[GH-327] Add Speed

apps/champions/lib/champions/battle/simulator.ex

@@ -6,34 +6,51 @@ defmodule Champions.Battle.Simulator do
   has no cooldown and it's cast whenever a unit reaches 500 energy. Energy is gained whenever the target attacks.
   The primary skill has a cooldown and it's cast when it's available if the ultimate is not.
 
-  Skills possess many effects with their own targets. Effects are composed of `Components`, `Modifiers` and
-  `Executions` (check module docs for more info on each).
+  Skills possess many mechanics. The only implemented mechanic right now is `ApplyEffectsTo`, which is composed of many effects
+  and a targeting strategy. Effects are composed of `Components`, `Modifiers` and `Executions` (check module docs for more info on each).
 
-  They have different application types (checked are implemented):
+  ### ApplyEffectsTo mechanics
+
+  Effects have different application types:
   [x] Instant - Applied once, irreversible.
   [x] Permanent - Applied once, is stored in the unit so that it can be reversed (with a dispel, for example)
   [x] Duration - Applied once and reverted once its duration ends.
+  [ ] Periodic - Applied every X steps  until duration ends.
 
-  They also have different targeting strategies:
+  The different targeting strategies are:
   [x] Random
-  [X] Nearest
-  [X] Furthest
-  [ ] Frontline - Heroes in slots 1 and 2
-  [ ] Backline - Heroes in slots 2 to 4
+  [x] Nearest
+  [x] Furthest
+  [x] Frontline - Heroes in slots 1 and 2
+  [x] Backline - Heroes in slots 2 to 4
+  [x] All
+  [ ] Self
   [ ] Factions
   [ ] Classes
   [ ] Min (STAT)
   [ ] Max (STAT)
 
-  And different ways in which their amount is interpreted:
-  [x] Additive
-  [x] Multiplicative
-  [x] Additive & based on stat - The amount is a % of one of the caster's stats
-  [ ] Multiplicative & based on stat?
+  It can also be chosen how many targets are affected by the effect, and if they are allies or enemies.
+
+
+  ### Simultaneous Battles
 
   Two units can attack the same unit at the same time and over-kill it. This is expected behavior that results
-  from having the battle be simultaneous.
+  from having the battle be simultaneous. If this weren't the case, the battle would be turn-based, since a unit
+  would base its actions on the state of the battle at the end of the previous unit's action.
+
+  ### Speed Stat
+  Units have a `speed` stat that affects the cooldown of their basic skill. The formula is:
+  `FINAL_CD = BASE_CD / [1 + MAX(-99, SPEED) / 100];`
+  For now, speed is only used to calculate the cooldown of newly cast skills, meaning it's not retroactive with
+  skills already on cooldown.
+
+  ### History
 
+  A "history" is built as the battle progresses. This history is used to animate the battle in the client. The history
+  is a list of maps, each map representing a step in the battle. Each step has a `step_number` and a list of `actions`.
+  These are all translated into Protobuf messages, together with the initial state of the battle and the result,
+  and then sent to the client.
   """
   alias Champions.Units
   alias GameBackend.Units.Skills.Skill
@@ -208,7 +225,7 @@ defmodule Champions.Battle.Simulator do
             |> put_in(
               [:units, unit.id, :basic_skill, :remaining_cooldown],
               # We need this + 1 because we're going to reduce the cooldown at the end of the step
-              unit.basic_skill.base_cooldown + 1
+              calculate_cooldown(unit.basic_skill, unit) + 1
             )
             |> update_in([:units, unit.id, :energy], &(&1 + unit.basic_skill.energy_regen))
 
@@ -267,6 +284,16 @@ defmodule Champions.Battle.Simulator do
     {new_state, new_history}
   end
 
+  defp calculate_cooldown(skill, unit) do
+    speed = calculate_unit_stat(unit, :speed) |> Decimal.from_float()
+
+    divisor = Decimal.div(Decimal.max(-99, speed), 100) |> Decimal.add(1)
+
+    Decimal.div(skill.base_cooldown, divisor)
+    |> Decimal.round()
+    |> Decimal.to_integer()
+  end
+
   # Reduces modifier timers and removes expired ones.
   # Called when processing a step for a unit.
   defp reduce_modifier_timers(modifiers, unit, history) do
@@ -966,6 +993,7 @@ defmodule Champions.Battle.Simulator do
          health: Units.get_health(unit),
          attack: Units.get_attack(unit),
          defense: Units.get_defense(unit),
+         speed: Units.get_speed(unit),
          energy: 0,
          modifiers: %{
            additives: [],
@@ -1104,6 +1132,7 @@ defmodule Champions.Battle.Simulator do
   defp string_to_atom("duration"), do: :duration
   defp string_to_atom("period"), do: :period
   defp string_to_atom("instant"), do: :instant
+  defp string_to_atom("permanent"), do: :permanent
 
   defp string_to_atom("ATTACK"), do: :ATTACK
   defp string_to_atom("DEFENSE"), do: :DEFENSE

apps/champions/lib/champions/units.ex

@@ -367,7 +367,7 @@ defmodule Champions.Units do
   @doc """
   Get a unit's health stat for battle, including modifiers from items.
 
-  Character and ItemTemplate must be preloaded.
+  Character, Items and ItemTemplates must be preloaded.
 
   ## Examples
 
@@ -380,7 +380,7 @@ defmodule Champions.Units do
   @doc """
   Get a unit's attack stat for battle, including modifiers from items.
 
-  Character and ItemTemplate must be preloaded.
+  Character, Items and ItemTemplates must be preloaded.
 
   ## Examples
 
@@ -393,7 +393,7 @@ defmodule Champions.Units do
   @doc """
   Get a unit's defense stat for battle, including modifiers from items.
 
-  Character and ItemTemplate must be preloaded.
+  Character, Items and ItemTemplates must be preloaded.
 
   ## Examples
 
@@ -403,6 +403,20 @@ defmodule Champions.Units do
   """
   def get_defense(unit), do: calculate_stat(unit.character.base_defense, unit, "defense")
 
+  @doc """
+  Get a unit's speed stat for battle, including modifiers from items.
+  Unlike other stats, speed is not affected by the unit's level, tier or rank.
+
+  Items and Templates must be preloaded.
+
+  ## Examples
+
+      iex> {:ok, unit} = Champions.Units.get_unit(unit_id)
+      iex> Champions.Units.get_speed(unit)
+      100
+  """
+  def get_speed(unit), do: factor_items(Decimal.new(0), unit.items, "speed")
+
   defp calculate_stat(base_stat, unit, stat_name),
     do:
       base_stat
@@ -459,17 +473,13 @@ defmodule Champions.Units do
   end
 
   defp get_additive_and_multiplicative_modifiers(items, attribute) do
-    item_modifiers =
-      Enum.flat_map(items, & &1.template.modifiers)
+    item_modifiers = Enum.flat_map(items, & &1.template.modifiers)
 
-    attribute_modifiers =
-      Enum.filter(item_modifiers, &(&1.attribute == attribute))
+    attribute_modifiers = Enum.filter(item_modifiers, &(&1.attribute == attribute))
 
-    additive_modifiers =
-      Enum.filter(attribute_modifiers, &(&1.operation == "Add"))
+    additive_modifiers = Enum.filter(attribute_modifiers, &(&1.operation == "Add"))
 
-    multiplicative_modifiers =
-      Enum.filter(attribute_modifiers, &(&1.operation == "Multiply"))
+    multiplicative_modifiers = Enum.filter(attribute_modifiers, &(&1.operation == "Multiply"))
 
     {additive_modifiers, multiplicative_modifiers}
   end