import { Injectable } from '@nestjs/common';
import { DataSource } from 'typeorm';
import { Freight } from '@edr/types';

/** Invoice statuses a customer can still settle (mirrors the portal's PAYABLE_STATUSES). */
const PAYABLE_INVOICE_STATUSES = ['ISSUED', 'PENDING', 'PARTIALLY_PAID', 'OVERDUE'];
/** Booking statuses at which the freight invoice is actually due (mirrors BookingsService). */
const FREIGHT_PAYABLE_BOOKING_STATUSES = [
  'FULLY_EXECUTED',
  'SELECTED_FOR_BATCH',
  'AWAITING_PAYMENT',
];

/**
 * One row per outstanding item. `invoices.status` / `bookings.status` are
 * Postgres enums, hence the ::text casts. `amount` is NULL for items that only need the
 * customer's review (a proposed clearance charge, a draft final invoice) so
 * they count but do not inflate "amount due".
 */
const SQL = `
  -- Central invoices on the booking: freight (only while the booking is in a
  -- payable status), wagon-cancellation fee, GL final invoice (+ its DRAFT,
  -- which waits for the customer's approval).
  SELECT i.source_id AS "bookingId", i.currency,
         CASE WHEN i.status::text = 'DRAFT' THEN NULL ELSE i.balance_amount END AS amount
    FROM freight.invoices i
    JOIN freight.bookings b ON b.id::text = i.source_id AND b.deleted_at IS NULL
   WHERE i.company_id = $1 AND i.deleted_at IS NULL AND i.source = 'booking'
     AND (
       (i.status::text = ANY($2::text[]) AND i.balance_amount > 0
        AND (i.type IN ('WAGON_CANCEL_FEE', 'GL_FINAL') OR b.status::text = ANY($3::text[])))
       OR (i.type = 'GL_FINAL' AND i.status::text = 'DRAFT')
     )
  UNION ALL
  -- Accepted clearance charges whose invoice is still unpaid.
  SELECT c.booking_id::text, i.currency, i.balance_amount
    FROM freight.invoices i
    JOIN freight.booking_clearance_charge c ON c.id::text = i.source_id AND c.deleted_at IS NULL
   WHERE i.company_id = $1 AND i.deleted_at IS NULL AND i.source = 'clearance_charge'
     AND i.status::text = ANY($2::text[]) AND i.balance_amount > 0
  UNION ALL
  -- Clearance charges waiting for the customer to accept or reject the price.
  SELECT c.booking_id::text, c.currency, NULL::numeric
    FROM freight.booking_clearance_charge c
    JOIN freight.bookings b ON b.id = c.booking_id AND b.deleted_at IS NULL
   WHERE b.company_id = $1 AND c.deleted_at IS NULL AND c.status = 'SENT'
  UNION ALL
  -- Duty / tax advised by customs, payment slip not uploaded yet.
  SELECT m.booking_id::text, m.metadata->>'dutyCurrency',
         NULLIF(m.metadata->>'dutyAmount', '')::numeric
    FROM freight.clearance_milestones m
    JOIN freight.bookings b ON b.id = m.booking_id AND b.deleted_at IS NULL
   WHERE b.company_id = $1 AND m.deleted_at IS NULL AND m.status = 'COMPLETED'
     AND (
       (m.milestone_code = 'DUTY_TAXES_ADVISED' AND NOT EXISTS (
          SELECT 1 FROM freight.clearance_milestones p
           WHERE p.booking_id = m.booking_id AND p.milestone_code = 'DUTY_TAX_PAID'
             AND p.status = 'COMPLETED' AND p.deleted_at IS NULL))
       OR
       (m.milestone_code = 'SECOND_DUTY_ADVISED' AND NOT EXISTS (
          SELECT 1 FROM freight.clearance_milestones p
           WHERE p.booking_id = m.booking_id AND p.milestone_code = 'SECOND_DUTY_PAID'
             AND p.status = 'COMPLETED' AND p.deleted_at IS NULL))
     )
`;

/**
 * Everything a customer still has to act on, per booking, in one query. Drives
 * the "Pay" badge on the home and booking-list rows; the booking's Payments tab
 * composes the same items client-side from the per-booking endpoints.
 */
@Injectable()
export class BookingPayablesService {
  constructor(private readonly dataSource: DataSource) {}

  async summarizeForCompany(
    companyId: string,
  ): Promise<Freight.BookingPayableSummary[]> {
    const rows: Array<{
      bookingId: string;
      currency: string | null;
      amount: string | null;
    }> = await this.dataSource.query(SQL, [
      companyId,
      PAYABLE_INVOICE_STATUSES,
      FREIGHT_PAYABLE_BOOKING_STATUSES,
    ]);

    const byBooking = new Map<string, Freight.BookingPayableSummary>();
    for (const r of rows) {
      const s = byBooking.get(r.bookingId) ?? {
        bookingId: r.bookingId,
        count: 0,
        totals: [],
      };
      s.count += 1;
      const amount = Number(r.amount ?? 0);
      if (r.currency && amount > 0) {
        const t = s.totals.find((x) => x.currency === r.currency);
        if (t) t.amount += amount;
        else s.totals.push({ currency: r.currency, amount });
      }
      byBooking.set(r.bookingId, s);
    }
    return [...byBooking.values()];
  }
}