import { NextResponse } from "next/server";
import { getCollection } from "@/lib/mongodb";
import { Coupon } from "@/models/Coupon";

export async function GET(request: Request) {
  try {
    const { searchParams } = new URL(request.url);
    const code = searchParams.get("code");
    const amount = parseFloat(searchParams.get("amount") || "0");

    if (!code) {
      return NextResponse.json({ error: "Coupon code is required" }, { status: 400 });
    }

    const couponsCollection = await getCollection<Coupon>("coupons");
    const coupon = await couponsCollection.findOne({
      code: code.toUpperCase(),
      active: true,
    });

    if (!coupon) {
      return NextResponse.json({ valid: false, error: "Invalid coupon code" });
    }

    // Check if coupon is expired
    const now = new Date();
    if (new Date(coupon.validFrom) > now || new Date(coupon.validUntil) < now) {
      return NextResponse.json({ valid: false, error: "Coupon has expired" });
    }

    // Check usage limit
    if (coupon.usageLimit && coupon.usedCount >= coupon.usageLimit) {
      return NextResponse.json({ valid: false, error: "Coupon usage limit reached" });
    }

    // Check minimum purchase
    if (coupon.minPurchase && amount < coupon.minPurchase) {
      return NextResponse.json({
        valid: false,
        error: `Minimum purchase of $${coupon.minPurchase} required`,
      });
    }

    // Calculate discount
    let discount = 0;
    if (coupon.type === "percentage") {
      discount = (amount * coupon.value) / 100;
      if (coupon.maxDiscount) {
        discount = Math.min(discount, coupon.maxDiscount);
      }
    } else {
      discount = coupon.value;
    }

    return NextResponse.json({
      valid: true,
      discount: Math.round(discount * 100) / 100,
      coupon: {
        code: coupon.code,
        type: coupon.type,
        value: coupon.value,
      },
    });
  } catch (error) {
    console.error("Error validating coupon:", error);
    return NextResponse.json(
      { error: "Failed to validate coupon" },
      { status: 500 }
    );
  }
}