app.rb

require 'sinatra'

get '/' do 
  output  = "<form method='post' action='/'>"
  output += "<input type='text' name='user_name' placeholder='name'>"
  output += "<input type='text' name='user_age' placeholder='age'>"
  output += "<button type='submit'>Submit</button>"
  output += "</form>"

  output
end

post '/' do
  name = params[:user_name]
  age  = params[:user_age].to_i # to_i converts the string "5" to the integer 5 

  if age >= 18
    output = "Hello #{name.capitalize}. Here's your drink."
  else
    output = "This bar isn't the place for you, #{name.capitalize}. You're too young."
  end

  output += " <br><br><a href='/'>again</a>"

  output
end

# get '/' do
#   erb :form
# end

# post '/' do
#   @name = params[:user_name]
#   @age  = params[:user_age].to_i

#   if @age >= 18
#     erb :drink
#   else
#     erb :no_drink
#   end
# end