import { createServer } from 'node:http';
import { randomBytes } from 'node:crypto';
import { NULL_DATE } from './digest.mjs';
// In-memory Vikunja v2.7.0 for tests. Statuses, error bodies and response shapes follow the
// recordings in tests/fixtures/v2-shapes.json and the probe notes (probes.md, slice1-s3):
// scope 401 before 404, bucket_id 0 outside the board and the move, `updated` reported to the
// second but filtered on the stored value, moves between open buckets not bumping `updated`,
// silent unassign, 403 on removing an absent label, and bot label visibility through the owner.
const ROUTES = [
  ['GET', /^\/info$/, null, 'info'],
  ['GET', /^\/labels$/, ['labels', 'read_all'], 'labels'],
  ['GET', /^\/projects\/(\d+)$/, ['projects', 'read_one'], 'project'],
  ['GET', /^\/projects\/(\d+)\/views$/, ['projects_views', 'read_all'], 'views'],
  ['GET', /^\/projects\/(\d+)\/views\/(\d+)\/buckets$/, ['projects', 'views_buckets'], 'buckets'],
  ['GET', /^\/projects\/(\d+)\/views\/(\d+)\/buckets\/tasks$/, ['projects', 'views_buckets_tasks_get'], 'board'],
  ['PUT', /^\/projects\/(\d+)\/views\/(\d+)\/buckets\/(\d+)\/tasks$/, ['projects', 'views_buckets_tasks'], 'move'],
  ['GET', /^\/projects\/(\d+)\/tasks$/, ['tasks', 'read_all'], 'list'],
  ['POST', /^\/projects\/(\d+)\/tasks$/, ['tasks', 'create'], 'create'],
  ['GET', /^\/tasks\/(\d+)$/, ['tasks', 'read_one'], 'read'],
  ['PATCH', /^\/tasks\/(\d+)$/, ['tasks', 'update'], 'patch'],
  ['DELETE', /^\/tasks\/(\d+)$/, ['tasks', 'delete'], 'remove'],
  ['GET', /^\/tasks\/(\d+)\/comments$/, ['tasks_comments', 'read_all'], 'comments'],
  ['POST', /^\/tasks\/(\d+)\/comments$/, ['tasks_comments', 'create'], 'comment'],
  ['POST', /^\/tasks\/(\d+)\/labels$/, ['tasks_labels', 'create'], 'labelAdd'],
  ['DELETE', /^\/tasks\/(\d+)\/labels\/(\d+)$/, ['tasks_labels', 'delete'], 'labelRemove'],
  ['POST', /^\/tasks\/(\d+)\/assignees$/, ['tasks_assignees', 'create'], 'assign'],
  ['DELETE', /^\/tasks\/(\d+)\/assignees\/(\d+)$/, ['tasks_assignees', 'delete'], 'unassign'],
  ['POST', /^\/tasks\/(\d+)\/relations$/, ['tasks_relations', 'create'], 'relate'],
  ['DELETE', /^\/tasks\/(\d+)\/relations\/([a-z]+)\/(\d+)$/, ['tasks_relations', 'delete'], 'unrelate'],
];
const PATCH_KEYS = new Set([
  'title',
  'description',
  'done',
  'due_date',
  'priority',
  'percent_done',
  'bucket_id',
  'hex_color',
  'repeat_after',
  'start_date',
  'end_date',
]);
const CREATE_KEYS = new Set(['title', 'description', 'due_date', 'priority', 'percent_done']);
const UNAUTHORIZED = { code: 11, message: 'missing, malformed, expired or otherwise invalid token provided' };
const forbidden = (detail = 'Forbidden') => ({ title: 'Forbidden', status: 403, detail });
const noTask = { title: 'Not Found', status: 404, detail: 'This task does not exist', code: 4002 };
const noProject = { title: 'Not Found', status: 404, detail: 'The project does not exist.', code: 3001 };
const bad = (detail, code) => ({ title: 'Bad Request', status: 400, detail, ...(code ? { code } : {}) });
const unprocessable = (detail) => ({ title: 'Unprocessable Entity', status: 422, detail });
const second = (ms) => new Date(Math.floor(ms / 1000) * 1000).toISOString().replace('.000Z', 'Z');
// Vikunja v2.7.0 keeps a due date to the second; a write's answer echoes what was sent, in Go's form
// (review r1, r1-vk-due-probe.txt). The probe can't tell floor from rounding; the adapter sends
// whole seconds, so it doesn't matter to it.
const dueIn = (x) => (x && x !== NULL_DATE ? second(Date.parse(x)) : null);
const dueEcho = (x) => (x && x !== NULL_DATE ? new Date(x).toISOString().replace(/\.?0+Z$/, 'Z') : NULL_DATE);
const fine = (ms) => new Date(ms).toISOString();
const page = (list, q) => {
  const per = Math.min(Math.max(Number(q.get('per_page')) || 50, 1), 50),
    n = Math.max(Number(q.get('page')) || 1, 1);
  return {
    items: list.slice((n - 1) * per, n * per),
    total: list.length,
    page: n,
    per_page: per,
    total_pages: Math.max(1, Math.ceil(list.length / per)),
  };
};

export class FakeVikunja {
  version;
  requests = [];
  #now;
  #seq = { user: 0, project: 0, view: 0, bucket: 0, task: 0, label: 0, comment: 0 };
  #users = new Map();
  #tokens = new Map();
  #projects = new Map();
  #views = new Map();
  #buckets = new Map();
  #tasks = new Map();
  #labels = new Map();
  #faults = [];
  constructor({ version = 'v2.7.0', now = () => Date.now() } = {}) {
    this.version = version;
    this.#now = now;
  }
  // Test setup. These act directly on the model, like an admin with database access.
  user(username, { owner = null } = {}) {
    const id = ++this.#seq.user;
    this.#users.set(id, { id, username, name: owner ? username.replace(/^bot-/, '') : '', bot: owner ?? 0, at: this.#now() });
    return id;
  }
  token(user, scopes = '*', { expires = null } = {}) {
    const t = 'tk_' + randomBytes(20).toString('hex');
    this.#tokens.set(t, { user, scopes, expires });
    return t;
  }
  revoke(token) {
    this.#tokens.delete(token);
  }
  project(title, owner) {
    const id = ++this.#seq.project;
    this.#projects.set(id, { id, title, owner, shares: new Map(), index: 0 });
    for (const [kind, position] of [
      ['list', 100],
      ['gantt', 200],
      ['table', 300],
    ])
      this.#view(id, kind[0].toUpperCase() + kind.slice(1), kind, position);
    const k = this.#view(id, 'Kanban', 'kanban', 400, 'manual');
    const [todo, , done] = ['To-Do', 'Doing', 'Done'].map((t) => this.bucket(k, t));
    Object.assign(this.#views.get(k), { default_bucket_id: todo, done_bucket_id: done });
    return id;
  }
  share(project, user, permission = 0) {
    this.#projects.get(project).shares.set(user, permission);
  }
  bucket(view, title) {
    const id = ++this.#seq.bucket;
    this.#buckets.set(id, { id, title, view, position: id * 100 });
    return id;
  }
  rename(bucket, title) {
    this.#buckets.get(bucket).title = title;
  }
  kanban(project) {
    return [...this.#views.values()].find((v) => v.project === project && v.view_kind === 'kanban');
  }
  view(id) {
    return this.#views.get(id);
  }
  addView(project, kind, mode = 'manual') {
    return this.#view(project, kind, kind, 500, mode);
  }
  // The runbook's install: rename the three defaults, add in-review and blocked.
  install(project) {
    const k = this.kanban(project);
    const ids = [...this.#buckets.values()].filter((b) => b.view === k.id).map((b) => b.id);
    ['todo', 'in-progress', 'done'].forEach((t, i) => this.rename(ids[i], t));
    this.bucket(k.id, 'in-review');
    this.bucket(k.id, 'blocked');
    return { view: k.id, buckets: this.bucketIds(k.id) };
  }
  bucketIds(view) {
    return Object.fromEntries([...this.#buckets.values()].filter((b) => b.view === view).map((b) => [b.title, b.id]));
  }
  label(title, owner) {
    const id = ++this.#seq.label;
    this.#labels.set(id, { id, title, owner, at: this.#now() });
    return id;
  }
  task(id) {
    return this.#tasks.get(id);
  }
  moveToProject(task, project) {
    const t = this.#tasks.get(task);
    t.project = project;
    t.buckets = new Map();
    this.#place(t);
    this.#touch(t);
  }
  // The route name a request matched, for tests that compare the fake against the recordings.
  routeName(method, path) {
    return ROUTES.find(([m, re]) => m === method && re.test(path))?.[3] ?? null;
  }
  // fault(method, pattern, status, {apply}) fails the next matching request. Status 0 is a network
  // error. With apply the change lands first, as when a reply is lost after the commit.
  fault(method, pattern, status, { apply = false } = {}) {
    this.#faults.push({ method, pattern, status, apply });
  }
  fetch = async (url, init = {}) => {
    const u = new URL(url);
    const method = (init.method ?? 'GET').toUpperCase();
    const path = u.pathname.replace(/^\/api\/v2/, '');
    const i = this.#faults.findIndex((f) => f.method === method && f.pattern.test(path));
    const fault = i >= 0 ? this.#faults.splice(i, 1)[0] : null;
    if (fault && !fault.apply) {
      this.requests.push({ method, path, status: fault.status });
      if (fault.status === 0) throw new TypeError('fetch failed');
      return new Response(JSON.stringify({ title: 'Internal Server Error', status: fault.status, detail: 'unexpected error occurred' }), { status: fault.status });
    }
    const headers = new Headers(init.headers ?? {});
    let body;
    try {
      body = init.body ? JSON.parse(init.body) : undefined;
    } catch {
      body = Symbol.for('bad');
    }
    const r = u.pathname.startsWith('/api/v2/') ? this.#route(method, path, u.searchParams, headers, body) : { status: 404, body: { message: 'Not Found' } };
    if (fault) {
      this.requests.push({ method, path, status: fault.status });
      if (fault.status === 0) throw new TypeError('fetch failed');
      return new Response(JSON.stringify({ title: 'Internal Server Error', status: fault.status }), { status: fault.status });
    }
    this.requests.push({ method, path, status: r.status });
    const h = { 'content-type': 'application/json', ...(r.etag ? { etag: r.etag } : {}) };
    return new Response([204, 304].includes(r.status) ? null : JSON.stringify(r.body), { status: r.status, headers: h });
  };
  // The same model over HTTP on 127.0.0.1, for code that should use the platform fetch.
  async listen() {
    const server = createServer(async (req, res) => {
      const chunks = [];
      for await (const c of req) chunks.push(c);
      const r = await this.fetch('http://fake' + req.url, {
        method: req.method,
        headers: req.headers,
        body: chunks.length ? Buffer.concat(chunks).toString() : undefined,
      }).catch(() => null);
      if (!r) return res.destroy();
      res.writeHead(r.status, Object.fromEntries(r.headers));
      res.end(Buffer.from(await r.arrayBuffer()));
    });
    await new Promise((ok) => server.listen(0, '127.0.0.1', ok));
    return {
      url: `http://127.0.0.1:${server.address().port}`,
      close: () => new Promise((ok) => server.close(ok)),
    };
  }
  #view(project, title, kind, position, mode = 'none') {
    const id = ++this.#seq.view;
    this.#views.set(id, {
      id,
      title,
      project,
      view_kind: kind,
      position,
      bucket_configuration_mode: mode,
      default_bucket_id: 0,
      done_bucket_id: 0,
      at: this.#now(),
    });
    return id;
  }
  #access(user, project) {
    const p = this.#projects.get(project);
    if (!p) return null;
    if (p.owner === user) return 2;
    return p.shares.has(user) ? p.shares.get(user) : null;
  }
  #userJson(id) {
    const u = this.#users.get(id);
    if (!u) return null;
    return {
      id: u.id,
      name: u.name,
      username: u.username,
      ...(u.bot ? { bot_owner_id: u.bot } : {}),
      created: second(u.at),
      updated: second(u.at),
    };
  }
  #labelJson(l) {
    return { id: l.id, title: l.title, description: '', hex_color: '', created_by: this.#userJson(l.owner), created: second(l.at), updated: second(l.at) };
  }
  #visibleLabel(user, label) {
    const u = this.#users.get(user);
    if (label.owner === user) return true;
    // Upstream #3592: a bot reads labels its owner created and labels sibling bots created.
    if (u?.bot && (label.owner === u.bot || this.#users.get(label.owner)?.bot === u.bot)) return true;
    return [...this.#tasks.values()].some((t) => t.labels.includes(label.id) && this.#access(user, t.project) !== null);
  }
  #place(t) {
    for (const v of this.#views.values())
      if (v.project === t.project && v.view_kind === 'kanban')
        t.buckets.set(v.id, t.done && v.done_bucket_id ? v.done_bucket_id : v.default_bucket_id);
  }
  #touch(t) {
    t.updated = Math.max(this.#now(), t.updated + 1);
    t.rev++;
  }
  #taskJson(t, { bucket = 0, empty = null, expand = false } = {}) {
    const related = {};
    for (const r of t.relations) (related[r.kind] ??= []).push({ id: r.other });
    return {
      id: t.id,
      title: t.title,
      description: t.description,
      project_id: t.project,
      done: t.done,
      done_at: t.doneAt ? fine(t.doneAt) : NULL_DATE,
      due_date: t.due ?? NULL_DATE,
      reminders: null,
      repeat_after: 0,
      repeat_mode: 0,
      priority: t.priority,
      start_date: NULL_DATE,
      end_date: NULL_DATE,
      assignees: t.assignees.length ? t.assignees.map((a) => this.#userJson(a)) : empty,
      labels: t.labels.length ? t.labels.map((l) => this.#labelJson(this.#labels.get(l))) : null,
      hex_color: '',
      percent_done: t.percent,
      identifier: `#${t.index}`,
      index: t.index,
      related_tasks: related,
      attachments: null,
      cover_image_attachment_id: 0,
      is_favorite: false,
      created: second(t.created),
      updated: second(t.updated),
      bucket_id: bucket,
      position: 0,
      reactions: null,
      created_by: this.#userJson(t.by),
      ...(expand ? { comment_count: t.comments.length } : {}),
    };
  }
  #bucketJson(b, extra = {}) {
    return {
      id: b.id,
      title: b.title,
      project_view_id: b.view,
      ...extra,
      limit: 0,
      count: [...this.#tasks.values()].filter((t) => t.buckets.get(b.view) === b.id).length,
      position: b.position,
      created: second(this.#views.get(b.view).at),
      updated: second(this.#views.get(b.view).at),
      created_by: null,
    };
  }
  #filter(text) {
    if (!text) return () => true;
    const tests = text.split(/\s*&&\s*/).map((clause) => {
      const m = /^(updated|id|done)\s*(>=|<=|!=|>|<|=)\s*(.+)$/.exec(clause.trim());
      if (!m) return null;
      const [, field, op, raw] = m;
      let value;
      if (field === 'updated') {
        const v = raw.replace(/^['"]|['"]$/g, '');
        if (!/^\d{4}-\d\d-\d\dT/.test(v) || !Number.isFinite(Date.parse(v))) return null;
        value = Date.parse(v);
      } else if (field === 'id') value = Number(raw);
      else value = raw === 'true';
      const get = (t) => (field === 'updated' ? t.updated : field === 'id' ? t.id : t.done);
      return (t) =>
        ({ '>': get(t) > value, '<': get(t) < value, '>=': get(t) >= value, '<=': get(t) <= value, '=': get(t) === value, '!=': get(t) !== value })[op];
    });
    if (tests.includes(null)) return null;
    return (t) => tests.every((f) => f(t));
  }
  #route(method, path, q, headers, body) {
    const hit = ROUTES.map(([m, re, scope, name]) => [m, re.exec(path), scope, name]).find(([m, x]) => m === method && x);
    if (!hit) return { status: 404, body: { message: 'Not Found' } };
    const [, match, scope, name] = hit;
    let user = null;
    if (scope) {
      const auth = /^Bearer (.+)$/.exec(headers.get('authorization') ?? '');
      const tok = auth && this.#tokens.get(auth[1]);
      if (!tok || (tok.expires !== null && tok.expires <= this.#now())) return { status: 401, body: UNAUTHORIZED };
      // The token check runs before the handler, so a missing scope is 401 even for a missing task.
      if (tok.scopes !== '*' && !tok.scopes[scope[0]]?.includes(scope[1])) return { status: 401, body: UNAUTHORIZED };
      user = tok.user;
    }
    if (body === Symbol.for('bad')) return { status: 400, body: bad('Invalid model provided.') };
    const args = match.slice(1).map((x) => (/^\d+$/.test(x) ? Number(x) : x));
    return this[`_${name}`](user, args, q, body ?? {}, headers);
  }
  #taskFor(user, id, write = false) {
    const t = this.#tasks.get(id);
    if (!t) return { error: { status: 404, body: noTask } };
    const a = this.#access(user, t.project);
    if (a === null || (write && a < 1)) return { error: { status: 403, body: forbidden(a === null ? "You don't have the permission to see this" : 'Forbidden') } };
    return { t };
  }
  #projectFor(user, id, write = false) {
    if (!this.#projects.has(id)) return { error: { status: 404, body: noProject } };
    const a = this.#access(user, id);
    if (a === null || (write && a < 1)) return { error: { status: 403, body: forbidden("You don't have the permission to see this") } };
    return { p: this.#projects.get(id) };
  }
  _info() {
    return { status: 200, body: { version: this.version, max_items_per_page: 50, task_comments_enabled: true } };
  }
  _labels(user, _a, q) {
    const list = [...this.#labels.values()].filter((l) => this.#visibleLabel(user, l)).map((l) => this.#labelJson(l));
    return { status: 200, body: page(list, q) };
  }
  _project(user, [p]) {
    const r = this.#projectFor(user, p);
    if (r.error) return r.error;
    return { status: 200, body: { id: p, title: r.p.title, description: '', owner: this.#userJson(r.p.owner), is_archived: false } };
  }
  _views(user, [p], q) {
    const r = this.#projectFor(user, p);
    if (r.error) return r.error;
    const list = [...this.#views.values()]
      .filter((v) => v.project === p)
      .map((v) => ({
        id: v.id,
        title: v.title,
        project_id: p,
        view_kind: v.view_kind,
        filter: null,
        position: v.position,
        bucket_configuration_mode: v.bucket_configuration_mode,
        bucket_configuration: null,
        default_bucket_id: v.default_bucket_id,
        done_bucket_id: v.done_bucket_id,
        updated: second(v.at),
        created: second(v.at),
      }));
    return { status: 200, body: page(list, q) };
  }
  _buckets(user, [p, k], q) {
    const r = this.#projectFor(user, p);
    if (r.error) return r.error;
    if (this.#views.get(k)?.project !== p) return { status: 404, body: { title: 'Not Found', status: 404, detail: 'This project view does not exist.', code: 13001 } };
    return { status: 200, body: page([...this.#buckets.values()].filter((b) => b.view === k).map((b) => this.#bucketJson(b)), q) };
  }
  _board(user, [p, k], q) {
    const r = this.#projectFor(user, p);
    if (r.error) return r.error;
    const v = this.#views.get(k);
    if (v?.project !== p) return { status: 404, body: { title: 'Not Found', status: 404, detail: 'This project view does not exist.', code: 13001 } };
    const f = q.get('filter') ?? '';
    if (f && f !== 'done = false') return { status: 400, body: bad('unsupported filter in the fake') };
    const per = Math.min(Number(q.get('per_page')) || 50, 50),
      n = Math.max(Number(q.get('page')) || 1, 1);
    const items = [...this.#buckets.values()]
      .filter((b) => b.view === k)
      .map((b) => {
        const all = [...this.#tasks.values()].filter((t) => t.buckets.get(k) === b.id && (!f || !t.done)).sort((a, b) => a.id - b.id);
        const tasks = all.slice((n - 1) * per, n * per).map((t) => this.#taskJson(t, { bucket: b.id }));
        return { ...this.#bucketJson(b, { tasks: tasks.length ? tasks : null }), count: all.length };
      });
    return { status: 200, body: { items } };
  }
  _move(user, [p, k, b], _q, body) {
    const r = this.#projectFor(user, p, true);
    if (r.error) return r.error;
    const v = this.#views.get(k),
      bucket = this.#buckets.get(b);
    if (v?.project !== p || bucket?.view !== k) return { status: 404, body: { title: 'Not Found', status: 404, detail: 'This bucket does not exist.', code: 10001 } };
    const x = this.#taskFor(user, body.task_id, true);
    if (x.error) return x.error;
    const t = x.t;
    if (t.project !== p) return { status: 400, body: bad('task is in another project') };
    const was = t.buckets.get(k);
    t.buckets.set(k, b);
    if (b === v.done_bucket_id && !t.done) {
      t.done = true;
      t.doneAt = this.#now();
      this.#touch(t);
    } else if (was === v.done_bucket_id && b !== was && t.done) {
      t.done = false;
      t.doneAt = null;
      this.#touch(t);
    } else t.rev++;
    return {
      status: 200,
      body: { bucket_id: b, bucket: this.#bucketJson(bucket), task_id: t.id, project_view_id: k, task: this.#taskJson(t) },
    };
  }
  _list(user, [p], q) {
    const r = this.#projectFor(user, p);
    if (r.error) return r.error;
    const f = this.#filter(q.get('filter'));
    if (!f) return { status: 400, body: bad('Invalid filter expression', 1) };
    const sorts = q.getAll('sort_by'),
      orders = q.getAll('order_by');
    const list = [...this.#tasks.values()].filter((t) => t.project === p && f(t));
    list.sort((a, b) => {
      for (const [i, s] of (sorts.length ? sorts : ['id']).entries()) {
        const d = (s === 'updated' ? a.updated - b.updated : a.id - b.id) * (orders[i] === 'desc' ? -1 : 1);
        if (d) return d;
      }
      return 0;
    });
    const expand = q.get('expand') === 'comment_count';
    const out = page(list, q);
    out.items = out.items.map((t) => this.#taskJson(t, { empty: null, expand }));
    return { status: 200, body: out };
  }
  _create(user, [p], _q, body) {
    const r = this.#projectFor(user, p, true);
    if (r.error) return r.error;
    if (Object.keys(body).some((k) => !CREATE_KEYS.has(k))) return { status: 422, body: unprocessable('unknown field') };
    if (typeof body.title !== 'string' || !body.title.trim()) return { status: 400, body: bad('The task title cannot be empty.', 4001) };
    const now = this.#now();
    const t = {
      id: ++this.#seq.task,
      project: p,
      index: ++r.p.index,
      title: body.title,
      description: body.description ?? '',
      done: false,
      doneAt: null,
      due: dueIn(body.due_date),
      priority: body.priority ?? 0,
      percent: body.percent_done ?? 0,
      labels: [],
      assignees: [],
      relations: [],
      comments: [],
      buckets: new Map(),
      created: now,
      updated: now,
      by: user,
      rev: 0,
    };
    this.#place(t);
    this.#tasks.set(t.id, t);
    const out = this.#taskJson(t, { empty: [] });
    out.related_tasks = null;
    if ('due_date' in body) out.due_date = dueEcho(body.due_date);
    out.created = fine(now);
    out.updated = fine(now);
    return { status: 201, body: out };
  }
  _read(user, [id], _q, _b, headers) {
    const x = this.#taskFor(user, id);
    if (x.error) return x.error;
    const etag = `"${x.t.id}-${x.t.rev}"`;
    if (headers.get('if-none-match') === etag) return { status: 304, etag };
    return { status: 200, body: this.#taskJson(x.t), etag };
  }
  _patch(user, [id], _q, body) {
    const x = this.#taskFor(user, id, true);
    if (x.error) return x.error;
    if (Object.keys(body).some((k) => !PATCH_KEYS.has(k))) return { status: 422, body: unprocessable('unknown field') };
    const t = x.t,
      before = JSON.stringify(this.#taskJson(t));
    if ('title' in body) t.title = body.title;
    if ('description' in body) t.description = body.description;
    if ('due_date' in body) t.due = dueIn(body.due_date);
    if ('priority' in body) t.priority = body.priority;
    if ('percent_done' in body) t.percent = body.percent_done;
    if ('done' in body && body.done !== t.done) {
      t.done = body.done;
      t.doneAt = t.done ? this.#now() : null;
      for (const v of this.#views.values())
        if (v.project === t.project && v.view_kind === 'kanban')
          t.buckets.set(v.id, t.done ? v.done_bucket_id : v.default_bucket_id);
    }
    // bucket_id is echoed and not applied (probes.md, "Writes and moves").
    if (JSON.stringify(this.#taskJson(t)) === before && !('bucket_id' in body)) return { status: 304 };
    if (JSON.stringify(this.#taskJson(t)) !== before) this.#touch(t);
    const out = this.#taskJson(t, { empty: [], bucket: body.bucket_id ?? 0 });
    if ('due_date' in body) out.due_date = dueEcho(body.due_date);
    return { status: 200, body: out };
  }
  _remove(user, [id]) {
    const x = this.#taskFor(user, id, true);
    if (x.error) return x.error;
    this.#tasks.delete(id);
    return { status: 204 };
  }
  _comments(user, [id], q) {
    const x = this.#taskFor(user, id);
    if (x.error) return x.error;
    return { status: 200, body: page(x.t.comments.map((c) => ({ ...c, created: second(c.at), updated: second(c.at), at: undefined })), q) };
  }
  _comment(user, [id], _q, body) {
    const x = this.#taskFor(user, id, true);
    if (x.error) return x.error;
    if (typeof body.comment !== 'string' || !body.comment) return { status: 400, body: bad('comment required') };
    const at = this.#now();
    const c = { id: ++this.#seq.comment, comment: body.comment, author: this.#userJson(user), reactions: null, at };
    x.t.comments.push(c);
    this.#touch(x.t);
    return { status: 201, body: { id: c.id, comment: c.comment, author: c.author, reactions: null, created: fine(at), updated: fine(at) } };
  }
  _labelAdd(user, [id], _q, body) {
    const x = this.#taskFor(user, id, true);
    if (x.error) return x.error;
    const l = this.#labels.get(body.label_id);
    if (!l || !this.#visibleLabel(user, l)) return { status: 403, body: forbidden() };
    if (x.t.labels.includes(l.id)) return { status: 400, body: bad('The label already exists on the task.', 8001) };
    x.t.labels.push(l.id);
    this.#touch(x.t);
    return { status: 201, body: { label_id: l.id, created: fine(this.#now()) } };
  }
  _labelRemove(user, [id, label]) {
    const x = this.#taskFor(user, id, true);
    if (x.error) return x.error;
    if (!x.t.labels.includes(label)) return { status: 403, body: forbidden() };
    x.t.labels = x.t.labels.filter((l) => l !== label);
    this.#touch(x.t);
    return { status: 204 };
  }
  _assign(user, [id], _q, body) {
    const x = this.#taskFor(user, id, true);
    if (x.error) return x.error;
    if (!this.#users.has(body.user_id)) return { status: 404, body: { title: 'Not Found', status: 404, detail: 'The user does not exist.', code: 1005 } };
    if (x.t.assignees.includes(body.user_id)) return { status: 400, body: bad('This user is already assigned to that task.', 4021) };
    x.t.assignees.push(body.user_id);
    this.#touch(x.t);
    return { status: 201, body: { user_id: body.user_id, created: NULL_DATE } };
  }
  _unassign(user, [id, who]) {
    const x = this.#taskFor(user, id, true);
    if (x.error) return x.error;
    if (x.t.assignees.includes(who)) {
      x.t.assignees = x.t.assignees.filter((a) => a !== who);
      this.#touch(x.t);
    }
    return { status: 204 };
  }
  _relate(user, [id], _q, body) {
    const x = this.#taskFor(user, id, true);
    if (x.error) return x.error;
    if (!this.#tasks.has(body.other_task_id)) return { status: 404, body: noTask };
    x.t.relations.push({ kind: body.relation_kind, other: body.other_task_id });
    this.#touch(x.t);
    return { status: 201, body: { task_id: id, other_task_id: body.other_task_id, relation_kind: body.relation_kind, created_by: this.#userJson(user), created: fine(this.#now()) } };
  }
  _unrelate(user, [id, kind, other]) {
    const x = this.#taskFor(user, id, true);
    if (x.error) return x.error;
    const i = x.t.relations.findIndex((r) => r.kind === kind && r.other === other);
    if (i < 0) return { status: 404, body: { title: 'Not Found', status: 404, detail: 'The task relation does not exist.', code: 4009 } };
    x.t.relations.splice(i, 1);
    this.#touch(x.t);
    return { status: 204 };
  }
}