/**
 * Minimal DOM shim for the tests/dom suite.
 *
 * Unlike the split/markdown shims (which only need statum to LOAD), this one
 * supports driving the render walk and the forms module end to end:
 *
 *  - elements with ORDERED attributes, get/set/has/removeAttribute, a real
 *    classList backed by the `class` attribute, children/parent hierarchy,
 *    appendChild/insertBefore/removeChild, nextElementSibling,
 *    cloneNode(true) with FRESH node identity (listeners and live control
 *    state are NOT copied; attributes and children are),
 *  - querySelectorAll for tag, `.class`, `[attr]`, `[attr="v"]`,
 *    `[attr~="v"]`, `*` and comma lists of those (everything the walk and
 *    the forms module ask for),
 *  - an EventTarget model on document AND elements with CAPTURE and bubble
 *    phases and event.target set — statum-forms.js relies on document-level
 *    capture listeners,
 *  - form semantics: el.form (owner form), form.reset() (fires a cancelable
 *    `reset` event, then restores control defaults from attributes),
 *    computed select.value/select.multiple/option.value, input.type,
 *  - the fetch-adjacent globals QuickJS lacks (Headers, URLSearchParams,
 *    FormData, btoa/TextEncoder) plus a scriptable fetch stub, and in-memory
 *    localStorage/sessionStorage.
 *
 * document.readyState stays 'loading' so statum-core.js only registers a
 * DOMContentLoaded listener; tests drive renderAll() directly.
 */
export function installShim() {
  var log = { errors: [], warns: [], messages: [] };
  var fetchCalls = [];
  var fetchHandler = null;

  // -------------------------------------------------------------------------
  // Events
  // -------------------------------------------------------------------------

  function makeEvent(type, opts) {
    return {
      type: type,
      target: null,
      currentTarget: null,
      eventPhase: '',
      cancelable: !opts || opts.cancelable !== false,
      defaultPrevented: false,
      preventDefault: function () { this.defaultPrevented = true; }
    };
  }

  function addEventTarget(obj) {
    obj._listeners = { capture: {}, bubble: {} };
    obj.addEventListener = function (type, fn, capture) {
      var bag = capture ? this._listeners.capture : this._listeners.bubble;
      (bag[type] = bag[type] || []).push(fn);
    };
    obj.removeEventListener = function () {};
    obj.dispatchEvent = function (evt) {
      evt.target = this;
      // Path from the target's parent up to (and including) document.
      var path = [];
      var n = this.parentNode;
      while (n) { path.push(n); n = n.parentNode; }
      function run(node, bag) {
        var list = bag[evt.type];
        if (!list) return;
        list = list.slice();
        for (var i = 0; i < list.length; i++) list[i].call(node, evt);
      }
      // Capture: outermost ancestor (document) down to the parent.
      evt.eventPhase = 'capture';
      for (var i = path.length - 1; i >= 0; i--) {
        evt.currentTarget = path[i];
        run(path[i], path[i]._listeners.capture);
      }
      // Target: both listener kinds.
      evt.eventPhase = 'target';
      evt.currentTarget = this;
      run(this, this._listeners.capture);
      run(this, this._listeners.bubble);
      // Bubble: parent up to document.
      evt.eventPhase = 'bubble';
      for (var j = 0; j < path.length; j++) {
        evt.currentTarget = path[j];
        run(path[j], path[j]._listeners.bubble);
      }
      return !evt.defaultPrevented;
    };
  }

  // -------------------------------------------------------------------------
  // Selector matching (tag / .class / [attr] / [attr=v] / [attr~=v] / *)
  // -------------------------------------------------------------------------

  function parseComplex(sel) {
    var preds = [];
    var s = sel.replace(/^\s+|\s+$/g, '');
    while (s) {
      var m;
      if (s.charAt(0) === '*') {
        preds.push(function () { return true; });
        s = s.slice(1);
      } else if ((m = s.match(/^([a-zA-Z][a-zA-Z0-9]*)/))) {
        var tag = m[1].toUpperCase();
        preds.push(function (el) { return el.tagName === tag; });
        s = s.slice(m[1].length);
      } else if ((m = s.match(/^\.([a-zA-Z0-9_-]+)/))) {
        var cls = m[1];
        preds.push(function (el) { return hasClass(el, cls); });
        s = s.slice(m[0].length);
      } else if ((m = s.match(/^\[([a-zA-Z0-9_-]+)(?:([~^|*]?=)("([^"]*)"|'([^']*)'|([^\]\s]+)))?\]/))) {
        var name = m[1], op = m[2] || null, val = m[4] != null ? m[4] : (m[5] != null ? m[5] : m[6]);
        preds.push(function (el) {
          var cur = el.getAttribute(name);
          if (cur === null) return false;
          if (!op) return true;
          if (op === '=') return cur === val;
          if (op === '~=') return (' ' + cur + ' ').split(/\s+/).indexOf(val) !== -1;
          if (op === '^=') return cur.indexOf(val) === 0;
          if (op === '$=') return cur.indexOf(val) === cur.length - val.length;
          if (op === '*=') return cur.indexOf(val) !== -1;
          if (op === '|=') return cur === val || cur.indexOf(val + '-') === 0;
          return false;
        });
        s = s.slice(m[0].length);
      } else {
        return null; // unsupported selector: matches nothing
      }
      s = s.replace(/^\s+/, '');
    }
    return preds.length ? preds : null;
  }

  function matches(el, complex) {
    for (var i = 0; i < complex.length; i++) {
      if (!complex[i](el)) return false;
    }
    return true;
  }

  function descendants(root, out) {
    var kids = root.children || [];
    for (var i = 0; i < kids.length; i++) {
      out.push(kids[i]);
      descendants(kids[i], out);
    }
    return out;
  }

  function qsa(root, selector) {
    var complexes = String(selector).split(',').map(function (c) { return parseComplex(c); });
    var all = descendants(root, []);
    var hits = [];
    for (var i = 0; i < all.length; i++) {
      for (var j = 0; j < complexes.length; j++) {
        if (complexes[j] && matches(all[i], complexes[j])) { hits.push(all[i]); break; }
      }
    }
    return hits;
  }

  // -------------------------------------------------------------------------
  // Elements
  // -------------------------------------------------------------------------

  function hasClass(el, cls) {
    var cur = el.getAttribute('class') || '';
    return cur.split(/\s+/).indexOf(cls) !== -1;
  }

  function makeElement(tag) {
    if (String(tag || '').toLowerCase() === 'form') return makeForm();
    var el = {
      nodeType: 1,
      tagName: (tag || 'div').toUpperCase(),
      /** Ordered {name, value} pairs; re-setting keeps the original slot. */
      attributes: [],
      children: [],
      parentNode: null,
      innerHTML: '',
      textContent: '',
      style: {},
      value: undefined,
      checked: undefined,
      selected: undefined
    };

    // ----- attributes -----
    el.setAttribute = function (n, v) {
      var hit = null;
      for (var i = 0; i < this.attributes.length; i++) {
        if (this.attributes[i].name === n) { hit = this.attributes[i]; break; }
      }
      if (hit) hit.value = String(v);
      else this.attributes.push({ name: n, value: String(v) });
    };
    el.removeAttribute = function (n) {
      this.attributes = this.attributes.filter(function (a) { return a.name !== n; });
    };
    el.hasAttribute = function (n) {
      for (var i = 0; i < this.attributes.length; i++) {
        if (this.attributes[i].name === n) return true;
      }
      return false;
    };
    el.getAttribute = function (n) {
      for (var i = 0; i < this.attributes.length; i++) {
        if (this.attributes[i].name === n) return this.attributes[i].value;
      }
      return null;
    };

    // ----- classList (backed by the `class` attribute) -----
    el.classList = {
      add: function (c) {
        var cur = el.getAttribute('class') || '';
        var parts = cur ? cur.split(/\s+/).filter(Boolean) : [];
        if (parts.indexOf(c) === -1) { parts.push(c); el.setAttribute('class', parts.join(' ')); }
      },
      remove: function (c) {
        var cur = el.getAttribute('class') || '';
        var parts = cur ? cur.split(/\s+/).filter(function (p) { return p && p !== c; }) : [];
        if (parts.length) el.setAttribute('class', parts.join(' '));
        else el.removeAttribute('class');
      },
      contains: function (c) { return hasClass(el, c); }
    };

    // ----- tree -----
    el.appendChild = function (c) {
      if (c.parentNode) c.parentNode.removeChild(c);
      c.parentNode = this;
      this.children.push(c);
      return c;
    };
    el.insertBefore = function (c, ref) {
      if (c.parentNode) c.parentNode.removeChild(c);
      c.parentNode = this;
      var i = ref ? this.children.indexOf(ref) : this.children.length;
      if (i < 0) i = this.children.length;
      this.children.splice(i, 0, c);
      return c;
    };
    el.removeChild = function (c) {
      var i = this.children.indexOf(c);
      if (i >= 0) this.children.splice(i, 1);
      c.parentNode = null;
      return c;
    };
    el.remove = function () { if (this.parentNode) this.parentNode.removeChild(this); };
    Object.defineProperty(el, 'nextElementSibling', {
      get: function () {
        if (!this.parentNode) return null;
        var i = this.parentNode.children.indexOf(this);
        return this.parentNode.children[i + 1] || null;
      }
    });
    Object.defineProperty(el, 'nextSibling', {
      get: function () { return this.nextElementSibling; }
    });
    el.contains = function (other) {
      while (other) { if (other === this) return true; other = other.parentNode; }
      return false;
    };
    Object.defineProperty(el, 'firstChild', { get: function () { return this.children[0] || null; } });
    el.cloneNode = function (deep) {
      var copy = makeElement(this.tagName);
      copy.attributes = this.attributes.map(function (a) { return { name: a.name, value: a.value }; });
      copy.innerHTML = this.innerHTML;
      if (this.textContent !== undefined && this.textContent !== '') copy.textContent = this.textContent;
      // value/checked/selected are live state, not attributes: NOT copied
      // (fresh controls read as clean, exactly like the browser).
      if (deep) {
        for (var i = 0; i < this.children.length; i++) copy.appendChild(this.children[i].cloneNode(true));
      }
      return copy;
    };
    el.querySelectorAll = function (sel) { return qsa(this, sel); };
    el.querySelector = function (sel) { return qsa(this, sel)[0] || null; };
    el.closest = function (sel) {
      var complexes = String(sel).split(',').map(function (c) { return parseComplex(c); });
      var n = this;
      while (n && n.nodeType === 1) {
        for (var j = 0; j < complexes.length; j++) {
          if (complexes[j] && matches(n, complexes[j])) return n;
        }
        n = n.parentNode;
      }
      return null;
    };
    Object.defineProperty(el, 'form', {
      get: function () {
        var n = this.parentNode;
        while (n) { if (n.tagName === 'FORM') return n; n = n.parentNode; }
        return null;
      }
    });

    // ----- control-type property semantics -----
    if (el.tagName === 'INPUT') {
      var live = { value: false, checked: false, _v: '', _c: false };
      Object.defineProperty(el, 'type', {
        get: function () { return this.getAttribute('type') || 'text'; },
        set: function (v) { this.setAttribute('type', v); }
      });
      Object.defineProperty(el, 'value', {
        get: function () {
          if (live.value) return live._v;
          var a = this.getAttribute('value');
          return a !== null ? a : '';
        },
        set: function (v) { live.value = true; live._v = v; }
      });
      Object.defineProperty(el, 'checked', {
        get: function () { return live.checked ? live._c : this.hasAttribute('checked'); },
        set: function (v) { live.checked = true; live._c = !!v; }
      });
    } else if (el.tagName === 'TEXTAREA') {
      var ta = { value: false, _v: '' };
      Object.defineProperty(el, 'value', {
        get: function () { return ta.value ? ta._v : (this.textContent || ''); },
        set: function (v) { ta.value = true; ta._v = v; }
      });
    } else if (el.tagName === 'SELECT') {
      Object.defineProperty(el, 'type', {
        get: function () { return this.multiple ? 'select-multiple' : 'select-one'; }
      });
      Object.defineProperty(el, 'multiple', {
        get: function () { return this.hasAttribute('multiple'); },
        set: function (v) { if (v) this.setAttribute('multiple', ''); else this.removeAttribute('multiple'); }
      });
      Object.defineProperty(el, 'value', {
        get: function () {
          var opts = qsa(this, 'option');
          for (var i = 0; i < opts.length; i++) {
            if (opts[i].selected) return opts[i].value;
          }
          return '';
        },
        set: function (v) {
          var opts = qsa(this, 'option');
          var s = v == null ? '' : String(v);
          for (var i = 0; i < opts.length; i++) opts[i].selected = opts[i].value === s;
        }
      });
    } else if (el.tagName === 'OPTION') {
      Object.defineProperty(el, 'value', {
        get: function () {
          var a = this.getAttribute('value');
          return a !== null ? a : (this.textContent || '');
        },
        set: function (v) { this.setAttribute('value', v); }
      });
    }

    addEventTarget(el);
    return el;
  }

  /** Restore a form's controls to their attribute-declared defaults. */
  function restoreDefaults(form) {
    var controls = qsa(form, 'input,select,textarea');
    for (var i = 0; i < controls.length; i++) {
      var c = controls[i];
      if (c.tagName === 'INPUT') {
        var t = c.getAttribute('type') || 'text';
        if (t === 'checkbox' || t === 'radio') {
          c.checked = c.hasAttribute('checked');
        } else if (t !== 'file') {
          c.value = c.getAttribute('value') !== null ? c.getAttribute('value') : '';
        }
      } else if (c.tagName === 'TEXTAREA') {
        c.value = c.getAttribute('value') !== null ? c.getAttribute('value') : (c.textContent || '');
      } else if (c.tagName === 'SELECT') {
        var opts = qsa(c, 'option');
        for (var j = 0; j < opts.length; j++) opts[j].selected = opts[j].hasAttribute('selected');
      }
    }
  }

  function makeForm() {
    var f = makeElement('_form'); // generic path; '_form' is not special-cased
    f.tagName = 'FORM';
    f.reset = function () {
      var evt = makeEvent('reset');
      this.dispatchEvent(evt);
      if (evt.defaultPrevented) return;
      restoreDefaults(this);
    };
    f.submit = function () {};
    return f;
  }

  // -------------------------------------------------------------------------
  // FormData / Headers / URLSearchParams
  // -------------------------------------------------------------------------

  function FormData(form) {
    this._pairs = [];
    if (!form) return;
    var controls = qsa(form, 'input,select,textarea');
    for (var i = 0; i < controls.length; i++) {
      var c = controls[i];
      var name = c.getAttribute('name');
      if (!name) continue;
      if (c.tagName === 'INPUT') {
        var t = c.getAttribute('type') || 'text';
        if (t === 'checkbox' || t === 'radio') { if (c.checked) this._pairs.push([name, c.value == null ? '' : String(c.value)]); }
        else if (t === 'file') { /* no file state in the shim */ }
        else this._pairs.push([name, c.value == null ? '' : String(c.value)]);
      } else if (c.tagName === 'TEXTAREA') {
        this._pairs.push([name, c.value == null ? '' : String(c.value)]);
      } else if (c.tagName === 'SELECT') {
        var opts = qsa(c, 'option');
        for (var j = 0; j < opts.length; j++) {
          if (opts[j].selected) this._pairs.push([name, opts[j].value]);
        }
      }
    }
  }
  FormData.prototype.forEach = function (fn) {
    for (var i = 0; i < this._pairs.length; i++) fn(this._pairs[i][1], this._pairs[i][0]);
  };

  /** Minimal File stand-in so `value instanceof File` checks in core pass. */
  function File() {}
  globalThis.File = File;

  function Headers(init) {
    this._h = {};
    if (init && typeof init.forEach === 'function') {
      var self = this;
      init.forEach(function (v, k) { self._h[String(k).toLowerCase()] = String(v); });
    }
  }
  Headers.prototype.set = function (n, v) { this._h[String(n).toLowerCase()] = String(v); };
  Headers.prototype.append = function (n, v) {
    var k = String(n).toLowerCase();
    this._h[k] = this._h[k] ? this._h[k] + ', ' + v : String(v);
  };
  Headers.prototype.get = function (n) {
    var k = Object.keys(this._h).filter(function (x) { return x === String(n).toLowerCase(); })[0];
    return k !== undefined ? this._h[k] : null;
  };

  function URLSearchParams(params) {
    this._pairs = [];
    if (params && typeof params === 'object') {
      var self = this;
      Object.keys(params).forEach(function (k) {
        var v = params[k];
        self._pairs.push([k, v == null ? '' : String(v)]);
      });
    }
  }
  URLSearchParams.prototype.toString = function () {
    return this._pairs.map(function (p) {
      return encodeURIComponent(p[0]) + '=' + encodeURIComponent(p[1]);
    }).join('&');
  };

  function makeStorage() {
    var m = {};
    return {
      get length() { return Object.keys(m).length; },
      key: function (i) { return Object.keys(m)[i] || null; },
      getItem: function (k) { return k in m ? m[k] : null; },
      setItem: function (k, v) { m[k] = String(v); },
      removeItem: function (k) { delete m[k]; }
    };
  }

  // -------------------------------------------------------------------------
  // Globals
  // -------------------------------------------------------------------------

  globalThis.console = {
    log: function () { log.messages.push(['log', Array.prototype.slice.call(arguments)]); },
    info: function () { log.messages.push(['info', Array.prototype.slice.call(arguments)]); },
    debug: function () { log.messages.push(['debug', Array.prototype.slice.call(arguments)]); },
    warn: function () {
      log.warns.push(Array.prototype.slice.call(arguments).join(' '));
      log.messages.push(['warn', Array.prototype.slice.call(arguments)]);
    },
    error: function () {
      log.errors.push(Array.prototype.slice.call(arguments).join(' '));
      log.messages.push(['error', Array.prototype.slice.call(arguments)]);
    }
  };

  var body = makeElement('body');
  var documentElement = makeElement('html');
  documentElement.appendChild(body);
  var doc = {
    nodeType: 9,
    readyState: 'loading',
    cookie: '',
    body: body,
    head: makeElement('head'),
    documentElement: documentElement,
    createElement: function (tag) { return tag.toLowerCase() === 'form' ? makeForm() : makeElement(tag); },
    createTextNode: function (t) { return { nodeType: 3, textContent: t }; },
    getElementById: function (id) {
      return qsa(documentElement, '*').filter(function (el) { return el.getAttribute('id') === id; })[0] || null;
    },
    querySelectorAll: function (sel) { return qsa(documentElement, sel); },
    querySelector: function (sel) { return qsa(documentElement, sel)[0] || null; }
  };
  addEventTarget(doc);
  globalThis.document = doc;
  // Event propagation continues through the document node (browsers run
  // document-level capture listeners before the target), so the tree root's
  // parent IS the document. qsa/closest must stop at element boundaries.
  documentElement.parentNode = doc;

  globalThis.window = globalThis;
  globalThis.location = { href: 'http://localhost/', protocol: 'http:', addEventListener: function () {} };
  globalThis.navigator = { userAgent: 'qjs' };
  globalThis.addEventListener = function () {};
  globalThis.removeEventListener = function () {};
  globalThis.alert = function () {};
  globalThis.confirm = function () { return true; };
  globalThis.Headers = Headers;
  globalThis.URLSearchParams = URLSearchParams;
  globalThis.FormData = FormData;
  globalThis.localStorage = makeStorage();
  globalThis.sessionStorage = makeStorage();
  globalThis.TextEncoder = function () {
    this.encode = function (s) {
      var out = [];
      for (var i = 0; i < s.length; i++) out.push(s.charCodeAt(i) & 0xff);
      return out;
    };
  };
  globalThis.btoa = function (s) {
    var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
    var out = '';
    for (var i = 0; i < s.length; i += 3) {
      var b1 = s.charCodeAt(i), b2 = s.charCodeAt(i + 1), b3 = s.charCodeAt(i + 2);
      out += chars.charAt(b1 >> 2);
      out += chars.charAt(((b1 & 3) << 4) | ((b2 || 0) >> 4));
      out += b2 !== undefined ? chars.charAt(((b2 & 15) << 2) | ((b3 || 0) >> 6)) : '=';
      out += b3 !== undefined ? chars.charAt(b3 & 63) : '=';
    }
    return out;
  };

  /** Canned responses for the fetch stub. */
  function okResponse(directives) {
    return {
      ok: true,
      status: 200,
      headers: { get: function (n) { return String(n).toLowerCase() === 'content-type' ? 'application/vnd.statum+json' : null; } },
      json: function () { return Promise.resolve(directives || []); }
    };
  }
  function failResponse(status) {
    return {
      ok: false,
      status: status || 500,
      headers: { get: function () { return null; } },
      json: function () { return Promise.resolve([]); }
    };
  }
  globalThis.fetch = function (url, init) {
    fetchCalls.push({
      url: String(url),
      method: (init && init.method) || 'GET',
      body: init && init.body
    });
    var res = fetchHandler
      ? fetchHandler(String(url), init || {})
      : okResponse([]);
    return Promise.resolve(res);
  };

  globalThis.__shim = {
    log: log,
    body: body,
    makeElement: makeElement,
    makeEvent: makeEvent,
    fetchCalls: fetchCalls,
    setFetch: function (fn) { fetchHandler = fn; },
    okResponse: okResponse,
    failResponse: failResponse
  };
  globalThis.__STATUM_TEST__ = true;
}