// apps/box-app-api/src/feature/auth/auth.service.ts
import { Injectable, Logger } from '@nestjs/common';
import { UserLoginEventPayload } from '@box/common/events/user-login-event.dto';
import { nowSecBigInt } from '@box/common/time/time.util';
import { RabbitmqPublisherService } from '../../rabbitmq/rabbitmq-publisher.service';
import { PrismaMongoStatsService } from '../../prisma/prisma-mongo-stats.service';
import { PrismaMongoService } from '../../prisma/prisma-mongo.service';
import { AdService } from '../ads/ad.service';

type LoginParams = {
  uid: string;
  ip: string;
  userAgent?: string;
  appVersion?: string;
  os?: string;
  channelId?: string;
  machine?: string;
};

type LoginResult = {
  uid: string;
  channelId: string;
  startupAds: any | null; // keep as any until you wire your Ad payload DTO
};

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

  constructor(
    private readonly rabbitmqPublisher: RabbitmqPublisherService,
    private readonly prismaMongoStatsService: PrismaMongoStatsService,
    private readonly prismaMongoService: PrismaMongoService, // box-admin
    private readonly adService: AdService,
  ) {}

  async login(params: LoginParams): Promise<LoginResult> {
    const { uid, ip, userAgent, appVersion, os } = params;
    const channelIdInput = this.normalizeOptional(params.channelId);
    const machine = this.normalizeOptional(params.machine);

    const nowSec = nowSecBigInt(); // BigInt epoch seconds

    // 1) Find user (in box-admin)
    let user = await this.getUserByUid(uid);

    // 2) First login: auto-register
    if (!user) {
      const resolvedChannel =
        await this.resolveFirstLoginChannel(channelIdInput);
      user = await this.createUser({
        uid,
        ip,
        os: os ?? 'unknown',
        channelId: resolvedChannel.channelId,
        machine,
        nowSec,
      });
    } else {
      // 3) Subsequent login: keep stored user.channelId (ignore incoming channelId)
      // Optionally update machine if provided (safe)
      if (
        machine &&
        machine !== this.normalizeOptional((user as any).machine)
      ) {
        try {
          user = await this.prismaMongoService.user.update({
            where: { uid },
            data: {
              machine,
              updateAt: nowSec,
              lastLoginAt: nowSec,
            },
          });
        } catch (e) {
          // non-blocking
          this.logger.warn(
            `Failed to update machine for uid=${uid}: ${String(e)}`,
          );
        }
      }
    }

    const finalChannelId = String((user as any).channelId);

    // 4) Publish login history event (fire-and-forget)
    const loginEvent: UserLoginEventPayload = {
      uid,
      ip,
      userAgent,
      appVersion,
      os,
      channelId: finalChannelId,
      machine: machine ?? undefined,
      // IMPORTANT: use seconds (BigInt not always serializable across MQ)
      loginAt: Number(nowSec), // if consumer expects ms, change consumer; per your rule we use seconds
    };

    this.publishLoginEvent(loginEvent).catch(() => {
      // already logged inside
    });

    // 5) startupAds (placeholder: you’ll wire channel-specific ads later)
    // For now return null to keep behaviour deterministic.
    const startupAds = await this.adService.listAdsByType(1, 20);

    return {
      uid,
      channelId: finalChannelId,
      startupAds,
    };
  }

  private async publishLoginEvent(
    payload: UserLoginEventPayload,
  ): Promise<void> {
    try {
      this.logger.log(`Publishing user login event for uid=${payload.uid}`);
      await this.rabbitmqPublisher.publishUserLogin(payload);
    } catch (error) {
      const errorMessage =
        error instanceof Error ? error.message : String(error);
      const errorStack = error instanceof Error ? error.stack : undefined;
      this.logger.error(
        `Failed to publish user login event for uid=${payload.uid}: ${errorMessage}`,
        errorStack,
      );
    }
  }

  private normalizeOptional(v?: string): string | undefined {
    const s = (v ?? '').trim();
    return s.length > 0 ? s : undefined;
  }

  // ---------------------------
  // User (box-admin)
  // ---------------------------

  private async getUserByUid(uid: string): Promise<any | null> {
    return this.prismaMongoService.user.findUnique({
      where: { uid },
    });
  }

  private async createUser(input: {
    uid: string;
    ip: string;
    os: string;
    channelId: string;
    machine?: string;
    nowSec: bigint;
  }): Promise<any> {
    const { uid, channelId, machine, nowSec } = input;

    // Validate uniqueness explicitly (clear intention; Prisma will also enforce unique if set)
    const existed = await this.getUserByUid(uid);
    if (existed) return existed;

    return this.prismaMongoService.user.create({
      data: {
        uid,
        ip: input.ip,
        os: input.os,
        channelId,
        machine: machine ?? null,
        createAt: nowSec,
        updateAt: nowSec,
        lastLoginAt: nowSec,
      },
    });
  }

  // ---------------------------
  // Channel resolution (box-admin)
  // ---------------------------

  private async resolveFirstLoginChannel(
    channelIdInput?: string,
  ): Promise<any> {
    // 1) If client provided channelId, validate it exists
    if (channelIdInput) {
      const byId = await this.getChannelByChannelId(channelIdInput);
      if (byId) return byId;
    }

    // 2) Use default channel where isDefault=true
    const def = await this.getDefaultChannel();
    if (def) return def;

    // 3) Last resort: first created channel (so system can still run)
    const first = await this.getFirstChannel();
    if (first) return first;

    // If no channel exists at all, this is a deployment/config error
    throw new Error(
      'No channel available (missing default channel and no channels exist)',
    );
  }

  private async getChannelByChannelId(channelId: string): Promise<any | null> {
    return this.prismaMongoService.channel.findUnique({
      where: { channelId },
    });
  }

  private async getDefaultChannel(): Promise<any | null> {
    return this.prismaMongoService.channel.findFirst({
      where: { isDefault: true },
      orderBy: { createAt: 'asc' },
    });
  }

  private async getFirstChannel(): Promise<any | null> {
    return this.prismaMongoService.channel.findFirst({
      orderBy: { createAt: 'asc' },
    });
  }
}