dmail-api/src/modules/ai-assistant/services/ai-assistant.service.ts

import { BadRequestException, Injectable, NotFoundException } from "@nestjs/common";
import { firstValueFrom } from "rxjs";

import { AiService } from "./ai.service";
import { AiMessage } from "../../../common/enums/message.enum";
import { MessageDetails } from "../../mail-server/interfaces/messages-response.interface";
import { WildDuckMessagesService } from "../../mail-server/services/wildduck-messages.service";
import { S3Service } from "../../uploader/providers/s3.service";
import { GenerateTemplateDto, TemplatePurposeEnum, TemplateStyleEnum, TemplateThemeEnum } from "../DTO/generate-template.dto";
import { SummarizeEmailDto } from "../DTO/summarize-email.dto";
import { AudioFormatEnum, SpeedEnum, TextToSpeechDto, VoiceEnum } from "../DTO/text-to-speech.dto";
import { WriteEmailAssistanceDto } from "../DTO/write-email-assistance.dto";
import { SummaryLengthEnum, SummaryToneEnum } from "../enums/ai.enum";
import { AITextToSpeechResponse } from "../interfaces/ai-service.interface";
import {
  IEmailData,
  ITemplateGenerationRequest,
  SummarizationOptions,
  TemplateGenerationOptions,
  TextToSpeechOptions,
} from "../interfaces/ai-service.interface";

@Injectable()
export class AiAssistantService {
  constructor(
    private readonly messagesService: WildDuckMessagesService,
    private readonly aiService: AiService,
    private readonly s3Service: S3Service,
  ) {}

  //************************************************* */
  async summarizeEmail(summarizeDto: SummarizeEmailDto, userId: string) {
    const message = await firstValueFrom(this.messagesService.getMessage(userId, summarizeDto.mailbox, summarizeDto.messageId));

    if (!message) throw new NotFoundException(AiMessage.MESSAGE_NOT_FOUND_OR_ACCESS_DENIED);

    const emailData = this.extractEmailData(message);

    const summary = await this.generateEmailSummary(emailData, summarizeDto.length, summarizeDto.tone);

    return summary;
  }

  //************************************************* */
  async assistEmailWriting(writeAssistanceDto: WriteEmailAssistanceDto, userId: string) {
    const assistance = await this.generateEmailWritingAssistance(writeAssistanceDto, userId);

    return { assistance };
  }

  //************************************************* */
  async generateTemplate(generateTemplateDto: GenerateTemplateDto) {
    if (!generateTemplateDto.description?.trim()) {
      throw new BadRequestException(AiMessage.DESCRIPTION_IS_REQUIRED);
    }

    const templateRequest: ITemplateGenerationRequest = {
      description: generateTemplateDto.description.trim(),
      options: this.buildTemplateGenerationOptions(generateTemplateDto),
    };

    const aiResponse = await this.aiService.generateTemplate(templateRequest);

    return {
      template: {
        name: aiResponse.templateName,
        description: aiResponse.description,
        structure: aiResponse.structure,
        rawHtml: aiResponse.rawHtml,
        colorScheme: aiResponse.colorScheme,
      },
      designInsights: {
        designPrinciples: aiResponse.designPrinciples,
        suggestedImprovements: aiResponse.suggestedImprovements,
      },
      metadata: {
        theme: generateTemplateDto.theme || TemplateThemeEnum.MODERN,
        style: generateTemplateDto.style || TemplateStyleEnum.PROFESSIONAL,
        purpose: generateTemplateDto.purpose || TemplatePurposeEnum.GENERAL,
        generatedAt: new Date().toISOString(),
      },
    };
  }

  //************************************************* */
  async textToSpeechEmailSummary(textToSpeechDto: TextToSpeechDto, userId: string) {
    const message = await firstValueFrom(this.messagesService.getMessage(userId, textToSpeechDto.mailbox, textToSpeechDto.messageId));

    if (!message) throw new NotFoundException(AiMessage.MESSAGE_NOT_FOUND_OR_ACCESS_DENIED);

    const emailData = this.extractEmailData(message);
    const summaryResponse = await this.generateEmailSummary(emailData, SummaryLengthEnum.MEDIUM, SummaryToneEnum.PROFESSIONAL);

    // const textForSpeech = this.buildTextForSpeech(summaryResponse, emailData);
    const textForSpeech = summaryResponse.summary;

    const ttsOptions: TextToSpeechOptions = {
      voice: textToSpeechDto.voice || VoiceEnum.ALLOY,
      speed: textToSpeechDto.speed || SpeedEnum.NORMAL,
      format: textToSpeechDto.format || AudioFormatEnum.MP3,
    };

    const audioResponse = await this.aiService.textToSpeech(textForSpeech, ttsOptions);

    const fileResponse = await this.saveAudioFile(audioResponse, textToSpeechDto, emailData);

    return {
      file: fileResponse,
      summary: summaryResponse,
      textUsed: textForSpeech,
    };
  }

  //************************************************* */
  private buildTemplateGenerationOptions(dto: GenerateTemplateDto): TemplateGenerationOptions {
    return {
      theme: dto.theme,
      style: dto.style,
      purpose: dto.purpose,
      templateName: dto.templateName,
      preferredColors: dto.preferredColors,
    };
  }

  //************************************************* */
  private extractEmailData(message: MessageDetails) {
    return {
      subject: message.subject,
      content: this.extractTextContent(message),
      htmlContent: this.extractHtmlContent(message),
      from: this.extractSenderInfo(message),
      to: this.extractRecipientInfo(message),
      date: message.date || new Date().toISOString(),
      attachments: message.attachments || [],
    };
  }

  //************************************************* */
  private extractTextContent(message: MessageDetails): string {
    if (message.text) {
      return typeof message.text === "string" ? message.text : message.text || "";
    }

    if (message.html) {
      return this.stripHtmlTags(typeof message.html === "string" ? message.html : message.html[0] || "");
    }

    return "";
  }

  //************************************************* */
  private extractHtmlContent(message: MessageDetails): string {
    if (message.html) {
      return typeof message.html === "string" ? message.html : message.html[0] || "";
    }
    return "";
  }

  //************************************************* */
  private extractSenderInfo(message: MessageDetails): string {
    if (message.from && message.from.address) {
      return message.from.name ? `${message.from.name} <${message.from.address}>` : message.from.address;
    }
    return "";
  }

  //************************************************* */
  private extractRecipientInfo(message: MessageDetails): string[] {
    const recipients: string[] = [];

    if (message.to && Array.isArray(message.to)) {
      recipients.push(...message.to.map((recipient) => (recipient.name ? `${recipient.name} <${recipient.address}>` : recipient.address)));
    }

    return recipients;
  }

  //************************************************* */
  private stripHtmlTags(html: string): string {
    return html
      .replace(/<[^>]*>/g, "")
      .replace(/&nbsp;/g, " ")
      .trim();
  }

  //************************************************* */
  private async generateEmailSummary(emailData: IEmailData, length?: SummaryLengthEnum, tone?: SummaryToneEnum) {
    const content = emailData.content || emailData.htmlContent;

    if (!content || !content.trim()) throw new BadRequestException(AiMessage.EMAIL_CONTENT_IS_EMPTY_OR_COULD_NOT_BE_EXTRACTED);

    const aiEmailData: IEmailData = {
      subject: emailData.subject,
      content: emailData.content,
      htmlContent: emailData.htmlContent,
      from: emailData.from,
      to: emailData.to,
      date: emailData.date,
      attachments: emailData.attachments,
    };

    const summarizationOptions: SummarizationOptions = {
      length: length || SummaryLengthEnum.MEDIUM,
      tone: tone || SummaryToneEnum.PROFESSIONAL,
    };

    const aiResponse = await this.aiService.summarizeEmail(aiEmailData, summarizationOptions);

    return {
      summary: aiResponse.summary,
      keyPoints: aiResponse.keyPoints,
      suggestedActions: aiResponse.suggestedActions,
      priority: aiResponse.priority,
      sentiment: aiResponse.sentiment,
    };
  }

  //************************************************* */
  private async saveAudioFile(audioResponse: AITextToSpeechResponse, textToSpeechDto: TextToSpeechDto, emailData: IEmailData) {
    const timestamp = Date.now();
    const sanitizedSubject = emailData.subject?.replace(/[^a-zA-Z0-9]/g, "_").substring(0, 50) || "email_summary";
    const fileName = `tts_${sanitizedSubject}_${timestamp}.${audioResponse.format}`;

    const s3Key = this.s3Service.generateFileKey(fileName, "audio");

    const s3Result = await this.s3Service.uploadFile(audioResponse.audioBuffer, s3Key, audioResponse.contentType, {
      originalName: fileName,
      messageId: textToSpeechDto.messageId.toString(),
      mailbox: textToSpeechDto.mailbox,
      voice: textToSpeechDto.voice || VoiceEnum.ALLOY,
      speed: (textToSpeechDto.speed || SpeedEnum.NORMAL).toString(),
      format: audioResponse.format,
      generatedAt: new Date().toISOString(),
    });

    return {
      fileUrl: s3Result.url,
      fileName,
      format: audioResponse.format,
      contentType: audioResponse.contentType,
      fileSize: audioResponse.audioBuffer.length,
      s3Key: s3Result.key,
    };
  }

  //************************************************* */
  // private buildTextForSpeech(summaryResponse: AISummaryResponse, emailData: IEmailData): string {
  //   let text = `Email Summary: `;

  //   if (emailData.subject) {
  //     text += `Subject: ${emailData.subject}. `;
  //   }

  //   if (emailData.from) {
  //     text += `From: ${emailData.from}. `;
  //   }

  //   if (summaryResponse.summary) {
  //     text += `Summary: ${summaryResponse.summary}. `;
  //   }

  //   if (summaryResponse.keyPoints && summaryResponse.keyPoints.length > 0) {
  //     text += `Key Points: ${summaryResponse.keyPoints.join(". ")}. `;
  //   }

  //   if (summaryResponse.suggestedActions && summaryResponse.suggestedActions.length > 0) {
  //     text += `Suggested Actions: ${summaryResponse.suggestedActions.join(". ")}. `;
  //   }

  //   if (summaryResponse.priority) {
  //     text += `Priority: ${summaryResponse.priority}.`;
  //   }

  //   return text;
  // }

  //************************************************* */
  private async generateEmailWritingAssistance(writeAssistanceDto: WriteEmailAssistanceDto, _userId: string) {
    const aiResponse = await this.aiService.assistEmailWriting(writeAssistanceDto.prompt);

    return {
      suggestion: {
        subject: aiResponse.subject,
        content: aiResponse.content,
        alternatives: aiResponse.alternatives,
      },
      tips: aiResponse.tips,
      improvements: aiResponse.improvements,
    };
  }
}