dmail-api/src/modules/templates/services/template-processor.service.ts

import { Injectable, Logger } from "@nestjs/common";

import { TemplatesService } from "./templates.service";
// import { PersonalityDataType, SectionItemType, TextType } from "../interfaces/structure.interface";

interface ProcessedTemplateResult {
  html: string;
  text: string;
  hasTemplate: boolean;
}

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

  constructor(private readonly templatesService: TemplatesService) {}

  /**
   * Process email content through business template
   */
  async processEmailWithTemplate(
    businessId: string,
    emailContent: { text?: string; html?: string; subject?: string },
    // userId?: string,
  ): Promise<ProcessedTemplateResult> {
    try {
      this.logger.log(`Processing email with template for business: ${businessId}`);

      // Get business templates
      const templates = await this.templatesService.getTemplatesByBusinessId(businessId);

      if (!templates || templates.length === 0) {
        this.logger.log(`No templates found for business: ${businessId}, using original content`);
        return {
          html: emailContent.html || this.convertTextToHtml(emailContent.text || ""),
          text: emailContent.text || this.stripHtmlTags(emailContent.html || ""),
          hasTemplate: false,
        };
      }

      // Use the first template
      const template = templates[0];

      this.logger.log(`Using template: ${template.name} for email processing`);

      // Process the template with email content
      const processedContent = await this.injectContentIntoTemplate(emailContent, template.rawHtml);

      return {
        html: processedContent.html,
        text: processedContent.text,
        hasTemplate: true,
      };
    } catch (error) {
      this.logger.error(`Failed to process email with template for business ${businessId}:`, error);

      // Fallback to original content if template processing fails
      return {
        html: emailContent.html || this.convertTextToHtml(emailContent.text || ""),
        text: emailContent.text || this.stripHtmlTags(emailContent.html || ""),
        hasTemplate: false,
      };
    }
  }

  /**
   * Inject email content into template structure
   */
  private async injectContentIntoTemplate(
    // templateStructure: Record<string, unknown>,
    emailContent: { text?: string; html?: string; subject?: string },
    rawHtml?: string,
  ): Promise<{ html: string; text: string }> {
    try {
      // If template has raw HTML, use it as base and inject content
      if (rawHtml) {
        const html = this.injectContentIntoRawHtml(rawHtml, emailContent);
        return {
          html,
          text: this.stripHtmlTags(html),
        };
      }

      // Otherwise, build simple HTML with email content
      const html = this.buildSimpleTemplate(emailContent);
      return {
        html,
        text: this.stripHtmlTags(html),
      };
    } catch (error) {
      this.logger.error("Failed to inject content into template:", error);
      throw error;
    }
  }

  /**
   * Inject email content into raw HTML template
   */
  private injectContentIntoRawHtml(rawHtml: string, emailContent: { text?: string; html?: string; subject?: string }): string {
    let processedHtml = rawHtml;

    // Replace placeholders with actual content
    const contentToInject = emailContent.html || this.convertTextToHtml(emailContent.text || "");

    // Common placeholder patterns
    const placeholders = [/\{\{content\}\}/gi, /\{\{message\}\}/gi, /\{\{body\}\}/gi, /\{content\}/gi, /\{message\}/gi, /\{body\}/gi];

    placeholders.forEach((placeholder) => {
      processedHtml = processedHtml.replace(placeholder, contentToInject);
    });

    // Replace subject placeholders
    if (emailContent.subject) {
      const subjectPlaceholders = [/\{\{subject\}\}/gi, /\{\{title\}\}/gi, /\{subject\}/gi, /\{title\}/gi];

      subjectPlaceholders.forEach((placeholder) => {
        processedHtml = processedHtml.replace(placeholder, emailContent.subject!);
      });
    }

    return processedHtml;
  }

  /**
   * Build simple HTML template
   */
  private buildSimpleTemplate(emailContent: { text?: string; html?: string; subject?: string }): string {
    const content = emailContent.html || this.convertTextToHtml(emailContent.text || "");

    return `
      <!DOCTYPE html>
      <html>
      <head>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>${emailContent.subject || "Email"}</title>
        <style>
          body { font-family: Arial, sans-serif; margin: 0; padding: 20px; line-height: 1.6; }
          .email-container { max-width: 600px; margin: 0 auto; }
          .content { padding: 20px; }
        </style>
      </head>
      <body>
        <div class="email-container">
          <div class="content">
            ${content}
          </div>
        </div>
      </body>
      </html>
    `;
  }

  /**
   * Convert plain text to HTML
   */
  private convertTextToHtml(text: string): string {
    return text
      .replace(/\n\n/g, "</p><p>")
      .replace(/\n/g, "<br>")
      .replace(/^(.*)$/, "<p>$1</p>");
  }

  /**
   * Strip HTML tags from content
   */
  private stripHtmlTags(html: string): string {
    return html
      .replace(/<[^>]*>/g, "")
      .replace(/&nbsp;/g, " ")
      .replace(/&amp;/g, "&")
      .replace(/&lt;/g, "<")
      .replace(/&gt;/g, ">")
      .replace(/&quot;/g, '"')
      .trim();
  }
}