import { db } from "@/db";
import { project_offers, offer_micros } from "@/db/schema";
import { eq } from "drizzle-orm";

export type ForecastMonth = {
  year: number;
  month: number;    // 1-12
  label: string;   // "giu 2026"
  total: number;
};

export async function getRevenueForecast12Months(): Promise<ForecastMonth[]> {
  // Load all project offers with micro duration info
  const offers = await db
    .select({
      start_date: project_offers.start_date,
      duration_months: offer_micros.duration_months,
      accepted_total: project_offers.accepted_total,
    })
    .from(project_offers)
    .innerJoin(offer_micros, eq(project_offers.micro_id, offer_micros.id));

  // Build 12-month bucket array starting from current month
  const now = new Date();
  const buckets: ForecastMonth[] = Array.from({ length: 12 }, (_, i) => {
    const d = new Date(now.getFullYear(), now.getMonth() + i, 1);
    return {
      year: d.getFullYear(),
      month: d.getMonth() + 1,
      label: d.toLocaleDateString("it-IT", { month: "short", year: "numeric" }),
      total: 0,
    };
  });

  for (const offer of offers) {
    // Skip offers with no accepted_total — they contribute 0 to forecast
    if (!offer.accepted_total) continue;
    const total = parseFloat(String(offer.accepted_total));
    if (isNaN(total) || total <= 0) continue;

    const perMonth = total / offer.duration_months;
    const start = new Date(offer.start_date);

    for (let m = 0; m < offer.duration_months; m++) {
      const offerMonth = new Date(start.getFullYear(), start.getMonth() + m, 1);
      const bucket = buckets.find(
        (b) => b.year === offerMonth.getFullYear() && b.month === offerMonth.getMonth() + 1
      );
      if (bucket) bucket.total += perMonth;
    }
  }

  // Round totals to 2 decimal places
  buckets.forEach((b) => { b.total = Math.round(b.total * 100) / 100; });

  return buckets;
}