string, chatId: number, messageId: number) {
    const info = await getReadInfo(chatId, messageId);
    entries[entryKey] = { fetching: info.can_fetch, info };
    if (!info.can_fetch) {
      return;
    }
    try {
      const { job_id } = await refreshReadInfo(chatId, messageId);
      if (job_id !== null) {
        await waitForJob(job_id);
      }
      entries[entryKey] = {
        fetching: false,
        info: await getReadInfo(chatId, messageId),
      };
    } finally {
      entries[entryKey].fetching = false;
    }
  }

  return {
    get(chatId: number, messageId: number): ReadEntry | undefined {
      return entries[key(chatId, messageId)];
    },
    open(chatId: number, messageId: number) {
      const entryKey = key(chatId, messageId);
      if (accounts.selectedId === null || inflight.has(entryKey)) {
        return;
      }
      inflight.add(entryKey);
      load(entryKey, chatId, messageId)
        .catch(() => undefined)
        .finally(() => {
          inflight.delete(entryKey);
        });
    },
  };
}

export const reads = createReads();