quill/val Public Public: anyone can read this; nobody can change it.

/**

 * The arena: one match, always running, and the seats people sit in.

 *

 * The match ticks whether anybody is watching or not, so a visitor never

 * arrives at a frozen board — they get the round that is happening. Taking a

 * seat replaces a bot in place: same body, same credits, same position, so

 * joining mid-round hands you a live player rather than a lobby.

 *

 * Every snapshot is built for one viewer: enemies they cannot see are not in

 * it. The client never learns a position it has no line of sight to.

 */

import { agentById, sightBlocked } from "./abilities.ts";

import { runBots } from "./bots.ts";

import { recordResult } from "./db.ts";

import { fallsBetween, marksOf, trimFeed, type Fall, type Mark } from "./killfeed.ts";

import type { Point } from "./map.ts";

import {

  buyAbility,

  buyShield,

  buyWeapon,

  newMatch,

  pickAgent,

  setInput,

  tick,

  visible,

} from "./match.ts";

import type { MatchState, Player } from "./state.ts";

import { isWeaponId, WEAPONS } from "./weapons.ts";

export const TICK = 1 / 30;

const BROADCAST_EVERY = 2;

export type Seat = { playerId: string; send: (data: string) => void };

let state: MatchState = newMatch();

const seats = new Map<string, Seat>();

let ticks = 0;

let lastResult: string | null = null;

// The kill feed is read off the match a tick at a time; the rules keep no

// list of their own, and this is a view, not a rule.

let marks: Mark[] = marksOf(state.players);

let feed: Fall[] = [];

export const match = (): MatchState => state;

export const findPlayer = (id: string): Player | undefined => state.players.find((p) => p.id === id);

/**

 * A name nobody else in this match is using.

 *

 * The kill feed, the round log and the scoreboard all address people by

 * name: two players called Kit make a line that reads as a team kill this

 * game cannot have. The bots are dealt distinct names; a person who picks

 * one that is taken gets a number after it, inside the sixteen characters a

 * name is allowed.

 */

function freeName(want: string, exceptId: string): string {

  const taken = new Set(state.players.filter((p) => p.id !== exceptId).map((p) => p.name));

  if (!taken.has(want)) return want;

  for (let n = 2; n < 100; n++) {

    const tried = `${want.slice(0, 13)} ${n}`;

    if (!taken.has(tried)) return tried;

  }

  return want;

}

/** Sit somebody down in the emptiest team, replacing a bot where it stands. */

export function takeSeat(session: string, name: string): Player | null {

  const existing = seats.get(session);

  const held = existing ? findPlayer(existing.playerId) : undefined;

  if (held) {

    held.name = freeName(name, held.id);

    return held;

  }

  const humans = { red: 0, blue: 0 };

  for (const player of state.players) if (!player.bot) humans[player.team] += 1;

  const wanted = humans.red <= humans.blue ? "red" : "blue";

  const seat =

    state.players.find((p) => p.bot && p.team === wanted) ?? state.players.find((p) => p.bot);

  if (!seat) return null;

  seat.bot = false;

  seat.name = freeName(name, seat.id);

  seat.think = 0;

  seat.input = { mx: 0, my: 0, angle: seat.angle, fire: false, use: false, reload: false, cast: null };

  return seat;

}

export function attach(session: string, playerId: string, send: (data: string) => void): void {

  seats.set(session, { playerId, send });

}

/** A person leaving gives the seat back to a bot, mid-round and all. */

export function release(session: string): void {

  const seat = seats.get(session);

  seats.delete(session);

  if (!seat) return;

  const player = findPlayer(seat.playerId);

  if (player && !stillHeld(seat.playerId)) {

    player.bot = true;

    player.think = 0;

    player.input.fire = false;

    player.input.use = false;

  }

}

const stillHeld = (playerId: string): boolean =>

  [...seats.values()].some((s) => s.playerId === playerId);

export const seatCount = (): number => seats.size;

// ------------------------------------------------------------- the commands

export type Command = { t: string; [key: string]: unknown };

const num = (value: unknown): number | undefined =>

  typeof value === "number" && Number.isFinite(value) ? value : undefined;

/** Everything a client may ask for, validated here and nowhere else. */

export function command(playerId: string, message: Command): void {

  const player = findPlayer(playerId);

  if (!player || player.bot) return;

  switch (message.t) {

    case "i":

      setInput(player, {

        mx: num(message.mx),

        my: num(message.my),

        angle: num(message.a),

        fire: typeof message.f === "boolean" ? message.f : undefined,

        use: typeof message.u === "boolean" ? message.u : undefined,

        reload: typeof message.r === "boolean" ? message.r : undefined,

        cast: message.c === "c" || message.c === "q" || message.c === "e" || message.c === "x" ? message.c : undefined,

      });

      break;

    case "buy": {

      const what = String(message.what ?? "");

      if (isWeaponId(what)) buyWeapon(state, player, what);

      else if (what === "light" || what === "heavy") buyShield(state, player, what);

      else if (what === "c" || what === "q") buyAbility(state, player, what);

      break;

    }

    case "agent":

      if (typeof message.id === "string") pickAgent(state, player, message.id);

      break;

  }

}

// ------------------------------------------------------------- the snapshot

const round2 = (n: number): number => Math.round(n * 10) / 10;

export function snapshot(viewerId: string): string {

  const me = findPlayer(viewerId) ?? state.players[0]!;

  const agent = agentById(me.agent);

  const seen = state.players.filter((p) => visible(state, me, p));

  const canSee = (point: Point): boolean => !sightBlocked(me, point, state.zones);

  return JSON.stringify({

    t: "s",

    phase: state.phase,

    clock: round2(Math.max(0, state.clock)),

    round: state.round,

    score: state.score,

    attackers: state.attackers,

    result: state.result,

    me: {

      id: me.id,

      side: me.side,

      team: me.team,

      agent: me.agent,

      alive: me.alive,

      x: round2(me.x),

      y: round2(me.y),

      angle: round2(me.angle),

      hp: Math.round(me.hp),

      armour: Math.round(me.armour),

      credits: me.credits,

      weapon: me.weapon,

      ammo: me.ammo,

      reloading: me.reloadIn > 0,

      charges: me.charges,

      cooldown: { c: round2(me.cooldown.c), q: round2(me.cooldown.q), e: round2(me.cooldown.e), x: 0 },

      ult: me.ult,

      ultNeeds: agent.abilities.x.points,

      blind: round2(me.blind),

      slow: round2(me.slow),

      haste: round2(me.haste),

      spike: me.spike,

      planting: round2(me.planting),

      bot: me.bot,

    },

    players: seen.map((p) => ({

      id: p.id,

      name: p.name,

      agent: p.agent,

      x: round2(p.x),

      y: round2(p.y),

      angle: round2(p.angle),

      hp: Math.round(p.hp),

      armour: Math.round(p.armour),

      alive: p.alive,

      mate: p.side === me.side,

      spike: p.spike,

      blind: p.blind > 0,

      revealed: p.revealed > 0,

    })),

    zones: state.zones

      .filter((z) => (z.kind === "trip" ? z.side === me.side : true))

      .map((z) => ({ k: z.kind, x: round2(z.x), y: round2(z.y), r: z.r, f: round2(z.fuse), l: round2(z.life) })),

    spike: {

      planted: state.spike.planted,

      carried: state.spike.carried !== null,

      fuse: round2(state.spike.fuse),

      defuse: round2(state.spike.defuse),

      checkpoint: state.spike.checkpoint,

      // A loose spike is the attackers' business until it is armed.

      x: state.spike.planted || me.side === "atk" ? round2(state.spike.x) : null,

      y: state.spike.planted || me.side === "atk" ? round2(state.spike.y) : null,

    },

    orbs: state.orbs.filter((o) => !o.taken).map((o) => ({ x: o.x, y: o.y })),

    shots: state.shots.filter((s) => canSee({ x: s.x1, y: s.y1 }) || canSee({ x: s.x2, y: s.y2 })),

    board: state.players.map((p) => ({

      id: p.id,

      name: p.name,

      team: p.team,

      side: p.side,

      agent: p.agent,

      bot: p.bot,

      alive: p.alive,

      kills: p.kills,

      deaths: p.deaths,

      damage: Math.round(p.damageDone),

      credits: p.team === me.team ? p.credits : null,

      ult: p.ult,

      ultNeeds: agentById(p.agent).abilities.x.points,

    })),

    events: state.events.slice(0, 5).map((e) => e.text),

    // Names and a gun, never a position: the feed says what happened, not

    // where, so it can never be read as a call-out.

    feed: feed.map((f) => ({

      k: f.killer,

      v: f.victim,

      w: f.weapon ? WEAPONS[f.weapon].name : null,

      h: f.headshot,

      t: round2(Math.max(0, state.now - f.at)),

    })),

  });

}

/**

 * Who fell on this tick. A shot that landed this tick and started where the

 * killer stands is what tells a gun kill from an ability kill — the position

 * is used here and goes no further.

 */

function readFalls(): void {

  const after = marksOf(state.players);

  const shooters = new Set<string>();

  for (const shot of state.shots) {

    if (!shot.hit || shot.age > 0) continue;

    for (const player of state.players)

      if (Math.hypot(player.x - shot.x1, player.y - shot.y1) < 2) shooters.add(player.id);

  }

  const falls = fallsBetween(marks, after, {

    at: state.now,

    events: state.events.slice(0, 6).map((e) => e.text),

    shooters,

  });

  marks = after;

  if (falls.length) feed = [...feed, ...falls];

  feed = trimFeed(feed, state.now);

}

// ----------------------------------------------------------------- the loop

function step(): void {

  runBots(state, TICK);

  tick(state, TICK);

  readFalls();

  if (state.result && state.result !== lastResult) {

    lastResult = state.result;

    recordResult(state.result, state.score.red, state.score.blue, state.round);

  }

  if (state.result === null) lastResult = null;

  ticks += 1;

  if (ticks % BROADCAST_EVERY !== 0) return;

  for (const seat of seats.values()) {

    try {

      seat.send(snapshot(seat.playerId));

    } catch {

      // A socket that will not take a frame is closed already; the close

      // handler gives the seat back.

    }

  }

}

let timer: ReturnType<typeof setInterval> | null = null;

export function startArena(): void {

  if (timer) return;

  timer = setInterval(step, TICK * 1000);

  // The clock must never hold the process open on its own.

  (timer as unknown as { unref?: () => void }).unref?.();

}

export function stopArena(): void {

  if (timer) clearInterval(timer);

  timer = null;

}

/** Used by the tests: run the arena forward without waiting for real time. */

export function advance(seconds: number): void {

  for (let i = 0; i < Math.round(seconds / TICK); i++) step();

}