A possible solution for the CoronaSafe Fellowship Todo CLI application

todo_cli_coronasafe.js

/*
https://fullstack.pupilfirst.org
https://github.com/nseadlc-2020/package-todo-cli-task/tree/master/shared
*/

const EOL = require('os').EOL
const fs = require('fs')

const PENDING_TODOS_FILE = 'todo.txt'
const COMPLETED_TODOS_FILE = 'done.txt'

const HELP_STRING = `Usage :-
$ ./todo add \"todo item\"  # Add a new todo
$ ./todo ls               # Show remaining todos
$ ./todo del NUMBER       # Delete a todo
$ ./todo done NUMBER      # Complete a todo
$ ./todo help             # Show usage
$ ./todo report           # Statistics`;

/* https://stackoverflow.com/a/57163283 */
let isEmpty = x => !Boolean(x);

/* https://stackoverflow.com/a/50130338 */
let getToday = () => {
  let date = new Date();
  return new Date(date.getTime() - (date.getTimezoneOffset() * 60000))
    .toISOString()
    .split("T")[0];
}

let readFile = (filename) => {
  if (!fs.existsSync(filename)) {
    return []
  }
  let text = fs.readFileSync(filename, {encoding: 'utf8', flag: 'r'})
  lines = text.split(EOL)
  return lines
}

let appendToFile = (filename, text) => {
  fs.appendFileSync(filename, text, {encoding: 'utf8', flag: 'a+'});
}

let writeFile = (filename, lines) => {
  let text = lines.join(EOL)
  fs.writeFileSync(filename, text, {encoding: 'utf8'});
}

let updateFile = (filename, updaterFn) => {
  let contents = readFile(filename)
  contents = updaterFn(contents)
  writeFile(filename, contents)
}

let cmdHelp = () => {
  console.log(HELP_STRING);
}

let cmdLs = () => {
  let todos = readFile(PENDING_TODOS_FILE)
  if (todos.length == 0) {
    console.log("There are no pending todos!")
    return
  }
  let length = todos.length
  todos = todos.reverse().map((todo, index) => `[${length - index}] ${todo}`)
  console.log(todos.join("\n"))
}

let cmdAddTodo = (text) => {
  if (isEmpty(text)) {
    console.log("Error: Missing todo string. Nothing added!")
    return
  }

  updateFile(PENDING_TODOS_FILE, todos => {
    return todos.concat([text])
  })

  console.log(`Added todo: "${text}"`)
}

let cmdDelTodo = (number) => {
  if (isEmpty(number)) {
    console.log(`Error: Missing NUMBER for deleting todo.`)
    return
  }
  number = Number(number)
  updateFile(PENDING_TODOS_FILE, todos => {
    if (number < 1 || number > todos.length) {
      console.log(`Error: todo #${number} does not exist. Nothing deleted.`)
    } else {
      todos.splice(number, 1)
      console.log(`Deleted todo #${number}`)
    }
    return todos
  });
}

let cmdMarkDone = (number) => {
  if (isEmpty(number)) {
    console.log(`Error: Missing NUMBER for marking todo as done.`)
    return
  }

  number = Number(number)
  let todos = readFile(PENDING_TODOS_FILE)

  if (number < 1 || number > todos.length) {
    console.log(`Error: todo #${number} does not exist.`)
    return
  }

  let completedTodo = todos.splice(number, 1)
  writeFile(PENDING_TODOS_FILE, todos)

  completedTodo = completedTodo[0] + EOL
  appendToFile(COMPLETED_TODOS_FILE, completedTodo)

  console.log(`Marked todo #${number} as done.`)
}

let cmdReport = () => {
  let pending = readFile(PENDING_TODOS_FILE).length - 1
  let completed = readFile(COMPLETED_TODOS_FILE).length - 1
  console.log(`${getToday()} Pending : ${pending} Completed : ${completed}`)
}

let argv = process.argv
let command = argv[2];
let arg = argv[3];

if (isEmpty(command)) {
  cmdHelp();
} else {
  switch (command.trim().toLowerCase()) {
    case 'help':
      cmdHelp()
      break;
    case 'ls':
      cmdLs()
      break
    case 'add':
      cmdAddTodo(arg)
      break
    case 'del':
      cmdDelTodo(arg)
      break
    case 'done':
      cmdMarkDone(arg)
      break
    case 'report':
      cmdReport()
      break
    default:
      cmdHelp()
  }
}

Good Morning Sir,
Iam beginner for this programming Language,Could you Please post the above program in C language for better understanding to me .
Thank you sir

@mohamedhazzali3 Sorry, we won't be able to port this to other languages.

impressive way of handling the io operations, I used js too and found it hard to keep the code clean, thank you for this

@mohamedhazzali3 You can see my approach todo-cli-c. I have divided the program into separate modules.

• fileHandling.c : to handle file operations
• commands.c: to handle the commands
• main.c: main entrypoint for the program
  It passed all the tests as well.
  Tried to follow the good practices in C. See if you can find some room for improvement.