// Authoritative game server, ported from scripts/server/game_server.gd. Owns
// the GameState, turns player orders into state changes and pushes snapshots
// back to every connected client. The `network` adapter supplies getPeerIds()
// and send(peerId, message); everything else is transport-agnostic.

import { EventEmitter } from "node:events";
import { GameState } from "../shared/game_state.js";
import { LoginManager } from "../shared/login_manager.js";
import { CIVILISATIONS } from "../shared/data.js";
import { dateString } from "../shared/game_clock.js";

const DEFAULT_CIV_IDS = [
  "france", "britain", "slovenia", "poland", "switzerland",
  "ticino", "galicia", "germany", "iran",
];

export class GameServer extends EventEmitter {
  constructor(network) {
    super();
    this.network = network;
    this.state = null;
    this.hostCiv = 0;
    this.peerCiv = new Map();
    this.login = new LoginManager();
    this.adminName = "";
    this.peerNames = new Map();
    this.identityCiv = new Map();
    this._configured = false;
    this._stateDirty = false;
  }

  isConfigured() {
    return this._configured;
  }

  gameList() {
    if (!this._configured || !this.state) return [];
    return [this.gameSummary()];
  }

  gameSummary() {
    return {
      id: this.state.seed,
      name: `Game ${this.state.seed}`,
      seed: this.state.seed,
      players: this.peerNames.size,
      civs: this.state.civilisations.map((c) => c.name),
      date: dateString(this.state.totalHours),
    };
  }

  authenticate(peerId, playerName, password) {
    const name = String(playerName || "").trim();
    if (name.length === 0) return { ok: false, reason: "Enter a player name." };
    if (String(password || "").length === 0) return { ok: false, reason: "Enter a password." };
    if (Array.from(this.peerNames.values()).includes(name)) {
      return { ok: false, reason: `${name} is already playing.` };
    }
    if (!this.login.login(name, password)) {
      return { ok: false, reason: `Wrong password for ${name}.` };
    }
    const isAdmin = this.adminName.length === 0;
    if (isAdmin) this.adminName = name;
    this.peerNames.set(peerId, name);
    return { ok: true, name, admin: name === this.adminName };
  }

  configureGame(setup) {
    if (this._configured) return;
    this.hostCiv = Number(setup.player_civ || 0);
    this.state = new GameState();
    this.state.configure(this._loadCivs(setup.civilisations || []), Number(setup.seed || 0));
    this.state.onChanged(() => {
      this._stateDirty = true;
    });
    this._configured = true;
    for (const peerId of this.network.getPeerIds()) {
      this._assignCiv(peerId, this.peerNames.get(peerId) || "");
    }
    this._broadcastState();
    this.emit("game_configured");
  }

  _loadCivs(ids) {
    const civs = [];
    for (const id of ids) {
      const civ = CIVILISATIONS.find((c) => c.id === id);
      if (civ) civs.push(civ);
    }
    if (civs.length === 0) {
      for (const id of DEFAULT_CIV_IDS) {
        const civ = CIVILISATIONS.find((c) => c.id === id);
        if (civ) civs.push(civ);
      }
    }
    return civs;
  }

  handleOrder(peerId, order) {
    if (!this._configured) return false;
    const civ = this.peerCiv.has(peerId) ? this.peerCiv.get(peerId) : -1;
    if (civ < 0) return false;
    const type = String(order.t || order.type || "");
    switch (type) {
      case "move":
        return this._handleMove(civ, order);
      case "train":
        return this._handleTrain(civ, order);
      case "build":
        return this._handleBuild(civ, order);
      case "demolish":
        return this._handleDemolish(civ, order);
      case "government":
        return this._handleGovernment(civ, order);
      case "technology":
        return this._handleTechnology(civ, order);
      case "declare_war":
        return this._handleDeclareWar(civ, order);
      default:
        return false;
    }
  }

  _handleMove(civ, order) {
    const unit = this.state.findUnit(Number(order.unit));
    if (!unit || unit.civ !== civ) return false;
    return this.state.requestMove(unit.id, coordsOf(order.coords));
  }

  _handleTrain(civ, order) {
    const city = this.state.findCity(Number(order.city));
    if (!city || city.civ !== civ) return false;
    return this.state.requestTrain(city.id, Number(order.proto));
  }

  _handleBuild(civ, order) {
    const city = this.state.findCity(Number(order.city));
    if (!city || city.civ !== civ) return false;
    return this.state.requestBuild(city.id, Number(order.building));
  }

  _handleDemolish(civ, order) {
    const city = this.state.findCity(Number(order.city));
    if (!city || city.civ !== civ) return false;
    return this.state.requestDemolish(city.id, Number(order.building));
  }

  _handleGovernment(civ, order) {
    return this.state.requestSetGovernment(civ, Number(order.government));
  }

  _handleTechnology(civ, order) {
    return this.state.requestResearchTechnology(civ, Number(order.technology));
  }

  _handleDeclareWar(civ, order) {
    const target = Number(order.target !== undefined ? order.target : order.civ);
    return this.state.requestDeclareWar(civ, target);
  }

  onPeerJoined(peerId, playerName = "") {
    if (!this._configured) return;
    // A returning player keeps the nation they claimed before.
    if (this._reclaimIdentity(peerId, playerName)) {
      this.network.send(peerId, { t: "game_state", state: this.state.snapshot(this.peerCiv.get(peerId)) });
      return;
    }
    // Otherwise offer every nation no one has claimed yet and let the player
    // pick. They stay a spectator (civ -1) until they answer.
    this.peerCiv.set(peerId, -1);
    const options = this.availableCivs();
    this.network.send(peerId, { t: "choose_civ", civs: options });
    if (options.length === 0) {
      this.network.send(peerId, { t: "game_state", state: this.state.snapshot(-1) });
    }
  }

  onPeerLeft(peerId) {
    this.peerCiv.delete(peerId);
    this.peerNames.delete(peerId);
  }

  // Indices of the civilisations no connected peer has claimed.
  availableCivs() {
    if (!this._configured || !this.state) return [];
    const used = new Set(this.peerCiv.values());
    const options = [];
    for (let i = 0; i < this.state.civilisations.length; i++) {
      if (used.has(i)) continue;
      const civ = this.state.civilisations[i];
      options.push({ index: i, id: civ.id, name: civ.name });
    }
    return options;
  }

  // Claims one of the offered civilisations for a joining peer. Rejects an
  // index that is out of range or already taken by someone else.
  claimCiv(peerId, index) {
    if (!this._configured || !this.state) return false;
    const choice = Number(index);
    if (!Number.isInteger(choice) || choice < 0 || choice >= this.state.civilisations.length) {
      return false;
    }
    if (Array.from(this.peerCiv.values()).includes(choice)) return false;
    this.peerCiv.set(peerId, choice);
    const name = this.peerNames.get(peerId);
    if (name) this.identityCiv.set(name, choice);
    this.network.send(peerId, { t: "civ_assigned", civ: choice });
    this._broadcastState();
    return true;
  }

  // Re-attaches a known player to the nation they held before, as long as no
  // one else has claimed it in the meantime.
  _reclaimIdentity(peerId, playerName) {
    if (!playerName || !this.identityCiv.has(playerName)) return false;
    const choice = this.identityCiv.get(playerName);
    if (choice < 0 || choice >= this.state.civilisations.length) return false;
    if (Array.from(this.peerCiv.values()).includes(choice)) return false;
    this.peerCiv.set(peerId, choice);
    this.network.send(peerId, { t: "civ_assigned", civ: choice });
    return true;
  }

  _assignCiv(peerId, playerName = "") {
    if (this._configured === false || this.state == null) return;
    const used = Array.from(this.peerCiv.values());
    let choice = -1;
    if (playerName && this.identityCiv.has(playerName)) choice = this.identityCiv.get(playerName);
    if (choice < 0 && peerId === this._adminPeerId()) choice = this.hostCiv;
    if (choice < 0 || used.includes(choice)) {
      choice = -1;
      for (let i = 0; i < this.state.civilisations.length; i++) {
        if (!used.includes(i)) {
          choice = i;
          break;
        }
      }
    }
    this.peerCiv.set(peerId, choice);
    if (playerName && choice >= 0) this.identityCiv.set(playerName, choice);
  }

  _adminPeerId() {
    for (const [peerId, name] of this.peerNames) {
      if (name === this.adminName) return peerId;
    }
    return 0;
  }

  tickHour() {
    if (!this._configured || !this.state) return;
    this.state.tickHour();
  }

  advanceMovement(hours) {
    if (!this._configured || !this.state) return;
    this.state.advanceMovement(hours);
  }

  flushIfDirty() {
    if (!this._stateDirty) return;
    this._stateDirty = false;
    this._broadcastState();
  }

  _broadcastState() {
    if (!this.state) return;
    const shared = this.state.serializeShared();
    const statsCache = new Map();
    for (const peerId of this.network.getPeerIds()) {
      const civ = this.peerCiv.has(peerId) ? this.peerCiv.get(peerId) : -1;
      if (!statsCache.has(civ)) statsCache.set(civ, this.state.viewerStats(civ));
      this.network.send(peerId, {
        t: "game_state",
        state: this.state.viewerSnapshot(shared, civ, statsCache.get(civ)),
      });
    }
  }
}

function coordsOf(value) {
  if (Array.isArray(value) && value.length >= 2) {
    return { x: Number(value[0]), y: Number(value[1]) };
  }
  return { x: -1, y: -1 };
}