import {
  Controller,
  Get,
  Post,
  Body,
  Param,
  Query,
  UseGuards,
  Request,
  BadRequestException,
  Inject,
  forwardRef,
} from '@nestjs/common';
import { AuthGuard } from '@nestjs/passport';
import { ApiTags, ApiOperation, ApiBearerAuth } from '@nestjs/swagger';
import { BillingService } from './billing.service';
import { assertStubGatewayAllowed } from './payment-gateway.util';
import { AppLifecycleService } from '../lifecycle/app-lifecycle.service';
import { ApplicationsService } from '../applications/applications.service';
import { ChargeWalletDto, PayApplicationDto } from './dto/billing.dto';
import { RolesGuard } from '../common/guards/roles.guard';
import { BillingCycle, InvoiceReason } from '../common/enums';

@ApiTags('Billing')
@ApiBearerAuth()
@Controller('billing')
@UseGuards(AuthGuard('jwt'), RolesGuard)
export class BillingWalletController {
  constructor(
    private readonly billingService: BillingService,
    @Inject(forwardRef(() => AppLifecycleService))
    private readonly lifecycleService: AppLifecycleService,
    @Inject(forwardRef(() => ApplicationsService))
    private readonly applicationsService: ApplicationsService,
  ) {}

  // ─── Wallet (User) ───────────────────────────────────────────────

  @Get('wallet')
  @ApiOperation({ summary: 'Get my wallet balance' })
  async getBalance(@Request() req: any) {
    return this.billingService.getBalance(req.user.id);
  }

  @Post('wallet/charge')
  @ApiOperation({ summary: 'Charge my wallet (self top-up)' })
  async chargeMyWallet(@Request() req: any, @Body() dto: ChargeWalletDto) {
    return this.billingService.chargeWallet(req.user.id, dto.amount, dto.description || 'Self top-up');
  }

  @Get('wallet/transactions')
  @ApiOperation({ summary: 'Get my wallet transactions' })
  async getTransactions(@Request() req: any, @Query('limit') limit?: string) {
    return this.billingService.getTransactions(req.user.id, limit ? parseInt(limit, 10) : 50);
  }

  @Get('resource-credits')
  @ApiOperation({ summary: 'List active prepaid resource credits (from deleted apps)' })
  async getResourceCredits(@Request() req: any) {
    const credits = await this.billingService.getActiveCredits(req.user.id);
    return credits.map((c) => this.billingService.formatCreditForApi(c));
  }

  @Post('wallet/pay/:applicationId')
  @ApiOperation({ summary: 'Pay for an application plan from wallet — activates/renews the app' })
  async payForApplication(
    @Request() req: any,
    @Param('applicationId') applicationId: string,
    @Body() body: PayApplicationDto,
  ) {
    const cycle = body.cycle as BillingCycle;
    if (!Object.values(BillingCycle).includes(cycle)) {
      throw new BadRequestException(`Invalid billing cycle: ${body.cycle}`);
    }

    const app = await this.applicationsService.findOne(applicationId, req.user.id);

    const payment = await this.billingService.resolveAppPayment(
      req.user.id,
      app,
      cycle,
    );

    const coupon = await this.billingService.resolveCoupon(
      req.user.id,
      body.couponCode,
      await this.billingService.getAppChargeBreakdown(app),
      cycle,
      payment.amountDue,
    );

    let invoice = null;
    if (payment.amountDue > 0) {
      invoice = await this.billingService.createInvoice({
        userId: req.user.id,
        applicationId: app.id,
        reason: InvoiceReason.DEPLOY,
        lines: [
          {
            label: `Application payment: ${app.name}`,
            description: `Billing cycle: ${cycle}`,
            amount: payment.amountDue,
            metadata: {
              cycle,
              waivedAmount: payment.waivedAmount,
              creditApplied: payment.creditId || null,
            },
          },
        ],
        metadata: {
          action: 'activate',
          cycle,
        },
        discount: coupon ?? undefined,
      });
    }

    let tx = null;
    if (invoice) {
      const paid = await this.billingService.payInvoiceWithWallet(invoice.id, req.user);
      tx = paid.transaction;
      invoice = paid.invoice;
    }

    const activated = await this.lifecycleService.activateApp(
      applicationId,
      cycle,
    );

    return {
      transaction: tx,
      invoice,
      creditApplied: payment.creditId || null,
      waivedAmount: payment.waivedAmount,
      discountAmount: coupon?.amount ?? 0,
      discountCode: coupon?.code ?? null,
      paidAmount: invoice ? Number(invoice.total) : 0,
      application: {
        id: activated.id,
        name: activated.name,
        lifecycleStatus: activated.lifecycleStatus,
        planExpiresAt: activated.planExpiresAt,
      },
      message: payment.waivedAmount > 0
        ? payment.amountDue > 0
          ? `Application "${activated.name}" activated — prepaid credit applied; you paid ${payment.amountDue} Toman for additional services.`
          : `Application "${activated.name}" activated using your prepaid resource credit (no charge).`
        : payment.amountDue > 0
          ? `Application "${activated.name}" activated until ${activated.planExpiresAt?.toISOString()}`
          : `Application "${activated.name}" activated`,
    };
  }

  // ─── Payment Gateway ─────────────────────────────────────────────

  @Post('gateway/initiate')
  @ApiOperation({ summary: 'Initiate a payment gateway transaction' })
  async initiateGateway(
    @Request() req: any,
    @Body() body: { amount: number; description?: string; callbackUrl: string },
  ) {
    assertStubGatewayAllowed();
    const trackingCode = `PAY-${Date.now()}-${Math.random().toString(36).substring(2, 8).toUpperCase()}`;
    return {
      success: true,
      trackingCode,
      gatewayUrl: `${body.callbackUrl}?trackingCode=${trackingCode}&amount=${body.amount}&status=success`,
      message: 'Redirect user to gatewayUrl to complete payment',
    };
  }

  @Post('gateway/verify')
  @ApiOperation({ summary: 'Verify a payment gateway transaction and charge wallet' })
  async verifyGateway(
    @Request() req: any,
    @Body() body: { trackingCode: string; amount: number },
  ) {
    assertStubGatewayAllowed();
    await this.billingService.chargeWallet(
      req.user.id,
      body.amount,
      `Payment gateway: ${body.trackingCode}`,
    );
    return {
      success: true,
      message: 'Payment verified and wallet charged',
      trackingCode: body.trackingCode,
    };
  }
}