import { Injectable, Logger } from '@nestjs/common';
import { ChatOpenAI } from '@langchain/openai';
import { ModelConfig } from '../types';
import { I18nService } from '../i18n/i18n.service';

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

  constructor(private i18nService: I18nService) {}

  // Simple health check method
  healthCheck() {
    return { status: 'ok', message: 'API is healthy' };
  }

  async getChatCompletion(
    prompt: string,
    modelConfig: ModelConfig,
  ): Promise<string> {
    // API key is optional - allows local models

    try {
      const llm = this.createLLM(modelConfig);
      const response = await llm.invoke(prompt);
      return response.content.toString();
    } catch (error) {
      this.logger.error('LangChain call failed:', error);
      if (error.message?.includes('401')) {
        throw new Error(this.i18nService.getMessage('invalidApiKey'));
      }
      throw new Error(
        this.i18nService.formatMessage('apiCallFailed', {
          message: error.message,
        }),
      );
    }
  }

  private createLLM(modelConfig: ModelConfig): ChatOpenAI {
    return new ChatOpenAI({
      temperature: 0.7,
      apiKey: modelConfig.apiKey,
      modelName: modelConfig.modelId,
      configuration: {
        baseURL: modelConfig.baseUrl || 'http://localhost:11434/v1',
      },
    });
  }
}