// Player-issued orders that are not movement: training, building, government,
// research and pillaging.

import { key } from "../hex.js";
import { ECONOMY } from "../data/economy.js";
import { GOVERNMENTS } from "../data/governments.js";
import { PILLAGE, pillageSteps } from "../data/combat.js";
import { transportImprovement } from "../data/improvements.js";
import { buildingBuildCost } from "../rules.js";
import { tileImprovementResourceCost } from "../resources.js";
import { TRAINING_QUEUE_LIMIT } from "./constants.js";

export const orderMethods = {
  // Adds one unit to the city's production queue. The queue is shared with
  // buildings and holds at most TRAINING_QUEUE_LIMIT entries; the first entry
  // is produced while the rest wait. The unit's price is paid up front from the
  // budget, then it takes production capacity to finish.
  requestTrain(cityId, protoIndex, free = false) {
    const city = this.findCity(cityId);
    if (!city) return false;
    if (protoIndex < 0 || protoIndex >= this.protoUnits.length) return false;
    const proto = this.protoUnits[protoIndex];
    // Aircraft and warships need the right installation in the city first.
    if (proto.requiresBuilding && !this.hasCityBuilding(city, proto.requiresBuilding)) return false;
    // The local testing shortcut: no cost, no production time, no queue.
    if (free) {
      this._spawnTrainedUnit(city, proto);
      this._visibilityDirty = true;
      this._emitChanged();
      return true;
    }
    const queue = this.training.get(cityId);
    if (queue && queue.length >= TRAINING_QUEUE_LIMIT) return false;
    // A free unit (the worker) needs neither money nor production time.
    if (proto.cost <= 0) {
      this._spawnTrainedUnit(city, proto);
      this._visibilityDirty = true;
      this._emitChanged();
      return true;
    }
    const capacity = ECONOMY.productionCapacity(this.getPlayerGdp(city.civ));
    if (capacity <= 0) return false;
    if (!this._spendBudget(city.civ, proto.cost, "training")) return false;
    const materials = this.constructionResourceCost(proto, 0, proto.cost);
    if (!this._payConstructionResources(city.civ, city.coords, materials, "training", proto.name)) {
      this._refundBudget(city.civ, proto.cost, "training");
      return false;
    }
    const entry = {
      kind: "unit",
      protoIndex,
      capacity,
      elapsedHours: 0,
      totalHours: (proto.cost / capacity) *
        this.constructionApprovalMultiplier(city) *
        this.constructionSpeedMultiplier(city.civ),
    };
    if (queue) queue.push(entry);
    else this.training.set(cityId, [entry]);
    this._emitChanged();
    return true;
  },

  // Cancels the queued entry at `index` in the city's production queue.
  // Nothing is refunded: the money and time already spent on it are lost.
  cancelTrain(cityId, index) {
    const queue = this.training.get(cityId);
    if (!queue) return false;
    const at = Number(index);
    if (!Number.isInteger(at) || at < 0 || at >= queue.length) return false;
    queue.splice(at, 1);
    if (queue.length === 0) this.training.delete(cityId);
    this._emitChanged();
    return true;
  },

  // Queues one more level of a building in the city's production queue. Like a
  // unit, the level is paid for up front from the budget and only rises once
  // its production time has elapsed. Repeated orders stack levels: the second
  // queued level is priced off the level the first will leave behind.
  requestBuild(cityId, protoIndex, free = false) {
    const city = this.findCity(cityId);
    if (!city || protoIndex < 0 || protoIndex >= this.protoBuildings.length) return false;
    const proto = this.protoBuildings[protoIndex];
    // Placement rules: a port needs the sea, a shipyard needs a port.
    if (proto.coastal && !this.isCoastalCity(city)) return false;
    if (proto.requiresBuilding && !this.hasCityBuilding(city, proto.requiresBuilding)) return false;
    if (proto.requiresTechnology && !this.hasTechnology(city.civ, proto.requiresTechnology)) return false;
    // The local testing shortcut: raise the next level at once, for free.
    if (free) {
      const level =
        this.getCityBuildingLevel(city, protoIndex) +
        this._pendingBuildingLevels(cityId, protoIndex);
      city.buildings[protoIndex] = level + 1;
      this._gdpPerCapitaCache.clear();
      this._touchModifiers();
      this._emitChanged();
      return true;
    }
    const queue = this.training.get(cityId);
    if (queue && queue.length >= TRAINING_QUEUE_LIMIT) return false;
    const level =
      this.getCityBuildingLevel(city, protoIndex) +
      this._pendingBuildingLevels(cityId, protoIndex);
    const cost = buildingBuildCost(proto, level);
    // A free improvement is raised at once.
    if (cost <= 0) {
      city.buildings[protoIndex] = level + 1;
      this._gdpPerCapitaCache.clear();
      this._touchModifiers();
      this._emitChanged();
      return true;
    }
    const capacity = ECONOMY.productionCapacity(this.getPlayerGdp(city.civ));
    if (capacity <= 0) return false;
    if (!this._spendBudget(city.civ, cost, "construction")) return false;
    const materials = this.constructionResourceCost(proto, level, cost);
    if (!this._payConstructionResources(city.civ, city.coords, materials, "construction", proto.name)) {
      this._refundBudget(city.civ, cost, "construction");
      return false;
    }
    const entry = {
      kind: "building",
      protoIndex,
      level,
      capacity,
      elapsedHours: 0,
      totalHours: (cost / capacity) *
        this.constructionApprovalMultiplier(city) *
        this.constructionSpeedMultiplier(city.civ),
    };
    if (queue) queue.push(entry);
    else this.training.set(cityId, [entry]);
    this._emitChanged();
    return true;
  },

  // Lays a road or railway on a land tile the civilisation controls. A tile
  // holds at most one transport improvement, so building one replaces whatever
  // is already there; the full price is still paid. The cost is charged up front
  // and the tile changes at once, and afterwards the nation pays an hourly
  // maintenance for every road and railway tile it holds.
  requestBuildImprovement(civ, coords, id, free = false) {
    if (civ < 0 || civ >= this.civilisations.length) return false;
    const improvement = transportImprovement(id);
    if (!improvement || !coords) return false;
    if (!Number.isFinite(coords.x) || !Number.isFinite(coords.y)) return false;
    const k = key(coords.x, coords.y);
    const tile = this.tiles[k];
    if (!tile || tile.terrainClass !== "Land") return false;
    if (this.civAt(coords) !== civ) return false;
    const current = this.railways.has(k) ? "railway" : this.roads.has(k) ? "road" : null;
    if (current === improvement.id) return false;
    if (!free) {
      if (!this._spendBudget(civ, improvement.buildCost, "tilebuild")) return false;
      const materials = tileImprovementResourceCost(improvement);
      if (!this._payConstructionResources(civ, coords, materials, "tilebuild", improvement.name)) {
        this._refundBudget(civ, improvement.buildCost, "tilebuild");
        return false;
      }
    }
    this.roads.delete(k);
    this.railways.delete(k);
    if (improvement.id === "railway") this.railways.add(k);
    else this.roads.add(k);
    this._improvementVersion += 1;
    this._emitChanged();
    return true;
  },

  // Removes whatever transport improvement stands on a land tile the
  // civilisation controls. Removal is immediate and free, so a mis-built road
  // can be cleared without a new one replacing it.
  requestRemoveImprovement(civ, coords) {
    if (civ < 0 || civ >= this.civilisations.length) return false;
    if (!coords) return false;
    if (!Number.isFinite(coords.x) || !Number.isFinite(coords.y)) return false;
    const k = key(coords.x, coords.y);
    const tile = this.tiles[k];
    if (!tile || tile.terrainClass !== "Land") return false;
    if (this.civAt(coords) !== civ) return false;
    const present = this.railways.has(k) || this.roads.has(k);
    if (!present) return false;
    this.roads.delete(k);
    this.railways.delete(k);
    this._improvementVersion += 1;
    this._emitChanged();
    return true;
  },

  requestDemolish(cityId, protoIndex) {
    const city = this.findCity(cityId);
    if (!city || protoIndex < 0 || protoIndex >= this.protoBuildings.length) return false;
    const level = this.getCityBuildingLevel(city, protoIndex);
    if (level <= 0) return false;
    // Downgrading refunds nothing: the money and materials already sunk into
    // the level are lost.
    if (level <= 1) delete city.buildings[protoIndex];
    else city.buildings[protoIndex] = level - 1;
    this._gdpPerCapitaCache.clear();
    this._touchModifiers();
    this._emitChanged();
    return true;
  },

  requestSetGovernment(civ, index) {
    if (civ < 0 || civ >= this.civilisations.length) return false;
    if (index < 0 || index >= this.governments.length) return false;
    if (this.getGovernment(civ) === index) return false;
    const cost = GOVERNMENTS[index].baseCost +
      GOVERNMENTS[index].costGdpFraction * Math.max(this.getPlayerGdp(civ), 0);
    if (cost > 0) this._spendBudget(civ, cost, "campaign");
    this.government.set(civ, index);
    this._gdpPerCapitaCache.clear();
    this._touchModifiers();
    this._emitChanged();
    return true;
  },

  // Focuses a nation's research on one technology. Every point it creates from
  // now on flows straight into it; nothing is charged up front and nothing is
  // banked while no technology is focused.
  requestFocusTechnology(civ, index) {
    if (!this.canResearchTechnology(civ, index)) return false;
    if (this.getFocusedTechnology(civ) === index) return true;
    // Progress is kept per technology, so switching focus never discards work
    // already done on either the old focus or the new one.
    this.focusTechnology.set(civ, index);
    this._emitChanged();
    return true;
  },

  // Whether the units may pillage the tile they stand on: all of them are on
  // one hostile tile where no battle is raging.
  canPillage(unitIds) {
    const units = this._unitsForOrder(unitIds);
    if (units.length === 0) return false;
    const coords = units[0].coords;
    const owner = this.civAt(coords);
    if (owner < 0 || owner === units[0].civ) return false;
    if (!units.every((unit) => unit.coords.x === coords.x && unit.coords.y === coords.y)) {
      return false;
    }
    return !this._battleTiles().some(
      (battle) => battle.coords.x === coords.x && battle.coords.y === coords.y
    );
  },

  // Pillages the tile the units stand on. Every unit in the stack takes a turn,
  // the weakest first (least HP relative to maximum): each removes 10% of the
  // remaining population, cuts the tile's production per head by 30% and heals
  // one hit point per 1000 people it drives off.
  requestPillage(unitIds) {
    const units = this._unitsForOrder(unitIds);
    if (!this.canPillage(unitIds)) return false;
    const coords = units[0].coords;
    const owner = this.civAt(coords);
    const k = key(coords.x, coords.y);
    const ordered = units.slice().sort((a, b) => a.hp / a.maxHp - b.hp / b.maxHp);
    let population = this.tilePopulation.get(k) || 0;
    const { steps } = pillageSteps(population, ordered.length);
    let penalty = this.tileProductionPenalty.get(k) !== undefined
      ? this.tileProductionPenalty.get(k)
      : 1;
    let drivenOff = 0;
    for (let i = 0; i < ordered.length; i++) {
      penalty *= PILLAGE.productionPenalty;
      const unit = ordered[i];
      unit.hp = Math.min(unit.maxHp, unit.hp + steps[i].heal);
      drivenOff += steps[i].removed;
    }
    population = steps.length > 0 ? steps[steps.length - 1].remaining : population;
    this.tilePopulation.set(k, population);
    this._populationVersion += 1;
    this.tileProductionPenalty.set(k, penalty);
    this._gdpPerCapitaCache.delete(k);
    // The people driven off the tile are civilians lost to its owner in the war
    // against the pillaging civilisation.
    if (owner >= 0) this._recordCasualties(owner, units[0].civ, "civilians", drivenOff);
    // Pillaging the defenceless is a war crime the world remembers.
    this._recordWarCrime(units[0].civ, coords, owner);
    this._emitChanged();
    return true;
  },

  // How many levels of `protoIndex` already sit in the city's production queue,
  // so the next order is priced off the level the waiting ones will reach.
  _pendingBuildingLevels(cityId, protoIndex) {
    const queue = this.training.get(cityId);
    if (!queue) return 0;
    let count = 0;
    for (const entry of queue) {
      if (entry.kind === "building" && entry.protoIndex === protoIndex) count += 1;
    }
    return count;
  },

  _unitsForOrder(unitIds) {
    const ids = Array.isArray(unitIds) ? unitIds : [unitIds];
    const units = [];
    for (const id of ids) {
      const unit = this.findUnit(Number(id));
      if (unit) units.push(unit);
    }
    return units;
  },
};