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

import './tp-flow-node-port.js';
import { LitElement, html, css } from 'lit';

export class TpFlowNode extends LitElement {
  static get styles() {
    return [
      css`
        :host {
          display: block;
          position: absolute;
          background: #2b2b2b;
          border-radius: 4px;
          color: #fff;
          min-width: 150px;
        }

        .node-body {
          display: grid;
          grid-template-columns: 20px 1fr 20px;
        }

        .node-content {
          padding: 20px;
        }

        .node-ports {
          justify-content: space-between;
          padding: 8px;
        }

        .input-ports, .output-ports {
          display: flex;
          flex-direction: column;
          gap: 8px;
          align-items: flex-start;
          justify-content: space-evenly;
        }

        .output-ports {
          align-items: flex-end;
        }

        header {
          display: flex;
          align-items: center;
          column-gap: 10px;
          padding: 2px 5px;
        }

        .delete-btn {
          cursor: pointer;
          opacity: 0.7;
          transition: opacity 0.2s;
        }

        .delete-btn:hover {
          opacity: 1;
        }
      `
    ];
  }

  render() {
    return html`
      ${this.renderNodeHeader()}
      <div class="node-body">
        <div class="input-ports">
          ${this.inputs.map((input, idx) => html`
            <tp-flow-node-port class="port" exportparts="connection-point"
              portType="input"
              .portId=${idx}
              .portName=${input.name}
              .tagContent=${input.tagContent}
              .shape=${input.shape}
              .color=${input.color}
              .dataTypes=${input.dataTypes}
              @mousedown="${this._handlePortClick}">
            </tp-flow-node-port>
          `)}
        </div>

        <div class="node-content" part="node-content">
          ${this.renderNodeContent()}
        </div>

        <div class="output-ports">
          ${this.outputs.map((output, idx) => html`
            <tp-flow-node-port class="port" exportparts="connection-point"
              portType="output"
              .portId=${idx}
              .portName=${output.name}
              .tagContent=${output.tagContent}
              .shape=${output.shape}
              .color=${output.color}
              .dataTypes=${output.dataTypes}
              @mousedown="${this._handlePortClick}">
            </tp-flow-node-port>
          `)}
        </div>
      </div>
    `;
  }

  renderNodeHeader() {
    return html`
      <header drag-node>
        A Node
        ${!this.readonly ? html`<div class="delete-btn" @click="${this._handleDelete}">✕</div>` : null}
      </header>
    `;
  }

  renderNodeContent() {
    console.warn('Your node should override the renderNodeContent method.');
    return null;
  }

  static get properties() {
    return {
      inputs: { type: Array },
      outputs: { type: Array },
      x: { type: Number },
      y: { type: Number },
      data: { type: Object },
      readonly: { type: Boolean, reflect: true }
    };
  }

  constructor() {
    super();
    this.inputs = [];
    this.outputs = [];
    this.x = 0;
    this.y = 0;
    this.data = {};
    this.readonly = false;

    this._handleConnectionDragStart = this._handleConnectionDragStart.bind(this);
    this._handleConnectionDragEnd = this._handleConnectionDragEnd.bind(this);
  }

  connectedCallback() {
    super.connectedCallback();

    this.addEventListener('connection-drag-start', this._handleConnectionDragStart);
    this.addEventListener('connection-drag-end', this._handleConnectionDragEnd);
  }

  disconnectedCallback() {
    super.disconnectedCallback();

    this.removeEventListener('connection-drag-start', this._handleConnectionDragStart);
    this.removeEventListener('connection-drag-end', this._handleConnectionDragEnd);
  }

  /**
   * Called when a connection drag starts somewhere on the canvas.
   * The detail contains the source node, port ID, and the source port's dataTypes.
   * Each node should evaluate its input ports and dim incompatible ones.
   *
   * Override `checkPortCompatibility(sourceDataTypes, targetDataTypes)` to implement
   * type-aware dimming. Return true if compatible, false if not.
   *
   * @param {CustomEvent} e — detail: { sourceNode, sourcePortId, sourceDataTypes }
   */
  _handleConnectionDragStart(e) {
    // Don't dim ports on the source node itself.
    if (e.detail.sourceNode === this) {
      return;
    }

    const sourceDataTypes = e.detail.sourceDataTypes || [];

    // Evaluate each input port.
    const inputPorts = this.shadowRoot.querySelectorAll('.input-ports tp-flow-node-port');

    inputPorts.forEach(port => {
      const targetDataTypes = port.dataTypes || [];

      const isCompatible = this.checkPortCompatibility(sourceDataTypes, targetDataTypes);

      if (isCompatible) {
        port.removeAttribute('dimmed');
        port.setAttribute('compatible', '');
      } else {
        port.setAttribute('dimmed', '');
        port.removeAttribute('compatible');
      }
    });
  }

  _handleConnectionDragEnd() {
    const ports = this.shadowRoot.querySelectorAll('tp-flow-node-port');

    ports.forEach(port => {
      port.removeAttribute('dimmed');
      port.removeAttribute('compatible');
    });
  }

  /**
   * Override this method to implement type-aware compatibility checking.
   * Default: everything is compatible (no dimming).
   *
   * @param {string[]} sourceDataTypes — data types of the source port
   * @param {string[]} targetDataTypes — data types of the target port
   * @returns {boolean} true if compatible
   */
  checkPortCompatibility(sourceDataTypes, targetDataTypes) {
    return true;
  }

  updated(changes) {
    super.updated(changes);

    this.dispatchEvent(new CustomEvent('update-layout', { detail: this, bubbles: true, composed: true }));
  }

  _handlePortClick(e) {
    e.stopPropagation();

    this.dispatchEvent(new CustomEvent('port-click', {
      detail: {
        node: this,
        port: e.target,
        dataTypes: e.target.dataTypes,
      },
      bubbles: true,
      composed: true
    }));
  }

  _handleDelete(e) {
    e.stopPropagation();
    this.dispatchEvent(new CustomEvent('node-delete-requested', {
      detail: { nodeId: this.id },
      bubbles: true,
      composed: true
    }));
  }

  exportData() {
    const transform = window.getComputedStyle(this).transform;
    const matrix = new DOMMatrix(transform);

    return {
      id: this.id,
      type: super.tagName.toLowerCase(),
      position: {
        x: matrix.m41,
        y: matrix.m42
      },
      data: this.data
    };
  }

  importData(data) {
    this.id = data.id;
    this.data = data.data;

    if (data.position) {
      this.style.transform = `translate(${data.position.x}px, ${data.position.y}px)`;
    }
  }

  dispatchDataUpdate() {
    this.dispatchEvent(new CustomEvent('flow-changed', {
      detail: {
        type: 'node-data-changed',
        data: this.exportData()
      },
      bubbles: true,
      composed: true
    }));
  }
}