# In Crystal, we use exceptions for error handling.
# We'll define a custom exception class for our specific error.
class CannotWorkWithFortyTwoError < Exception
end

# We define a method that may raise an exception
def f(arg : Int32) : Int32
  if arg == 42
    # Instead of returning an error, we raise an exception
    raise CannotWorkWithFortyTwoError.new("can't work with 42")
  end
  
  # If no exception is raised, we simply return the result
  arg + 3
end

# We can define custom error classes for specific scenarios
class OutOfTeaError < Exception
end

class PowerError < Exception
end

def make_tea(arg : Int32)
  case arg
  when 2
    raise OutOfTeaError.new("no more tea available")
  when 4
    # In Crystal, we don't need to wrap errors. We can just raise a new exception.
    raise PowerError.new("can't boil water")
  end
end

# Main execution
begin
  [7, 42].each do |i|
    begin
      result = f(i)
      puts "f worked: #{result}"
    rescue ex : CannotWorkWithFortyTwoError
      puts "f failed: #{ex.message}"
    end
  end

  5.times do |i|
    begin
      make_tea(i)
      puts "Tea is ready!"
    rescue ex : OutOfTeaError
      puts "We should buy new tea!"
    rescue ex : PowerError
      puts "Now it is dark."
    rescue ex
      puts "unknown error: #{ex.message}"
    end
  end
rescue ex
  puts "An unexpected error occurred: #{ex.message}"
end