/**
 * Main Bot Logic Module
 * Initializes Telegraf bot and defines commands/events.
 */

const { Telegraf, Markup } = require('telegraf');
const https = require('https');

// Helper function: Resolve IP via Google DNS-over-HTTPS
// This bypasses local system DNS (UDP:53) which is often blocked on free hosting.
async function resolveDoH(hostname) {
    return new Promise((resolve, reject) => {
        const options = {
            hostname: 'dns.google',
            port: 443,
            path: `/resolve?name=${hostname}&type=A`,
            method: 'GET',
            headers: { 'Accept': 'application/dns-json' }
        };

        const req = https.request(options, (res) => {
            let data = '';
            res.on('data', (chunk) => { data += chunk; });
            res.on('end', () => {
                try {
                    const json = JSON.parse(data);
                    // Check if Answer exists and has data
                    if (json.Answer && json.Answer.length > 0) {
                        // Return the first IP address found
                        console.log(`[DNS-over-HTTPS] Resolved ${hostname} to ${json.Answer[0].data}`);
                        resolve(json.Answer[0].data);
                    } else {
                        reject(new Error('No DNS Answer found'));
                    }
                } catch (e) {
                    reject(e);
                }
            });
        });

        req.on('error', (e) => {
            console.error('[DNS-over-HTTPS] Request failed:', e);
            reject(e);
        });
        req.end();
    });
}


// This function will be called from index.js
function setupBot(token, webAppUrl) {
    if (!token) {
        throw new Error('BOT_TOKEN is missing!');
    }

    const botOptions = {};

    // Only apply this fix in production (on Hugging Face)
    if (process.env.NODE_ENV === 'production') {
        console.log('[Bot] Production mode: Configuring DNS-over-HTTPS agent.');

        const agent = new https.Agent({
            keepAlive: true,
            family: 4,
            lookup: async (hostname, options, callback) => {
                // Only intercept api.telegram.org
                if (hostname === 'api.telegram.org') {
                    try {
                        const ip = await resolveDoH('api.telegram.org');
                        return callback(null, ip, 4);
                    } catch (err) {
                        console.error('[Bot] DoH failed, falling back to system DNS:', err);
                        // Fallback to system DNS if DoH fails (unlikely if outbound HTTPS works)
                        const dns = require('dns');
                        return dns.lookup(hostname, options, callback);
                    }
                }
                // Default behavior for other domains
                const dns = require('dns');
                return dns.lookup(hostname, options, callback);
            }
        });

        botOptions.telegram = { agent };
    }

    // Pass botOptions to Telegraf constructor
    const bot = new Telegraf(token, botOptions);

    // Initial setup for the menu button
    bot.start(async (ctx) => {
        const welcomeMessage = `
    Привет! Я AI Post Generator Bot. 🤖

    Я помогу тебе создавать уникальные посты и изображения.
    Нажми кнопку ниже (или "Меню" -> "Настройки"), чтобы настроить параметры генерации.
        `;

        try {
            await ctx.setChatMenuButton({
                type: 'web_app',
                text: 'Настройки',
                web_app: { url: `${webAppUrl}/app/index.html` }
            });
            console.log('Menu button set for user:', ctx.from.id);
        } catch (e) {
            console.error('Failed to set menu button:', e);
        }

        await ctx.reply(welcomeMessage, Markup.inlineKeyboard([
            Markup.button.webApp('Открыть настройки ⚙️', `${webAppUrl}/app/index.html`)
        ]));
    });

    // Imports for logic
    const { buildStoryPrompt, buildImagePrompt, buildEditPrompt, buildImageRegenerationPrompt } = require('../../prompts/promptBuilder');
    const { generateText } = require('../../services/llmService');
    const { generateImage, regenerateImage } = require('../../services/imageService');
    const { storySystemPrompt } = require('../../prompts/storySystemPrompt');
    const { stylePresets } = require('../../prompts/stylePresets');
    const { getCurrentPreset, getUserSession, updateLastGeneration, updateLastImage, setAwaitingEdit, setAwaitingImageEdit } = require('./userSession');
    const { handleEditCommand, handleEditImageCommand } = require('./actions');

    bot.help((ctx) => ctx.reply('Send /start to open the settings app.'));

    // Command Handlers
    bot.command('edit_story', handleEditCommand);
    bot.command('edit_image', handleEditImageCommand);

    // Text Message Handler
    bot.on('text', async (ctx) => {
        const userMessage = ctx.message.text;

        // Ignore commands
        if (userMessage.startsWith('/')) return;

        try {
            // Show typing status
            await ctx.sendChatAction('typing');

            // 1. Get Settings from session
            const userId = ctx.from.id;
            const session = getUserSession(userId);
            const selectedPreset = getCurrentPreset(userId);

            console.log(`[Bot] Active Preset: ${selectedPreset.preset_name}, Awaiting Edit: ${session.awaitingEdit}, Awaiting Image Edit: ${session.awaitingImageEdit}`);

            // --- 2a. Check for Image Edit State ---
            if (session.awaitingImageEdit && session.lastImage) {
                console.log(`[Bot] Processing IMAGE EDIT request.`);
                const regenPrompt = buildImageRegenerationPrompt(userMessage);

                // Regenerate
                const newBase64 = await regenerateImage(regenPrompt, session.lastImage);

                // Send and Save
                await ctx.replyWithPhoto({ source: Buffer.from(newBase64, 'base64') });
                updateLastImage(userId, newBase64);
                setAwaitingImageEdit(userId, false);
                return; // Stop here, don't generate story
            }

            let currentPrompt = "";

            // 2. Build Prompt based on state (Text Edit)
            if (session.awaitingEdit && session.lastPrompt && session.lastStory) {
                console.log(`[Bot] Processing TEXT EDIT request from user ${userId}`);
                currentPrompt = buildEditPrompt(userMessage, session.lastPrompt, session.lastStory);
            } else {
                currentPrompt = buildStoryPrompt(
                    userMessage,
                    storySystemPrompt,
                    selectedPreset
                );
            }

            // 3. Call LLM Service for Story
            let responseText = await generateText(currentPrompt);

            // --- Tags Logic ---
            const userTagsString = session.tags || "";
            // Split user tags by space/newline, filter empty, ensure they start with #
            const userTagsArray = userTagsString.split(/[\s\n]+/).filter(t => t.startsWith('#'));

            // Regex to capture hashtags at the end of the text
            const tagRegex = /((?:#[\w\u0590-\u05ff]+(?:\s+|$))+)$/u;

            let storyText = responseText.trim();
            const llmTagsArray = [];

            const match = storyText.match(tagRegex);
            if (match) {
                const tagsPart = match[1];
                storyText = storyText.substring(0, storyText.length - tagsPart.length).trim();
                const extracted = tagsPart.match(/#[\w\u0590-\u05ff]+/gu);
                if (extracted) {
                    llmTagsArray.push(...extracted);
                }
            }

            // Merge unique tags
            const allTags = [...new Set([...llmTagsArray, ...userTagsArray])];

            // Format: Story text + double newline + all tags in one line
            const finalMessage = `${storyText}\n\n${allTags.join(' ')}`;

            // 4. Send Story Response to user
            await ctx.reply(finalMessage);

            // --- Save History and Reset State ---
            updateLastGeneration(userId, currentPrompt, storyText);
            setAwaitingEdit(userId, false);


            // 5. Generate Image Prompt based on the Story
            await ctx.sendChatAction('upload_photo');

            // Keep "upload_photo" status alive
            const statusInterval = setInterval(() => {
                ctx.sendChatAction('upload_photo').catch(e => console.error('[Bot] Action error:', e));
            }, 4000);

            try {
                // If this was an edit, we might want to regenerate image for the new story OR just keep it.
                // Current workflow: Always generate new image for new story/edited story.

                // If it's a Text Edit, we probably want a new image too? 
                // Let's assume yes for now, or we can make it optional. 
                // The user requested to uncomment the block, implying we want images back.

                const imagePromptLayout = buildImagePrompt(
                    responseText,
                    selectedPreset.image_style_suffix
                );

                // Get refined prompt from LLM
                const refinedImagePrompt = await generateText(imagePromptLayout);
                console.log('[Bot] Refined Image Prompt:', refinedImagePrompt);

                // 6. Generate Image
                const base64Image = await generateImage(refinedImagePrompt);

                // 7. Send Photo
                await ctx.replyWithPhoto({ source: Buffer.from(base64Image, 'base64') });

                // Save for future edits
                updateLastImage(userId, base64Image);

            } finally {
                clearInterval(statusInterval);
            }


        } catch (error) {
            console.error('Error handling message:', error);
            await ctx.reply('Произошла ошибка при генерации ответа. Попробуйте позже.');
        }
    });

    return bot;
}

module.exports = { setupBot };