tres exemplos de controllers Command para a landing page

calculator_command.rb

class CalculatorCommand < AppCommand
  class Error < StandardError; end

  def self.sum(a, b)= a + b
  def self.sub(a, b)= a - b
  def self.mul(a, b)= a * b
  def self.div(a, b)= a / b

  def self.call (args)
    log "Called #{self}.#{__method__} with args #{args}"
    new.call(args)
  end

  def call(args)
    log "Called #{self}.#{__method__} with args #{args}"
    return help if args.empty?

    @args = args
    handle_args
    validate_args
    calculate_result
  rescue StandardError => error
    @error = error
    handle_error
  end

  def handle_args
    log "Called #{self}.#{__method__}"
    raise Error, "liza calculator 0 + 0" if @args.size != 3

    @a  = @args[0].to_f
    @op = @args[1].to_sym
    @b  = @args[2].to_f

    log "@a  = #{@a}"
    log "@op = #{@op}"
    log "@b  = #{@b}"
  end
  
  def validate_args
    log "Called #{self}.#{__method__}"
    raise Error, "#{@op} is not a valid operator" unless [:+, :-, :*, :/].include? @op
  end

  def calculate_result
    log "Called #{self}.#{__method__}"
    @result = \
      case @op
      when :+
        self.class.sum(@a, @b)
      when :-
        self.class.sub(@a, @b)
      when :*
        self.class.mul(@a, @b)
      when :/
        self.class.div(@a, @b)
      end
    log "RESULT: #{@result}"
    log render "success.txt"
  end

  def handle_error
    log "Called #{self}.#{__method__}"
    log "an error occured: #{@error}"
    puts
    puts render "error.txt"
    puts
    help
  end

  def help
    log "Called #{self}.#{__method__}"
    puts
    puts render "help.txt"
    puts
  end

end

__END__

# success.txt.erb

RESULT:
  <%= @result %>

# error.txt.erb

ERROR:
  <%= @error %>

# help.txt.erb

NAME:

  liza calculator

DESCRIPTION:

  Calculates the result of an arithmetic operation.

USAGE:

  liza calculator <a> <op> <b>

  where <a> and <b> are numbers and <op> is one of the following operators:

  +   addition
  -   subtraction
  *   multiplication
  /   division

EXAMPLES:

  liza calculator 1 + 2
  liza calculator 3 - 4
  liza calculator 5 * 6
  liza calculator 7 / 8

calendar_command.rb

class CalendarCommand < AppCommand
  class Error < StandardError; end

  def self.wday(year, month, day)
    Date.new(year, month, day).strftime("%A")
  end

  def self.call(args)
    log "Called #{self}.#{__method__} with args #{args}"
    new.call(args)
  end

  def call(args)
    log "Called #{self}.#{__method__} with args #{args}"
    return help if args.empty?

    @args = args
    handle_args
    validate_args
    calculate_result
  rescue StandardError => error
    @error = error
    handle_error
  end

  def handle_args
    log "Called #{self}.#{__method__}"
    raise Error, "liza calendar 2020 10 1" if @args.size != 3

    @year  = @args[0].to_i
    @month = @args[1].to_i
    @day   = @args[2].to_i

    log "@year  = #{@year}"
    log "@month = #{@month}"
    log "@day   = #{@day}"
  end

  def validate_args
    log "Called #{self}.#{__method__}"

    raise Error, "#{@year} is not a valid year" unless (1900..2100).include? @year
    raise Error, "#{@month} is not a valid month" unless (1..12).include? @month
    raise Error, "#{@day} is not a valid day" unless (1..31).include? @day
  end

  def calculate_result
    log "Called #{self}.#{__method__}"

    @result = self.class.wday(@year, @month, @day)
    log "RESULT: #{@result}"
    log render "success.txt"
  end

  def handle_error
    log "Called #{self}.#{__method__}"
    log render "error.txt"
  end

  def help
    log "Called #{self}.#{__method__}"
    log render "help.txt"
  end
end

__END__

# success.txt.erb

RESULT:
  <%= @result %>

# error.txt.erb

ERROR:
  <%= @error %>

# help.txt.erb

NAME:

  liza calendar

DESCRIPTION:

  Displays the week day of a given year, month and day.

USAGE:

  liza calendar <year> <month> <day>

EXAMPLES:

  liza calendar 2020 10 1
  liza calendar 2020 11 1
  liza calendar 2020 12 1

temperature_command.rb

# frozen_string_literal: true
class TemperatureCommand < AppCommand
  class Error < StandardError; end

  def self.c_to_f(c)= (c * 9.0 / 5.0) + 32
  def self.f_to_c(f)= (f - 32) * 5.0 / 9.0
  
  def self.call (args)
    log "Called #{self}.#{__method__} with args #{args}"
    new.call(args)
  end

  def call(args)
    log "Called #{self}.#{__method__} with args #{args}"
    return help if args.empty?
    
    @args = args
    handle_args
    validate_args
    calculate_result
  rescue StandardError => error
    @error = error
    handle_error
  end

  def handle_args
    log "Called #{self}.#{__method__}"
    raise Error, "liza temperature 0 c to f" if @args.size != 4
    raise Error, "liza temperature 0 c to f" if @args[-2] != "to"

    @value = @args[0].to_f
    @from = @args[1].to_sym
    @to = @args[3].to_sym

    log "value = #{@value}"
    log "from  = #{@from}"
    log "to    = #{@to}"
  end

  def validate_args
    log "Called #{self}.#{__method__}"
    raise Error, "#{@from} is not a valid temperature unit" unless [:c, :f].include? @from
    raise Error, "#{@to} is not a valid temperature unit" unless [:c, :f].include? @to
    log "valid"
  end

  def calculate_result
    log "Called #{self}.#{__method__}"
    return @value if @from == @to

    @result = \
      case @from
      when :c
        self.class.c_to_f(@value)
      when :f
        self.class.f_to_c(@value)
      else
        raise Error, "can't convert from #{@from} to #{@to}"
      end
    log "@result = #{@result}"
    log render "success.txt"
  end

  def handle_error
    log "Called #{self}.#{__method__}"
    log "an error occured: #{@error}"
    log render "error.txt"
  end

  def help
    log "Called #{self}.#{__method__}"
    log render "help.txt"
  end

end

__END__

# success.txt.erb

SUCCESS:
  <%= @args.join(" ").upcase %> is <%= @result %>

# error.txt.erb

ERROR:
  <%= @error %>

# help.txt.erb

NAME:
  liza temperature

DESCRIPTION:
  Convert temperature from one unit to another

USAGE:
  liza temperature <temp> <from> to <to>

  where <temp> is a number
  and <from> is a temperature unit (c or f)
  and <to> is a temperature unit (c or f)

EXAMPLES:
  liza temperature 0 c to f
  liza temperature 32 f to c