// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import {FocusEvent, SelectRelatedEvent, ToolTipEvent} from '../events.mjs';
import {CSSColor, DOM, V8CustomElement} from '../helper.mjs';

DOM.defineCustomElement('./view/map-panel/map-transitions',
                        (templateText) =>
                            class MapTransitions extends V8CustomElement {
  _timeline;
  _map;
  _edgeToColor = new Map();
  _selectedLogEntries;
  _displayedMapsInTree;
  _toggleSubtreeHandler = this._handleToggleSubtree.bind(this);
  _mapClickHandler = this._handleMapClick.bind(this);
  _mapDoubleClickHandler = this._handleMapDoubleClick.bind(this);
  _mouseoverMapHandler = this._handleMouseoverMap.bind(this);

  constructor() {
    super(templateText);
    this.currentNode = this.transitionView;
  }

  get transitionView() {
    return this.$('#transitionView');
  }

  set timeline(timeline) {
    this._timeline = timeline;
    this._edgeToColor.clear();
    timeline.getBreakdown().forEach(breakdown => {
      this._edgeToColor.set(breakdown.key, CSSColor.at(breakdown.id));
    });
  }

  set selectedLogEntries(list) {
    this._selectedLogEntries = list;
    this.requestUpdate();
  }

  _update() {
    this.transitionView.style.display = 'none';
    DOM.removeAllChildren(this.transitionView);
    if (this._selectedLogEntries.length == 0) return;
    this._displayedMapsInTree = new Set();
    // Limit view to 200 maps for performance reasons.
    this._selectedLogEntries.slice(0, 200).forEach(
        (map) => this._addMapAndParentTransitions(map));
    this._displayedMapsInTree = undefined;
    this.transitionView.style.display = '';
  }

  _addMapAndParentTransitions(map) {
    if (map === undefined) return;
    if (this._displayedMapsInTree.has(map)) return;
    this._displayedMapsInTree.add(map);
    this.currentNode = this.transitionView;
    let parents = map.getParents();
    if (parents.length > 0) {
      this._addTransitionTo(parents.pop());
      parents.reverse().forEach((each) => this._addTransitionTo(each));
    }
    let mapNode = this._addSubtransitions(map);
    // Mark and show the selected map.
    mapNode.classList.add('selected');
    if (this.selectedMap == map) {
      setTimeout(
          () => mapNode.scrollIntoView({
            behavior: 'smooth',
            block: 'nearest',
            inline: 'nearest',
          }),
          1);
    }
  }

  _addSubtransitions(map) {
    let mapNode = this._addTransitionTo(map);
    // Draw outgoing linear transition line.
    let current = map;
    while (current.children.length == 1) {
      current = current.children[0].to;
      this._addTransitionTo(current);
    }
    return mapNode;
  }

  _addTransitionEdge(map) {
    let classes = ['transitionEdge'];
    let edge = DOM.div(classes);
    edge.style.backgroundColor = this._edgeToColor.get(map.edge.type);
    let labelNode = DOM.div('transitionLabel');
    labelNode.innerText = map.edge.toString();
    edge.appendChild(labelNode);
    return edge;
  }

  _addTransitionTo(map) {
    // transition[ transitions[ transition[...], transition[...], ...]];
    this._displayedMapsInTree?.add(map);
    let transition = DOM.div('transition');
    if (map.isDeprecated()) transition.classList.add('deprecated');
    if (map.edge) {
      transition.appendChild(this._addTransitionEdge(map));
    }
    let mapNode = this._addMapNode(map);
    transition.appendChild(mapNode);

    let subtree = DOM.div('transitions');
    transition.appendChild(subtree);

    this.currentNode.appendChild(transition);
    this.currentNode = subtree;

    return mapNode;
  }

  _addMapNode(map) {
    let node = DOM.div('map');
    if (map.edge)
      node.style.backgroundColor = this._edgeToColor.get(map.edge.type);
    node.map = map;
    node.onclick = this._mapClickHandler
    node.ondblclick = this._mapDoubleClickHandler
    node.onmouseover = this._mouseoverMapHandler
    if (map.children.length > 1) {
      node.innerText = map.children.length;
      const showSubtree = DOM.div('showSubtransitions');
      showSubtree.onclick = this._toggleSubtreeHandler
      node.appendChild(showSubtree);
    }
    else if (map.children.length == 0) {
      node.innerHTML = '●';
    }
    this.currentNode.appendChild(node);
    return node;
  }

  _handleMapClick(event) {
    const map = event.currentTarget.map;
    this.dispatchEvent(new FocusEvent(map));
  }

  _handleMapDoubleClick(event) {
    this.dispatchEvent(new SelectRelatedEvent(event.currentTarget.map));
  }

  _handleMouseoverMap(event) {
    this.dispatchEvent(new ToolTipEvent(
        event.currentTarget.map, event.currentTarget, event.ctrlKey));
  }

  _handleToggleSubtree(event) {
    event.stopImmediatePropagation();
    const node = event.currentTarget.parentElement;
    const map = node.map;
    event.target.classList.toggle('opened');
    const transitionsNode = node.parentElement.querySelector('.transitions');
    const subtransitionNodes = transitionsNode.children;
    if (subtransitionNodes.length <= 1) {
      // Add subtransitions except the one that's already shown.
      let visibleTransitionMap = subtransitionNodes.length == 1 ?
          transitionsNode.querySelector('.map').map :
          undefined;
      map.children.forEach((edge) => {
        if (edge.to != visibleTransitionMap) {
          this.currentNode = transitionsNode;
          this._addSubtransitions(edge.to);
        }
      });
    } else {
      // remove all but the first (currently selected) subtransition
      for (let i = subtransitionNodes.length - 1; i > 0; i--) {
        transitionsNode.removeChild(subtransitionNodes[i]);
      }
    }
    return false;
  }
});