regenerate mana on the server

at type 0 the client stopped working the elixir bar out for itself and
started reading it from the summoner in our snapshot - which never
moved, so the bar sat where the opening state left it and no card could
be afforded.

the rule from LogicSummoner::tick: an accumulator gains five thousand a
tick and one mana is granted for every MANA_REGEN_MS * 100 / MAX_MANA it
holds, the remainder carried rather than dropped. that works out at
2.8 seconds a mana with the shipped globals, and halves in the last
sixty seconds through MANA_REGEN_MS_END, which is the speed-up the game
has always had.

crates/game-service/src/battle_session.rs

@@ -163,7 +163,7 @@ impl BattleSession {
         while self.tick < tick {
             self.tick += 1;
             self.release_queued(self.tick);
-            self.mode.battle.tick();
+            self.mode.battle.tick(self.tick);
             if self.pushes_snapshots() && self.tick >= self.next_snapshot {
                 self.next_snapshot = self.tick + SNAPSHOT_INTERVAL_TICKS;
                 if let Some(message) = self.snapshot_message() {

crates/logic/src/battle/logic_simulation.rs

@@ -1,8 +1,15 @@
 use crate::battle::logic_battle::LogicBattle;
 use crate::battle::logic_component::{LogicComponent, COMPONENT_COMBAT, COMPONENT_HITPOINT};
-use crate::battle::logic_game_object::LogicGameObjectEntry;
+use crate::battle::logic_game_object::{LogicGameObjectEntry, LogicObjectBody};
+use crate::battle::logic_battle::BATTLE_TICKS_PER_SECOND;
 use crate::data::LogicDataRef;
 pub const TICK_MILLISECONDS: i32 = 50;
+pub const MANA_ACCUMULATOR_STEP: i32 = 5000;
+pub const MANA_RATE_SCALE: i32 = 100;
+pub const GLOBAL_MAX_MANA: &str = "MAX_MANA";
+pub const GLOBAL_MANA_REGEN: &str = "MANA_REGEN_MS";
+pub const GLOBAL_MANA_REGEN_END: &str = "MANA_REGEN_MS_END";
+pub const GLOBAL_MANA_SPEED_UP_SECONDS: &str = "MANA_SPEED_UP_WHEN_REMAINING_SECONDS";
 pub const COLUMN_SPEED: &str = "Speed";
 pub const COLUMN_SIGHT_RANGE: &str = "SightRange";
 pub const COLUMN_RANGE: &str = "Range";
@@ -131,7 +138,34 @@ impl LogicGameObjectEntry {
     }
 }
 impl LogicBattle {
-    pub fn tick(&mut self) {
+    fn regenerate_mana(&mut self, tick: i32) {
+        let max_mana = crate::LogicGlobals::number(GLOBAL_MAX_MANA).max(1);
+        let seconds_left = (self.match_length_seconds() - tick / BATTLE_TICKS_PER_SECOND).max(0);
+        let speed_up = crate::LogicGlobals::number(GLOBAL_MANA_SPEED_UP_SECONDS);
+        let regen = if seconds_left <= speed_up {
+            crate::LogicGlobals::number(GLOBAL_MANA_REGEN_END)
+        } else {
+            crate::LogicGlobals::number(GLOBAL_MANA_REGEN)
+        };
+        let step = regen.saturating_mul(MANA_RATE_SCALE) / max_mana;
+        if step < 1 {
+            return;
+        }
+        for entry in self.objects.objects.iter_mut() {
+            let LogicObjectBody::Summoner(summoner) = &mut entry.body else {
+                continue;
+            };
+            summoner.mana_regen_timer += MANA_ACCUMULATOR_STEP;
+            let gained = summoner.mana_regen_timer / step;
+            if gained < 1 {
+                continue;
+            }
+            summoner.mana_regen_timer -= gained * step;
+            summoner.mana = (summoner.mana + gained).clamp(0, max_mana);
+        }
+    }
+    pub fn tick(&mut self, tick: i32) {
+        self.regenerate_mana(tick);
         self.retarget();
         self.move_objects();
         self.resolve_attacks();