import { GoogleGenAI } from "@google/genai";

const getClient = () => {
  const apiKey = process.env.API_KEY;
  if (!apiKey) return null;
  return new GoogleGenAI({ apiKey });
};

export const generateEmailContent = async (
  prompt: string, 
  section: 'header' | 'body' | 'footer'
): Promise<string> => {
  const client = getClient();
  if (!client) {
    throw new Error("API Key not found");
  }

  // Model selection based on text task complexity
  const modelId = 'gemini-2.5-flash';

  const systemInstruction = `
    You are an expert email marketing developer. 
    You are generating HTML content for an email template ${section}.
    
    RULES:
    1. Return ONLY the HTML code. Do not include markdown ticks, 'html' labels, or explanations.
    2. Use inline CSS styles for compatibility.
    3. Use the Handlebars syntax for placeholders: {{variable_name}}.
    4. If the user asks for a specific variable, format it correctly.
    5. For Header: Include logo placeholders or standard menu links if asked.
    6. For Footer: Include unsubscribe links and copyright info if asked.
    7. For Body: Focus on clean, readable content.
  `;

  try {
    const response = await client.models.generateContent({
      model: modelId,
      contents: prompt,
      config: {
        systemInstruction: systemInstruction,
        temperature: 0.7,
      }
    });

    let text = response.text || "";
    // Cleanup if model adds markdown despite instructions
    text = text.replace(/```html/g, '').replace(/```/g, '').trim();
    return text;
  } catch (error) {
    console.error("Gemini API Error:", error);
    throw new Error("Failed to generate content");
  }
};