defmodule Calculator do
  def add(left, right), do: left + right
  def sub(left, right), do: left - right
  def div(left, right), do: left / right
  def mul(left, right), do: left * right
end

defmodule Zad2 do
  def isEven(number), do: rem(number, 2) == 0
end

defmodule Figures do
  def squareArea(squareSide), do: squareSide ** 2
  def rectangleArea(width, height), do: width * height
  def checkTriangle(x, y, z) do
    cond do
      (x === y and y === z) -> "Equilateral"
      (x === y or y === z or x === z) -> "Isosceles"
      true -> "Scalene"
    end
  end
end

defmodule Zad3 do
  def mapExercise do
    sample = %{:first => 1, 2 => 2, 3 => 3, 4 => 4, :last => 5}
    IO.inspect(sample)

    sample = %{sample | :last => 10, :first => 50}
    IO.inspect(sample)

    sample = Map.drop(sample, [:first, :last])
    IO.inspect(sample)
  end

  def stringInterpolation(left, right), do: left <> right

  def fileOperations do
    {:ok, file} = File.open('test.txt', [:write, :read])
    IO.write(file, 'sample')
    File.close(file)

    {:ok, content} = File.read('test.txt')
    IO.puts content
  end
end

defmodule Book do
  defstruct isbn: '', author: '', title: '', description: '', price: 0.0, genre: ''

  defimpl String.Chars, for: Book do
    def to_string(book) do
      """
      ISBN: #{book.isbn}
      Author: #{book.author}
      Title: #{book.title}
      Description: #{book.description}
      Price: #{book.price}
      Genre: #{book.genre}
      """
    end
  end
end



defmodule Main do
  def main do
    IO.puts Calculator.add(4, 3)
    IO.puts Calculator.sub(4, 3)
    IO.puts Calculator.mul(4, 3)
    IO.puts Calculator.div(4, 3)

    IO.puts Zad2.isEven(4)

    IO.puts Figures.squareArea(4)
    IO.puts Figures.rectangleArea(4, 5)
    IO.puts Figures.checkTriangle(8, 7, 5)

    #
    # Zad 3
    #
    Zad3.mapExercise()
    IO.puts Zad3.stringInterpolation("Dajba", "mamkamu")
    Zad3.fileOperations()


    # Zad 4

    book = %Book{}
    IO.puts book

    book = %Book{book | author: 'Astrit Lintgren', isbn: '01111', title: 'Pipi Linstocking', description:  'It\'s about a girl names Pipi', price: 10.00, genre: 'novel'}
    IO.puts book
    IO.puts "Author: #{book.author}"

    stream = -5..5
    newStream = Enum.map(stream, &(&1 ** 3))

    IO.inspect Enum.to_list(stream)
    IO.inspect newStream

    for number <- stream,  do: if rem(number, 5) === 0 or rem(number, 2) === 0, do: IO.puts number
  end
end

Main.main()