3 files changed, 191 insertions, 0 deletions
diff --git a/planetwars-server/src/modules/matches.rs b/planetwars-server/src/modules/matches.rs
new file mode 100644
index 0000000..201c6d4
--- /dev/null
+++ b/planetwars-server/src/modules/matches.rs
@@ -0,0 +1,102 @@
+use std::path::PathBuf;
+
+use diesel::{PgConnection, QueryResult};
+use planetwars_matchrunner::{self as runner, docker_runner::DockerBotSpec, BotSpec, MatchConfig};
+use runner::MatchOutcome;
+use tokio::task::JoinHandle;
+
+use crate::{
+    db::{self, matches::MatchData},
+    util::gen_alphanumeric,
+    ConnectionPool, BOTS_DIR, MAPS_DIR, MATCHES_DIR,
+};
+
+const PYTHON_IMAGE: &str = "python:3.10-slim-buster";
+
+pub struct RunMatch<'a> {
+    log_file_name: String,
+    player_code_bundles: Vec<&'a db::bots::CodeBundle>,
+    match_id: Option<i32>,
+}
+
+impl<'a> RunMatch<'a> {
+    pub fn from_players(player_code_bundles: Vec<&'a db::bots::CodeBundle>) -> Self {
+        let log_file_name = format!("{}.log", gen_alphanumeric(16));
+        RunMatch {
+            log_file_name,
+            player_code_bundles,
+            match_id: None,
+        }
+    }
+
+    pub fn runner_config(&self) -> runner::MatchConfig {
+        runner::MatchConfig {
+            map_path: PathBuf::from(MAPS_DIR).join("hex.json"),
+            map_name: "hex".to_string(),
+            log_path: PathBuf::from(MATCHES_DIR).join(&self.log_file_name),
+            players: self
+                .player_code_bundles
+                .iter()
+                .map(|b| runner::MatchPlayer {
+                    bot_spec: code_bundle_to_botspec(b),
+                })
+                .collect(),
+        }
+    }
+
+    pub fn store_in_database(&mut self, db_conn: &PgConnection) -> QueryResult<MatchData> {
+        // don't store the same match twice
+        assert!(self.match_id.is_none());
+
+        let new_match_data = db::matches::NewMatch {
+            state: db::matches::MatchState::Playing,
+            log_path: &self.log_file_name,
+        };
+        let new_match_players = self
+            .player_code_bundles
+            .iter()
+            .map(|b| db::matches::MatchPlayerData {
+                code_bundle_id: b.id,
+            })
+            .collect::<Vec<_>>();
+
+        let match_data = db::matches::create_match(&new_match_data, &new_match_players, &db_conn)?;
+        self.match_id = Some(match_data.base.id);
+        Ok(match_data)
+    }
+
+    pub fn spawn(self, pool: ConnectionPool) -> JoinHandle<MatchOutcome> {
+        let match_id = self.match_id.expect("match must be saved before running");
+        let runner_config = self.runner_config();
+        tokio::spawn(run_match_task(pool, runner_config, match_id))
+    }
+}
+
+pub fn code_bundle_to_botspec(code_bundle: &db::bots::CodeBundle) -> Box<dyn BotSpec> {
+    let bundle_path = PathBuf::from(BOTS_DIR).join(&code_bundle.path);
+
+    Box::new(DockerBotSpec {
+        code_path: bundle_path,
+        image: PYTHON_IMAGE.to_string(),
+        argv: vec!["python".to_string(), "bot.py".to_string()],
+    })
+}
+
+async fn run_match_task(
+    connection_pool: ConnectionPool,
+    match_config: MatchConfig,
+    match_id: i32,
+) -> MatchOutcome {
+    let outcome = runner::run_match(match_config).await;
+
+    // update match state in database
+    let conn = connection_pool
+        .get()
+        .await
+        .expect("could not get database connection");
+
+    db::matches::set_match_state(match_id, db::matches::MatchState::Finished, &conn)
+        .expect("could not update match state");
+
+    return outcome;
+}
diff --git a/planetwars-server/src/modules/mod.rs b/planetwars-server/src/modules/mod.rs
index 57c1ef5..bea28e0 100644
--- a/planetwars-server/src/modules/mod.rs
+++ b/planetwars-server/src/modules/mod.rs
@@ -1,3 +1,5 @@
 // This module implements general domain logic, not directly
 // tied to the database or API layers.
 pub mod bots;
+pub mod matches;
+pub mod ranking;
diff --git a/planetwars-server/src/modules/ranking.rs b/planetwars-server/src/modules/ranking.rs
new file mode 100644
index 0000000..cc81f0f
--- /dev/null
+++ b/planetwars-server/src/modules/ranking.rs
@@ -0,0 +1,87 @@
+use crate::{db::bots::Bot, DbPool};
+
+use crate::db;
+use crate::modules::matches::RunMatch;
+use rand::seq::SliceRandom;
+use std::time::Duration;
+use tokio;
+
+const RANKER_INTERVAL: u64 = 60;
+const START_RATING: f64 = 0.0;
+const SCALE: f64 = 100.0;
+const MAX_UPDATE: f64 = 10.0;
+
+pub async fn run_ranker(db_pool: DbPool) {
+    // TODO: make this configurable
+    // play at most one match every n seconds
+    let mut interval = tokio::time::interval(Duration::from_secs(RANKER_INTERVAL));
+    let db_conn = db_pool
+        .get()
+        .await
+        .expect("could not get database connection");
+    loop {
+        interval.tick().await;
+        let bots = db::bots::find_all_bots(&db_conn).unwrap();
+        if bots.len() < 2 {
+            // not enough bots to play a match
+            continue;
+        }
+        let selected_bots: Vec<Bot> = {
+            let mut rng = &mut rand::thread_rng();
+            bots.choose_multiple(&mut rng, 2).cloned().collect()
+        };
+        play_ranking_match(selected_bots, db_pool.clone()).await;
+    }
+}
+
+async fn play_ranking_match(selected_bots: Vec<Bot>, db_pool: DbPool) {
+    let db_conn = db_pool.get().await.expect("could not get db pool");
+    let mut code_bundles = Vec::new();
+    for bot in &selected_bots {
+        let code_bundle = db::bots::active_code_bundle(bot.id, &db_conn)
+            .expect("could not get active code bundle");
+        code_bundles.push(code_bundle);
+    }
+
+    let code_bundle_refs = code_bundles.iter().map(|b| b).collect::<Vec<_>>();
+
+    let mut run_match = RunMatch::from_players(code_bundle_refs);
+    run_match
+        .store_in_database(&db_conn)
+        .expect("could not store match in db");
+    let outcome = run_match
+        .spawn(db_pool.clone())
+        .await
+        .expect("running match failed");
+
+    let mut ratings = Vec::new();
+    for bot in &selected_bots {
+        let rating = db::ratings::get_rating(bot.id, &db_conn)
+            .expect("could not get bot rating")
+            .unwrap_or(START_RATING);
+        ratings.push(rating);
+    }
+
+    // simple elo rating
+
+    let scores = match outcome.winner {
+        None => vec![0.5; 2],
+        Some(player_num) => {
+            // TODO: please get rid of this offset
+            let player_ix = player_num - 1;
+            let mut scores = vec![0.0; 2];
+            scores[player_ix] = 1.0;
+            scores
+        }
+    };
+
+    for i in 0..2 {
+        let j = 1 - i;
+
+        let scaled_difference = (ratings[j] - ratings[i]) / SCALE;
+        let expected = 1.0 / (1.0 + 10f64.powf(scaled_difference));
+        let new_rating = ratings[i] + MAX_UPDATE * (scores[i] - expected);
+        db::ratings::set_rating(selected_bots[i].id, new_rating, &db_conn)
+            .expect("could not update bot rating");
+    }
+}