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1 files changed, 279 insertions, 0 deletions

diff --git a/src/battle/attack.erl b/src/battle/attack.erl
new file mode 100644
index 0000000..7384f78
--- /dev/null
+++ b/src/battle/attack.erl
@@ -0,0 +1,279 @@
+-module(attack).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+% TODO: find better names for those types.
+-type hits() :: ('misses' | 'grazes' | 'hits').
+-type critical() :: ('critical' | 'basic').
+-type attack_order() :: 'first' | 'second' | 'counter'.
+-type attack_order_with_parry() :: {attack_order(), boolean()}.
+-type attack_category() ::
+   (
+      attack_order()
+      | {attack_order(), 'parry'}
+   ).
+-type attack_effect() :: {hits(), critical(), non_neg_integer()}.
+-type attack_desc() ::
+   (
+      {attack_category(), attack_effect()}
+      | 'nothing'
+   ).
+
+-export_type
+(
+   [
+      hits/0,
+      critical/0,
+      attack_category/0,
+      attack_effect/0,
+      attack_desc/0
+   ]
+).
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+-export
+(
+   [
+      get_sequence/3,
+      get_description_of/3,
+      apply_to_healths/3
+   ]
+).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+-spec roll_hits
+   (
+      statistics:struct(),
+      statistics:struct()
+   )
+   -> hits().
+roll_hits (AttackerStatistics, DefenderStatistics) ->
+   DefenderDodges = statistics:get_dodges(DefenderStatistics),
+   AttackerAccuracy = statistics:get_accuracy(AttackerStatistics),
+   MissChance = max(0, (DefenderDodges - AttackerAccuracy)),
+   case roll:percentage() of
+      X when (X =< MissChance) -> misses;
+      X when (X =< (MissChance * 2)) -> grazes;
+      _ -> hits
+   end.
+
+-spec roll_damage
+   (
+      statistics:struct(),
+      statistics:struct()
+   )
+   -> {critical(), non_neg_integer()}.
+roll_damage (AttackerStatistics, _DefenderStatistics) ->
+   {MinimumDamage, MaximumDamage} = statistics:get_damages(AttackerStatistics),
+   MaximumRoll = max(1, MaximumDamage - MinimumDamage),
+   BaseDamage = MinimumDamage + (rand:uniform(MaximumRoll) - 1),
+   CriticalHitChance = statistics:get_critical_hits(AttackerStatistics),
+   case roll:percentage() of
+      X when (X =< CriticalHitChance) -> {critical, (BaseDamage * 2)};
+      _ -> {basic, BaseDamage}
+   end.
+
+-spec effect_of_attack
+   (
+      statistics:struct(),
+      statistics:struct()
+   )
+   -> attack_effect().
+effect_of_attack (AttackerStatistics, DefenderStatistics) ->
+   Hits = roll_hits(AttackerStatistics, DefenderStatistics),
+   {Critical, Damage} = roll_damage(AttackerStatistics, DefenderStatistics),
+   case Hits of
+      misses -> {Hits, Critical, 0};
+      grazes -> {Hits, Critical, trunc(Damage / 2)};
+      hits -> {Hits, Critical, Damage}
+   end.
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% EXPORTED FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-spec get_description_of
+   (
+      attack_order_with_parry(),
+      statistics:struct(),
+      statistics:struct()
+   )
+   -> attack_desc().
+get_description_of
+(
+   {first, DefenderCanParry},
+   AttackerStatistics,
+   DefenderStatistics
+) ->
+   DefenderParryChance = statistics:get_parries(DefenderStatistics),
+   ParryRoll =
+      case DefenderCanParry of
+         true -> roll:percentage();
+         _ -> 101
+      end,
+   if
+      (ParryRoll =< DefenderParryChance) ->
+            {
+               {first, parry},
+               effect_of_attack(DefenderStatistics, AttackerStatistics)
+            };
+
+      true ->
+         {first, effect_of_attack(AttackerStatistics, DefenderStatistics)}
+   end;
+get_description_of
+(
+   {second, DefenderCanParry},
+   AttackerStatistics,
+   DefenderStatistics
+) ->
+   DefenderParryChance = statistics:get_parries(DefenderStatistics),
+   ParryRoll =
+      case DefenderCanParry of
+         true -> roll:percentage();
+         _ -> 101
+      end,
+   AttackerDoubleAttackChange = statistics:get_double_hits(AttackerStatistics),
+   DoubleAttackRoll = roll:percentage(),
+   if
+      (DoubleAttackRoll > AttackerDoubleAttackChange) ->
+         nothing;
+
+      (ParryRoll =< DefenderParryChance) ->
+            {
+               {second, parry},
+               effect_of_attack(DefenderStatistics, AttackerStatistics)
+            };
+
+      true ->
+         {second, effect_of_attack(AttackerStatistics, DefenderStatistics)}
+   end;
+get_description_of
+(
+   {counter, AttackerCanParry},
+   AttackerStatistics,
+   DefenderStatistics
+) ->
+   AttackerParryChance = statistics:get_parries(AttackerStatistics),
+   ParryRoll =
+      case AttackerCanParry of
+         true -> roll:percentage();
+         _ -> 101
+      end,
+   if
+      (ParryRoll =< AttackerParryChance) ->
+            {
+               {counter, parry},
+               effect_of_attack(AttackerStatistics, DefenderStatistics)
+            };
+
+      true ->
+         {counter, effect_of_attack(DefenderStatistics, AttackerStatistics)}
+   end.
+
+-spec apply_to_healths
+   (
+      attack_desc(),
+      non_neg_integer(),
+      non_neg_integer()
+   )
+   -> {attack_desc(), non_neg_integer(), non_neg_integer()}.
+apply_to_healths
+(
+   nothing,
+   AttackerHealth,
+   DefenderHealth
+) ->
+   {nothing, AttackerHealth, DefenderHealth};
+apply_to_healths
+(
+   {Attack, Effect},
+   AttackerHealth,
+   DefenderHealth
+)
+when
+(
+   (Attack == first)
+   or (Attack == second)
+   or (Attack == {counter, parry})
+) ->
+   {_Hits, _Critical, Damage} = Effect,
+   case AttackerHealth of
+      0 ->
+         {nothing, AttackerHealth, DefenderHealth};
+
+      _ ->
+         {
+            {Attack, Effect},
+            AttackerHealth,
+            max(0, (DefenderHealth - Damage))
+         }
+   end;
+apply_to_healths
+(
+   {Attack, Effect},
+   AttackerHealth,
+   DefenderHealth
+)
+when
+(
+   (Attack == {first, parry})
+   or (Attack == {second, parry})
+   or (Attack == counter)
+) ->
+   {_Hits, _Critical, Damage} = Effect,
+   case DefenderHealth of
+      0 ->
+         {nothing, AttackerHealth, DefenderHealth};
+
+      _ ->
+         {
+            {Attack, Effect},
+            max(0, (AttackerHealth - Damage)),
+            DefenderHealth
+         }
+   end.
+
+-spec get_sequence
+   (
+      non_neg_integer(),
+      weapon:struct(),
+      weapon:struct()
+   )
+   -> list(attack_order_with_parry()).
+get_sequence (AttackRange, AttackerWeapon, DefenderWeapon) ->
+   {AttackerDefenseRange, AttackerAttackRange} =
+      weapon:get_ranges(AttackerWeapon),
+   {DefenderDefenseRange, DefenderAttackRange} =
+      weapon:get_ranges(DefenderWeapon),
+
+   AttackerCanAttack = (AttackRange =< AttackerAttackRange),
+   AttackerCanDefend =
+      (AttackerCanAttack and (AttackRange > AttackerDefenseRange)),
+   AttackerCanParry =
+      (AttackerCanDefend and weapon:can_parry(AttackerWeapon)),
+
+   DefenderCanAttack = (AttackRange =< DefenderAttackRange),
+   DefenderCanDefend =
+      (DefenderCanAttack and (AttackRange > DefenderDefenseRange)),
+   DefenderCanParry =
+      (DefenderCanDefend and weapon:can_parry(DefenderWeapon)),
+
+   First = {first, DefenderCanParry},
+   Second = {second, DefenderCanParry},
+   Counter = {counter, AttackerCanParry},
+
+   if
+      (not AttackerCanAttack) ->
+         [];
+
+      (not DefenderCanDefend) ->
+         [First, Second];
+
+      true ->
+         [First, Counter, Second]
+   end.