"use server";

import config from "@payload-config";
import { isPayloadUser } from "@/utils/access-control/isPayloadUser";
import { getPayload } from "payload";
import type { User } from "@/payload-types";
import { hasPermission } from "@/utils/access-control/hasPermission";
import { hasLogisticsQualification } from "@/utils/access-control/hasLogisticsQualification";
import { emitGameEvent } from "@/utils/event-log/emit";
import { EventTypes } from "@/utils/event-log/eventTypes";
import {
  applyTransaction,
  createAccount,
  ensurePersonalAccount,
  getMainCurrencyName,
} from "@/lib/banking";
import { notifyUser } from "@/lib/notifications";

interface ActionResult<T = undefined> {
  success: boolean;
  error?: string;
  data?: T;
}

async function authenticate() {
  const payloadConfig = await config;
  const payload = await getPayload({ config: payloadConfig });
  const { headers } = await import("next/headers");
  const hdrs = await headers();
  const { user } = await payload.auth({
    headers: hdrs,
    canSetHeaders: false,
  });

  if (!isPayloadUser(user)) {
    throw new Error("Unauthorized");
  }

  return { payload, user };
}

async function isBankingManager(
  payload: Awaited<ReturnType<typeof getPayload>>,
  user: User,
): Promise<boolean> {
  if (await hasPermission(payload, user, "banking:manage")) return true;
  return hasLogisticsQualification(payload, user);
}

export async function createBankAccount(input: {
  name: string;
  accountType: "treasury" | "faction" | "personal";
  ownerFactionId?: number;
  ownerUserId?: number;
}): Promise<ActionResult<number>> {
  try {
    const { payload, user } = await authenticate();
    const manager = await isBankingManager(payload, user);

    if (input.accountType === "personal") {
      const ownerId = input.ownerUserId ?? (user.id as number);
      if (!manager && ownerId !== user.id) {
        return {
          success: false,
          error: "You can only create a personal account for yourself.",
        };
      }
      const existing = await payload.find({
        collection: "bank-accounts",
        where: {
          and: [{ accountType: { equals: "personal" } }, { ownerUser: { equals: ownerId } }],
        },
        limit: 1,
        depth: 0,
        overrideAccess: true,
      });
      if (existing.docs.length > 0) {
        return {
          success: false,
          error: "This user already has a personal account.",
        };
      }
      const account = await createAccount(payload, {
        name: input.name,
        accountType: "personal",
        ownerUserId: ownerId,
      });
      await emitGameEvent(payload, {
        type: EventTypes.BankAccountCreate,
        message: `Created personal account "${account.name}"`,
        actor: user.id,
        targetCollection: "bank-accounts",
        targetId: account.id,
        data: { accountType: "personal", ownerUserId: ownerId },
      });
      return { success: true, data: account.id };
    }

    if (!manager) {
      return {
        success: false,
        error: "Insufficient permissions. Logistics personnel or higher can manage unit accounts.",
      };
    }

    if (input.accountType === "faction" && !input.ownerFactionId) {
      return {
        success: false,
        error: "A faction account requires an owner faction.",
      };
    }

    const account = await createAccount(payload, {
      name: input.name,
      accountType: input.accountType,
      ownerFactionId: input.ownerFactionId,
    });
    await emitGameEvent(payload, {
      type: EventTypes.BankAccountCreate,
      message: `Created ${input.accountType} account "${account.name}"`,
      actor: user.id,
      targetCollection: "bank-accounts",
      targetId: account.id,
      data: { accountType: input.accountType, ownerFactionId: input.ownerFactionId },
    });
    return { success: true, data: account.id };
  } catch (error) {
    const message = error instanceof Error ? error.message : "Unknown error";
    if (message === "Unauthorized") {
      return { success: false, error: "You must be logged in." };
    }
    return { success: false, error: message };
  }
}

export async function ensureMyAccount(): Promise<ActionResult<number>> {
  try {
    const { payload, user } = await authenticate();
    const account = await ensurePersonalAccount(payload, user.id as number);
    await emitGameEvent(payload, {
      type: EventTypes.BankAccountCreate,
      message: `Created personal account "${account.name}"`,
      actor: user.id,
      targetCollection: "bank-accounts",
      targetId: account.id,
      data: { accountType: "personal", ownerUserId: user.id },
    });
    return { success: true, data: account.id };
  } catch (error) {
    const message = error instanceof Error ? error.message : "Unknown error";
    if (message === "Unauthorized") {
      return { success: false, error: "You must be logged in." };
    }
    return { success: false, error: message };
  }
}

export async function depositFunds(
  accountId: number,
  amount: number,
  memo?: string,
): Promise<ActionResult<number>> {
  return moveFunds("deposit", undefined, accountId, amount, memo);
}

export async function withdrawFunds(
  accountId: number,
  amount: number,
  memo?: string,
): Promise<ActionResult<number>> {
  return moveFunds("withdrawal", accountId, undefined, amount, memo);
}

export async function transferFunds(
  fromAccountId: number,
  toAccountId: number,
  amount: number,
  memo?: string,
): Promise<ActionResult<number>> {
  return moveFunds("transfer", fromAccountId, toAccountId, amount, memo);
}

async function moveFunds(
  type: "deposit" | "withdrawal" | "transfer",
  fromAccountId: number | undefined,
  toAccountId: number | undefined,
  amount: number,
  memo?: string,
): Promise<ActionResult<number>> {
  try {
    const { payload, user } = await authenticate();
    if (!(await hasPermission(payload, user, "bank-accounts:create"))) {
      return { success: false, error: "Insufficient permissions." };
    }
    if (!amount || amount <= 0) {
      return { success: false, error: "Amount must be greater than zero." };
    }

    const manager = await isBankingManager(payload, user);

    const accountChecks: { id?: number; label: string }[] = [];
    if (fromAccountId) accountChecks.push({ id: fromAccountId, label: "source" });
    if (toAccountId) accountChecks.push({ id: toAccountId, label: "destination" });

    const accountOwners = new Map<number, number | null>();

    for (const check of accountChecks) {
      const account = (await payload
        .findByID({
          collection: "bank-accounts",
          id: check.id as number,
          depth: 0,
          overrideAccess: true,
        })
        .catch(() => null)) as unknown as {
        id: number;
        accountType: string;
        ownerUser?: number | { id: number } | null;
        status: string;
      } | null;
      if (!account) {
        return { success: false, error: `${check.label} account not found.` };
      }
      if (account.status === "closed") {
        return { success: false, error: `${check.label} account is closed.` };
      }
      const ownerId =
        typeof account.ownerUser === "object" ? account.ownerUser?.id : account.ownerUser;
      accountOwners.set(check.id as number, ownerId ?? null);
      if (account.accountType === "personal") {
        if (!manager && ownerId !== user.id) {
          return {
            success: false,
            error: "You can only move funds on your own personal account.",
          };
        }
      } else if (!manager) {
        return {
          success: false,
          error: "Insufficient permissions. Logistics personnel or higher can move unit funds.",
        };
      }
    }

    if (type === "transfer" && (!fromAccountId || !toAccountId)) {
      return {
        success: false,
        error: "A transfer requires both a source and a destination account.",
      };
    }
    if (type === "deposit" && !toAccountId) {
      return { success: false, error: "A deposit requires a destination account." };
    }
    if (type === "withdrawal" && !fromAccountId) {
      return { success: false, error: "A withdrawal requires a source account." };
    }

    const transaction = await applyTransaction(payload, {
      type,
      fromAccountId,
      toAccountId,
      amount,
      memo,
      actorId: user.id as number,
    });

    const currency = await getMainCurrencyName(payload);
    const suffix = currency ? ` ${currency}` : "";
    const amountLabel = `${amount.toLocaleString()}${suffix}`;

    const eventType =
      type === "deposit"
        ? EventTypes.FinanceDeposit
        : type === "withdrawal"
          ? EventTypes.FinanceWithdraw
          : EventTypes.FinanceTransfer;

    const eventMessage =
      type === "deposit"
        ? `Deposited ${amountLabel} into account #${toAccountId}`
        : type === "withdrawal"
          ? `Withdrew ${amountLabel} from account #${fromAccountId}`
          : `Transferred ${amountLabel} from account #${fromAccountId} to account #${toAccountId}`;

    await emitGameEvent(payload, {
      type: eventType,
      message: eventMessage,
      actor: user.id,
      targetCollection: "bank-transactions",
      targetId: transaction.id,
      data: { fromAccountId, toAccountId, amount, type },
    });

    const notifications: { userId: number; message: string; link: string }[] = [];
    if (type === "deposit" && toAccountId) {
      const ownerId = accountOwners.get(toAccountId) ?? null;
      if (ownerId != null) {
        notifications.push({
          userId: ownerId,
          message: `Deposited ${amountLabel} into your account (#${toAccountId}).`,
          link: `/logistics/banking/${toAccountId}`,
        });
      }
    } else if (type === "withdrawal" && fromAccountId) {
      const ownerId = accountOwners.get(fromAccountId) ?? null;
      if (ownerId != null) {
        notifications.push({
          userId: ownerId,
          message: `Withdrew ${amountLabel} from your account (#${fromAccountId}).`,
          link: `/logistics/banking/${fromAccountId}`,
        });
      }
    } else if (type === "transfer" && fromAccountId && toAccountId) {
      const fromOwner = accountOwners.get(fromAccountId) ?? null;
      const toOwner = accountOwners.get(toAccountId) ?? null;
      if (fromOwner != null) {
        notifications.push({
          userId: fromOwner,
          message: `Transferred ${amountLabel} from your account (#${fromAccountId}) to account #${toAccountId}.`,
          link: `/logistics/banking/${fromAccountId}`,
        });
      }
      if (toOwner != null && toOwner !== fromOwner) {
        notifications.push({
          userId: toOwner,
          message: `Received ${amountLabel} in account #${toAccountId} from account #${fromAccountId}.`,
          link: `/logistics/banking/${toAccountId}`,
        });
      }
    }

    const notifType =
      type === "deposit"
        ? "finance:deposit"
        : type === "withdrawal"
          ? "finance:withdraw"
          : "finance:transfer";
    const notifTitle =
      type === "deposit"
        ? "Bank deposit"
        : type === "withdrawal"
          ? "Bank withdrawal"
          : "Bank transfer";
    for (const n of notifications) {
      await notifyUser(payload, {
        userId: n.userId,
        type: notifType,
        title: notifTitle,
        message: n.message,
        link: n.link,
      });
    }

    return { success: true, data: transaction.id };
  } catch (error) {
    const message = error instanceof Error ? error.message : "Unknown error";
    if (message === "Unauthorized") {
      return { success: false, error: "You must be logged in." };
    }
    return { success: false, error: message };
  }
}