import { NextRequest, NextResponse } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/lib/auth';
import { db } from '@/lib/db';

interface RouteContext {
  params: Promise<{ id: string }>;
}

// GET /api/sales/[id] - Get a single sale with items, payments, and products
export async function GET(
  request: NextRequest,
  context: RouteContext
) {
  try {
    const session = await getServerSession(authOptions);

    if (!session?.user) {
      return NextResponse.json(
        { error: 'Unauthorized' },
        { status: 401 }
      );
    }

    const { id } = await context.params;

    const sale = await db.sale.findFirst({
      where: {
        id,
        createdBy: {
          organizationId: session.user.organizationId,
        },
      },
      include: {
        items: {
          include: {
            product: {
              select: {
                id: true,
                name: true,
                sku: true,
                price: true,
                image: true,
                category: {
                  select: {
                    id: true,
                    name: true,
                  },
                },
              },
            },
          },
        },
        payments: {
          select: {
            id: true,
            amount: true,
            paymentType: true,
            reference: true,
            notes: true,
            createdAt: true,
          },
        },
        client: {
          select: {
            id: true,
            firstName: true,
            lastName: true,
            email: true,
            phone: true,
          },
        },
        createdBy: {
          select: {
            id: true,
            firstName: true,
            lastName: true,
            email: true,
          },
        },
        cashRegister: {
          select: {
            id: true,
            openedAt: true,
            closedAt: true,
            site: {
              select: {
                id: true,
                name: true,
              },
            },
            user: {
              select: {
                id: true,
                firstName: true,
                lastName: true,
              },
            },
          },
        },
      },
    });

    if (!sale) {
      return NextResponse.json(
        { error: 'Sale not found' },
        { status: 404 }
      );
    }

    return NextResponse.json(sale);
  } catch (error) {
    console.error('Error fetching sale:', error);
    return NextResponse.json(
      { error: 'Failed to fetch sale' },
      { status: 500 }
    );
  }
}

// DELETE /api/sales/[id] - Void/cancel a sale and restore stock
export async function DELETE(
  request: NextRequest,
  context: RouteContext
) {
  try {
    const session = await getServerSession(authOptions);

    if (!session?.user) {
      return NextResponse.json(
        { error: 'Unauthorized' },
        { status: 401 }
      );
    }

    // Check if user has admin role
    const allowedRoles = ['SUPER_ADMIN', 'ORG_ADMIN', 'SITE_ADMIN'];
    if (!allowedRoles.includes(session.user.role)) {
      return NextResponse.json(
        { error: 'Forbidden: Insufficient permissions to void sales' },
        { status: 403 }
      );
    }

    const { id } = await context.params;

    // Fetch the sale with items
    const sale = await db.sale.findFirst({
      where: {
        id,
        createdBy: {
          organizationId: session.user.organizationId,
        },
      },
      include: {
        items: {
          include: {
            product: true,
          },
        },
        cashRegister: true,
      },
    });

    if (!sale) {
      return NextResponse.json(
        { error: 'Sale not found' },
        { status: 404 }
      );
    }

    // If sale is associated with a closed cash register, we cannot void it
    if (sale.cashRegister && sale.cashRegister.closedAt) {
      return NextResponse.json(
        { error: 'Cannot void a sale from a closed cash register' },
        { status: 400 }
      );
    }

    // If user is SITE_ADMIN, verify they have access to the cash register's site
    if (session.user.role === 'SITE_ADMIN' && sale.cashRegister) {
      if (session.user.siteId !== sale.cashRegister.siteId) {
        return NextResponse.json(
          { error: 'Forbidden: You do not have access to void this sale' },
          { status: 403 }
        );
      }
    }

    // Void the sale within a transaction
    await db.$transaction(async (tx) => {
      // Restore stock for each item
      for (const item of sale.items) {
        if (item.product.trackStock) {
          await tx.product.update({
            where: { id: item.productId },
            data: {
              stock: {
                increment: item.quantity,
              },
            },
          });
        }
      }

      // Delete payments associated with this sale
      await tx.payment.deleteMany({
        where: { saleId: id },
      });

      // Delete sale items
      await tx.saleItem.deleteMany({
        where: { saleId: id },
      });

      // Delete the sale
      await tx.sale.delete({
        where: { id },
      });
    });

    return NextResponse.json({
      message: 'Sale voided successfully',
      restoredItems: sale.items.map(item => ({
        productId: item.productId,
        productName: item.product.name,
        quantity: item.quantity,
        stockRestored: item.product.trackStock,
      })),
    });
  } catch (error) {
    console.error('Error voiding sale:', error);
    return NextResponse.json(
      { error: 'Failed to void sale' },
      { status: 500 }
    );
  }
}