Research in the library: rooms, spells, towers, traps and doors are discovered in a fixed order

- studying creatures collect research points (mages and owls best, higher levels faster); studying gives less mana than before
- free play starts with the basics; campaign missions know what their story allows and can research what the next four missions would bring
- research shown in the top bar; the library's info lists the current item and what comes next; locked tools say whether they can be researched

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/research.rs

@@ -0,0 +1,140 @@
+// Research: creatures studying in the library collect research points, and rooms, spells,
+// towers, traps and doors are discovered one after another in a fixed order. Free play starts
+// with the basics; a campaign mission knows what its story allows and may research what the
+// next few missions would bring.
+
+use crate::game::*;
+
+// what is researched, in this order: (index in ui::TOOLS, research points)
+pub const RESEARCH: &[(usize, f32)] = &[
+    (5, 200.0),   // training hall
+    (10, 250.0),  // heal
+    (21, 300.0),  // forge
+    (22, 250.0),  // spike pit
+    (29, 250.0),  // wooden door
+    (15, 400.0),  // cannon tower
+    (12, 450.0),  // torture chamber
+    (26, 300.0),  // alarm bell
+    (11, 500.0),  // summon
+    (13, 550.0),  // temple
+    (23, 500.0),  // poison vent
+    (30, 500.0),  // iron door
+    (18, 550.0),  // aerie
+    (16, 650.0),  // magic tower
+    (24, 650.0),  // fire jet
+    (25, 650.0),  // stone roller
+    (19, 700.0),  // steel walls
+    (28, 800.0),  // frost glow
+    (27, 900.0),  // rune mine
+    (31, 1100.0), // magic door
+];
+
+// known from the start in free play
+pub const BASE_TOOLS: &[usize] = &[0, 1, 2, 3, 4, 6, 7, 8, 9, 14, 17, 20];
+
+// campaign: what the next missions bring may be researched early
+const LOOKAHEAD: usize = 4;
+
+impl Game {
+    // free play (None) or campaign mission i: what is known, what can be researched
+    pub fn init_research(&mut self, mission: Option<usize>) {
+        let n = crate::ui::TOOLS.len();
+        match mission {
+            None => {
+                self.known = (0..n).map(|i| BASE_TOOLS.contains(&i)).collect();
+                self.researchable = vec![true; n];
+            }
+            Some(m) => {
+                let unlock = |i: usize| crate::campaign::TOOL_UNLOCK.get(i).copied().unwrap_or(0);
+                self.known = (0..n).map(|i| unlock(i) <= m).collect();
+                self.researchable = (0..n).map(|i| unlock(i) <= m + LOOKAHEAD && i != crate::game::RUNE_TOOL).collect();
+            }
+        }
+        self.research = 0.0;
+    }
+
+    pub fn known(&self, tool: usize) -> bool {
+        self.known.get(tool).copied().unwrap_or(true)
+    }
+
+    // the item being researched now: (index in RESEARCH)
+    pub fn research_target(&self) -> Option<usize> {
+        if self.known.is_empty() {
+            return None;
+        }
+        RESEARCH.iter().position(|&(t, _)| !self.known(t) && self.researchable.get(t).copied().unwrap_or(false))
+    }
+
+    // the next items after the current one (for the library's info)
+    pub fn research_queue(&self, n: usize) -> Vec<usize> {
+        RESEARCH.iter().enumerate().filter(|(_, &(t, _))| !self.known(t) && self.researchable.get(t).copied().unwrap_or(false)).map(|(k, _)| k).take(n).collect()
+    }
+
+    // could this tool still be researched (for the locked-tool message)?
+    pub fn can_research(&self, tool: usize) -> bool {
+        !self.known(tool) && self.researchable.get(tool).copied().unwrap_or(false) && RESEARCH.iter().any(|&(t, _)| t == tool)
+    }
+
+    pub(crate) fn add_research(&mut self, points: f32) {
+        if self.research_target().is_some() {
+            self.research += points;
+        }
+    }
+
+    pub(crate) fn update_research(&mut self) {
+        let Some(k) = self.research_target() else { return };
+        let (tool, cost) = RESEARCH[k];
+        if self.research >= cost {
+            self.research -= cost;
+            if let Some(v) = self.known.get_mut(tool) {
+                *v = true;
+            }
+            let name = crate::ui::tool_info(crate::ui::TOOLS[tool]).name;
+            self.msg("msg.researched", vec![name]);
+            self.sfx_ui(Sfx::LevelUp);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::map::*;
+
+    #[test]
+    fn studying_discovers_the_next_item() {
+        let mut g = Game::new(9, 64, 64);
+        assert!(!g.tool_allowed(5), "training hall must be researched");
+        assert!(g.tool_allowed(2) && g.tool_allowed(6));
+        let (cx, cy) = g.map.core;
+        for y in cy - 8..=cy - 5 {
+            for x in cx..=cx + 4 {
+                let t = &mut g.map.t[idx(x, y)];
+                t.kind = Kind::Library;
+                t.owner = Owner::Player;
+            }
+        }
+        g.recount();
+        for k in 0..4 {
+            g.spawn(EK::Mage, false, cx as f32 + 0.5 + k as f32, cy as f32 - 6.5, 3);
+        }
+        let mut found = false;
+        for _ in 0..(20 * 400) {
+            g.update(0.05);
+            if g.tool_allowed(5) {
+                found = true;
+                break;
+            }
+        }
+        assert!(found, "research points {}", g.research);
+    }
+
+    #[test]
+    fn missions_know_their_tools_and_research_ahead() {
+        let g = crate::campaign::start_mission(2, None);
+        assert!(g.tool_allowed(5), "training hall known from mission 3");
+        assert!(!g.tool_allowed(12));
+        assert!(g.can_research(10), "heal comes soon and can be researched");
+        assert!(!g.can_research(31), "magic doors are far away");
+    }
+}