text: // @flow
  /*
    Copyright(c) 2018 Uber Technologies, Inc.
  
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at
  
            http://www.apache.org/licenses/LICENSE-2.0
  
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
  */
  
  import { type IEdge } from '../../components/edge';
  import { type INode } from '../../components/node';
  import Transformer, { type IGraphInput } from './transformer';
  
  export default class BwdlTransformer extends Transformer {
    static transform(input: any) {
      if (!input.States) {
        return {
          edges: [],
          nodes: [],
        };
      }
  
      const nodeNames = Object.keys(input.States);
  
      const nodes: INode[] = [];
      const edges: IEdge[] = [];
  
      nodeNames.forEach(name => {
        const currentNode = input.States[name];
  
        if (!currentNode) {
          return;
        }
  
        const nodeToAdd: INode = {
          title: name,
          type: currentNode.Type,
          text: currentNode.text,
          x: currentNode.x || 0,
          y: currentNode.y || 0,
        };
  
        if (name === input.StartAt) {
          nodes.unshift(nodeToAdd);
        } else {
          nodes.push(nodeToAdd);
        }
  
        // create edges
        if (currentNode.Type === 'Choice') {
          // multiple edges
          currentNode.Choices.forEach(choice => {
            if (input.States[choice.Next]) {
              edges.push({
                source: name,
                target: choice.Next,
              });
            }
          });
  
          // Choice nodes carry both a Choices list and an optional Default value which is not part of the list.
          if (currentNode.Default) {
            edges.push({
              source: name,
              target: currentNode.Default,
            });
          }
        } else if (currentNode.Next) {
          if (input.States[currentNode.Next]) {
            // single edge
            edges.push({
              source: name,
              target: currentNode.Next,
            });
          }
        }
      });
  
      return {
        edges,
        nodes,
      };
    }
  
    static revert(graphInput: IGraphInput) {
      return graphInput;
    }
  }
  