services/imageService.js

/**
 * Image Service
 * Handles communication with Image Generation APIs.
 */

const axios = require('axios'); // Assuming axios might be used

// Placeholder for API Key configuration
const API_KEY = process.env.IMG_API_KEY || process.env.LLM_API_KEY || '';
const MODEL = 'gemini-3-pro-image-preview';
const API_URL = `https://generativelanguage.googleapis.com/v1beta/models/${MODEL}:generateContent`;

/**
 * Generates an image based on the text prompt.
 * @param {string} prompt - The text description for the image.
 * @param {Object} options - Optional parameters (aspectRatio, etc.)
 * @returns {Promise<string>} - The base64 string of the generated image.
 */
async function generateImage(prompt, options = {}) {
  if (!API_KEY) {
    throw new Error("IMG_API_KEY or LLM_API_KEY is not defined in environment variables.");
  }

  try {
    console.log(`[Image Service] Sending request to ${MODEL}...`, prompt);

    const url = `${API_URL}?key=${API_KEY}`;

    const payload = {
      contents: [{
        parts: [{
          text: prompt
        }]
      }]
    };

    // Add optional configuration if supported by the model and needed
    /*
    if (options.aspectRatio) {
        payload.generationConfig = {
            aspectRatio: options.aspectRatio // e.g., "1:1", "4:3", "16:9"
        };
    }
    */

    const response = await axios.post(url, payload, {
      headers: {
        'Content-Type': 'application/json'
      },
      timeout: 120000 // 2 minutes timeout
    });

    // Extract base64 image data from Gemini response structure
    if (response.data && response.data.candidates && response.data.candidates.length > 0) {
      const candidate = response.data.candidates[0];
      if (candidate.content && candidate.content.parts) {
        const imagePart = candidate.content.parts.find(p => p.inlineData);
        if (imagePart && imagePart.inlineData) {
          return imagePart.inlineData.data; // This is the base64 string
        }
      }
    }

    console.warn("[Image Service] Unexpected response structure:", JSON.stringify(response.data));
    throw new Error("Empty or invalid response from Image Generation API.");

  } catch (error) {
    console.error('[Image Service] Error generating image:', error.response ? JSON.stringify(error.response.data) : error.message);
    throw error;
  }
}

/**
 * Regenerates/Edits an image based on a text prompt and an existing image.
 * 
 * @param {string} prompt - The text instruction.
 * @param {string} imageBase64 - The base64 string of the previous image.
 * @returns {Promise<string>} - The base64 string of the new image.
 */
async function regenerateImage(prompt, imageBase64) {
  if (!API_KEY) {
    throw new Error("IMG_API_KEY or LLM_API_KEY is not defined.");
  }

  try {
    console.log(`[Image Service] Regenerating image with prompt: ${prompt}`);

    const url = `${API_URL}?key=${API_KEY}`;

    const payload = {
      contents: [{
        parts: [
          { text: prompt },
          {
            inline_data: {
              mime_type: "image/png", // Assuming PNG for now, simplest for base64
              data: imageBase64
            }
          }
        ]
      }]
    };

    const response = await axios.post(url, payload, {
      headers: { 'Content-Type': 'application/json' },
      timeout: 120000
    });

    if (response.data && response.data.candidates && response.data.candidates.length > 0) {
      const candidate = response.data.candidates[0];
      if (candidate.content && candidate.content.parts) {
        const imagePart = candidate.content.parts.find(p => p.inlineData);
        if (imagePart && imagePart.inlineData) {
          return imagePart.inlineData.data;
        }
      }
    }

    console.warn("[Image Service] Unexpected response structure:", JSON.stringify(response.data));
    throw new Error("Empty or invalid response from Image Generation API.");

  } catch (error) {
    console.error('[Image Service] Error regenerating image:', error.response ? JSON.stringify(error.response.data) : error.message);
    throw error;
  }
}

module.exports = {
  generateImage,
  regenerateImage
};