Converts commonJS requires to es6 imports

requiresToImports.js

/**

### Regular component require statement
```
const Token = require('v2/core/components/tokenizer/token');
-> import Token from 'v2/core/components/tokenizer/token';
```

### Destructured require statement
```
const {OverlayTrigger, Tooltip} = require('react-bootstrap');
-> import {OverlayTrigger, Tooltip} from 'react-bootstrap';
```

### Regular require with member expression
```
const identity = require('underscore').identity;
-> import {identity} from 'underscore';
```

### Destructured require with member expression
```
const {
 PERFORMANCE_QUESTION,
 PREPARATION_QUESTION,
 SATISFACTION_QUESTION,
 PLANNING_QUESTION,
} = require('v2/core/constants/studentAssessmentReflection').REFLECTION_QUESTIONS
-> import {REFLECTION_QUESTIONS} from 'v2/core/constants/studentAssessmentReflection';
-> const {
 PERFORMANCE_QUESTION,
 PREPARATION_QUESTION,
 SATISFACTION_QUESTION,
 PLANNING_QUESTION,
} = REFLECTION_QUESTIONS;
```
*/
'use strict';

module.exports = function(fileInfo, api) {
  var j = api.jscodeshift;
  var root = j(fileInfo.source);

  // This converts straight forward requires like ; const thing = require('thing');
  root
    .find(j.VariableDeclaration, {
      declarations: [{
        type: 'VariableDeclarator',
        init: {
          type: 'CallExpression',
          callee: {
            type: 'Identifier',
            name: 'require',
          },
        },
      }],
    })
    .filter(isTopLevel)
    .forEach(function(path) {
      const dec = path.value.declarations[0];
      const id = dec.id;
      const source = dec.init.arguments[0];
      const comments = path.value.comments;
      const loc = path.value.loc;

      path.replace(
        j.importDeclaration(
          [{
            type: 'ImportDefaultSpecifier',
            id
          }],
          source
        )
      );
      path.value.loc = loc;
      path.value.comments = comments;
    });

  // This handles more complicated cases like; const {A, B} = require('stuff').THINGS;
  root
    .find(j.VariableDeclaration, {
      declarations: [{
        type: 'VariableDeclarator',
        init: {
          type: 'MemberExpression',
          object: {
            type: 'CallExpression',
            callee: {
              type: 'Identifier',
              name: 'require'
            },
          },
        },
      }],
    })
    .filter(isTopLevel)
    .forEach(function(path) {
      const dec = path.value.declarations[0];
      const name = dec.id;
      const source = dec.init.object.arguments[0];
      const id = dec.init.property;
      const comments = path.value.comments;
      const loc = path.value.loc;

      let spec = {
        type: 'ImportSpecifier',
        id,
      }

      if (name.name !== id.name && name.type !== 'ObjectPattern') {
        spec['name'] = name;
      }

      if (name.type === 'ObjectPattern') {
        // Handle destructured member expression with two statements
        path.insertAfter(j.variableDeclaration('const',[
          j.variableDeclarator(name, id),
        ]));
      }

      path.replace(j.importDeclaration([spec], source));
      path.value.loc = loc;
      path.value.comments = comments;
    });

  return root.toSource();
};

function isTopLevel(path) {
  return !path.parentPath.parentPath.parentPath.parentPath;
}

testFile.js

// Regular component require statement; should be
// import Token from 'core/components/tokenizer/token';
const Token = require('core/components/tokenizer/token');

// Destructured require statement; should be
// import {OverlayTrigger, Tooltip} from 'react-bootstrap';
const {OverlayTrigger, Tooltip} = require('react-bootstrap');

// Regular require with member expression; should be
// import {identity} from 'underscore';
const identity = require('underscore').identity;

// Destructured require with member expression; should be
// import {REFLECTION_QUESTIONS} from 'core/constants/reflection';
// const {
//  PERFORMANCE_QUESTION,
//  PREPARATION_QUESTION,
//  SATISFACTION_QUESTION,
//  PLANNING_QUESTION,
// } = REFLECTION_QUESTIONS;
const {
  PERFORMANCE_QUESTION,
  PREPARATION_QUESTION,
  SATISFACTION_QUESTION,
  PLANNING_QUESTION,
} = require('core/constants/reflection').REFLECTION_QUESTIONS;