/* <== définition Multi-Select ==> */

/**
 * Permet d'afficher un sélecteur multiple d'options.
 * Pour chaque option cela affichera un checkbox.
 * Les options peuvent être regroupées dans des optgroup.
 *
 * 
 * Utilisation : 
 * <multi-select>
        <optgroup label="Groupe A">
            <option value="val1">Option 1</option>
            <option value="val2">Option 2</option>
        </optgroup>
        <optgroup label="Groupe B">
            <option value="valB1">Option B1</option>
            <option value="valB2">Option B2</option>
        </optgroup>
    </multi-select>

    <multi-select>.values() => ["val1",...]
    <multi-select>.values(["val1",...]) => // sélectionne les options correspondantes (ne vérifie pas les options "single")
    <multi-select>.on("change", (values) => {}) => // écoute le changement de valeur
 */

class MultiSelect extends HTMLElement {
  static formAssociated = true;

  get form() {
    return this._internals.form;
  }
  get name() {
    return this.getAttribute("name");
  }

  get label() {
    return this.getAttribute("label");
  }

  set label(value) {
    this.setAttribute("label", value);
  }

  get type() {
    return this.localName;
  }

  constructor() {
    super();
    this.attachShadow({ mode: "open" });

    // HTML/CSS du composant
    this.shadowRoot.innerHTML = `
                  <style>
                    *{
                      box-sizing: border-box;
                    }
                      
                    .dropdown {
                      position: relative;
                      display: inline-block;
                      border-radius: 10px;
                      user-select: none;
                    }
                    .dropdown-button {
                      // padding: 10px;
                      // background-color: #f1f1f1;
                      // border: 1px solid #ccc;
                      cursor: pointer;
                      font-family: inherit;
                      font-size: inherit;
                      line-height: inherit;
                    }
                    .dropdown-content {
                      display: none;
                      position: absolute;
                      background-color: #fff;
                      min-width: 200px;
                      box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
                      z-index: 1;
                    }
                    .dropdown-content .optgroup {
                      padding: 4px 8px;
                      width: 100%;
                    }
                    .dropdown-content .optgroup div {
                      font-weight: bold;
                    }
                    .dropdown-button::after{
                      content: "";
                      display: inline-block;
                      width: 0;
                      height: 0;
                      margin-left: 4px;
                      vertical-align: middle;
                      border-top: 4px dashed;
                      border-right: 4px solid transparent;
                      border-left: 4px solid transparent;
                    }

                    .dropdown-content .option {
                      display: flex;
                      align-items: center;
                    }
                    .dropdown-content .option input[type="checkbox"] {
                      margin-right: 0.5em;
                    }
                    label.selected{
                      background-color: #C2DBFB;
                    }
                    label{
                      cursor: pointer;
                      transition: all 0.3s;
                    }
                    label:hover{
                      background-color: #f1f1f1;
                    }
                  </style>
                  <div class="dropdown">
                    <button class="dropdown-button">Select options</button>
                    <div class="dropdown-content multi-select-container"></div>
                  </div>
                `;

    this.exportFormat = null;
    this.observer = new MutationObserver(() => this.render());

    this.toggleDropdown = this.toggleDropdown.bind(this);
    this.handleDocumentClick = this.handleDocumentClick.bind(this);

    this._internals = this.attachInternals();
    this._internals.setFormValue([]);
  }

  connectedCallback() {
    this.render();
    this.observer.observe(this, { childList: true, subtree: true });
    const btn = this.shadowRoot.querySelector(".dropdown-button");
    btn.addEventListener("click", this.toggleDropdown);
    document.addEventListener("click", this.handleDocumentClick);

    this._updateSelect();
  }

  disconnectedCallback() {
    this.observer.disconnect();
    document.removeEventListener("click", this.handleDocumentClick);
  }

  toggleDropdown(event) {
    event.stopPropagation();
    const dropdownContent = this.shadowRoot.querySelector(".dropdown-content");
    dropdownContent.style.display =
      dropdownContent.style.display === "block" ? "none" : "block";
  }

  handleDocumentClick(event) {
    if (!this.contains(event.target)) {
      this.shadowRoot.querySelector(".dropdown-content").style.display = "none";
    }
  }

  render() {
    const container = this.shadowRoot.querySelector(".multi-select-container");
    container.innerHTML = "";

    const optgroups = this.querySelectorAll("optgroup");

    optgroups.forEach((optgroup) => {
      const groupDiv = document.createElement("div");
      groupDiv.className = "optgroup";

      const groupLabel = document.createElement("div");
      groupLabel.textContent = optgroup.label;
      groupDiv.appendChild(groupLabel);

      const options = optgroup.querySelectorAll("option");
      options.forEach((option) => {
        const optionDiv = document.createElement("label");
        optionDiv.className = "option";

        const checkbox = document.createElement("input");
        checkbox.type = "checkbox";
        checkbox.value = option.value;
        checkbox.name = this.getAttribute("name");
        if (option.hasAttribute("selected")) {
          checkbox.checked = true;
          optionDiv.classList.add("selected");
        }
        checkbox.addEventListener("change", () => {
          this.handleCheckboxChange(checkbox);
        });

        optionDiv.appendChild(checkbox);
        optionDiv.appendChild(document.createTextNode(option.textContent));
        groupDiv.appendChild(optionDiv);
      });

      container.appendChild(groupDiv);
    });

    this._updateSelect();
  }

  handleCheckboxChange(checkbox) {
    const opt = this.querySelector(`option[value="${checkbox.value}"]`);
    const isSingle = opt.hasAttribute("single");
    if (!checkbox.checked) {
      checkbox.parentElement.classList.remove("selected");
    } else {
      checkbox.parentElement.classList.add("selected");
      // Gestion de l'option "single"
      if (isSingle) {
        // Uncheck all other checkboxes
        const checkboxes = this.shadowRoot.querySelectorAll(
          'input[type="checkbox"]'
        );
        checkboxes.forEach((cb) => {
          if (cb !== checkbox) {
            cb.checked = false;
            cb.parentElement.classList.remove("selected");
          }
        });
      } else {
        // Uncheck the single checkbox if present
        const singleCheckbox = Array.from(
          this.shadowRoot.querySelectorAll('input[type="checkbox"]')
        ).find((cb) =>
          this.querySelector(`option[value="${cb.value}"]`).hasAttribute(
            "single"
          )
        );
        if (singleCheckbox) {
          singleCheckbox.checked = false;
          singleCheckbox.parentElement.classList.remove("selected");
        }
      }
    }
    this._updateSelect();
  }

  _updateSelect() {
    const checkboxes = this.shadowRoot.querySelectorAll(
      'input[type="checkbox"]'
    );
    const checkedBoxes = Array.from(checkboxes).filter(
      (checkbox) => checkbox.checked
    );

    const values = checkedBoxes.map((checkbox) => checkbox.value);

    const opts = checkedBoxes.map((checkbox) => {
      return this.querySelector(`option[value="${checkbox.value}"]`);
    });

    const btn = this.shadowRoot.querySelector(".dropdown-button");

    if (checkedBoxes.length === 0) {
      btn.textContent = this.label || "Select options";
    } else if (checkedBoxes.length < 4) {
      btn.textContent = opts.map((opt) => opt.textContent).join(", ") + "";
    } else {
      btn.textContent = `${checkedBoxes.length} sélections`;
    }
    this.dispatchEvent(new Event("change"));
  }

  _values(newValues = null) {
    const checkboxes = this.shadowRoot.querySelectorAll(
      'input[type="checkbox"]'
    );
    if (newValues === null) {
      // Get selected values
      const values = Array.from(checkboxes)
        .filter((checkbox) => checkbox.checked)
        .map((checkbox) => checkbox.value);
      if (this.exportFormat) {
        return this.exportFormat(values);
      }
      return values;
    } else {
      // Set selected values
      checkboxes.forEach((checkbox) => {
        checkbox.checked = newValues.includes(checkbox.value);
      });

      this._internals.setFormValue(this._values());
      this._updateSelect();
    }
  }

  get value() {
    return this._values();
  }

  set value(values) {
    this._values(values);
  }

  on(callback) {
    this.addEventListener("change", callback);
  }

  format(callback) {
    this.exportFormat = callback;
  }
}

customElements.define("multi-select", MultiSelect);