import type { SimContent } from "./board";
import type { RealTime } from "./clock";
import type { DispatchRecord } from "./dispatch";
import { findLocation } from "./dispatch";
import { dutyAfterTrip, dutyLimit, needsRest, restEndsAt, tripGameHours } from "./duty";
import { affordableRefuel, fuelPriceAt, type Tank } from "./fuel";
import { splitLoanRepayment } from "./loan";
import { pilotShare } from "./pay";
import type { SkillLevels } from "./pilot";
import { deliveryXp } from "./xp";
import { payoutAfterEvent, type AppliedEvent } from "./events";

/** Auto top-up (default) fills the tank on landing; Manual never does (decision 0.5.97). */
export type RefuelPolicy = "auto" | "manual";

/** Fuel an Auto top-up bought on landing (decision 0.5.97). */
export interface TopUp {
  locationId: string;
  boughtFu: number;
  /** Credits per fu. */
  price: number;
  /** Whole credits, paid on top of the delivery's `credits`. */
  cost: number;
  /** The tank afterwards. */
  tank: Tank;
}

export interface Resolution {
  /**
   * Credits to add: payout minus pilot pay, minus the loan repayment. Fuel
   * came out of the tank at departure; any top-up is `topUp.cost`.
   */
  credits: number;
  /** Auto top-up on landing, or null (Manual, nothing bought, or no tank). */
  topUp: TopUp | null;
  /** A hired pilot's share of this delivery's profit; 0 for the avatar, tutorial runs and deadheads (CR-010). */
  pilotPay: number;
  /** Credits that went to the lender out of this payout (decision 0.5.32). */
  loanRepayment: number;
  pilotXp: number;
  /** Where the ship (or tutorial loaner) is now. */
  shipLocationId: string;
  /** True when this delivery discovers the destination. */
  discoversDestination: boolean;
  /** The pilot's duty hours after this trip: 0 if it ended in mandatory rest (CR-004). */
  pilotDutyHours: number;
  /** Mandatory rest from the arrival time, or null (decision 0.5.45). */
  pilotRestEndsAt: RealTime | null;
}

export type ResolveResult =
  { status: "in-flight" } | { status: "resolved"; resolution: Resolution };

export interface ResolveInput {
  record: DispatchRecord;
  /** The avatar is exempt from pilot pay (decision 0.5.12). */
  pilotIsAvatar: boolean;
  discoveredIds: ReadonlySet<string>;
  /** The company's loan balance before this resolution. */
  loanBalance: number;
  /** The pilot's duty hours before this trip, and skills (Long Haul sets the limit). */
  pilotDutyHours: number;
  pilotSkills: SkillLevels;
  now: RealTime;
  /**
   * The ship's tank on landing, its policy, and the company's credits before this
   * resolution (Auto top-up buys what they cover). Absent: no top-up (the
   * tutorial loaner uses no fuel).
   */
  fuel?: { tank: Tank; capacityFu: number; refuelPolicy: RefuelPolicy; credits: number };
  /** The trip's event once applied (CR-026): it changes the pay and XP. */
  event?: AppliedEvent | null;
}

/** Auto top-up on landing (decision 0.5.97): as much as the credits after this trip cover. */
function topUpOnLanding(input: ResolveInput, net: number, content: SimContent): TopUp | null {
  const { fuel, record } = input;
  if (!fuel || record.tutorial || fuel.refuelPolicy !== "auto") return null;
  const location = findLocation(record.destinationId, content);
  if (!location.sellsFuel) return null;
  const price = fuelPriceAt(location, content.config);
  const bought = affordableRefuel(fuel.tank, fuel.capacityFu, price, fuel.credits + net);
  if (bought.boughtFu <= 0) return null;
  return {
    locationId: location.id,
    boughtFu: bought.boughtFu,
    price,
    cost: bought.cost,
    tank: bought.tank,
  };
}

/**
 * The pilot's duty after a trip (decisions 0.5.42–0.5.45): the trip's game
 * hours are added (tutorial runs add none); at or over the limit, rest starts
 * at the arrival time and duty resets, however late the trip is resolved.
 */
function dutyOutcome(input: ResolveInput, content: SimContent) {
  const { record, pilotDutyHours, pilotSkills } = input;
  const hours = tripGameHours(record.departureAt, record.arrivalAt, content.config);
  const duty = dutyAfterTrip(pilotDutyHours, hours, record.tutorial);
  if (!record.tutorial && needsRest(duty, dutyLimit(pilotSkills, content.config))) {
    return { pilotDutyHours: 0, pilotRestEndsAt: restEndsAt(record.arrivalAt, content.config) };
  }
  return { pilotDutyHours: duty, pilotRestEndsAt: null };
}

/**
 * XP for a delivery (Step 6.8); tutorial runs earn it × the tutorial XP
 * multiplier, so the avatar has a skill point by the deal (decision 0.5.107).
 */
export function deliveryXpFor(record: DispatchRecord, tier: number, content: SimContent): number {
  const xp = deliveryXp(record.distanceMillionKm, tier, content.config);
  return record.tutorial ? Math.round(xp * content.config.tutorialXpMultiplier) : xp;
}

/** Resolves a dispatch once it has arrived. Same inputs always give the same result. */
export function resolveDispatch(input: ResolveInput, content: SimContent): ResolveResult {
  const { record, pilotIsAvatar, discoveredIds, loanBalance, now } = input;
  if (now < record.arrivalAt) return { status: "in-flight" };

  const { contract } = record;
  const base = { shipLocationId: record.destinationId, ...dutyOutcome(input, content) };
  if (contract === null) {
    // Deadheads earn nothing and only fly to discovered locations.
    return {
      status: "resolved",
      resolution: {
        ...base,
        credits: 0,
        topUp: topUpOnLanding(input, 0, content),
        pilotPay: 0,
        loanRepayment: 0,
        pilotXp: 0,
        discoversDestination: false,
      },
    };
  }

  // An event's losses, fees and bonuses change what the shipper pays (CR-026).
  const payout = payoutAfterEvent(contract.payout, input.event);
  // Profit-share pay (decision 0.5.12, CR-010), taken before the loan repayment (0.5.69).
  const pilotPay =
    record.tutorial || pilotIsAvatar ? 0 : pilotShare(payout, record.fuelCost, content.config);
  // Tutorial contracts already store exactly the tutorial share as their payout.
  const { repayment, net } = splitLoanRepayment(
    payout - pilotPay,
    loanBalance,
    content.config.loanRepaymentShare,
  );
  return {
    status: "resolved",
    resolution: {
      ...base,
      credits: net,
      topUp: topUpOnLanding(input, net, content),
      pilotPay,
      loanRepayment: repayment,
      pilotXp: Math.round(
        deliveryXpFor(record, contract.tier, content) * (1 + (input.event?.xpBonusPct ?? 0) / 100),
      ),
      discoversDestination: !discoveredIds.has(record.destinationId),
    },
  };
}