fs.ts

import fs from 'node:fs'
import path from 'node:path'
import detectIndent from 'detect-indent'
import { detectNewline } from 'detect-newline'

/**
 * Describes a plain-text file.
 */
export interface TextFile {
  path: string
  data: string
}

/**
 * Describes a JSON file.
 */
interface JsonFile {
  path: string
  data: unknown
  indent: string
  newline: string | undefined
}

/**
 * Reads a JSON file and returns the parsed data.
 */
export async function readJsonFile(name: string, cwd: string): Promise<JsonFile> {
  const file = await readTextFile(name, cwd)
  const data = JSON.parse(file.data) as unknown
  const indent = detectIndent(file.data).indent
  const newline = detectNewline(file.data)

  return { ...file, data, indent, newline }
}

/**
 * Writes the given data to the specified JSON file.
 */
export async function writeJsonFile(file: JsonFile): Promise<void> {
  let json = JSON.stringify(file.data, undefined, file.indent)

  if (file.newline)
    json += file.newline

  return writeTextFile({ ...file, data: json })
}

/**
 * Reads a text file and returns its contents.
 */
export function readTextFile(name: string, cwd: string): Promise<TextFile> {
  return new Promise((resolve, reject) => {
    const filePath = path.join(cwd, name)

    fs.readFile(filePath, 'utf8', (err, text) => {
      if (err) {
        reject(err)
      }
      else {
        resolve({
          path: filePath,
          data: text,
        })
      }
    })
  })
}

/**
 * Writes the given text to the specified file.
 */
export function writeTextFile(file: TextFile): Promise<void> {
  return new Promise((resolve, reject) => {
    fs.writeFile(file.path, file.data, (err) => {
      if (err)
        reject(err)

      else
        resolve()
    })
  })
}