import { lstatSync } from 'node:fs';
import { BusError } from '../../bus/src/broker.mjs';
import { client, apiRoot } from './vikunja.mjs';
import { startup } from './startup.mjs';
import { tick, reconcile } from './sync.mjs';
import { verbs } from './verbs.mjs';
// S3's adapter for startBroker({tasks}). `trackers` is the host's plain-data boot config:
// {<business>: {baseUrl, project, pollSeconds, reconcileMinutes}}. A business with no entry has
// no tracker, and its task verbs refuse. Startup runs in the background so the broker boots
// without waiting on Vikunja; verbs refuse with tracker-starting until it passes.
export const TIMEOUT = 60000;
// Refusals that a later startup attempt can clear. A scope or install refusal waits for a restart.
const TRANSIENT = new Set(['tracker-unavailable', 'tracker-rate-limited', 'service-failed']);
const code = (e) => (e instanceof BusError ? e.code : 'adapter-failed');
const positive = (x) => Number.isSafeInteger(x) && x > 0;
function settings(name, t, b) {
  if (!b || !t || typeof t !== 'object') throw new BusError('tracker-config');
  apiRoot(t.baseUrl);
  const pollSeconds = t.pollSeconds ?? 30,
    reconcileMinutes = t.reconcileMinutes ?? 60;
  if (!positive(t.project) || !Number.isSafeInteger(pollSeconds) || pollSeconds < 10 || !positive(reconcileMinutes))
    throw new BusError('tracker-config');
  if (!positive(b.tracker?.sync?.botId)) throw new BusError('tracker-config');
  const roles = {};
  for (const [role, r] of Object.entries(b.roles ?? {}))
    if (r.tracker) {
      if (!positive(r.tracker.botId) || typeof r.definition !== 'string') throw new BusError('tracker-config');
      roles[role] = { definition: r.definition, botId: r.tracker.botId };
    }
  const pms = Object.keys(roles).filter((r) => roles[r].definition === 'pm');
  if (pms.length !== 1) throw new BusError('tracker-config');
  const labels = new Map();
  for (const [title, id] of Object.entries(b.tracker.labels ?? {})) {
    if (!positive(id)) throw new BusError('tracker-config');
    labels.set(id, title);
  }
  return { business: name, baseUrl: t.baseUrl, project: t.project, pollSeconds, reconcileMinutes, roles, pm: pms[0], labels };
}
// Files behind the business's Vikunja references, to notice a token rotated on disk.
function files(b) {
  const out = {};
  for (const [role, r] of Object.entries(b.roles ?? {})) if (r.credentials?.vikunja?.file) out[role] = r.credentials.vikunja.file;
  if (b.tracker?.sync?.credentials?.vikunja?.file) out['@sync'] = b.tracker.sync.credentials.vikunja.file;
  return out;
}
const stamp = (file) => {
  try {
    const s = lstatSync(file);
    return `${s.ino}:${s.size}:${s.mtimeMs}`;
  } catch {
    return 'missing';
  }
};
export function tasksAdapter({
  trackers = {},
  fetch = globalThis.fetch,
  clock = Date.now,
  timers = globalThis,
  log = (line) => process.stderr.write(line + '\n'),
  autostart = true,
} = {}) {
  return async function factory({ broker, credentials, businesses }) {
    const contexts = new Map();
    for (const [name, t] of Object.entries(trackers)) {
      const s = settings(name, t, businesses[name]);
      const call = client({ baseUrl: s.baseUrl, fetch });
      const use = (instance) => (method, path, opts) =>
        credentials.use(`${name}/${instance}`, 'vikunja', (token) => call(token, method, path, opts));
      const ctx = {
        ...s,
        broker,
        credentials,
        clock,
        call,
        per: 50,
        view: null,
        bots: new Set([businesses[name].tracker.sync.botId, ...Object.values(s.roles).map((r) => r.botId)]),
        sync: use('@sync'),
        as: (role, method, path, opts) => use(role)(method, path, opts),
        state: 'starting',
        refused: null,
        queue: Promise.resolve(),
        pending: 0,
        lastStart: null,
        lastReconcile: null,
        lastComment: new Map(),
        commentsAt: new Map(),
        commentCount: new Map(),
        files: Object.fromEntries(Object.entries(files(businesses[name])).map(([i, f]) => [i, { file: f, stamp: stamp(f) }])),
        told: new Set(),
        timers: [],
      };
      ctx.syncCall = (_token, method, path, opts) => ctx.sync(method, path, opts);
      ctx.asCall = (role) => (_token, method, path, opts) => ctx.as(role, method, path, opts);
      ctx.handle = verbs(ctx);
      contexts.set(name, ctx);
    }
    let closed = false;
    // One operation at a time per business: a tick never reads mid-write.
    const serial = (ctx, fn) => {
      const run = ctx.queue.then(() => (closed ? Promise.reject(new BusError('tracker-closed')) : fn()));
      ctx.queue = run.catch(() => {});
      return run;
    };
    const background = (ctx, what, fn) => {
      if (ctx.pending > 1) return Promise.resolve();
      ctx.pending++;
      return serial(ctx, fn)
        .catch((e) => {
          if (!closed) log(`tasks ${ctx.business} ${what} ${code(e)}`);
        })
        .finally(() => ctx.pending--);
    };
    // credential.expiring, .expired and .changed, each once per instance per process.
    function notify(ctx) {
      const events = [];
      const tell = (kind, instance, date) => {
        const key = kind + ' ' + instance;
        if (ctx.told.has(key)) return;
        ctx.told.add(key);
        events.push({ kind, body: { service: 'vikunja', instance, ...(date ? { date } : {}) } });
      };
      for (const s of credentials.status())
        if (s.service === 'vikunja' && s.instance.startsWith(ctx.business + '/') && s.state !== 'valid')
          tell(`credential.${s.state}`, s.instance, s.date);
      for (const [instance, f] of Object.entries(ctx.files))
        if (stamp(f.file) !== f.stamp) tell('credential.changed', `${ctx.business}/${instance}`, null);
      if (events.length) broker.recordTask({ business: ctx.business, events });
    }
    async function start(ctx) {
      try {
        await startup(ctx);
        await reconcile(ctx);
        ctx.state = 'ready';
        ctx.refused = null;
        if (ctx.untested) log(`tasks ${ctx.business} startup untested-version`);
      } catch (e) {
        ctx.state = 'refused';
        ctx.refused = code(e);
        log(`tasks ${ctx.business} startup ${ctx.refused}`);
      }
      try {
        notify(ctx);
      } catch (e) {
        log(`tasks ${ctx.business} credentials ${code(e)}`);
      }
    }
    const api = {
      timeout: TIMEOUT,
      ready: null,
      async handle(cap, verb, args) {
        const { business } = broker.identity(cap);
        const ctx = contexts.get(business);
        if (!ctx) throw new BusError('tracker-unconfigured');
        if (ctx.state !== 'ready') throw new BusError(ctx.state === 'starting' ? 'tracker-starting' : ctx.refused);
        return serial(ctx, () => ctx.handle(cap, verb, args));
      },
      // For tests and the host's status verb. Each returns once the operation has run.
      start: (business) => serial(contexts.get(business), () => start(contexts.get(business))),
      tick: (business) => serial(contexts.get(business), () => tick(contexts.get(business))),
      reconcile: (business) => serial(contexts.get(business), () => reconcile(contexts.get(business))),
      notify: (business) => serial(contexts.get(business), async () => notify(contexts.get(business))),
      status: () =>
        [...contexts.values()].map((c) => ({
          business: c.business,
          state: c.state,
          refused: c.refused,
          version: c.version ?? null,
          untested: c.untested ?? null,
          lastPoll: c.lastStart === null ? null : new Date(c.lastStart).toISOString(),
          lastReconcile: c.lastReconcile === null ? null : new Date(c.lastReconcile).toISOString(),
        })),
      async close() {
        closed = true;
        for (const c of contexts.values()) for (const t of c.timers) timers.clearInterval(t);
        await Promise.all([...contexts.values()].map((c) => c.queue));
      },
    };
    const every = (ctx, ms, fn) => {
      const t = timers.setInterval(fn, ms);
      t?.unref?.();
      ctx.timers.push(t);
    };
    if (autostart) {
      api.ready = Promise.all(
        [...contexts.values()].map((ctx) => {
          every(ctx, ctx.pollSeconds * 1000, () => {
            if (ctx.state === 'ready')
              background(ctx, 'tick', async () => {
                await tick(ctx);
                notify(ctx);
              });
            else if (ctx.state === 'refused' && TRANSIENT.has(ctx.refused)) background(ctx, 'startup', () => start(ctx));
          });
          every(ctx, ctx.reconcileMinutes * 60000, () => {
            if (ctx.state === 'ready') background(ctx, 'reconcile', () => reconcile(ctx));
          });
          return background(ctx, 'startup', () => start(ctx));
        }),
      );
    }
    return api;
  };
}