/* =============================================================
 * @whynot/design — form.js
 * ------------------------------------------------------------
 *   <wn-input>, <wn-textarea>, <wn-select>,
 *   <wn-search-input>, <wn-field-row>
 *
 * Each wraps a real native element. Form participation works
 * because the native input is part of the light DOM via the
 * `name` attribute being copied through; for richer integration
 * use ElementInternals (deferred — see CHANGELOG).
 * ============================================================= */

import { LitElement, html, nothing } from "lit";
import { WnBase } from "./atoms.js";

/* ---------- <wn-input> ---------- */
export class WnInput extends WnBase {
  static properties = {
    name:        { type: String, reflect: true },
    type:        { type: String, reflect: true },
    value:       { type: String },
    placeholder: { type: String },
    required:    { type: Boolean, reflect: true },
    disabled:    { type: Boolean, reflect: true },
    readonly:    { type: Boolean, reflect: true },
    autocomplete:{ type: String },
    error:       { type: Boolean, reflect: true },
    help:        { type: String },
    errorText:   { type: String, attribute: "error-text" },
  };
  constructor() {
    super();
    this.type = "text";
    this.value = "";
    this.required = false;
    this.disabled = false;
    this.readonly = false;
    this.error = false;
  }
  _onInput(e) {
    this.value = e.target.value;
    this.dispatchEvent(new CustomEvent("wn-input", { detail: { value: this.value }, bubbles: true, composed: true }));
  }
  render() {
    const cls = "wn-input" + (this.error ? " wn-input--error" : "");
    return html`
      <input class=${cls}
             part="input"
             name=${this.name ?? nothing}
             type=${this.type}
             .value=${this.value}
             placeholder=${this.placeholder ?? nothing}
             ?required=${this.required}
             ?disabled=${this.disabled}
             ?readonly=${this.readonly}
             autocomplete=${this.autocomplete ?? nothing}
             @input=${this._onInput}>
      ${this.error && this.errorText
        ? html`<span class="wn-form-error">${this.errorText}</span>`
        : this.help
          ? html`<span class="wn-form-help">${this.help}</span>`
          : nothing}
    `;
  }
}

/* ---------- <wn-textarea> ---------- */
export class WnTextarea extends WnBase {
  static properties = {
    name:        { type: String, reflect: true },
    value:       { type: String },
    placeholder: { type: String },
    rows:        { type: Number },
    required:    { type: Boolean, reflect: true },
    disabled:    { type: Boolean, reflect: true },
    error:       { type: Boolean, reflect: true },
    help:        { type: String },
    errorText:   { type: String, attribute: "error-text" },
  };
  constructor() { super(); this.value = ""; this.rows = 4; }
  _onInput(e) {
    this.value = e.target.value;
    this.dispatchEvent(new CustomEvent("wn-input", { detail: { value: this.value }, bubbles: true, composed: true }));
  }
  render() {
    const cls = "wn-textarea" + (this.error ? " wn-textarea--error" : "");
    return html`
      <textarea class=${cls}
                part="textarea"
                name=${this.name ?? nothing}
                rows=${this.rows}
                placeholder=${this.placeholder ?? nothing}
                ?required=${this.required}
                ?disabled=${this.disabled}
                @input=${this._onInput}
                .value=${this.value}></textarea>
      ${this.error && this.errorText
        ? html`<span class="wn-form-error">${this.errorText}</span>`
        : this.help
          ? html`<span class="wn-form-help">${this.help}</span>`
          : nothing}
    `;
  }
}

/* ---------- <wn-select> ----------
 * Slot <option> elements; they're cloned into the inner <select>. */
export class WnSelect extends WnBase {
  static properties = {
    name:     { type: String, reflect: true },
    value:    { type: String },
    required: { type: Boolean, reflect: true },
    disabled: { type: Boolean, reflect: true },
    error:    { type: Boolean, reflect: true },
    help:     { type: String },
  };
  _onSlotChange(e) {
    const slot = e.target;
    const select = this.shadowRoot?.querySelector("select.wn-select");
    if (!select) return;
    const options = slot.assignedElements({ flatten: true }).filter(el => el.tagName === "OPTION");
    select.innerHTML = "";
    for (const opt of options) select.appendChild(opt.cloneNode(true));
    if (this.value != null) select.value = this.value;
  }
  _onChange(e) {
    this.value = e.target.value;
    this.dispatchEvent(new CustomEvent("wn-change", { detail: { value: this.value }, bubbles: true, composed: true }));
  }
  render() {
    const cls = "wn-select" + (this.error ? " wn-select--error" : "");
    return html`
      <select class=${cls}
              part="select"
              name=${this.name ?? nothing}
              ?required=${this.required}
              ?disabled=${this.disabled}
              @change=${this._onChange}></select>
      <slot @slotchange=${this._onSlotChange} style="display:none"></slot>
      ${this.help ? html`<span class="wn-form-help">${this.help}</span>` : nothing}
    `;
  }
}

/* ---------- <wn-search-input> ---------- */
export class WnSearchInput extends WnBase {
  static properties = {
    placeholder: { type: String },
    kbd:         { type: String },
    value:       { type: String },
    name:        { type: String, reflect: true },
  };
  constructor() { super(); this.placeholder = "Search…"; this.kbd = "⌘ K"; this.value = ""; }
  _onInput(e) {
    this.value = e.target.value;
    this.dispatchEvent(new CustomEvent("wn-input", { detail: { value: this.value }, bubbles: true, composed: true }));
  }
  render() {
    return html`
      <label class="wn-search" part="root">
        <wn-icon name="search" size="sm"></wn-icon>
        <input type="search"
               name=${this.name ?? nothing}
               .value=${this.value}
               placeholder=${this.placeholder}
               @input=${this._onInput}>
        ${this.kbd ? html`<span class="wn-search__kbd">${this.kbd}</span>` : nothing}
      </label>
    `;
  }
}

/* ---------- <wn-field-row> ---------- */
export class WnFieldRow extends WnBase {
  static properties = {
    label:   { type: String },
    aside:   { type: String },
    stacked: { type: Boolean, reflect: true },
    narrow:  { type: Boolean, reflect: true },
    htmlFor: { type: String, attribute: "for" },
  };
  render() {
    const cls = ["wn-field-row",
      this.stacked ? "wn-field-row--stacked" : "",
      this.narrow  ? "wn-field-row--narrow"  : "",
    ].filter(Boolean).join(" ");
    return html`
      <div class=${cls} part="root">
        <label class="wn-field-row__label" for=${this.htmlFor ?? nothing}>${this.label}</label>
        <div class="wn-field-row__value"><slot></slot></div>
        ${this.aside
          ? html`<div class="wn-field-row__aside">${this.aside}<slot name="aside"></slot></div>`
          : html`<div class="wn-field-row__aside"><slot name="aside"></slot></div>`}
      </div>
    `;
  }
}

export function defineForm() {
  if (!customElements.get("wn-input"))         customElements.define("wn-input",         WnInput);
  if (!customElements.get("wn-textarea"))      customElements.define("wn-textarea",      WnTextarea);
  if (!customElements.get("wn-select"))        customElements.define("wn-select",        WnSelect);
  if (!customElements.get("wn-search-input"))  customElements.define("wn-search-input",  WnSearchInput);
  if (!customElements.get("wn-field-row"))     customElements.define("wn-field-row",     WnFieldRow);
}