import type { Asset, LockerStorage, MarketListing, User } from "@/payload-types";
import {
  ensureLockerStorage,
  findLockerEmptySpot,
  getLockerGridDimensions,
  getLockerItemFootprint,
  lockerIsStackable,
  lockerMaxStack,
  resolveAssetId,
  toLockerGridItems,
} from "@/lib/locker";
import {
  applyTransaction,
  ensurePersonalAccount,
  getMainCurrencyId,
  getTreasuryAccountId,
} from "@/lib/banking";

export { getTreasuryAccountId } from "@/lib/banking";

type PayloadType = Awaited<ReturnType<typeof import("payload").getPayload>>;

export type ListingStatus = "active" | "sold" | "cancelled" | "expired";

export type LockerItemEntry = NonNullable<LockerStorage["items"]>[number];

/** User listings last 30 days before stock is returned to the seller. */
export const USER_LISTING_DURATION_MS = 30 * 24 * 60 * 60 * 1000;
/** Auto-generated NPC entries rotate weekly. */
export const AUTO_LISTING_DURATION_MS = 7 * 24 * 60 * 60 * 1000;

export const RARITY_LABELS: Record<string, string> = {
  basic: "Basic",
  common: "Common",
  uncommon: "Uncommon",
  rare: "Rare",
  veryRare: "Very Rare",
  epic: "Epic",
  legendary: "Legendary",
  unique: "Unique",
};

export function getRarityLabel(asset: Asset): string | null {
  const rarity = asset.marketTrading?.Rarity;
  return rarity ? (RARITY_LABELS[rarity] ?? rarity) : null;
}

export function getBaseBuyPrice(asset: Asset): number | null {
  const value = asset.marketTrading?.perceivedValue?.baseBuyPrice;
  return typeof value === "number" && value > 0 ? value : null;
}

export function getBaseSellPrice(asset: Asset): number | null {
  const value = asset.marketTrading?.perceivedValue?.baseSellPrice;
  return typeof value === "number" && value > 0 ? value : null;
}

export function listingTotal(listing: Pick<MarketListing, "price" | "quantity">): number {
  return (listing.price ?? 0) * (listing.quantity ?? 1);
}

export interface NegotiationRange {
  /** Lowest per-unit price the seller will accept. */
  min: number;
  /** Price the seller is hoping to achieve (defaults to the asking price). */
  desired: number;
}

/** Resolve a listing's negotiation range. Non-negotiable listings have min === desired. */
export function negotiationRange(
  listing: Pick<MarketListing, "price" | "desiredPrice" | "minPrice">,
): NegotiationRange {
  const desired = listing.desiredPrice ?? listing.price ?? 0;
  const min = listing.minPrice ?? desired;
  return { min, desired };
}

/** A listing is negotiable when the seller has set a floor below the asking price. */
export function isNegotiable(
  listing: Pick<MarketListing, "price" | "desiredPrice" | "minPrice">,
): boolean {
  const { min, desired } = negotiationRange(listing);
  return min < desired;
}

/** An entry is sellable if it carries no attachments or applied skin (those would be lost on sale). */
export function isEntryClean(entry: LockerItemEntry): boolean {
  const attachments = entry.equipment?.attachments ?? [];
  const skinId = resolveAssetId(entry.equipment?.skin);
  return attachments.length === 0 && skinId == null;
}

/** Total clean (sellable) quantity of an asset across a locker. */
export function countCleanQuantity(locker: LockerStorage, assetId: number): number {
  return (locker.items ?? []).reduce((sum, entry) => {
    if (resolveAssetId(entry.asset) !== assetId) return sum;
    if (!isEntryClean(entry)) return sum;
    return sum + (entry.quantity ?? 0);
  }, 0);
}

/**
 * Remove `quantity` of `assetId` from the locker, consuming clean entries
 * only. Throws if the locker does not hold enough clean stock.
 */
export function deductLockerQuantity(
  locker: LockerStorage,
  assetId: number,
  quantity: number,
): LockerItemEntry[] {
  const items = [...(locker.items ?? [])] as LockerItemEntry[];
  let remaining = quantity;

  const result: LockerItemEntry[] = [];
  for (const entry of items) {
    if (resolveAssetId(entry.asset) !== assetId || !isEntryClean(entry) || remaining <= 0) {
      result.push(entry);
      continue;
    }
    const take = Math.min(entry.quantity, remaining);
    remaining -= take;
    if (entry.quantity - take > 0) {
      result.push({ ...entry, quantity: entry.quantity - take });
    }
  }

  if (remaining > 0) {
    throw new Error("Not enough sellable stock in locker for this listing.");
  }

  return result;
}

/**
 * Add `quantity` of `assetId` to a user's locker, merging into existing
 * stacks and filling empty grid spots. Throws if there is no space.
 */
export async function creditLockerQuantity(
  payload: PayloadType,
  userId: number,
  assetId: number,
  quantity: number,
): Promise<LockerStorage> {
  const locker = await ensureLockerStorage(payload, userId);
  const lockerFull = (await payload.findByID({
    collection: "locker-storages",
    id: locker.id,
    depth: 1,
    overrideAccess: true,
  })) as unknown as LockerStorage;

  const asset = (await payload.findByID({
    collection: "assets",
    id: assetId,
    depth: 0,
    overrideAccess: true,
  })) as unknown as Asset;
  if (!asset) throw new Error("Asset not found.");

  const grid = await getLockerGridDimensions(payload);
  const items = [...(lockerFull.items ?? [])];
  const gridItems = toLockerGridItems(items);
  const stackable = lockerIsStackable(asset);
  const maxStack = lockerMaxStack(asset);
  const footprint = getLockerItemFootprint(asset, false);

  let remaining = quantity;

  if (stackable) {
    for (const entry of gridItems) {
      if (remaining <= 0) break;
      if (entry.assetId !== assetId) continue;
      const space =
        maxStack === Infinity
          ? remaining
          : Math.max(0, Math.min(maxStack - entry.quantity, remaining));
      if (space <= 0) continue;
      const idx = items.findIndex((e) => e.id === entry.id);
      if (idx >= 0) {
        items[idx] = { ...items[idx], quantity: (items[idx].quantity ?? 0) + space };
        remaining -= space;
      }
    }
  }

  while (remaining > 0) {
    const stackAmount = Math.min(remaining, maxStack === Infinity ? remaining : maxStack);
    const spot = findLockerEmptySpot(
      gridItems,
      footprint.width,
      footprint.height,
      grid.width,
      grid.height,
    );
    if (!spot) {
      throw new Error(
        `No space in buyer's locker for ${asset.name}. Needs ${footprint.width}×${footprint.height} free cells.`,
      );
    }
    items.push({
      asset: assetId,
      quantity: stackAmount,
      gridX: spot.x,
      gridY: spot.y,
      rotated: false,
    });
    gridItems.push({
      id: `new-${items.length}`,
      assetId,
      quantity: stackAmount,
      gridX: spot.x,
      gridY: spot.y,
      rotated: false,
      asset,
    });
    remaining -= stackAmount;
  }

  return (await payload.update({
    collection: "locker-storages",
    id: locker.id,
    data: { items },
    overrideAccess: true,
    depth: 1,
  })) as unknown as LockerStorage;
}

export interface BuyResult {
  transactionId: number;
  total: number;
  unitPrice: number;
  quantity: number;
  currencyId: number | null;
  listing: MarketListing;
}

/**
 * Execute a purchase of an active listing:
 * 1. Ensures buyer + seller personal accounts (and treasury for NPC stock).
 * 2. Moves funds via `applyTransaction` (`payment` type).
 * 3. Credits the buyer's locker with `quantity` units.
 * 4. Decrements the listing's stock; the listing is marked sold only when the
 *    last unit is bought (partial purchases leave it active).
 *
 * Pass `unitPrice` to buy at an agreed negotiation price instead of the
 * listing's asking price, and `quantity` to buy a subset of the stock
 * (defaults to the whole listing).
 */
export async function buyListing(
  payload: PayloadType,
  listing: MarketListing,
  buyer: User,
  options?: { unitPrice?: number; quantity?: number },
): Promise<BuyResult> {
  if (listing.status !== "active") {
    throw new Error("This listing is no longer active.");
  }

  const asset = listing.asset as Asset;
  if (!asset || typeof asset === "number") {
    throw new Error("Listing asset is not available.");
  }

  const sellerId =
    typeof listing.seller === "object" && listing.seller
      ? listing.seller.id
      : (listing.seller as number | null);
  if (sellerId != null && sellerId === buyer.id) {
    throw new Error("You cannot buy your own listing.");
  }

  const stock = listing.quantity ?? 1;
  const quantity = options?.quantity ?? stock;
  if (!Number.isInteger(quantity) || quantity <= 0 || quantity > stock) {
    throw new Error(`Quantity must be between 1 and ${stock}.`);
  }

  const currencyId = listing.currency
    ? typeof listing.currency === "object" && "id" in listing.currency
      ? (listing.currency.id as number)
      : (listing.currency as number)
    : await getMainCurrencyId(payload);

  const unitPrice = options?.unitPrice ?? listing.price;
  if (typeof unitPrice !== "number" || unitPrice <= 0) {
    throw new Error("Listing price must be greater than zero.");
  }

  const total = unitPrice * quantity;

  const buyerAccount = await ensurePersonalAccount(payload, buyer.id as number);
  let sellerAccountId: number | undefined;
  if (sellerId != null) {
    const sellerAccount = await ensurePersonalAccount(payload, sellerId);
    sellerAccountId = sellerAccount.id;
  } else {
    const treasuryId = await getTreasuryAccountId(payload);
    if (treasuryId) sellerAccountId = treasuryId;
  }

  const transaction = await applyTransaction(payload, {
    type: "payment",
    fromAccountId: buyerAccount.id,
    toAccountId: sellerAccountId,
    amount: total,
    memo: `Market purchase: ${quantity}× ${asset.name} @ ${unitPrice}`,
    actorId: buyer.id as number,
  });

  await creditLockerQuantity(payload, buyer.id as number, asset.id, quantity);

  const remaining = stock - quantity;
  const updated = (await payload.update({
    collection: "market-listings",
    id: listing.id,
    data:
      remaining > 0
        ? { quantity: remaining }
        : { status: "sold", buyer: buyer.id as number, soldAt: new Date().toISOString() },
    overrideAccess: true,
    depth: 1,
  })) as unknown as MarketListing;

  return {
    transactionId: transaction.id,
    total,
    unitPrice,
    quantity,
    currencyId,
    listing: updated,
  };
}

/**
 * Expire a listing. User listings have their stock returned to the seller's
 * locker; auto-generated entries simply close. Throws if stock cannot be
 * returned (e.g. no locker space).
 */
export async function expireListing(
  payload: PayloadType,
  listing: MarketListing,
): Promise<MarketListing> {
  const sellerId =
    typeof listing.seller === "object" && listing.seller
      ? listing.seller.id
      : (listing.seller as number | null);

  if (sellerId != null && !listing.isAutoGenerated) {
    await creditLockerQuantity(
      payload,
      sellerId,
      resolveAssetId(listing.asset) as number,
      listing.quantity,
    );
  }

  return (await payload.update({
    collection: "market-listings",
    id: listing.id,
    data: { status: "expired" },
    overrideAccess: true,
    depth: 0,
  })) as unknown as MarketListing;
}

/**
 * Price an auto-generated entry as a deviation around the asset's base buy
 * price. `kind` mirrors the resting valuation: `buy` prices NPC stock near
 * the base buy price, `sell` prices it near the base sell price.
 */
export function autoPrice(asset: Asset, kind: "buy" | "sell" = "buy"): number | null {
  const base = kind === "buy" ? getBaseBuyPrice(asset) : getBaseSellPrice(asset);
  if (base == null || base <= 0) return null;
  const deviation = (Math.random() * 2 - 1) * 0.15;
  return Math.max(1, Math.round(base * (1 + deviation)));
}

/** Suggested auto-generated quantity: a few units for stackables, else 1. */
export function autoQuantity(asset: Asset): number {
  if (lockerIsStackable(asset)) {
    return Math.max(1, Math.floor(Math.random() * 3) + 1);
  }
  return 1;
}