/**
@license
Copyright (c) 2024 trading_peter
This program is available under Apache License Version 2.0
*/

import { LitElement, html, css } from 'lit';
import { DomQuery } from '@tp/helpers/dom-query.js';
import { EventHelpers } from '@tp/helpers/event-helpers.js';
import { closest } from '@tp/helpers/closest.js';

class TpTagInputPopup extends DomQuery(EventHelpers(LitElement)) {
  static get styles() {
    return [
      css`
        :host {
          display: none;
          position: fixed;
          border-radius: 2px;
          background: #ffffff;
          z-index: 1;
          left: 0;
          width: 100%;
          margin-top: 5px;
          box-shadow: var(--tp-tag-input-popup-shadow, none);
        }

        #list {
          max-height: 150px;
          overflow-y: auto;
        }

        .item {
          line-height: 25px;
          padding: 3px 10px;
          white-space: nowrap;
          overflow: hidden;
          cursor: pointer;
          text-overflow: ellipsis;
        }

        .item[selected] {
          background: #e4e4e4;
        }
      `
    ];
  }

  render() {
    const { selection } = this;

    return html`
      <div class="wrap">
        <div id="list" @click=${this._onItemClick}>
          ${this.filteredItems.map((item, idx) => html`
            <div class="item" .item=${item} ?selected=${item.value === this.value || idx === selection}>${item.label}</div>
          `)}
        </div>
      </div>
    `;
  }

  static get is() { return 'era-autocomplete-popup'; }

  static get properties() {
    return {
      /**
      * The choosen item.
      */
      value: { type: String },

      /**
      * List of items available for auto complete.
      */
      items: { type: Array },
      filteredItems: { type: Array },

      /**
      * The filter string to narrow down the items.
      */
      filter: { type: String },

      selection: { type: Number },

      visible: { type: Boolean }
    };
  }

  constructor() {
    super();
    this.visible = false;
    this.filteredItems = [];
  }

  get target() {
    return closest(this, 'tp-tag-input', true);
  }

  shouldUpdate(changes) {
    if (changes.has('filter') || changes.has('items')) {
      this._filterItemsByTerm();
    }

    return true;
  }

  firstUpdated() {
    this.listen(this.$.list, 'mousedown', '_onItemClick');
  }

  disconnectedCallback() {
    super.disconnectedCallback();
    this.unlisten(this.$.list, 'mousedown', '_onItemClick');
  }

  show() {
    if (this.visible) {
      return;
    }

    var targetRect = this.target.getBoundingClientRect();
    this.style.top = (targetRect.top + targetRect.height) + 'px';
    this.style.left = targetRect.left + 'px';
    this.style.width = Math.max(100, targetRect.width) + 'px';

    this.listen(this.target, 'keydown', '_onHostKeydown');
    this.style.display = 'block';
    this.visible = true;
  }

  hide() {
    this.style.display = 'none';
    this.unlisten(this.target, 'keydown', '_onHostKeydown');
    this.visible = false;
  }

  _onItemClick(e) {
    const item = closest(e.composedPath()[0], '.item', true);
    if (!item) return;
    this.value = item.item;
    this.dispatchEvent(new CustomEvent('selection-changed', { detail: this.value, bubbles: true, composed: true }));
    this.hide();
    this.target.focus();
  }

  _filterItemsByTerm() {
    if (!Array.isArray(this.items)) return;

    if (!this.filter) {
      this.filteredItems = this.items;
    } else {
      const term = this.filter.toLowerCase();
      this.filteredItems = this.items.filter(item => item.label.toLowerCase().includes(term));
    }
  }

  _onHostKeydown(e) {
    const count = this.$.list.querySelectorAll('.item').length;
    let el;

    switch (e.keyCode) {
      case 38: // Up
        this.selection = this.selection - 1 < 0 ? count - 1 : this.selection - 1;
        el = this.$.list.querySelector('.item[selected]');
        this._scrollIntoView(el, this.$.list);
        e.preventDefault();
        e.stopPropagation();
        return;
      case 40: // Down
        if (isNaN(this.selection) || this.selection === null) {
          this.selection = 0;
        } else {
          this.selection = (this.selection + 1) % count;
        }
        el = this.$.list.querySelector('.item[selected]');
        this._scrollIntoView(el, this.$.list);
        e.preventDefault();
        e.stopPropagation();
        return;
      case 13: // Enter
        const item = this.$.list.querySelector('.item[selected]');
        if (item) {
          this.value = item.item;
          this.dispatchEvent(new CustomEvent('selection-changed', { detail: this.value, bubbles: true, composed: true }));
        }
        this.hide();
        e.preventDefault();
        e.stopPropagation();
        return;
      case 27: // Esc
        this.hide();
        e.preventDefault();
        e.stopPropagation();
        return;
    }
  }

  _scrollIntoView(element, container) {
    if (!element) {
      return;
    }

    const containerTop = container.scrollTop;
    const containerBottom = containerTop + container.offsetHeight;
    const elTop = element.offsetTop;
    const elBottom = elTop + element.offsetHeight;

    if (elTop < containerTop) {
      container.scrollTop = elTop;
    } else if (elBottom > containerBottom) {
      container.scrollTop = elBottom - container.offsetHeight;
    }
  }
}

window.customElements.define('tp-tag-input-popup', TpTagInputPopup);