import {
  BadGatewayException,
  Injectable,
  NotFoundException,
} from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import axios from 'axios';
import { createHmac } from 'crypto';
import { Prisma } from '@prisma/client';
import { PrismaService } from '../prisma/prisma.service';
import { AuditService } from '../audit/audit.service';

const SUPER_SETTINGS_CANONICAL_PATH = '/api/super/settings';

@Injectable()
export class SettingsProxyService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly audit: AuditService,
    private readonly config: ConfigService,
  ) {}

  async getSettings(tenantId: string) {
    const tenant = await this.requireTenant(tenantId);
    const auth = this.buildAuthHeaders(tenant, 'GET');

    if (!auth) {
      return {
        stub: true,
        message:
          'نه remoteApiToken و نه SMS_REMOTE_SHARED_SECRET تنظیم شده؛ push ممکن نیست.',
        tenant: {
          id: tenant.id,
          slug: tenant.slug,
          nodeServer: tenant.nodeServer,
        },
        settings: [],
      };
    }

    try {
      const { data } = await axios.get(this.resolveSettingsUrl(tenant.nodeServer), {
        headers: {
          ...auth,
          Accept: 'application/json',
        },
        timeout: 15000,
      });
      return { stub: false, settings: data };
    } catch (error) {
      throw new BadGatewayException(
        this.axiosMessage(error, 'خواندن تنظیمات از سرور نسخه ناموفق بود'),
      );
    }
  }

  async updateSettings(
    tenantId: string,
    payload: Record<string, unknown>,
    userId?: string,
  ) {
    const tenant = await this.requireTenant(tenantId);
    const auth = this.buildAuthHeaders(tenant, 'POST');

    if (!auth) {
      await this.audit.log({
        action: 'settings.proxy.stub_update',
        entityType: 'tenant_settings',
        entityId: tenantId,
        tenantId,
        userId,
        after: payload as Prisma.InputJsonValue,
        meta: { stub: true },
      });

      return {
        stub: true,
        message:
          'نه remoteApiToken و نه SMS_REMOTE_SHARED_SECRET تنظیم شده؛ تغییر فقط در audit ثبت شد (stub).',
        accepted: payload,
      };
    }

    try {
      const { data } = await axios.post(
        this.resolveSettingsUrl(tenant.nodeServer),
        payload,
        {
          headers: {
            ...auth,
            Accept: 'application/json',
            'Content-Type': 'application/json',
          },
          timeout: 20000,
        },
      );

      await this.audit.log({
        action: 'settings.proxy.update',
        entityType: 'tenant_settings',
        entityId: tenantId,
        tenantId,
        userId,
        after: payload as Prisma.InputJsonValue,
        meta: {
          authMode: auth.Authorization ? 'bearer' : 'hmac',
        } as Prisma.InputJsonValue,
      });

      return { stub: false, result: data };
    } catch (error) {
      throw new BadGatewayException(
        this.axiosMessage(error, 'ذخیره تنظیمات روی سرور نسخه ناموفق بود'),
      );
    }
  }

  /**
   * Auth to product:
   * 1) Tenant remoteApiToken as Bearer (per-tenant)
   * 2) Else SMS shared secret as Bearer (CDN-safe; same secret as SMS)
   *    + optional HMAC headers for non-CDN installs
   */
  private buildAuthHeaders(
    tenant: {
      remoteApiToken: string | null;
      domain: string | null;
      domains: unknown;
      nodeServer: string | null;
    },
    method: 'GET' | 'POST',
  ): Record<string, string> | null {
    const token = String(tenant.remoteApiToken || '').trim();
    if (token) {
      return { Authorization: `Bearer ${token}` };
    }

    const shared = String(
      this.config.get<string>('SMS_REMOTE_SHARED_SECRET') || '',
    ).trim();
    if (!shared) {
      return null;
    }

    // Bearer with shared secret survives CDNs that strip custom X-* headers.
    const headers: Record<string, string> = {
      Authorization: `Bearer ${shared}`,
    };

    const domain = this.resolveTenantDomain(tenant);
    if (domain) {
      const timestamp = String(Math.floor(Date.now() / 1000));
      const payload = `${timestamp}.${method}.${SUPER_SETTINGS_CANONICAL_PATH}.${domain}`;
      const signature = createHmac('sha256', shared)
        .update(payload, 'utf8')
        .digest('hex');
      headers['X-Abshode-Domain'] = domain;
      headers['X-Abshode-Timestamp'] = timestamp;
      headers['X-Abshode-Signature'] = signature;
    }

    return headers;
  }

  private resolveTenantDomain(tenant: {
    domain: string | null;
    domains: unknown;
    nodeServer: string | null;
  }): string {
    // Prefer host of the URL we call — must match product SUPERADMIN_SMS_DOMAIN
    const fromNode = this.normalizeHost(tenant.nodeServer);
    if (fromNode) return fromNode;

    const primary = this.normalizeHost(tenant.domain);
    if (primary) return primary;

    for (const value of this.readDomains(tenant.domains)) {
      const host = this.normalizeHost(value);
      if (host) return host;
    }
    return '';
  }

  private readDomains(raw: unknown): string[] {
    if (!raw) return [];
    if (Array.isArray(raw)) return raw.map(String);
    if (typeof raw === 'string') {
      try {
        const parsed = JSON.parse(raw);
        return Array.isArray(parsed) ? parsed.map(String) : [];
      } catch {
        return [];
      }
    }
    return [];
  }

  private normalizeHost(value?: string | null) {
    if (!value) return '';
    return String(value)
      .trim()
      .toLowerCase()
      .replace(/^https?:\/\//, '')
      .split('/')[0]
      .split(':')[0];
  }

  private async requireTenant(tenantId: string) {
    const tenant = await this.prisma.tenant.findUnique({
      where: { id: tenantId },
    });
    if (!tenant) {
      throw new NotFoundException('نسخه یافت نشد');
    }
    return tenant;
  }

  private joinUrl(base: string, path: string) {
    return `${base.replace(/\/$/, '')}${path}`;
  }

  /**
   * nodeServer may be `https://host` or `https://host/api`.
   * Laravel exposes both `/super/settings` (web) and `/api/super/settings`.
   */
  private resolveSettingsUrl(nodeServer: string): string {
    const base = String(nodeServer || '').replace(/\/$/, '');
    if (/\/api$/i.test(base)) {
      return this.joinUrl(base, '/super/settings');
    }
    return this.joinUrl(base, '/api/super/settings');
  }

  private axiosMessage(error: unknown, fallback: string) {
    if (axios.isAxiosError(error)) {
      const status = error.response?.status;
      const body = error.response?.data;
      return `${fallback}${status ? ` (HTTP ${status})` : ''}${
        body ? `: ${JSON.stringify(body)}` : ''
      }`;
    }
    return fallback;
  }
}