add 99.99% accurate (probably) mp calculation

src/world/Action/Action.cpp

@@ -34,6 +34,9 @@ Sapphire::Action::Action::Action( Entity::CharaPtr caster, uint32_t actionId,
 
   m_costType = static_cast< Common::ActionCostType >( action->costType );
   m_cost = action->cost;
+
+  if( caster->isPlayer() && isCastedAction() )
+    calculateMPCost();
 }
 
 uint32_t Sapphire::Action::Action::getId() const
@@ -41,6 +44,86 @@ uint32_t Sapphire::Action::Action::getId() const
   return m_id;
 }
 
+void Sapphire::Action::Action::calculateMPCost()
+{
+  auto level = m_pSource->getLevel();
+
+  // each level range is 1-10, 11-20, 21-30, ... therefore:
+  // level 50 should be in the 4th group, not the 5th
+  // dividing by 10 on the border will break this unless we subtract 1
+  auto levelGroup = std::max< uint8_t >( level - 1, 1 ) / 10;
+
+  float cost = m_cost;
+
+  // thanks to andrew for helping me figure this shit out, should be pretty accurate
+  switch( levelGroup )
+  {
+    // level 1-10
+    case 0:
+    {
+      // r^2 = 0.9999
+      cost = 0.0952f * level + 0.9467f;
+      break;
+    }
+
+    // level 11-20
+    case 1:
+    {
+      // r^2 = 1
+      cost = 0.19f * level;
+      break;
+    }
+
+    // level 21-30
+    case 2:
+    {
+      // r^2 = 1
+      cost = 0.38f * level - 3.8f;
+      break;
+    }
+
+    // level 31-40
+    case 3:
+    {
+      // r^2 = 1
+      cost = 0.6652f * level - 12.358f;
+      break;
+    }
+
+    // level 41-50
+    case 4:
+    {
+      // r^2 = 1
+      cost = 1.2352f * level - 35.159f;
+      break;
+    }
+
+    // level 51-60
+    case 5:
+    {
+      // r^2 = 1
+      cost = 0.0654f * std::exp( 0.1201f * level );
+      break;
+    }
+
+    // level 61-70
+    case 6:
+    {
+      // r^2 = 0.9998
+      cost = 0.2313f * ( level * level ) - 26.98f * level + 875.21f;
+      break;
+    }
+  }
+
+  // m_cost is the base cost, cost is the multiplier for the current player level
+  m_cost = static_cast< uint16_t >( std::round( cost * m_cost ) );
+}
+
+void Sapphire::Action::Action::subtractCostFromCaster()
+{
+
+}
+
 void Sapphire::Action::Action::setPos( Sapphire::Common::FFXIVARR_POSITION3 pos )
 {
   m_pos = pos;

src/world/Action/Action.h

@@ -74,6 +74,9 @@ namespace Sapphire::Action
 
   protected:
 
+    void calculateMPCost();
+    void subtractCostFromCaster();
+
     /*!
      * @brief Some actions are capable of both healing and dealing damage. This identifies them.
      */