From 977345fb81ef5f3131902299754b87d32a9543ac Mon Sep 17 00:00:00 2001
From: Pierre Hubert <pierre.git@communiquons.org>
Date: Tue, 20 Sep 2022 17:37:44 +0200
Subject: [PATCH] Can check if shooting a location is worthwhile or not

---
 .../src/data/current_game_status.rs           | 92 ++++++++++++++++++-
 1 file changed, 91 insertions(+), 1 deletion(-)

diff --git a/sea_battle_backend/src/data/current_game_status.rs b/sea_battle_backend/src/data/current_game_status.rs
index 2197dd7..9d64d05 100644
--- a/sea_battle_backend/src/data/current_game_status.rs
+++ b/sea_battle_backend/src/data/current_game_status.rs
@@ -65,7 +65,8 @@ pub struct CurrentGameStatus {
 impl CurrentGameStatus {
     /// Check if opponent can fire at a given location
     pub fn can_fire_at_location(&self, location: Coordinates) -> bool {
-        !self.opponent_map.successful_strikes.contains(&location)
+        location.is_valid(&self.rules)
+            && !self.opponent_map.successful_strikes.contains(&location)
             && !self.opponent_map.failed_strikes.contains(&location)
     }
 
@@ -211,6 +212,35 @@ impl CurrentGameStatus {
         boats_size.first().cloned()
     }
 
+    fn get_unshoot_room(&self, start: Coordinates, diff_x: i32, diff_y: i32) -> usize {
+        let mut size = 0;
+
+        let mut c = start;
+
+        loop {
+            c = c.add_x(diff_x).add_y(diff_y);
+            if !self.can_fire_at_location(c) {
+                break;
+            }
+            size += 1;
+        }
+
+        size
+    }
+
+    /// Check whether it is relevant to fire a location or not
+    pub fn should_fire_at_location(&self, c: Coordinates) -> bool {
+        if !self.can_fire_at_location(c) {
+            return false;
+        }
+
+        let smallest_boat = self.get_size_of_smallest_un_sunk_boat().unwrap_or_default();
+
+        (self.get_unshoot_room(c, -1, 0) + 1 + self.get_unshoot_room(c, 0, 1)) >= smallest_boat
+            || (self.get_unshoot_room(c, 0, -1) + 1 + self.get_unshoot_room(c, 0, 1))
+                >= smallest_boat
+    }
+
     pub fn get_your_map(&self) -> String {
         PrintableCurrentGameMapStatus(self.rules.clone(), self.your_map.clone()).get_map()
     }
@@ -353,4 +383,64 @@ mod test {
             status.get_size_of_smallest_un_sunk_boat().unwrap()
         );
     }
+
+    #[test]
+    fn relevant_fire_location_empty_game() {
+        let status = CurrentGameStatus::default();
+        assert!(status.can_fire_at_location(Coordinates::new(0, 0)));
+        assert!(status.should_fire_at_location(Coordinates::new(0, 0)));
+    }
+
+    #[test]
+    fn relevant_fire_location_two_failed_attempt_around() {
+        let mut status = CurrentGameStatus::default();
+        status
+            .opponent_map
+            .failed_strikes
+            .push(Coordinates::new(0, 1));
+        status
+            .opponent_map
+            .failed_strikes
+            .push(Coordinates::new(1, 0));
+        assert!(status.can_fire_at_location(Coordinates::new(0, 0)));
+        assert!(!status.should_fire_at_location(Coordinates::new(0, 0)));
+    }
+
+    #[test]
+    fn relevant_fire_location_two_failed_attempt_smallest_boat_not_sunk() {
+        let mut status = CurrentGameStatus::default();
+        status
+            .opponent_map
+            .failed_strikes
+            .push(Coordinates::new(0, 2));
+        status
+            .opponent_map
+            .failed_strikes
+            .push(Coordinates::new(2, 0));
+        assert!(status.can_fire_at_location(Coordinates::new(0, 0)));
+        assert!(status.should_fire_at_location(Coordinates::new(0, 0)));
+    }
+
+    #[test]
+    fn relevant_fire_location_two_failed_attempt_smallest_boat_sunk() {
+        let mut status = CurrentGameStatus::default();
+        status
+            .opponent_map
+            .failed_strikes
+            .push(Coordinates::new(0, 2));
+        status
+            .opponent_map
+            .failed_strikes
+            .push(Coordinates::new(2, 0));
+        status.opponent_map.sunk_boats.push(BoatPosition {
+            start: Coordinates::new(
+                status.rules.map_width as i32 - 1,
+                status.rules.map_height as i32 - 1,
+            ),
+            len: 2,
+            direction: BoatDirection::Left,
+        });
+        assert!(status.can_fire_at_location(Coordinates::new(0, 0)));
+        assert!(!status.should_fire_at_location(Coordinates::new(0, 0)));
+    }
 }