// This is a mock service. In a real application, you would import and use the @google/genai library.
// import { GoogleGenAI, Chat } from "@google/genai";

import { ChatMessage } from '../types';

// Mock response structure to emulate the real API
interface MockGenerateContentResponse {
    text: string;
}

class MockChat {
    private systemInstruction: string;

    constructor(config?: { systemInstruction: string }) {
        this.systemInstruction = config?.systemInstruction || "You are a helpful assistant.";
        console.log("MockChat initialized with instruction:", this.systemInstruction);
    }

    sendMessage(message: { message: string }): Promise<MockGenerateContentResponse> {
        console.log("MockChat received message:", message.message);
        
        return new Promise(resolve => {
            setTimeout(() => {
                const responses = [
                    "That's a very interesting question! Let me think...",
                    "Based on your persona settings, I would say the best approach is to be direct and informative.",
                    "I'm sorry, I cannot answer that question based on my current knowledge base.",
                    "Of course! I can help with that. What are the specific details you need?",
                    "Analyzing your request... It seems you're asking about product features. Our product excels in A, B, and C."
                ];
                
                const randomResponse = responses[Math.floor(Math.random() * responses.length)];
                resolve({ text: randomResponse });
            }, 800);
        });
    }
}

class MockGoogleGenAI {
    public chats = {
        create: (config?: { systemInstruction: string }) => {
            return new MockChat(config);
        }
    };
}

const mockAi = new MockGoogleGenAI();
let mockChat: MockChat | null = null;

export const createAIChatSession = (persona: string) => {
    mockChat = mockAi.chats.create({ systemInstruction: persona });
};

export const sendChatMessage = async (message: string): Promise<ChatMessage> => {
    if (!mockChat) {
       createAIChatSession("You are a helpful assistant."); // Default persona
    }
    
    const response = await mockChat!.sendMessage({ message });
    const aiResponse: ChatMessage = { id: `msg-ai-${Date.now()}`, sender: 'ai', text: response.text };
    return aiResponse;
};

export const polishScript = async (originalScript: string): Promise<string[]> => {
    console.log("Mock polishScript called with:", originalScript);
    // In a real app, you would call Gemini here.
    // const response = await ai.models.generateContent({ model: 'gemini-2.5-flash', contents: `Rewrite the following script in 3 different styles (professional, witty, and casual):\n\n"${originalScript}"` });
    // For now, return mock data.
    return new Promise(resolve => {
        setTimeout(() => {
            resolve([
                `[Professional] We are pleased to welcome you to our presentation. We have some exciting updates to share.`,
                `[Witty] Settle in, folks! You're about to witness a presentation of epic proportions.`,
                `[Casual] Hey everyone, thanks for joining. Let's get started with our presentation.`
            ]);
        }, 1200);
    });
};

export const generateArticle = async (topic: string): Promise<{ title: string; summary: string; content: string; }> => {
    console.log("Mock generateArticle called with:", topic);
    // In a real app, you would call Gemini here.
    return new Promise(resolve => {
        setTimeout(() => {
            resolve({
                title: `Exploring the Wonders of ${topic}`,
                summary: `A brief overview of the key aspects and fascinating details surrounding ${topic}. Discover why it's a subject of great interest.`,
                content: `The topic of ${topic} is a multifaceted and deeply engaging subject. Historically, its roots can be traced back to ancient civilizations where it played a pivotal role in culture and daily life. \n\nScientifically, ${topic} presents a complex set of principles that continue to be studied by experts worldwide. The implications of these studies are far-reaching, potentially impacting technology, medicine, and our understanding of the universe. \n\nFrom a cultural standpoint, ${topic} has inspired countless works of art, literature, and music, proving its enduring relevance in the human experience. As we look to the future, the evolution of ${topic} promises even more exciting developments.`
            });
        }, 1500);
    });
};

export const mockProductDatabase = [
    { title: "Smart Noise-Cancelling Headphones", price: "$149.99" },
    { title: "Ergonomic Mechanical Keyboard", price: "$89.99" },
    { title: "4K Ultra-HD Webcam", price: "$69.99" },
    { title: "Organic French Press Coffee Beans", price: "$22.50" },
    { title: "Minimalist Desk Lamp with Wireless Charging", price: "$45.00" },
    { title: "Hand-Poured Soy Wax Candle", price: "$18.00" },
    { title: "The Alchemist by Paulo Coelho", price: "$12.99" },
    { title: "Atomic Habits by James Clear", price: "$15.99" },
    { title: "Lightweight Waterproof Hiking Backpack", price: "$79.95" },
    { title: "Insulated Stainless Steel Water Bottle", price: "$25.00" },
    { title: "Professional Chef's Knife - 8 Inch", price: "$120.00" },
    { title: "Non-Stick Ceramic Frying Pan Set", price: "$59.99" },
    { title: "Portable Blender for Shakes and Smoothies", price: "$34.99" },
    { title: "Yoga Mat with Carrying Strap", price: "$29.99" },
    { title: "Adjustable Dumbbell Set", price: "$199.99" },
];

// Simple hash function to get a consistent index from a string
const simpleHash = (str: string) => {
    let hash = 0;
    for (let i = 0; i < str.length; i++) {
        const char = str.charCodeAt(i);
        hash = (hash << 5) - hash + char;
        hash |= 0; // Convert to 32bit integer
    }
    return Math.abs(hash);
};


export const parseProductUrl = async (url: string): Promise<{ title: string; imageUrl: string; price: string; }> => {
    console.log("Mock parseProductUrl called with:", url);
    // In a real app, this might be a backend call that scrapes the page or calls an API.
    // Here, we simulate it by using the URL to predictably pick from a larger mock database.
    return new Promise(resolve => {
        setTimeout(() => {
            const hash = simpleHash(url);
            const product = mockProductDatabase[hash % mockProductDatabase.length];
            const imageUrl = `https://picsum.photos/seed/${encodeURIComponent(url)}/400/400`;
            
            resolve({ ...product, imageUrl });
        }, 800 + Math.random() * 500); // Simulate network delay
    });
};