import { content, type Location, type ShipModel } from "@deadhead/content";
import type { Ship } from "@deadhead/schema";
import {
  checkRoute,
  effectiveStats,
  MS_PER_HOUR,
  routeDistance,
  travelTimeGameHours,
  type EffectiveStats,
  type ShipState,
} from "@deadhead/sim";

/** Client-side predictions with the same sim the server uses (rule 0.1.6). */

export function location(id: string): Location {
  const found = content.location(id);
  if (!found) throw new Error(`Unknown location ${id}`);
  return found;
}

export function shipModel(id: string): ShipModel {
  const found = content.shipModel(id);
  if (!found) throw new Error(`Unknown ship model ${id}`);
  return found;
}

/** Route distance in million km; fixed (decision 0.5.93). */
export function distanceAt(originId: string, destinationId: string): number {
  return routeDistance(location(originId), location(destinationId));
}

/** Trip duration in real milliseconds for a ship carrying `massTonnes`. */
export function tripRealMs(
  model: ShipModel,
  originId: string,
  destinationId: string,
  massTonnes: number,
) {
  const hours = travelTimeGameHours(
    model,
    distanceAt(originId, destinationId),
    massTonnes,
    content.config,
  );
  return (hours * MS_PER_HOUR) / content.config.timeCompression;
}

/** A ship's effective stats: its model plus its upgrades (decision 0.5.63). */
export function shipStatsOf(ship: Pick<Ship, "modelId" | "upgrades">): EffectiveStats {
  return effectiveStats(shipModel(ship.modelId), ship.upgrades, content);
}

/** The sim's view of an owned ship: location, flight, upgrades and shop time (CR-009). */
export function simShip(ship: Ship): ShipState {
  return {
    id: ship.id,
    modelId: ship.modelId,
    locationId: ship.locationId ?? "",
    inFlight: ship.status === "in-flight",
    upgrades: ship.upgrades,
    inShopUntil: ship.inShopUntil,
  };
}

const legKey = (fromId: string, toId: string) => `${fromId}>${toId}`;
const legCache = new Map<string, Set<string>>();

/** Legs a model can fly (the map is fixed, decision 0.5.93). */
function legsInRange(model: ShipModel): Set<string> {
  let legs = legCache.get(model.id);
  if (!legs) {
    legs = new Set();
    for (const from of content.locations) {
      for (const to of content.locations) {
        if (from.id !== to.id && checkRoute(model, from, to).ok) legs.add(legKey(from.id, to.id));
      }
    }
    legCache.set(model.id, legs);
  }
  return legs;
}

export interface ShipReach {
  /** Per origin, the locations in range right now. */
  now: { originId: string; destinationIds: string[] }[];
  /** Reachable directly from an origin, but not right now. */
  otherDates: string[];
  /** Reachable only through other locations. */
  byHopping: string[];
}

/**
 * Where a base model can fly from `originIds` (Market, Step 10L.7): legs in
 * range from each origin, and places it can reach only by hopping. On the fixed
 * map (decision 0.5.93) `otherDates` is always empty; it goes with its wording
 * in Step 15.8.
 */
export function shipReach(model: ShipModel, originIds: string[]): ShipReach {
  const ever = legsInRange(model);
  const ids = content.locations.map((l) => l.id);
  const origins = new Set(originIds);
  const nowLegs = originIds.map((originId) => ({
    originId,
    destinationIds: ids.filter(
      (to) => to !== originId && checkRoute(model, location(originId), location(to)).ok,
    ),
  }));
  const inRangeNow = new Set(nowLegs.flatMap((l) => l.destinationIds));
  const direct = new Set(ids.filter((to) => originIds.some((o) => ever.has(legKey(o, to)))));
  const reached = new Set(originIds);
  const queue = [...originIds];
  while (queue.length > 0) {
    const from = queue.shift()!;
    for (const to of ids) {
      if (!reached.has(to) && ever.has(legKey(from, to))) {
        reached.add(to);
        queue.push(to);
      }
    }
  }
  return {
    now: nowLegs,
    otherDates: ids.filter((id) => direct.has(id) && !inRangeNow.has(id) && !origins.has(id)),
    byHopping: ids.filter((id) => reached.has(id) && !direct.has(id) && !origins.has(id)),
  };
}