import React, { useState, useEffect } from 'react';

import Graph, { isEdge, removeElements, addEdge, MiniMap, Controls } from 'react-flow-renderer';

import ColorSelectorNode from './ColorSelectorNode';

const onNodeDragStop = node => console.log('drag stop', node);
const onElementClick = element => console.log('click', element);
const onLoad = (graph) => {
  console.log('graph loaded:', graph);
};

const initBgColor = '#f0e742';

const CustomNodeGraph = () => {
  const [elements, setElements] = useState([]);
  const [bgColor, setBgColor] = useState(initBgColor);

  useEffect(() => {
    const onChange = (evt) => {
      setElements(els => els.map(e => {
        if (isEdge(e) || e.id !== '2') {
          return e;
        }

        const color = evt.target.value;

        setBgColor(color);

        return {
          ...e,
          data: {
            ...e.data,
            color
          }
        };
      }));
    };

    setElements([
      { id: '1', type: 'input', data: { label: 'An input node' }, position: { x: 0, y: 50 }, sourcePosition: 'right' },
      { id: '2', type: 'selectorNode', data: { onChange: onChange, color: initBgColor }, position: { x: 250, y: 50 } },
      { id: '3', type: 'output', data: { label: 'Output A' }, position: { x: 550, y: 25 }, targetPosition: 'left' },
      { id: '4', type: 'output', data: { label: 'Output B' }, position: { x: 550, y: 100 }, targetPosition: 'left' },

      { id: 'e1-2', source: '1', target: '2', animated: true, style: { stroke: '#fff' } },
      { id: 'e2a-3', source: '2__a', target: '3', animated: true, style: { stroke: '#fff' } },
      { id: 'e2b-4', source: '2__b', target: '4', animated: true, style: { stroke: '#fff' } },
    ])
  }, []);

  const onElementsRemove = (elementsToRemove) => setElements(els => removeElements(elementsToRemove, els));
  const onConnect = (params) => setElements(els => addEdge(params, els));

  return (
    <Graph
      elements={elements}
      onElementClick={onElementClick}
      onElementsRemove={onElementsRemove}
      onConnect={onConnect}
      onNodeDragStop={onNodeDragStop}
      style={{ width: '100%', height: '100%', background: bgColor }}
      onLoad={onLoad}
      nodeTypes={{
        selectorNode: ColorSelectorNode,
      }}
      connectionLineStyle={{ stroke: '#ddd', strokeWidth: 2 }}
      connectionLineType="bezier"
      backgroundColor="#888"
      backgroundGap={16}
      snapToGrid={true}
      snapGrid={[16, 16]}
    >
      <MiniMap
        nodeColor={n => {
          if (n.type === 'input') return 'blue';
          if (n.type === 'selectorNode') return bgColor;
          if (n.type === 'output') return 'green';
        }}
      />
      <Controls />
    </Graph>
  );
}

export default CustomNodeGraph;