/**
@license
Copyright (c) 2022 trading_peter
This program is available under Apache License Version 2.0
*/

import '@tp/tp-scroll-threshold/tp-scroll-threshold.js';
import '@lit-labs/virtualizer';
import '@tp/tp-icon/tp-icon.js';
import '@tp/tp-checkbox/tp-checkbox.js';
import './tp-table-item.js';
import { DomQuery } from '@tp/helpers/dom-query.js';
import { closest } from '@tp/helpers/closest.js';
import { LitElement, html, css, svg } from 'lit';
import ColumnResizer from './column-resizer.js';
import ColumnMover from './column-mover.js';

export class TpTable extends DomQuery(LitElement) {
  static get styles() {
    return [
      css`
        :host {
          display: block;
          padding: 20px;
          position: relative;
        }

        [hidden] {
          display: none;
        }

        .wrap {
          overflow-y: auto;
          position: absolute;
          left: 0;
          right: 0;
          top: 0;
          bottom: 0;
          display: flex;
          flex-direction: column;
        }

        .list {
          position: relative;
          flex: 1;
        }

        #tableHeader {
          display: grid;
          overflow-x: hidden;
        }

        #virtualList,
        .empty-message {
          position: absolute !important;
          left: 0;
          right: 0;
          top: 0;
          bottom: 0;
        }

        #virtualList {
          height: auto;
        }

        .empty-message {
          display: flex;
          flex-direction: column;
          align-items: center;
          justify-content: center;
        }

        a.sort-link,
        a.no-sort-link {
          text-decoration: none;
          font-weight: bold;
          position: relative;
          border-right: solid 1px #c1c1c1;
          padding: 10px 20px 10px 20px;
          display: flex;
          flex-direction: row;
          overflow: hidden;
          cursor: pointer;
          user-select: none;
        }

        a.sort-link:hover,
        a.no-sort-link:hover {
          border-right: solid 1px #c1c1c1;
        }

        a.sort-link tp-icon[part="sort-icon"] {
          position: absolute;
          left: 0;
          --tp-icon-width: 18px;
          --tp-icon-height: 18px;
        }

        div.col-label {
          flex: 1;
          text-overflow: ellipsis;
          white-space: nowrap;
        }

        .width-handle {
          position: absolute;
          z-index: 1;
          top: 0;
          right: -2px;
          cursor: col-resize;
          width: 6px;
          height: 100%;
        }

        .width-handle > div {
          margin: auto;
          width: 2px;
          height: 100%;
          background: transparent;
        }

        #tableHeader:not(.col-dragging) .width-handle:hover > div {
          background: var(--tp-table-handle-color-hover);
        }

        .width-handle.dragging {
          position: fixed;
          height: 300px;
          z-index: 100;
          border-style: none;
          width: 3px;
          background: var(--tp-table-handle-color-dragging, linear-gradient(180deg, rgba(59, 164, 240, 1), rgba(59, 164, 240, 0)));
        }

        .select-col {
          display: flex;
          align-items: center;
          justify-content: center;
          height: 100%;
        }

        .select-col tp-checkbox::part(label) {
          display: none;
        }

        lit-virtualizer {
          overflow-x: hidden;
        }

        lit-virtualizer::-webkit-scrollbar {
          width: 12px;
        }

        lit-virtualizer::-webkit-scrollbar-track {
          background: var(--scrollbar-track, #c1c1c1);
        }

        lit-virtualizer::-webkit-scrollbar-thumb {
          background-color: var(--scrollbar-thumb, #5a5a5a);
          outline: none;
          border-radius: var(--scrollbar-thumb-border-radius, 4px);
        }

        [item]:hover {
          background: var(--table-row-hl);
          --list-columns-h-borders: var(--list-columns-h-borders-hover);
        }
      `
    ];
  }

  render() {
    const columns = this.columns || [];
    const items = this.items || [];

    return html`
      <div class="wrap">
        ${this.renderTableHeader(columns)}
        <div class="list" @row-selection-changed=${(e) => this._selectionChanged(e)}>
          ${!Array.isArray(items) || items.length === 0 ? html`
            <div class="empty-message">
              <slot name="empty-message"></slot>
            </div>
          ` : null}
          <lit-virtualizer id="virtualList" part="list" scroller .items=${items} .renderItem=${(item, idx) => this.renderItem(item, idx, columns, this._selItems.has(this.getItemId(item)))}></lit-virtualizer>
        </div>

        <tp-scroll-threshold id="threshold" lowerThreshold="40"></tp-scroll-threshold>
      </div>
    `;
  }

  renderTableHeader(columns) {
    return html`
      <div id="tableHeader" part="header" class="list-headline" @track=${this._colResizeTracked} @track-move=${this._colMoveTracked}>
        ${this.selectable ? html`
          <div class="select-col" part="chkAll"><tp-checkbox @toggled=${e => this._checkedChanged(e)}></tp-checkbox></div>
        ` : null}
        ${columns.map((column, idx) => this.renderColumnHeader(column, idx))}
      </div>
    `;
  }

  renderColumnHeader(column, idx) {
    if (column.visible !== true && column.required !== true) return null;

    const { name, width, label, sortable } = column;
    const sorting = this.sorting || {};
    const isSortedBy = sorting.column === name;
    const sortDirection = isSortedBy ? sorting.direction : 'desc';
    const canSort = sortable !== false;

    return html`
      <a part="column-label" class="${canSort ? 'sort-link' : 'no-sort-link'}" @click=${() => canSort ? this._sort(column, sortDirection) : null} .name=${name} .width=${width}>
        ${canSort ? html`
          <tp-icon part="sort-icon" .icon=${sortDirection === 'asc' ? TpTable.downIcon : TpTable.upIcon} ?hidden=${!isSortedBy}></tp-icon>
        ` : null}
        <div class="col-label">${label}</div>
        <div class="width-handle" part="width-handle"><div part="width-handle-bar"></div></div>
        ${this.renderColumnHeaderAddons(column)}
      </a>
    `;
  }

  renderColumnHeaderAddons(column) {
    return null;
  }

  static get downIcon() {
    return svg`<path fill="var(--tp-table-icon-color)" d="M7,10L12,15L17,10H7Z">`;
  }

  static get upIcon() {
    return svg`<path fill="var(--tp-table-icon-color)" d="M7,15L12,10L17,15H7Z">`;
  }

  renderItem(item, idx, columns, selected) {
    return html`
      <tp-table-item
        exportparts="cell,odd,even,row,chk"
        item
        .index=${idx}
        .item=${item}
        .selected=${selected}
        .selectable=${this.selectable}
        .columns=${columns}>
      </tp-table-item>
    `;
  }

  static get properties() {
    return {
      /** @type {{label: string, name: string, width: number, [required]: boolean, [visible]: boolean, [sortable]: boolean}[]} */
      columns: { type: Array },

      sorting: { type: Object },
      selectable: { type: Boolean },
      items: { type: Array },
      columnMoveHandle: { type: String },
      _selItems: { type: Map },
      _visibleColumns: { type: Array },
      _advFilters: { type: Array },
      _advFilterActive: { type: Boolean },
      _advFilterFields: { type: Object },
      _filter: { type: String },
      _totalCount: { type: Number },
    };
  }

  constructor() {
    super();
    this._selItems = new Map();
  }

  updated(changes) {
    if (changes.has('columns')) {
      this._updateColumns();
    }
  }

  get _emptyMessage() {
    return null;
  }

  get sortingPath() {
    return `${this.dataKey}.sorting`;
  }

  get statusFilterPath() {
    return `${this.dataKey}.filtering.statusFilter`;
  }

  set filter(val) {
    this._advFilterActive = false;
    this._filter = this._clone(val);
    this.reloadPagedList();
  }

  set statusFilter(val) {
    this._statusFilter = this._clone(val);
    this.reloadPagedList();
  }

  set advancedFilter(val) {
    this._advFilterActive = val ? true : false;
    this._advFilters = this._clone(val);
    this.reloadPagedList();
  }

  // Override this to change how the table derives item ids.
  getItemId(item) {
    return item._id || item.id;
  }

  scrollToIndex(idx, position) {
    this.$.virtualList.scrollToIndex(idx, position);
  }

  firstUpdated() {
    this.$.virtualList.addEventListener('scroll', e => this._onScroll(e), true);

    this.shadowRoot.querySelector('tp-scroll-threshold').target = this.$.virtualList;
    new ColumnResizer(this.$.tableHeader, '.width-handle');

    if (this.columnMoveHandle) {
      this.colMover = new ColumnMover(this.$.tableHeader, this.columnMoveHandle);
    }
  }

  _onScroll(e) {
    this.$.tableHeader.style.paddingRight = (this.$.virtualList.offsetWidth - this.$.virtualList.clientWidth) + 'px';
    this.$.tableHeader.scrollLeft = this.$.virtualList.scrollLeft;
  }

  shouldUpdate(changes) {
    if (changes.has('items')) {
      this._updateSelEntries();
    }

    return true;
  }

  _sort(column, direction) {
    if (this._draggedColumn) return;

    this.sorting = { column: column.name, direction: direction === 'asc' ? 'desc' : 'asc' };
    this.dispatchEvent(new CustomEvent('sorting-changed', { detail: this.sorting, bubbles: true, composed: true }));
  }

  _updateColumns() {
    this.$.tableHeader.style.gridTemplateColumns = this._updateColumnWidths(this.selectable ? ['40px'] : []).join(' ');
  }

  _updateColumnWidths(prepend) {
    return [...(prepend || []), ...this.columns.filter(col => col.required || col.visible).map(col => col.width)];
  }

  _colResizeTracked(e) {
    const handle = closest(e.target, '.width-handle');
    const data = e.detail;

    if (data.state === 'start') {
      this._draggedColumn = true;
      const rect = handle.getBoundingClientRect();
      document.body.style.userSelect = 'none';
      handle.style.top = `${rect.top}px`;
      handle.style.left = `${rect.left}px`;
      handle.style.transform = `translateX(${data.dx}px)`;
      handle.classList.add('dragging');
      this.$.tableHeader.classList.add('col-dragging');
    } else if (data.state === 'end') {
      document.body.style.userSelect = '';
      handle.classList.remove('dragging');
      handle.style.transform = '';
      handle.style.top = '';
      handle.style.left = '';
      this.$.tableHeader.classList.remove('col-dragging');

      const colLink = closest(handle, 'a');
      const { name, width } = colLink;
      const newWidth = (parseInt(width, 10) + data.dx) + 'px';
      const colDef = this.columns.find(col => col.name === name);
      colDef.width = newWidth;
      this.columns = [...this.columns];

      setTimeout(() => {
        this._draggedColumn = false;
        this.dispatchEvent(new CustomEvent('column-width-changed', { detail: this.columns, bubbles: true, composed: true }));
      });
    } else if (data.state === 'track') {
      handle.style.transform = `translateX(${data.dx}px)`;
    }
  }

  _colMoveTracked(e) {
    const { target, state, x } = e.detail;
    const headers = this.shadowRoot.querySelectorAll('[part="column-label"]');

    let targetIdx = -1;
    let moveTo = -1;

    const getHeader = name => {
      for (const header of headers) {
        if (header.name === name) {
          return header;
        }
      }
    };

    for (let idx = 0; idx < this.columns.length; idx++) {
      const header = getHeader(this.columns[idx].name);

      if (!header) continue;

      if (header === target.parentNode) {
        targetIdx = idx;
      }

      const coords = header.getBoundingClientRect();
      const result = this._isOverlapping(coords, x);

      if (Math.abs(x - this.offsetWidth + this.offsetLeft) < 50) {
        this.$.virtualList.scrollBy({
          left: 200,
          behavior: 'smooth'
        });
      }

      if (x > this.offsetLeft && Math.abs(x - this.offsetLeft) < 50) {
        this.$.virtualList.scrollBy({
          left: -200,
          behavior: 'smooth'
        });
      }


      if (result.overlap !== 0) {
        if (state === 'track') {
          this.colMover.showIndicator(result.x, coords.top);
        }

        moveTo = idx;

        // User wants to move the column to the left side of the hovered column.
        // This means we need to decrease the index by one.
        if (result.overlap === -1) {
          moveTo = idx - 1;
        }
      }
    }

    if (state === 'end') {
      if (moveTo === targetIdx) return;

      if (targetIdx > moveTo) {
        moveTo++;
      }
      this.columns.splice(moveTo, 0, this.columns.splice(targetIdx, 1)[0])
      this.columns = [ ...this.columns ];
      this.dispatchEvent(new CustomEvent('column-moved', { detail: { from: targetIdx, to: moveTo, columns: this.columns }, bubbles: true, composed: true }));
    }
  }

  /**
   * Determines if the mouse is hovering over the left or right half of a column header element.
   * This check only happens on the x-axis.
   *
   * @param {{left: number, right: number}} coords Coordinates of the column header element.
   * @param {number} x X-coordinate of the mouse pointer.
   * @returns {{overlap: number, x: number}} overlap is -1 if overlap on the left half, 1 if overlap on the right half, 0 if no overlap.
   * X is the border coordinate of the element, so either the right or left bound. Depending on the overlap side.
   */
  _isOverlapping(coords, x) {
    const half = coords.left + ((coords.right - coords.left) / 2);
    if (x > coords.left && x <= half) return { overlap: -1, x: coords.left };
    if (x > half && x <= coords.right) return { overlap: 1, x: coords.right };
    return { overlap: 0, x: 0 };
  }

  clearTriggers() {
    if (this.$.threshold) {
      this.$.threshold.clearTriggers();
    }
  }

  _listOverflows() {
    return this.$.virtualList.scrollHeight > this.$.virtualList.offsetHeight;
  }

  _checkedChanged(e) {
    if (Array.isArray(this.items) === false) return;

    if (e.detail) {
      this._selectAll();
    } else {
      this._selectNone();
    }
  }

  setSelection(items) {
    this._selItems = new Map();
    items.forEach(item => {
      this._selItems.set(this.getItemId(item), item);
    });

    this._selectionChanged();
  }

  _selectAll() {
    this._selItems = new Map();
    this.items.forEach(item => {
      this._selItems.set(this.getItemId(item), item);
    });

    this._selectionChanged();
  }

  _selectNone() {
    this._selItems = new Map();
    this._selectionChanged();
  }

  _selectionChanged(e) {
    if (e !== undefined) {
      if (e.detail.selected) {
        this._selItems.set(this.getItemId(e.detail.item), e.detail.item);
      } else {
        this._selItems.delete(this.getItemId(e.detail.item));
      }
    }

    this.dispatchEvent(new CustomEvent('item-selection-changed', { detail: Array.from(this._selItems.values()), bubbles: true, composed: true }));
  }

  _updateSelEntries() {
    if (!this.items) {
      this._selItems = new Map();
    }

    for (const selItem of this._selItems.values()) {
      if (this.items.findIndex(item => this.getItemId(item) === this.getItemId(selItem)) > -1) {

      }
    }
  }
}

window.customElements.define('tp-table', TpTable);