import type { GameConfig } from "@deadhead/content";
import { generateContractBoard, type SimContent } from "../src/board";
import { checkRoute } from "../src/eligibility";
import { routeDistance } from "../src/distance";
import { fuelPriceAt, legFuel } from "../src/fuel";

/** One ship model on one route it can fly (decision 0.5.110). */
export interface FuelShare {
  modelId: string;
  originId: string;
  destinationId: string;
  /** Fuel for the leg bought at the origin's price, in credits. */
  fuelCost: number;
  /** Median payout of the contracts on this route that fit the ship. */
  medianPayout: number;
  /** How many such contracts the boards offered. */
  contracts: number;
  /** fuelCost ÷ medianPayout. */
  share: number;
}

export interface FuelShareOptions {
  /** Board periods sampled at every origin, per world. */
  periods?: number;
  worldSeeds?: readonly number[];
}

function median(values: number[]): number {
  const sorted = [...values].sort((a, b) => a - b);
  const mid = Math.floor(sorted.length / 2);
  return sorted.length % 2 ? sorted[mid]! : (sorted[mid - 1]! + sorted[mid]!) / 2;
}

/**
 * The fuel-to-payout check (CR-018 Step 18.1): for every purchasable ship model
 * and every route it can fly, the fuel a leg burns (fuel has no mass, so any
 * load burns the same) at the origin's price, against the median payout of
 * the contracts on that route that fit the ship, over generated boards with
 * every location discovered and that ship as the fleet.
 */
export function fuelShares(content: SimContent, options: FuelShareOptions = {}): FuelShare[] {
  const { periods = 40, worldSeeds = [12345, 777, 4242] } = options;
  const config: GameConfig = content.config;
  const discoveredIds = new Set(content.locations.map((l) => l.id));
  const rows: FuelShare[] = [];
  for (const model of content.shipModels.filter((m) => m.purchasable)) {
    const payouts = new Map<string, number[]>();
    for (const origin of content.locations) {
      for (const worldSeed of worldSeeds) {
        for (let periodIndex = 0; periodIndex < periods; periodIndex++) {
          const board = generateContractBoard(
            {
              location: origin,
              discoveredIds,
              periodIndex,
              worldSeed,
              fleet: [{ modelId: model.id, skills: {} }],
            },
            content,
          );
          for (const contract of board) {
            if (contract.massTonnes > model.cargoCapacityTonnes) continue;
            const key = `${contract.originId}>${contract.destinationId}`;
            payouts.set(key, [...(payouts.get(key) ?? []), contract.payout]);
          }
        }
      }
    }
    for (const origin of content.locations) {
      for (const destination of content.locations) {
        if (origin.id === destination.id) continue;
        if (!checkRoute(model, origin, destination, config).ok) continue;
        const offered = payouts.get(`${origin.id}>${destination.id}`) ?? [];
        if (offered.length === 0) continue;
        const fuelCost =
          legFuel(model, origin, routeDistance(origin, destination), config) *
          fuelPriceAt(origin, config);
        const medianPayout = median(offered);
        rows.push({
          modelId: model.id,
          originId: origin.id,
          destinationId: destination.id,
          fuelCost,
          medianPayout,
          contracts: offered.length,
          share: fuelCost / medianPayout,
        });
      }
    }
  }
  return rows;
}

/** The check as a table, one line per ship and route (for the balance script). */
export function formatFuelShares(rows: readonly FuelShare[]): string {
  const lines = rows.map(
    (r) =>
      `${r.modelId.padEnd(12)} ${`${r.originId} → ${r.destinationId}`.padEnd(50)} ` +
      `${Math.round(r.fuelCost).toString().padStart(7)}  ${Math.round(r.medianPayout).toString().padStart(8)}  ` +
      `${(r.share * 100).toFixed(1).padStart(5)}%`,
  );
  return [
    "ship         route                                                 fuel    median   share",
    ...lines,
  ].join("\n");
}