"use server";

import { revalidatePath } from "next/cache";
import { auth } from "@/lib/auth";
import { prisma } from "@/lib/prisma";
import { rcon } from "@/lib/services/rcon";
import { sendCurrency } from "@/lib/services/send-currency";

/** Feedback returned to the <RedeemForm/> client component via useActionState. */
export type RedeemState = { ok: boolean; message: string } | null;

/**
 * Redeem a shop voucher for the SIGNED-IN user. Faithful to AtomCMS's
 * ShopVoucherController:
 *   - the user id is re-read from the session (auth()), NEVER from FormData,
 *     so a crafted form cannot redeem on another account;
 *   - a code that is missing or expired is rejected;
 *   - each voucher may be redeemed once per user (website_used_shop_vouchers);
 *   - on success the reward `amount` is granted, the used-row is inserted,
 *     use_count is incremented, and the voucher is expired once max_uses is hit.
 *
 * The reward is delivered through sendCurrency({ rcon, db: prisma }); the
 * voucher schema carries a single `amount`, granted as the website credits
 * wallet currency.
 */
export async function redeem(
	_prev: RedeemState,
	formData: FormData,
): Promise<RedeemState> {
	const session = await auth();
	if (!session?.user?.id) {
		return { ok: false, message: "You must be signed in to redeem a voucher." };
	}

	const userId = Number(session.user.id);
	if (!Number.isFinite(userId)) {
		return {
			ok: false,
			message: "Your session is invalid. Please sign in again.",
		};
	}

	const code = String(formData.get("code") ?? "")
		.normalize("NFC")
		.trim();
	if (!code) {
		return { ok: false, message: "Please enter a voucher code." };
	}

	// Look up the code (website_shop_vouchers.code is unique).
	let voucher: {
		id: bigint;
		amount: number;
		maxUses: number;
		useCount: number;
		expiresAt: Date | null;
	} | null;
	try {
		voucher = await prisma.websiteShopVouchers.findUnique({
			where: { code },
			select: {
				id: true,
				amount: true,
				maxUses: true,
				useCount: true,
				expiresAt: true,
			},
		});
	} catch {
		return {
			ok: false,
			message: "We couldn't reach the server. Please try again.",
		};
	}

	// Not found OR already expired -> generic "no active voucher" (matches AtomCMS).
	if (
		!voucher ||
		(voucher.expiresAt && voucher.expiresAt.getTime() <= Date.now())
	) {
		return {
			ok: false,
			message: "No active voucher with the given code was found.",
		};
	}

	// One redemption per user.
	try {
		const already = await prisma.websiteUsedShopVouchers.findFirst({
			where: { userId, voucherId: voucher.id },
			select: { id: true },
		});
		if (already) {
			return { ok: false, message: "You can only use each shop voucher once." };
		}
	} catch {
		return {
			ok: false,
			message: "We couldn't reach the server. Please try again.",
		};
	}

	// Record the redemption first so a successful grant can never be double-claimed.
	try {
		await prisma.websiteUsedShopVouchers.create({
			data: { userId, voucherId: voucher.id },
		});
	} catch {
		// Most likely a race (another tab redeemed it) — treat as already used.
		return { ok: false, message: "You can only use each shop voucher once." };
	}

	// Grant the reward. The voucher carries a single amount, delivered as credits.
	try {
		await sendCurrency({ rcon, db: prisma }, userId, "credits", voucher.amount);
	} catch {
		// sendCurrency already falls back to a direct DB write; if it still throws,
		// the used-row stands and the balance simply wasn't credited — surface that.
		return {
			ok: false,
			message:
				"Your voucher was accepted but the reward could not be delivered. Contact staff.",
		};
	}

	// Bump use_count and expire the voucher once the cap is reached.
	try {
		const updated = await prisma.websiteShopVouchers.update({
			where: { id: voucher.id },
			data: { useCount: { increment: 1 } },
			select: { maxUses: true, useCount: true },
		});
		if (updated.maxUses && updated.useCount >= updated.maxUses) {
			await prisma.websiteShopVouchers.update({
				where: { id: voucher.id },
				data: { expiresAt: new Date() },
			});
		}
	} catch {
		// Reward already delivered; the counter bump is best-effort.
	}

	revalidatePath("/redeem");

	return {
		ok: true,
		message: `Success! Your balance has been increased by ${voucher.amount.toLocaleString()} credits.`,
	};
}