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|
/// The planet wars game rules.
#[derive(Debug)]
pub struct PwState {
pub players: Vec<Player>,
pub planets: Vec<Planet>,
pub expeditions: Vec<Expedition>,
// How many expeditions were already dispatched.
// This is needed for assigning expedition identifiers.
pub expedition_num: u64,
pub turn_num: u64,
pub max_turns: u64,
}
#[derive(Debug)]
pub struct Player {
pub id: usize,
pub alive: bool,
}
#[derive(Debug)]
pub struct Fleet {
pub owner: Option<usize>,
pub ship_count: u64,
}
#[derive(Debug)]
pub struct Planet {
pub id: usize,
pub name: String,
pub fleets: Vec<Fleet>,
pub x: f64,
pub y: f64,
}
#[derive(Debug)]
pub struct Expedition {
pub id: u64,
pub origin: usize,
pub target: usize,
pub fleet: Fleet,
pub turns_remaining: u64,
}
#[derive(Debug)]
pub struct Dispatch {
pub origin: usize,
pub target: usize,
pub ship_count: u64,
}
impl PwState {
pub fn dispatch(&mut self, dispatch: &Dispatch) {
let distance = self.planets[dispatch.origin].distance(&self.planets[dispatch.target]);
let origin = &mut self.planets[dispatch.origin];
origin.fleets[0].ship_count -= dispatch.ship_count;
let expedition = Expedition {
id: self.expedition_num,
origin: dispatch.origin,
target: dispatch.target,
turns_remaining: distance,
fleet: Fleet {
owner: origin.owner(),
ship_count: dispatch.ship_count,
},
};
// increment counter
self.expedition_num += 1;
self.expeditions.push(expedition);
}
// Play one step of the game
pub fn step(&mut self) {
self.turn_num += 1;
// Initially mark all players dead, re-marking them as alive once we
// encounter a sign of life.
for player in self.players.iter_mut() {
player.alive = false;
}
self.step_expeditions();
self.resolve_combat();
}
pub fn repopulate(&mut self) {
for planet in self.planets.iter_mut() {
if planet.owner().is_some() {
planet.fleets[0].ship_count += 1;
}
}
}
fn step_expeditions(&mut self) {
let mut i = 0;
let exps = &mut self.expeditions;
while i < exps.len() {
// compare with 1 to avoid issues with planet distance 0
if exps[i].turns_remaining <= 1 {
// remove expedition from expeditions, and add to fleet
let exp = exps.swap_remove(i);
let planet = &mut self.planets[exp.target];
planet.orbit(exp.fleet);
} else {
exps[i].turns_remaining -= 1;
if let Some(owner_num) = exps[i].fleet.owner {
// owner has an expedition in progress; this is a sign of life.
self.players[owner_num].alive = true;
}
// proceed to next expedition
i += 1;
}
}
}
fn resolve_combat(&mut self) {
for planet in self.planets.iter_mut() {
planet.resolve_combat();
if let Some(owner_num) = planet.owner() {
// owner owns a planet; this is a sign of life.
self.players[owner_num].alive = true;
}
}
}
pub fn is_finished(&self) -> bool {
let remaining = self.players.iter().filter(|p| p.alive).count();
remaining < 2 || self.turn_num >= self.max_turns
}
pub fn living_players(&self) -> Vec<usize> {
self.players
.iter()
.filter_map(|p| if p.alive { Some(p.id) } else { None })
.collect()
}
}
impl Planet {
pub fn owner(&self) -> Option<usize> {
self.fleets.first().and_then(|f| f.owner)
}
pub fn ship_count(&self) -> u64 {
self.fleets.first().map_or(0, |f| f.ship_count)
}
/// Make a fleet orbit this planet.
fn orbit(&mut self, fleet: Fleet) {
// If owner already has a fleet present, merge
for other in self.fleets.iter_mut() {
if other.owner == fleet.owner {
other.ship_count += fleet.ship_count;
return;
}
}
// else, add fleet to fleets list
self.fleets.push(fleet);
}
fn resolve_combat(&mut self) {
// The player owning the largest fleet present will win the combat.
// Here, we resolve how many ships he will have left.
// note: in the current implementation, we could resolve by doing
// winner.ship_count -= second_largest.ship_count, but this does not
// allow for simple customizations (such as changing combat balance).
self.fleets
.sort_by(|a, b| a.ship_count.cmp(&b.ship_count).reverse());
while self.fleets.len() > 1 {
let fleet = self.fleets.pop().unwrap();
// destroy some ships
for other in self.fleets.iter_mut() {
other.ship_count -= fleet.ship_count;
}
// remove dead fleets
while self.fleets.last().map(|f| f.ship_count) == Some(0) {
self.fleets.pop();
}
}
}
fn distance(&self, other: &Planet) -> u64 {
let dx = self.x - other.x;
let dy = self.y - other.y;
(dx.powi(2) + dy.powi(2)).sqrt().ceil() as u64
}
}
|
