// Small event harness for testing requests and state transitions, not layout.
import assert from 'node:assert/strict';

export class Element {
  constructor(tag) {
    this.tagName = tag;
    this.attributes = {};
    this.children = [];
    this.listeners = {};
    this.className = '';
    this.value = '';
    this.checked = false;
    this.disabled = false;
    this.files = [];
    this.style = {};
  }
  append(...children) {
    for (const child of children) {
      if (child instanceof Element) child.parent = this;
      this.children.push(child);
    }
  }
  replaceChildren(...children) {
    for (const child of this.children) if (child instanceof Element) child.parent = null;
    this.children = [];
    this.append(...children);
  }
  setAttribute(name, value) { this.attributes[name] = String(value); }
  getAttribute(name) { return this.attributes[name] ?? null; }
  removeAttribute(name) { delete this.attributes[name]; }
  addEventListener(name, fn) { this.listeners[name] = fn; }
  focus() { document.activeElement = this; }
  remove() { if (this.parent) this.parent.children = this.parent.children.filter((child) => child !== this); }
  get firstElementChild() { return this.children.find((child) => child instanceof Element); }
  get textContent() { return this.children.map((child) => child instanceof Element ? child.textContent : String(child)).join(''); }
  set textContent(value) { this.replaceChildren(value); }
}

export const nodes = (root) => root instanceof Element ? [root, ...root.children.flatMap(nodes)] : [];
export const find = (root, tag, text) => nodes(root).find((el) => el.tagName === tag && el.textContent === text);
export const field = (root, label) => nodes(root).find((el) => el.attributes['aria-label'] === label || el.attributes.id === label || el.attributes.name === label);
export const section = (root, title) => nodes(root).find((el) => ['section', 'details'].includes(el.tagName) && (find(el, 'h2', title) || find(el, 'h1', title)));
export const emit = (el, event) => {
  assert.ok(el, `Missing control for ${event}`);
  assert.ok(el.listeners[event], `No ${event} handler on ${el.tagName}`);
  return el.listeners[event]({ target: el, preventDefault() {} });
};
export const click = (root, label) => emit(find(root, 'button', label), 'click');
export const input = (el, value) => { el.value = value; return emit(el, 'input'); };
export const change = (el, value) => {
  if (el.attributes.type === 'checkbox') el.checked = value;
  else el.value = value;
  return emit(el, 'change');
};
export const settle = async () => { for (let i = 0; i < 4; i++) await new Promise((resolve) => setImmediate(resolve)); };

export function install() {
  const app = new Element('div');
  const toasts = new Element('div');
  const documentEvents = {};
  const windowEvents = {};
  globalThis.document = {
    hidden: false,
    createElement: (tag) => new Element(tag),
    getElementById: (id) => id === 'bindery-app' ? app : id === 'toasts' ? toasts : nodes(app).find((el) => el.attributes.id === id),
    addEventListener: (name, fn) => { documentEvents[name] = fn; },
    querySelectorAll: () => nodes(app).filter((el) => el.tagName === 'nav').flatMap((el) => nodes(el).filter((child) => child.tagName === 'a')),
  };
  globalThis.window = {
    location: { hash: '#/', reload() {} }, confirm: () => true, scrollTo() {},
    addEventListener: (name, fn) => { windowEvents[name] = fn; },
  };
  globalThis.DOMParser = class {
    parseFromString(html) {
      return { body: { textContent: html.replace(/<[^>]*>/g, ''), querySelectorAll: () => [] } };
    }
  };
  return { app, toasts, documentEvents, windowEvents };
}

export function server(t) {
  const routes = new Map();
  const requests = [];
  const unexpected = [];
  t.mock.method(globalThis, 'fetch', async (url, options) => {
    const request = { method: options.method, path: url.replace(/^api\//, ''),
      body: typeof options.body === 'string' ? JSON.parse(options.body) : options.body, headers: options.headers };
    requests.push(request);
    const key = `${request.method} ${request.path}`;
    const route = routes.get(key);
    if (!route) { unexpected.push(key); throw new Error(`Unexpected request: ${key}`); }
    const body = typeof route.body === 'function' ? await route.body(request) : route.body;
    return { ok: route.status < 400, status: route.status, statusText: 'Error', json: async () => structuredClone(body) };
  });
  t.after(() => assert.deepEqual(unexpected, [], 'No unexpected API calls'));
  return {
    on(method, path, body, status = 200) { routes.set(`${method} ${path}`, { body, status }); },
    requests,
    sent: (method, path) => requests.filter((r) => r.method === method && r.path === path),
  };
}