From 82ceee2c432d26589834e803af59b710a66a2636 Mon Sep 17 00:00:00 2001
From: Justin Wernick <justin@worthe-it.co.za>
Date: Fri, 10 Apr 2020 22:00:38 +0200
Subject: Most of the game rules

---
 src/consts.rs |  11 +++++
 src/main.rs   |   1 +
 src/state.rs  | 135 +++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 137 insertions(+), 10 deletions(-)
 create mode 100644 src/consts.rs

diff --git a/src/consts.rs b/src/consts.rs
new file mode 100644
index 0000000..6ebc9af
--- /dev/null
+++ b/src/consts.rs
@@ -0,0 +1,11 @@
+pub const SPEED_0: usize = 0;
+pub const SPEED_1: usize = 3;
+pub const SPEED_2: usize = 6;
+pub const SPEED_3: usize = 8;
+pub const SPEED_4: usize = 9;
+pub const SPEED_BOOST: usize = 15;
+
+pub const BOOST_DURATION: usize = 5;
+
+pub const HEIGHT: usize = 4;
+pub const WIDTH: usize = 1500;
diff --git a/src/main.rs b/src/main.rs
index a565e73..81bc3b4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,6 +2,7 @@ use std::io::prelude::*;
 use std::io::stdin;
 
 mod command;
+mod consts;
 mod json;
 mod state;
 
diff --git a/src/state.rs b/src/state.rs
index 2f81d5d..b87db1b 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -1,12 +1,30 @@
 use crate::command::Command;
+use crate::consts::*;
 
 pub struct GameState {
     players: [Player; 2],
+    obstacles: Vec<Position>,
+    powerup_oils: Vec<Position>,
+    powerup_boosts: Vec<Position>,
+}
+
+pub struct Player {
+    position: Position,
+    next_position: Position,
+    speed: usize,
+    boost_remaining: usize,
+    oils: usize,
+    boosts: usize,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Position {
+    x: usize,
+    y: usize,
 }
 
-pub struct Player {}
 impl GameState {
-    fn update(&mut self, commands: [Command; 2]) {
+    pub fn update(&mut self, commands: [Command; 2]) {
         self.do_command(0, &commands[0]);
         self.do_command(1, &commands[1]);
         self.update_player_collisions();
@@ -16,22 +34,119 @@ impl GameState {
     fn do_command(&mut self, player_index: usize, command: &Command) {
         use Command::*;
 
+        // TODO: Command validation assertions
         match command {
             Nothing => {}
-            Accelerate => unimplemented!(),
-            Decelerate => unimplemented!(),
-            TurnLeft => unimplemented!(),
-            TurnRight => unimplemented!(),
-            UseBoost => unimplemented!(),
-            UseOil => unimplemented!(),
+            Accelerate => self.players[player_index].accelerate(),
+            Decelerate => self.players[player_index].decelerate(),
+            TurnLeft => self.players[player_index].turn(false),
+            TurnRight => self.players[player_index].turn(true),
+            UseBoost => self.players[player_index].boost(),
+            UseOil => {
+                self.players[player_index].oils -= 1;
+                let player_position = self.players[player_index].position;
+                self.obstacles.push(Position {
+                    x: player_position.x - 1,
+                    y: player_position.y,
+                });
+            }
         }
+
+        self.players[player_index].set_next_position_x();
     }
 
     fn update_player_collisions(&mut self) {
-        //TODO
+
+        // TODO: One player rear-ending another
+        // TODO: Ending up in the same block from different lanes
     }
 
     fn update_player_travel(&mut self) {
-        //TODO
+        for player in &mut self.players {
+            player.move_along(&self.obstacles, &self.powerup_oils, &self.powerup_boosts);
+        }
+    }
+}
+
+impl Player {
+    fn accelerate(&mut self) {
+        self.speed = match self.speed {
+            i if i < SPEED_1 => SPEED_1,
+            i if i < SPEED_2 => SPEED_2,
+            i if i < SPEED_3 => SPEED_3,
+            _ => SPEED_4,
+        };
+    }
+
+    fn decelerate(&mut self) {
+        self.speed = match self.speed {
+            i if i <= SPEED_1 => SPEED_0,
+            i if i <= SPEED_2 => SPEED_1,
+            i if i <= SPEED_3 => SPEED_2,
+            i if i <= SPEED_4 => SPEED_3,
+            _ => SPEED_4,
+        };
+        self.boost_remaining = 0;
+    }
+
+    fn decelerate_from_obstacle(&mut self) {
+        self.speed = match self.speed {
+            i if i <= SPEED_2 => SPEED_1,
+            i if i <= SPEED_3 => SPEED_2,
+            i if i <= SPEED_4 => SPEED_3,
+            _ => SPEED_4,
+        };
+        self.boost_remaining = 0;
+    }
+
+    fn turn(&mut self, right: bool) {
+        if right {
+            self.next_position.y = self.position.y + 1;
+        } else {
+            self.next_position.y = self.position.y - 1;
+        }
+    }
+
+    fn boost(&mut self) {
+        self.speed = SPEED_BOOST;
+        self.boost_remaining = BOOST_DURATION;
+        self.boosts -= 1;
+    }
+
+    fn set_next_position_x(&mut self) {
+        if self.position.y == self.next_position.y {
+            self.next_position.x = self.position.x + self.speed;
+        } else {
+            self.next_position.x = self.position.x + self.speed - 1;
+        }
+    }
+
+    fn move_along(
+        &mut self,
+        obstacles: &[Position],
+        powerup_oils: &[Position],
+        powerup_boosts: &[Position],
+    ) {
+        let start_x = if self.position.y == self.next_position.y {
+            self.position.x + 1
+        } else {
+            self.position.x
+        };
+        for x in start_x..=self.next_position.x {
+            let position = Position {
+                x,
+                y: self.next_position.y,
+            };
+            if obstacles.contains(&position) {
+                self.decelerate_from_obstacle();
+            }
+            if powerup_oils.contains(&position) {
+                self.oils += 1;
+            }
+            if powerup_boosts.contains(&position) {
+                self.boosts += 1;
+            }
+        }
+        self.position = self.next_position;
     }
 }
-- 
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