rm initClass AST based post-processor for decaffeinate

rm-initClass.js

#!/usr/bin/env node
// fixes the decaffeinate result: rm all the static initClass functions
// node scripts/coffee2es6jsx/rm-initClass.mjs files

// todo: rm Search.initClass();

const fs = require('fs');
const Glob = require('glob');

const parser = require("@babel/parser");
const traverse = require("@babel/traverse").default;
// const template = require("@babel/template").default; // quasiquotes
const generate = require("@babel/generator").default;
const t = require("@babel/types");

const read = name => fs.readFileSync(name, 'utf8')
const glob = (glob, each) => Glob(glob, (err, files) => files && files.filter(file => file).map(each))

const createClassProp = (nameNode, valNode, { isStatic } = {}) => {
  return {
    ...t.classProperty(nameNode, valNode),
    static: isStatic,
  }
}

function findAst(globPattern) {
  glob(globPattern, file => {

    const code = read(file)
    const ast = parser.parse(code, {
      // locations: true,
      // allowHashBang: true,
      sourceType: "module",
      plugins: ["jsx", 'optionalChaining', 'classProperties'],
    })

    traverse(ast, {
      ClassMethod(path) {
        const { node } = path;
        if (!(node.static && node.key.name === 'initClass')) return;

        const { body } = node.body
        const items = body
          .filter(item => {
            if (!(item.type === 'ExpressionStatement' && item.expression.type === 'AssignmentExpression')) return false;
            const assgn = item.expression.left;
            if (!(assgn.type === 'MemberExpression')) return false;
            return true;
          })
          .map((item) => {
            const assgn = item.expression.left;
            // (this.prototype).smth = ... -> static smth = ...
            const { name } = assgn.property;
            const valueNode = item.expression.right;
            if (assgn.object.type === 'MemberExpression' && assgn.object.property.name === 'prototype') {
              return createClassProp(t.identifier(name), valueNode);
            }
            // this.smth = ... -> smth = ...
            else {
              return createClassProp(t.identifier(name), valueNode, { isStatic: true });
            }
          });
        path.replaceWithMultiple(items);
      }
    });
    process.stdout.write(generate(ast).code);
  })
}

findAst(process.argv[2])

/*
  //
  // RAW:

  static initClass() {
    this.propTypes =
      {onChange: PropTypes.func.isRequired};

    this.prototype.state = {
      term: "",
      results: null,
      inProgress: false,
      resetTermHack: null,
      qrInputMode: 'input'
    };

    this.prototype.url = "/admin/package_creations/search_card";
  }
*/

/*
  //
  // Target:

  static propTypes = {onChange: PropTypes.func.isRequired};

  state = {
    term: "",
    results: null,
    inProgress: false,
    resetTermHack: null,
    qrInputMode: 'input'
  }

  url = "/admin/package_creations/search_card"
*/