import { content } from "@deadhead/content";
import type { Bay, Pilot, SaveDocument, Ship } from "@deadhead/schema";
import {
  effectiveStats,
  emergencyFuel,
  fuelPriceAt,
  isResting,
  pilotLevel,
  refuel,
  restEndsAt,
  skillPointsAvailable,
  validateUpgrade,
  type RealTime,
} from "@deadhead/sim";
import type { RandomSource } from "../core";
import { fail } from "./errors";
import { UPGRADE_MESSAGES, VALIDATION_MESSAGES } from "./messages";
import { pilotName, shipName } from "./names";
import {
  deliveredTank,
  discoveredIds,
  hasBayAt,
  requirePilot,
  requireShip,
  requireTutorialOver,
  shipState,
  spend,
  toApiPilot,
  toApiShip,
} from "./state";

/** Leases a bay at a discovered location for its one-time price (Step 6.6). */
export function leaseBay(
  save: SaveDocument,
  locationId: string,
  random: RandomSource,
  now: RealTime,
): Bay {
  requireTutorialOver(save, "leasing a bay");
  const location = content.location(locationId);
  if (!location) throw fail("not-found", `No location "${locationId}".`);
  if (!save.discoveredLocations.some((d) => d.locationId === locationId)) {
    throw fail("location-undiscovered", `Deliver to ${location.name} before leasing a bay there.`);
  }
  if (hasBayAt(save, locationId)) {
    throw fail("bay-already-leased", `You already have a bay at ${location.name}.`);
  }
  spend(save, location.bayLeasePrice, `a bay at ${location.name}`);
  const bay = { id: random.id(), locationId, createdAt: now };
  save.bays.push(bay);
  return { id: bay.id, locationId };
}

/** Buys a ship model, delivered idle and uncrewed to one of the bays (Steps 6.5, 10B.6; decision 0.5.35). */
export function buyShip(
  save: SaveDocument,
  input: { modelId: string; bayId: string },
  random: RandomSource,
  now: RealTime,
): Ship {
  requireTutorialOver(save, "buying a ship");
  const model = content.shipModel(input.modelId);
  if (!model?.purchasable) throw fail("not-found", `No ship model "${input.modelId}" for sale.`);
  const bay = save.bays.find((b) => b.id === input.bayId);
  if (!bay) throw fail("not-found", "You have no such bay.");
  spend(save, model.price, `a ${model.name}`);
  const ship: SaveDocument["ships"][number] = {
    id: random.id(),
    modelId: model.id,
    name: shipName(save.player.worldSeed, save.ships.length),
    status: "idle",
    locationId: bay.locationId,
    upgrades: {},
    inShopUntil: null,
    shopUpgradeId: null,
    shopLevel: null,
    fromDeal: false,
    createdAt: now,
    lastArrivalAt: now,
    // Delivered with a full tank, included in the price (decision 0.5.94).
    ...deliveredTank(model.id, bay.locationId),
  };
  save.ships.push(ship);
  return toApiShip(save, ship, now);
}

/** Hires a level-0 pilot at one of the bays (Step 6.8, decision 0.5.22). */
export function hirePilot(
  save: SaveDocument,
  locationId: string,
  random: RandomSource,
  now: RealTime,
): Pilot {
  requireTutorialOver(save, "hiring pilots");
  if (!hasBayAt(save, locationId)) {
    throw fail("no-bay-at-location", "Pilots can only be hired at one of your bays.");
  }
  spend(save, content.config.pilotHireCost, "a new pilot");
  const hired = save.pilots.filter((p) => !p.isAvatar).length;
  const pilot: SaveDocument["pilots"][number] = {
    id: random.id(),
    name: pilotName(save.player.worldSeed, hired),
    isAvatar: false,
    isVeteran: false,
    xp: 0,
    skills: {},
    skillPointsSpent: 0,
    assignedShipId: null,
    locationId,
    status: "idle",
    dutyHours: 0,
    restEndsAt: null,
    createdAt: now,
  };
  save.pilots.push(pilot);
  return toApiPilot(save, pilot, now);
}

/**
 * Assigns an idle, unassigned pilot to an idle, uncrewed ship at the same
 * location. The avatar flies the loaner during the tutorial (decision 0.5.23).
 */
export function assignPilot(
  save: SaveDocument,
  input: { pilotId: string; shipId: string },
  now: RealTime,
): Pilot {
  const pilot = requirePilot(save, input.pilotId);
  const ship = requireShip(save, input.shipId);
  if (pilot.isAvatar && save.player.tutorialActive) {
    throw fail("avatar-in-tutorial", "You fly the company loaner until the tutorial ends.");
  }
  if (pilot.status === "in-flight")
    throw fail("pilot-not-idle", VALIDATION_MESSAGES["pilot-not-idle"]);
  if (pilot.assignedShipId !== null) {
    throw fail("pilot-already-assigned", "That pilot already has a ship. Unassign them first.");
  }
  if (ship.status === "in-flight")
    throw fail("ship-not-idle", VALIDATION_MESSAGES["ship-not-idle"]);
  if (ship.locationId !== pilot.locationId) {
    throw fail("ship-not-idle-here", "The pilot and the ship must be at the same location.");
  }
  if (save.pilots.some((p) => p.assignedShipId === ship.id)) {
    throw fail("ship-crewed", "That ship already has a pilot.");
  }
  Object.assign(pilot, { assignedShipId: ship.id, locationId: null });
  return toApiPilot(save, pilot, now);
}

/** Unassigns a pilot from its ship, only where the player has a bay (decision 0.5.2). */
export function unassignPilot(save: SaveDocument, pilotId: string, now: RealTime): Pilot {
  const pilot = requirePilot(save, pilotId);
  if (pilot.assignedShipId === null)
    throw fail("pilot-not-assigned-to-ship", "That pilot has no ship.");
  if (pilot.status === "in-flight")
    throw fail("pilot-not-idle", VALIDATION_MESSAGES["pilot-not-idle"]);
  const ship = requireShip(save, pilot.assignedShipId);
  if (ship.locationId === null || !hasBayAt(save, ship.locationId)) {
    throw fail("no-bay-at-location", "Pilots can only leave their ship at one of your bays.");
  }
  Object.assign(pilot, { assignedShipId: null, locationId: ship.locationId });
  return toApiPilot(save, pilot, now);
}

/** Rests an idle pilot now, at any duty level (CR-004): duty resets and they can't fly until it ends. */
export function restPilot(save: SaveDocument, pilotId: string, now: RealTime): Pilot {
  requireTutorialOver(save, "resting a pilot");
  const pilot = requirePilot(save, pilotId);
  if (pilot.status === "in-flight")
    throw fail("pilot-not-idle", VALIDATION_MESSAGES["pilot-not-idle"]);
  if (isResting(pilot.restEndsAt, now))
    throw fail("pilot-resting", "That pilot is already resting.");
  Object.assign(pilot, { dutyHours: 0, restEndsAt: restEndsAt(now, content.config) });
  return toApiPilot(save, pilot, now);
}

/** Spends one available skill point on a skill below its max level (Step 6.12). */
export function spendSkillPoint(
  save: SaveDocument,
  input: { pilotId: string; skillId: string },
  now: RealTime,
): Pilot {
  const pilot = requirePilot(save, input.pilotId);
  const skill = content.skill(input.skillId);
  if (!skill) throw fail("unknown-skill", `No skill "${input.skillId}".`);
  const level = pilotLevel(pilot.xp, content.config);
  if (skillPointsAvailable(level, pilot.skillPointsSpent, content.config) <= 0) {
    throw fail("no-skill-points", "That pilot has no skill points to spend.");
  }
  const current = pilot.skills[skill.id] ?? 0;
  if (current >= skill.maxLevel)
    throw fail("skill-maxed", `${skill.name} is already at its maximum level.`);
  pilot.skills = { ...pilot.skills, [skill.id]: current + 1 };
  pilot.skillPointsSpent += 1;
  return toApiPilot(save, pilot, now);
}

/**
 * Starts the next level of an upgrade on a ship (CR-009): validate, charge,
 * raise the level now, and keep the ship in the shop until the work is done.
 */
export function startUpgrade(
  save: SaveDocument,
  input: { shipId: string; upgradeId: string },
  now: RealTime,
): Ship {
  const upgrade = content.upgrade(input.upgradeId);
  if (!upgrade) throw fail("not-found", `No upgrade "${input.upgradeId}".`);
  const ship = requireShip(save, input.shipId);
  const check = validateUpgrade(
    {
      ship: shipState(ship),
      upgrade,
      atHq: ship.locationId !== null && hasBayAt(save, ship.locationId),
      tutorialActive: save.player.tutorialActive,
      credits: save.company.credits,
      now,
    },
    content,
  );
  if (!check.ok) throw fail(check.reason, UPGRADE_MESSAGES[check.reason]);
  save.company.credits -= check.cost;
  ship.upgrades = { ...ship.upgrades, [upgrade.id]: check.level };
  Object.assign(ship, {
    inShopUntil: check.shopUntil,
    shopUpgradeId: upgrade.id,
    shopLevel: check.level,
  });
  return toApiShip(save, ship, now);
}

/**
 * Marks "while you were away" summaries as seen (Step 6.13): only resolved,
 * unseen dispatches. Clears finished upgrade jobs the player has now seen
 * (CR-009); ships still in the shop keep theirs. Returns how many changed.
 */
export function acknowledge(
  save: SaveDocument,
  input: { dispatchIds: string[]; shipIds?: string[] },
  now: RealTime,
): number {
  const ids = new Set(input.dispatchIds);
  let count = 0;
  for (const d of save.dispatches) {
    if (ids.has(d.id) && d.status === "resolved" && d.acknowledgedAt === null) {
      d.acknowledgedAt = now;
      count++;
    }
  }
  const shipIds = new Set(input.shipIds ?? []);
  for (const ship of save.ships) {
    if (
      shipIds.has(ship.id) &&
      ship.shopUpgradeId !== null &&
      ship.inShopUntil !== null &&
      ship.inShopUntil <= now
    ) {
      Object.assign(ship, { shopUpgradeId: null, shopLevel: null });
      count++;
    }
  }
  return count;
}

type SavedShip = SaveDocument["ships"][number];

/** An idle ship's location; refuelling happens only where the ship stands. */
function idleAt(ship: SavedShip) {
  const location =
    ship.status === "idle" && ship.locationId ? content.location(ship.locationId) : undefined;
  if (!location)
    throw fail("ship-not-idle-here", "The ship has to be idle at a location to take on fuel.");
  return location;
}

function tankCapacity(ship: SavedShip): number {
  return effectiveStats(content.shipModel(ship.modelId)!, ship.upgrades, content).tankCapacityFu;
}

/**
 * Buys fuel where the ship is (decision 0.5.97): fills the tank, or adds
 * `amountFu` (never past full), at the local price. Refused if the player
 * can't pay for all of it.
 */
export function refuelShip(
  save: SaveDocument,
  input: { shipId: string; amountFu?: number },
  now: RealTime,
): Ship {
  const ship = requireShip(save, input.shipId);
  const location = idleAt(ship);
  if (!location.sellsFuel) throw fail("no-fuel-here", `${location.name} sells no fuel.`);
  const capacity = tankCapacity(ship);
  const space = capacity - ship.fuelFu;
  if (space <= 1e-9) throw fail("tank-full", "The tank is already full.");
  const bought = refuel(
    { fuelFu: ship.fuelFu, avgPrice: ship.fuelAvgPrice },
    capacity,
    input.amountFu ?? space,
    fuelPriceAt(location, content.config),
  );
  spend(save, bought.cost, "fuel");
  ship.fuelFu = bought.tank.fuelFu;
  ship.fuelAvgPrice = bought.tank.avgPrice;
  return toApiShip(save, ship, now);
}

/** Auto top-up on landing, or Manual (decision 0.5.97). */
export function setRefuelPolicy(
  save: SaveDocument,
  input: { shipId: string; policy: "auto" | "manual" },
  now: RealTime,
): Ship {
  const ship = requireShip(save, input.shipId);
  ship.refuelPolicy = input.policy;
  return toApiShip(save, ship, now);
}

/**
 * Emergency fuel (decision 0.5.99): only when the sim offers it. Adds fuel for
 * the cheapest way out at 2.5 × the local price, and that cost to the loan.
 */
export function orderEmergencyFuel(
  save: SaveDocument,
  input: { shipId: string },
  now: RealTime,
): Ship {
  const ship = requireShip(save, input.shipId);
  idleAt(ship);
  const offer = emergencyFuel(
    { ship: shipState(ship), credits: save.company.credits, discoveredIds: discoveredIds(save) },
    content,
  );
  if (!offer) {
    throw fail(
      "emergency-fuel-unavailable",
      "Emergency fuel is only for a ship that can't reach anywhere when you can't afford the fuel.",
    );
  }
  const bought = refuel(
    { fuelFu: ship.fuelFu, avgPrice: ship.fuelAvgPrice },
    tankCapacity(ship),
    offer.amountFu,
    offer.price,
  );
  ship.fuelFu = bought.tank.fuelFu;
  ship.fuelAvgPrice = bought.tank.avgPrice;
  save.company.loanBalance += offer.cost;
  return toApiShip(save, ship, now);
}