import { Injectable, NotFoundException, BadRequestException, Logger } from '@nestjs/common';
import { PrismaService } from '../../common/prisma.service';
import { AuditService } from '../../common/audit.service';
import { AUDIT_ACTIONS, AUDIT_ENTITIES } from '../../common/audit.actions';
import { SmsClientService } from '../notifications/sms-client.service';
import { EmailClientService } from '../notifications/email-client.service';
import { PaymentClientService } from './payment-client.service';
import { CurrencyService } from '../currency/currency.service';
import {
  PaymentReferenceType,
  PaymentService as PaymentServiceEnum,
  ProviderMethod,
  ProviderPaymentStatus,
} from '@edr/types';
import { PaymentPlatformDto } from './payments.dto';
import { PaymentMethodType } from '@prisma/client';

const CHARGE_TTL_MS = 72 * 60 * 60 * 1000; // 72 hours

/**
 * WALLET is an internal balance debit handled inside this app, not a provider — the payment
 * microservice rejects it as one. Supplementary charges have no wallet path, so it is refused up
 * front with a message the payer can act on rather than a 502 from the gateway layer.
 */
const UNSUPPORTED_METHODS = new Set<string>([PaymentMethodType.WALLET]);

/**
 * Push-debit methods charge an account we must be told up front — CAC Bank SMSes a one-time
 * password to it, eBirr pushes a USSD PIN prompt to it. Neither opens a hosted page that could
 * collect the number later (mirrors PaymentsService and ExcessBaggageService).
 */
const METHODS_REQUIRING_PAYER_ACCOUNT = new Set<string>([
  PaymentMethodType.CAC_BANK,
  PaymentMethodType.EBIRR,
]);

@Injectable()
export class SupplementaryChargesService {
  private readonly logger = new Logger(SupplementaryChargesService.name);

  constructor(
    private prisma: PrismaService,
    private auditService: AuditService,
    private smsClient: SmsClientService,
    private emailClient: EmailClientService,
    private paymentClient: PaymentClientService,
    private currencyService: CurrencyService,
  ) {}

  async create(dto: {
    bookingRef: string;
    amountMinor: number;
    reason: string;
    notes?: string;
    contactPhone?: string;
    contactEmail?: string;
    createdBy: string;
  }) {
    const booking = await this.prisma.booking.findUnique({
      where: { bookingRef: dto.bookingRef },
      include: { passenger: { include: { user: true } } },
    });
    if (!booking) throw new NotFoundException('Booking not found');
    if (!['CONFIRMED', 'BOARDED'].includes(booking.status)) {
      throw new BadRequestException('Booking must be CONFIRMED or BOARDED to raise a supplementary charge');
    }
    if (dto.amountMinor <= 0) throw new BadRequestException('Amount must be positive');

    const expiresAt = new Date(Date.now() + CHARGE_TTL_MS);
    const charge = await this.prisma.supplementaryCharge.create({
      data: {
        bookingId: booking.id,
        reason: dto.reason,
        amountMinor: dto.amountMinor,
        notes: dto.notes ?? null,
        createdBy: dto.createdBy,
        expiresAt,
      },
    });

    const phone = dto.contactPhone?.trim() || (booking.contactPhone ?? booking.passenger?.user?.phone ?? null);
    const email = dto.contactEmail?.trim() || (booking.contactEmail ?? booking.passenger?.user?.email ?? null);
    await this.sendLink(charge, booking.bookingRef, phone, email);

    await this.auditService.log({
      action: AUDIT_ACTIONS.CREATE,
      entityType: AUDIT_ENTITIES.SupplementaryCharge,
      entityId: charge.id,
      newData: {
        bookingId: booking.id,
        bookingRef: dto.bookingRef,
        amountMinor: dto.amountMinor,
        currency: charge.currency,
        reason: dto.reason,
        notes: dto.notes,
        createdBy: dto.createdBy,
        status: charge.status,
        expiresAt: charge.expiresAt?.toISOString(),
      },
    });
    return charge;
  }

  async getAll(filters: { bookingRef?: string; status?: string; page?: number; pageSize?: number }) {
    const { bookingRef, status, page = 1, pageSize = 20 } = filters;
    const skip = (page - 1) * pageSize;
    const where: any = {};
    if (status) where.status = status;
    if (bookingRef) where.booking = { bookingRef: { contains: bookingRef, mode: 'insensitive' } };

    await this.prisma.supplementaryCharge.updateMany({
      where: { status: 'PENDING', expiresAt: { lt: new Date() } },
      data: { status: 'EXPIRED' },
    });

    const [items, total] = await Promise.all([
      this.prisma.supplementaryCharge.findMany({
        where,
        include: { booking: { select: { bookingRef: true, status: true, contactPhone: true, contactEmail: true } } },
        orderBy: { createdAt: 'desc' },
        skip,
        take: pageSize,
      }),
      this.prisma.supplementaryCharge.count({ where }),
    ]);
    return { items, total, page, pageSize };
  }

  async getByToken(token: string) {
    const charge = await this.prisma.supplementaryCharge.findUnique({
      where: { paymentToken: token },
      include: { booking: { select: { bookingRef: true } } },
    });
    if (!charge) throw new NotFoundException('Payment link not found');
    if (charge.status === 'PAID') throw new BadRequestException('This charge has already been paid');
    if (charge.status === 'WAIVED') throw new BadRequestException('This charge has been waived');
    if (charge.status === 'EXPIRED' || (charge.expiresAt && new Date() > charge.expiresAt)) {
      if (charge.status === 'PENDING') {
        await this.prisma.supplementaryCharge.update({ where: { id: charge.id }, data: { status: 'EXPIRED' } });
      }
      throw new BadRequestException('This payment link has expired');
    }
    return charge;
  }

  async markPaid(id: string, providerTxnId?: string) {
    const charge = await this.prisma.supplementaryCharge.findUnique({ where: { id } });
    if (!charge) throw new NotFoundException('Charge not found');
    if (charge.status === 'PAID') return charge;

    // Conditional update rather than a plain update: this transition is also reachable from the
    // payment webhook, and claiming it atomically means exactly one of the two racing callers
    // writes the audit row.
    const { count } = await this.prisma.supplementaryCharge.updateMany({
      where: { id, status: { not: 'PAID' } },
      data: { status: 'PAID', paidAt: new Date(), providerTxnId: providerTxnId ?? null },
    });

    const updated = await this.prisma.supplementaryCharge.findUnique({ where: { id } });

    if (count === 1) {
      await this.auditService.log({
        action: AUDIT_ACTIONS.PAY,
        entityType: AUDIT_ENTITIES.SupplementaryCharge,
        entityId: id,
        oldData: { status: charge.status },
        newData: {
          status: 'PAID',
          bookingId: charge.bookingId,
          amountMinor: charge.amountMinor,
          currency: charge.currency,
          providerTxnId: providerTxnId ?? null,
        },
      });
    }

    return updated!;
  }

  /**
   * What the payer is actually charged when settling this charge with `method`.
   *
   * The charge is raised in ETB, but the selected method settles in its own currency — WAAFI and
   * D-Money in DJF, CARD in USD, the Ethiopian wallets in ETB — recorded on the PaymentMethod row.
   * The payment microservice is currency-agnostic and hands whatever it is given straight to the
   * gateway, so the ETB->settlement conversion has to happen here or the provider is asked to
   * debit an ETB number labelled as its own currency.
   *
   * Both the quote shown to the payer and the amount sent to the provider come through this one
   * method, so the price on the button and the price debited cannot drift apart.
   */
  private async resolveChargeAmount(
    charge: { amountMinor: number; currency: string },
    method: string,
  ): Promise<{ amount: number; currency: string }> {
    if (UNSUPPORTED_METHODS.has(method)) {
      throw new BadRequestException(
        `${method} is not available for balance payments`,
      );
    }

    const paymentMethod = await this.prisma.paymentMethod.findUnique({
      where: { type: method as PaymentMethodType },
    });
    // CBE settles ETB only (docs/cbe/CBE_IMPLEMENTATION_PLAN.md D8) — never converted.
    const chargeCurrency =
      method === PaymentMethodType.CBE_BILL
        ? 'ETB'
        : (paymentMethod?.currency ?? charge.currency).toUpperCase();

    // Applies the target currency's own precision — DJF rounds to whole francs, ETB/USD to cents.
    const amount = await this.currencyService.convertMinorToChargeMajor(
      charge.amountMinor,
      charge.currency,
      chargeCurrency,
    );
    return { amount, currency: chargeCurrency };
  }

  /**
   * Price quote for the pay page: what `method` would debit, in that method's settlement
   * currency. The payer sees this before committing, and pay() recomputes it the same way.
   */
  async quoteAmount(token: string, method: string) {
    const charge = await this.getByToken(token);
    const { amount, currency } = await this.resolveChargeAmount(charge, method);
    return { chargeId: charge.id, method, currency, amount };
  }

  /**
   * Bare status for the pay/result pages to poll. Unlike getByToken this does NOT reject a paid,
   * expired or waived charge — reporting those states is the entire point. A CBE bill can settle
   * long after the payer closed the tab, and redirect methods only converge when the settlement
   * event lands, so the page needs something it can watch.
   */
  async getStatus(token: string) {
    const charge = await this.prisma.supplementaryCharge.findUnique({
      where: { paymentToken: token },
      select: {
        id: true,
        status: true,
        paidAt: true,
        amountMinor: true,
        currency: true,
        expiresAt: true,
      },
    });
    if (!charge) throw new NotFoundException('Payment link not found');
    return {
      chargeId: charge.id,
      status: charge.status,
      paid: charge.status === 'PAID',
      paidAt: charge.paidAt,
      amountMinor: charge.amountMinor,
      currency: charge.currency,
      expiresAt: charge.expiresAt,
    };
  }

  /**
   * Full_Name for CBE's confirmation screen — mandatory in its envelope. The traveller the balance
   * is owed against: lead passenger on the booking, falling back to the account holder.
   */
  private async resolvePayerName(bookingId: string): Promise<string | null> {
    const booking = await this.prisma.booking.findUnique({
      where: { id: bookingId },
      include: { seats: true, passenger: { include: { user: true } } },
    });
    if (!booking) return null;
    return (
      booking.seats?.find((s: any) => s.leg === 1)?.passengerName ??
      booking.seats?.[0]?.passengerName ??
      booking.passenger?.user?.fullName ??
      null
    );
  }

  /**
   * Submit the one-time password for a COLLECT_OTP provider (CAC Bank). The bank SMSed it to the
   * payerAccount given at pay(); this forwards it to the payment service and marks the charge paid
   * when the debit settles. A wrong or expired OTP bubbles up as a 400 and the intent stays open,
   * so the payer can simply re-enter it.
   *
   * Deliberately reads the charge directly rather than through getByToken: the bank is already
   * holding a debit against this payer, and refusing to submit their OTP because the link TTL
   * lapsed while they read the SMS would strand a payment that is mid-flight.
   */
  async confirmOtp(token: string, otp: string) {
    const charge = await this.prisma.supplementaryCharge.findUnique({
      where: { paymentToken: token },
    });
    if (!charge) throw new NotFoundException('Payment link not found');
    if (charge.status === 'PAID') {
      return { chargeId: charge.id, status: 'SUCCEEDED', alreadyPaid: true };
    }

    const snapshot = await this.paymentClient.getIntentByReference(
      PaymentReferenceType.SUPPLEMENTARY_CHARGE,
      charge.id,
    );
    if (!snapshot) {
      throw new NotFoundException('No active payment to confirm for this charge');
    }

    const confirmed = await this.paymentClient.confirmOtp(
      snapshot.intentId,
      otp,
    );
    if (confirmed.status === ProviderPaymentStatus.SUCCEEDED) {
      await this.markPaid(charge.id, confirmed.providerTxnId);
    }

    return {
      chargeId: charge.id,
      status: confirmed.status,
      alreadyPaid: false,
    };
  }

  async pay(
    token: string,
    method: string,
    platform?: PaymentPlatformDto,
    requestOrigin?: string | null,
    payerAccount?: string,
  ) {
    const charge = await this.getByToken(token); // validates status/expiry

    if (METHODS_REQUIRING_PAYER_ACCOUNT.has(method) && !payerAccount?.trim()) {
      throw new BadRequestException(
        `payerAccount (mobile number) is required for ${method}`,
      );
    }

    const paymentMethod = method as ProviderMethod;
    // Self-pay links are opened on whichever portal domain the recipient used
    // (bookingedr.et vs passenger.edrsc.com), so the return pages must live on
    // that same domain. `requestOrigin` is already allowlist-validated by the
    // controller; PORTAL_URL is the fallback for non-browser callers.
    const portalUrl =
      requestOrigin ?? process.env.PORTAL_URL ?? 'http://localhost:5174';
    const returnUrl = `${portalUrl}/pay-balance/${token}/success`;
    const failureUrl = `${portalUrl}/pay-balance/${token}/failed`;

    const { amount, currency } = await this.resolveChargeAmount(charge, method);

    // CBE_BILL is inbound-only: no provider session is opened, the bill simply sits in CBE's
    // system until someone pays it. It needs a real deadline and a payer name (Full_Name is
    // mandatory in CBE's envelope) rather than the redirect flow's session semantics.
    //
    // Unlike an excess baggage charge (30-minute link TTL), this charge already carries a 72-hour
    // deadline of its own, which is a sane bill lifetime — so it is passed straight through with
    // no extension. That deadline is what stops the reconciliation sweep from expiring the intent
    // early (CBE_IMPLEMENTATION_PLAN.md §6.4). A charge with no expiry at all yields no intent
    // expiry either, which is correct: an open-ended debt backs an open-ended bill.
    let payerName: string | undefined;
    let expiresAt: string | undefined;
    if (method === PaymentMethodType.CBE_BILL) {
      expiresAt = charge.expiresAt?.toISOString();
      payerName = (await this.resolvePayerName(charge.bookingId)) ?? undefined;
    }

    const snapshot = await this.paymentClient.initiate({
      service: PaymentServiceEnum.PASSENGER,
      referenceType: PaymentReferenceType.SUPPLEMENTARY_CHARGE,
      referenceId: charge.id,
      orderRef: `SC-${charge.id.substring(0, 8)}`,
      // `amountMinor` is the contract's name but its value is MAJOR units — the provider layer
      // charges it verbatim at the currency's own precision (see PaymentIntentSnapshot).
      amountMinor: amount,
      currency,
      provider: paymentMethod,
      platform,
      payerAccount: payerAccount?.trim() || undefined,
      payerName,
      expiresAt,
      returnUrl,
      failureUrl,
    });

    return snapshot;
  }

  async waive(id: string, notes: string, waivedBy: string) {
    const charge = await this.prisma.supplementaryCharge.findUnique({ where: { id } });
    if (!charge) throw new NotFoundException('Charge not found');
    if (charge.status === 'PAID') throw new BadRequestException('Cannot waive a paid charge');
    const updated = await this.prisma.supplementaryCharge.update({
      where: { id },
      data: { status: 'WAIVED', notes },
    });
    await this.auditService.log({
      action: AUDIT_ACTIONS.WAIVE,
      entityType: AUDIT_ENTITIES.SupplementaryCharge,
      entityId: id,
      oldData: { status: charge.status },
      newData: {
        status: 'WAIVED',
        bookingId: charge.bookingId,
        amountMinor: charge.amountMinor,
        currency: charge.currency,
        waivedBy,
        notes,
      },
    });
    return updated;
  }

  async resendLink(id: string) {
    const charge = await this.prisma.supplementaryCharge.findUnique({
      where: { id },
      include: { booking: { select: { bookingRef: true, contactPhone: true, contactEmail: true } } },
    });
    if (!charge) throw new NotFoundException('Charge not found');
    if (charge.status !== 'PENDING') throw new BadRequestException('Can only resend link for PENDING charges');
    const updated = await this.prisma.supplementaryCharge.update({
      where: { id },
      data: { expiresAt: new Date(Date.now() + CHARGE_TTL_MS) },
    });
    await this.sendLink(updated, charge.booking.bookingRef, charge.booking.contactPhone, charge.booking.contactEmail);
    // Re-exposes a live payment token and extends its deadline, so it is a state change worth
    // attributing even though the charge's status is unchanged. Contact details stay out of the
    // row — only the fact that a link was re-sent.
    await this.auditService.log({
      action: AUDIT_ACTIONS.RESEND,
      entityType: AUDIT_ENTITIES.SupplementaryCharge,
      entityId: id,
      oldData: { expiresAt: charge.expiresAt?.toISOString() },
      newData: {
        bookingRef: charge.booking.bookingRef,
        expiresAt: updated.expiresAt?.toISOString(),
      },
    });
    return { sent: true };
  }

  private async sendLink(charge: any, bookingRef: string, phone: string | null, email: string | null) {
    const portalUrl = process.env.PORTAL_URL ?? 'http://localhost:5174';
    const payUrl = `${portalUrl}/pay-balance/${charge.paymentToken}`;
    const amount = (charge.amountMinor / 100).toFixed(2);
    const msg = `EDR: A balance of ${amount} ETB is outstanding for booking ${bookingRef}. Pay here: ${payUrl}`;

    if (phone) {
      try { await this.smsClient.sendSms({ to: phone, message: msg }); }
      catch (err) { this.logger.warn(`SMS failed for supplementary charge ${charge.id}: ${err}`); }
    }
    if (email) {
      try {
        await this.emailClient.sendEmail({
          to: email,
          subject: `EDR — Outstanding balance for booking ${bookingRef}`,
          text: msg,
        });
      } catch (err) { this.logger.warn(`Email failed for supplementary charge ${charge.id}: ${err}`); }
    }
    if (!phone && !email) {
      this.logger.warn(`No contact info for supplementary charge ${charge.id}`);
    }
  }
}