Add build command

src/game/building.cr

@@ -1,5 +1,5 @@
 module Game
-  struct Production
+  class Production
     def initialize(@ts : TimeSpan, @input : Resources, @output : Resources)
     end
 
@@ -8,7 +8,7 @@ module Game
     getter output
   end
 
-  struct Restoration
+  class Restoration
     def initialize(@ts : TimeSpan, @type : Resources::Type, @cap : Capacity)
     end
 
@@ -17,7 +17,7 @@ module Game
     getter cap
   end
 
-  struct Construction
+  class Construction
     def initialize(@ts : TimeSpan, @cost : Resources, @requirements : Array(Building::Type))
     end
 

src/game/command.cr

@@ -16,8 +16,13 @@ module Game
     end
 
     def start(world : World) : TimeSpan
+      construction = @building.construction
+      if !world.resources.has(construction.cost)
+        raise NotEnoughtResources.new
+      end
+      # @todo check requirements
       world.map.set(ConstructionSiteTile.new(@point))
-      @building.construction.ts
+      construction.ts
     end
 
     def finish(world : World)

src/game/resources.cr

@@ -6,10 +6,10 @@ class Game::Resources
     Terraformation
   end
 
-  alias Capacity = Int32
-
   alias ResourceBag = Hash(Type, Capacity)
 
+  @values : ResourceBag
+
   def initialize(vals : ResourceBag | Nil = nil)
     @values = {} of Type => Capacity
     Type.each { |t, v| @values[t] = 0 }
@@ -37,6 +37,10 @@ class Game::Resources
     end
   end
 
+  def has(vs : self) : Bool
+    has vs.to_hash
+  end
+
   def inc(t : Type, value : Capacity)
     new_value = @values.fetch(t, 0) + value
     if new_value < 0
@@ -56,4 +60,8 @@ class Game::Resources
   def dec(t : Type, value : Capacity)
     inc(t, -value)
   end
+
+  def to_hash : ResourceBag
+    @values.clone
+  end
 end