import { Injectable, Logger } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import axios from 'axios';

@Injectable()
export class LoggingService {
  private readonly logger = new Logger(LoggingService.name);
  private readonly graylogUrl: string;
  private readonly environment: string;

  constructor(private readonly configService: ConfigService) {
    this.graylogUrl =
      this.configService.get<string>('GRAYLOG_URL') ||
      'http://localhost:12201/gelf';
    this.environment = this.configService.get<string>('PROFILE') || 'dev';
  }

  async log(
    level: string,
    serviceName: string,
    methodName: string,
    message: string,
    parameters?: unknown[],
    debugInfo?: unknown[],
  ) {
    const logLevel = level.toLowerCase().trim();
    const logMessage = `${serviceName}.${methodName}: ${message} | Params: ${JSON.stringify(
      parameters,
    )} | Debug: ${JSON.stringify(debugInfo)}`;

    // Console output via NestJS Logger
    switch (logLevel) {
      case 'debug':
      case 'info':
        this.logger.debug(logMessage);
        break;
      case 'warn':
        this.logger.warn(logMessage);
        break;
      case 'error':
        this.logger.error(logMessage);
        break;
      default:
        this.logger.log(logMessage);
    }

    // Send to Graylog asynchronously
    this.sendToGraylog({
      version: '1.1',
      host: serviceName || 'nestjs-app',
      short_message: message,
      full_message: logMessage,
      level: this.mapLogLevel(logLevel),
      _service: serviceName,
      _method: methodName,
      _parameters: parameters,
      _debug: debugInfo,
      _environment: this.environment,
      timestamp: Date.now() / 1000,
    });
  }

  private async sendToGraylog(payload: Record<string, any>) {
    try {
      await axios.post(this.graylogUrl, payload, {
        headers: { 'Content-Type': 'application/json' },
        timeout: 2000, // short timeout
      });
    } catch (err) {
      this.logger.warn(`Graylog send failed: ${err.message}`);
    }
  }

  private mapLogLevel(level: string): number {
    // Graylog levels: 0 (emerg) → 7 (debug)
    const mapping: Record<string, number> = {
      emerg: 0,
      alert: 1,
      crit: 2,
      error: 3,
      warn: 4,
      notice: 5,
      info: 6,
      debug: 7,
    };
    return mapping[level] ?? 6;
  }
}