import { createAdminClient } from "@/lib/supabase/server";
import { auth } from "@clerk/nextjs/server";
import { NextResponse } from "next/server";

/**
 * GET /api/usage
 * Returns current month's usage counts and estimated cost.
 */
export async function GET() {
  try {
    const { userId } = await auth();
    if (!userId) return NextResponse.json({ error: "Unauthenticated" }, { status: 401 });

    const supabase = await createAdminClient();

    const { data: member } = await supabase
      .from("organisation_members")
      .select("organisation_id")
      .eq("user_id", userId)
      .single();

    if (!member) return NextResponse.json({ error: "No organisation" }, { status: 404 });

    const orgId = member.organisation_id;
    const now = new Date();
    const monthStart = `${now.getFullYear()}-${String(now.getMonth() + 1).padStart(2, "0")}-01`;

    // Invoice count
    const { count: invoices } = await supabase
      .from("invoices")
      .select("*", { count: "exact", head: true })
      .eq("organisation_id", orgId)
      .gte("created_at", monthStart);

    // Employee count
    const { count: employees } = await supabase
      .from("employees")
      .select("*", { count: "exact", head: true })
      .eq("organisation_id", orgId);

    // Payroll runs this month
    const { count: payrollRuns } = await supabase
      .from("payroll_runs")
      .select("*", { count: "exact", head: true })
      .eq("organisation_id", orgId)
      .gte("created_at", monthStart);

    // Expenses this month
    const { count: expenses } = await supabase
      .from("expenses")
      .select("*", { count: "exact", head: true })
      .eq("organisation_id", orgId)
      .gte("created_at", monthStart);

    // Leave requests this month
    const { count: leaveRequests } = await supabase
      .from("leave_requests")
      .select("*", { count: "exact", head: true })
      .eq("organisation_id", orgId)
      .gte("created_at", monthStart);

    const invoiceCount = invoices || 0;
    const employeeCount = employees || 0;
    const payrollCount = payrollRuns || 0;
    const expenseCount = expenses || 0;
    const leaveCount = leaveRequests || 0;

    // Estimated cost
    const estimatedCost =
      invoiceCount * 50 +       // $0.50 × invoices
      employeeCount * 100 +      // $1.00 × employees
      payrollCount * 300 +       // $3.00 × payroll runs
      expenseCount * 25 +        // $0.25 × expenses
      leaveCount * 50;           // $0.50 × leave requests

    return NextResponse.json({
      invoices: invoiceCount,
      employees: employeeCount,
      payrollRuns: payrollCount,
      estimatedCost,
    });
  } catch {
    return NextResponse.json({ error: "Failed to fetch usage" }, { status: 500 });
  }
}