Split GoLang file methods into new files

split_go_file.js

import fs from 'fs';
import path from 'path';

const rootPath = "/Users/angelo/www/my-app"
const contextRelativePath = "pkg/some_package"
const fileName = "file_name.go"

const fileLines = fs
  .readFileSync(path.join(rootPath, contextRelativePath, fileName))
  .toString()
  .trim()
  .split("\n");

const indexOfFirstOption = fileLines.findIndex(line => line.includes("func "));

const commonHeader = fileLines.slice(0, indexOfFirstOption).join("\n")

const indexesOfFunctionsDeclarations = fileLines.reduce(
  (acc, next, index) => {
    if (next.includes("func ")) {
      acc.push(index);
    }

    return acc;
  },
  [],
);

const methods = indexesOfFunctionsDeclarations.reduce(
  (acc, declarationStartIndex) => {
    let scopeLevel = 0
    let foundAtLeastOneScope = false

    const methodPossibleSlice = fileLines.slice(declarationStartIndex);

    const methodName = fileLines[declarationStartIndex].match(
      /func\s+(\([\w\s\*\d]+\)\s+)?(\w+)\s*\(/,
    )[2];

    for (let i = 0; i < methodPossibleSlice.length; i++) {
      const sliceLine = methodPossibleSlice[i];

      scopeLevel += (sliceLine.match(/{/g) || []).length;
      scopeLevel -= (sliceLine.match(/}/g) || []).length;

      if (!foundAtLeastOneScope) {
        foundAtLeastOneScope = (sliceLine.match(/{/g) || []).length > 0
      }

      if (scopeLevel === 0 && foundAtLeastOneScope) {
        acc.push(
          {
            name: methodName,
            file_name: (() => {
              let as_snake = methodName
                .replace(/([A-Z])/g, " $1")
                .split(' ')
                .join('_')
                .toLowerCase();

              if (as_snake[0] === "_") {
                as_snake = as_snake.slice(1);
              }

              return as_snake
            })() + ".go",
            content: [
              commonHeader,
              fileLines.slice(
                declarationStartIndex,
                declarationStartIndex + i + 1,
              ).join("\n")
            ].join("\n"),
          }
        );

        break
      }
    }

    return acc
  },
  [],
)

methods.forEach(method => {
  fs.writeFileSync(
    path.join(rootPath, contextRelativePath, method.file_name),
    method.content,
  )
})