Building Browsergames

def heal(amount)
  if (amount < 0 or amount > self.gold)
    amount = self.gold
  end
 
  if (amount > (self.max_hp - self.cur_hp))
    amount = self.max_hp - self.cur_hp
  end
 
  self.gold -= amount
  self.cur_hp += amount
  self.save
 
  amount
end

<p>Welcome to the healer. You currently have 
<strong><%= current_user.cur_hp %></strong> HP out of a maximum of 
<strong><%= current_user.max_hp %></strong>.</p>
 
<p>You have <strong><%= current_user.gold%></strong> gold to heal yourself with, 
and it will cost you <strong>1 gold per HP healed</strong> to heal yourself.</p>
 
<% form_tag('/healer/do_some_healing', :method => :post) do %>
  <%= text_field_tag 'amount' %>
  <%= submit_tag 'Heal Me'%>
<% end %>
<p><%= link_to "Home", :controller => 'welcome' %></p>
 
<script type="text/javascript">
  window.onload = function() {
    document.getElementById('amount').focus();
  }
</script>

class HealerController < ApplicationController
  def index
  end
 
  def do_some_healing
    # The amount we actually healed might be different than the amount requested
    # due to a variety of factors (i.e. they didn't need that much healing, they
    # didn't have enough gold, etc.) so we record the amount they actually healed
    # which comes back from the method call.
    amount = current_user.heal(params[:amount].to_i)
 
    flash[:notice] = "You have been healed for #{amount} HP."
    render :action => "index"
  end
end

<%= link_to "The Healer", :controller => "healer" %>