// Custom code for predictive lifecycle stage management
exports.main = (functionContext, sendResponse) => {
  // Get contact properties from the workflow
  const { 
    contact_id, 
    current_lifecycle_stage, 
    lead_score, 
    first_conversion_date, 
    page_views, 
    email_clicks,
    form_submissions,
    company_size,
    industry
  } = functionContext.parameters;
  
  // Initialize HubSpot client
  const hubspot = require('@hubspot/api-client');
  const hubspotClient = new hubspot.Client({
    accessToken: process.env.PRIVATE_APP_ACCESS_TOKEN
  });
  
  async function predictNextStage() {
    try {
      // Calculate days since first conversion
      const daysSinceConversion = calculateDaysSinceConversion(first_conversion_date);
      
      // Get historical data for similar contacts
      const similarContactsData = await getSimilarContactsData(company_size, industry);
      
      // Build prediction model input
      const modelInput = {
        current_stage: current_lifecycle_stage,
        lead_score: parseInt(lead_score),
        days_in_pipeline: daysSinceConversion,
        page_view_count: parseInt(page_views),
        email_click_count: parseInt(email_clicks),
        form_submission_count: parseInt(form_submissions),
        similar_contacts_avg_days_to_next_stage: similarContactsData.avgDaysToNextStage,
        similar_contacts_conversion_rate: similarContactsData.conversionRate
      };
      
      // Make prediction
      const prediction = predictStageProgression(modelInput);
      
      // Return prediction results
      sendResponse({
        statusCode: 200,
        body: {
          recommended_next_stage: prediction.nextStage,
          probability: prediction.probability,
          estimated_days_to_conversion: prediction.daysToConversion,
          confidence_score: prediction.confidenceScore,
          key_factors: prediction.keyFactors
        }
      });
    } catch (error) {
      // Handle errors
      sendResponse({
        statusCode: 500,
        body: {
          error: error.message
        }
      });
    }
  }
  
  // Helper function to calculate days since first conversion
  function calculateDaysSinceConversion(conversionDate) {
    const firstConversion = new Date(conversionDate);
    const today = new Date();
    const diffTime = Math.abs(today - firstConversion);
    return Math.ceil(diffTime / (1000 * 60 * 60 * 24));
  }
  
  // Helper function to get data on similar contacts
  async function getSimilarContactsData(companySize, industry) {
    // In a real implementation, this would query HubSpot for contacts with
    // similar attributes who have successfully progressed through stages
    
    // For this example, we'll return mock data
    return {
      avgDaysToNextStage: 14,
      conversionRate: 0.35
    };
  }
  
  // Helper function to predict stage progression
  function predictStageProgression(modelInput) {
    // This is where you would implement your prediction logic
    // Could use a simple rule-based approach or integrate with an external ML service
    
    // Simplified example using rule-based logic:
    let nextStage;
    let probability;
    let daysToConversion;
    let confidenceScore;
    let keyFactors = [];
    
    switch(modelInput.current_stage) {
      case 'SUBSCRIBER':
        nextStage = 'LEAD';
        probability = 0.9;
        daysToConversion = 1;
        confidenceScore = 'HIGH';
        keyFactors = ['Email subscription active'];
        break;
        
      case 'LEAD':
        if (modelInput.lead_score > 30 && modelInput.page_view_count > 5) {
          nextStage = 'MARKETING QUALIFIED LEAD';
          probability = 0.75;
          daysToConversion = Math.max(0, 10 - modelInput.days_in_pipeline);
          confidenceScore = 'MEDIUM';
          keyFactors = ['Lead score above threshold', 'High page view count'];
        } else {
          nextStage = 'LEAD';
          probability = 0.3;
          daysToConversion = 15;
          confidenceScore = 'LOW';
          keyFactors = ['Insufficient engagement'];
        }
        break;
        
      case 'MARKETING QUALIFIED LEAD':
        if (modelInput.lead_score > 70 && modelInput.form_submission_count > 2) {
          nextStage = 'SALES QUALIFIED LEAD';
          probability = 0.6;
          daysToConversion = Math.max(0, modelInput.similar_contacts_avg_days_to_next_stage - modelInput.days_in_pipeline);
          confidenceScore = 'MEDIUM';
          keyFactors = ['High lead score', 'Multiple form submissions'];
        } else {
          nextStage = 'MARKETING QUALIFIED LEAD';
          probability = 0.4;
          daysToConversion = 20;
          confidenceScore = 'LOW';
          keyFactors = ['Needs more nurturing'];
        }
        break;
        
      // Additional cases for other lifecycle stages
      default:
        nextStage = modelInput.current_stage;
        probability = 0.1;
        daysToConversion = 30;
        confidenceScore = 'VERY LOW';
        keyFactors = ['Insufficient data'];
    }
    
    return {
      nextStage,
      probability,
      daysToConversion,
      confidenceScore,
      keyFactors
    };
  }
  
  // Execute the main function
  predictNextStage();
};