const fs = require('fs');
const path = require('path');
const axios = require('axios');
const config = require('../config');
const { query } = require('../config/db');
const localGen = require('./localCoverGenerator');
const aiUsage = require('./aiUsage');

const UPLOADS_DIR = process.env.UPLOADS_DIR || '/var/www/zeropost-uploads';

// Опциональная оптимизация — если sharp есть, конвертим в WebP
let sharp = null;
try { sharp = require('sharp'); } catch {}

if (!fs.existsSync(UPLOADS_DIR)) {
  fs.mkdirSync(UPLOADS_DIR, { recursive: true });
}

/**
 * 6 визуальных стилей обложек.
 * Выбор детерминированный по articleId — одна статья всегда получает
 * один стиль при регенерации, но разные статьи выглядят по-разному.
 */
const COVER_STYLES = [
  {
    name: 'emerald-flow',
    palette: 'emerald green (#10b981, #34d399) as primary, soft teal, warm off-white background (#fafaf9), subtle dark accents',
    style: 'flat geometric shapes, smooth flowing curves, layered planes, vector-clean lines',
    mood: 'clean, modern, calm, intellectual — Stripe Press / Linear / Anthropic brand aesthetic',
    composition: 'balanced asymmetry, flowing diagonal forms, generous negative space',
  },
  {
    name: 'midnight-blueprint',
    palette: 'deep navy (#0f172a, #1e3a5f) as background, electric blue (#3b82f6, #60a5fa) as accent, crisp white details, subtle cyan highlights',
    style: 'precise isometric geometry, technical grid lines, architectural cross-sections, blueprint-inspired forms',
    mood: 'focused, technical, precise, trustworthy — like a well-engineered system',
    composition: 'structured grid layout, strong geometric hierarchy, tight angular forms',
  },
  {
    name: 'amber-terrain',
    palette: 'warm amber (#f59e0b, #fbbf24) as primary, burnt sienna (#c2410c), cream (#fef3c7) background, deep brown accents',
    style: 'organic flowing shapes, topographic contour lines, layered paper-cut planes, earthy textures',
    mood: 'warm, grounded, thoughtful, human — like physical craftsmanship',
    composition: 'layered depth with overlapping organic planes, horizon-inspired layout',
  },
  {
    name: 'violet-gradient',
    palette: 'deep purple (#7c3aed, #6d28d9) transitioning to lavender (#c4b5fd), pale rose (#fce7f3) background, soft white highlights',
    style: 'smooth gradient fields, soft abstract blobs, gentle radial forms, dreamy overlapping circles',
    mood: 'creative, forward-thinking, imaginative, innovative',
    composition: 'radial soft composition, overlapping translucent shapes, dreamy depth',
  },
  {
    name: 'monochrome-sharp',
    palette: 'near-black (#111827) and pure white (#ffffff) as primary, single bold vivid red (#ef4444) accent used sparingly on one element only',
    style: 'bold stark geometry, high contrast hard edges, strong typographic-inspired forms, Swiss design influence',
    mood: 'bold, editorial, authoritative, direct — like a magazine cover',
    composition: 'strong visual tension, deliberate asymmetry, dominant single focal element',
  },
  {
    name: 'coral-horizon',
    palette: 'coral (#f97316, #fb923c) as primary, dusty rose (#fda4af), soft warm grey (#e5e7eb) background, muted sage green accents',
    style: 'rounded soft shapes, gentle gradient washes, warm abstract landscape forms, approachable curves',
    mood: 'warm, accessible, optimistic, friendly — welcoming and human',
    composition: 'wide horizon-like bands, soft rounded forms, gentle layered gradients',
  },
];

/**
 * Детерминированный хэш articleId → индекс стиля.
 */
function pickStyleIndex(articleId) {
  let hash = 0;
  const s = String(articleId);
  for (let i = 0; i < s.length; i++) {
    hash = (hash * 31 + s.charCodeAt(i)) >>> 0;
  }
  return hash % COVER_STYLES.length;
}

/**
 * Промпт для обложки — стиль выбирается по articleId, содержание по теме статьи.
 */
/**
 * Промпт для обложки.
 * Приоритет: rubric.prompt → channelStyle.image_style → COVER_STYLES rotation.
 * Рубрика полностью задаёт визуальный язык — ограничения внутри неё.
 */
function buildCoverPrompt({ title, tags = [], articleId = 0, channelStyle = null, rubric = null }) {
  const subject = title.replace(/[«»\\\":?!.]/g, '').slice(0, 100);
  const tagHint = tags.slice(0, 2).join(', ');

  // Если рубрика выбрана — она задаёт весь визуальный язык
  if (rubric?.prompt) {
    return `${rubric.prompt}

Article subject: "${subject}".${tagHint ? ` Theme: ${tagHint}.` : ''}
Wide 16:9 format. No text, no letters, no logos, no identifiable real human faces.`;
  }

  let styleDesc, paletteDesc, moodDesc, compositionDesc;

  // Если задано несколько стилей через запятую — берём случайный из них
  const rawStyle = channelStyle?.image_style || '';
  const styleList = rawStyle.split(',').map(s => s.trim()).filter(s => s && s !== 'auto');
  const csStyle = styleList.length > 0
    ? styleList[Math.floor(Math.random() * styleList.length)]
    : null;
  const STYLE_MAP = {
    'realistic-photo': { style: 'photorealistic, high-quality photography, natural lighting, sharp focus, realistic textures', mood: 'professional, realistic', comp: 'rule of thirds, natural depth of field' },
    'flat-illustration': { style: 'flat vector illustration, clean geometric shapes, modern editorial style, smooth gradients, minimal', mood: 'clean, modern', comp: 'balanced, centered focal point' },
    '3d-render': { style: '3D render, soft studio lighting, isometric perspective, smooth surfaces, modern materials, Blender-quality', mood: 'polished, technical, premium', comp: 'three-quarter view, dramatic lighting' },
    'cartoon': { style: 'cartoon illustration, bold outlines, vibrant colors, expressive shapes, comic book style', mood: 'playful, energetic', comp: 'dynamic, high contrast' },
    'minimal': { style: 'extremely minimalist, single focal element, generous negative space, monochrome or duotone', mood: 'calm, sophisticated, editorial', comp: 'single centered element, maximum negative space' },
    'abstract': { style: 'abstract artwork, layered geometric shapes, conceptual composition, mood and texture focused', mood: 'creative, sophisticated, tech-forward', comp: 'asymmetric layers, visual tension' },
    'sketch': { style: 'hand-drawn sketch style, pencil and ink, loose confident lines, editorial illustration', mood: 'authentic, crafted, organic', comp: 'dynamic gestural lines, sketch book aesthetic' },
    'cyberpunk': { style: 'cyberpunk aesthetic, neon glowing lights, futuristic dark atmosphere, Blade Runner vibe', mood: 'bold, futuristic, dark', comp: 'dramatic angles, foreground/background depth' },
  };

  if (csStyle && csStyle !== 'auto' && STYLE_MAP[csStyle]) {
    const s = STYLE_MAP[csStyle];
    styleDesc = s.style; moodDesc = s.mood; compositionDesc = s.comp + '. Wide 16:9 format.';
    paletteDesc = null;
  } else {
    const s = COVER_STYLES[pickStyleIndex(articleId)];
    styleDesc = s.style; paletteDesc = s.palette; moodDesc = s.mood; compositionDesc = s.composition + '. Wide 16:9 format.';
  }

  if (channelStyle?.image_custom_colors) {
    paletteDesc = `custom brand palette: ${channelStyle.image_custom_colors}`;
  } else if (channelStyle?.image_palette && channelStyle.image_palette !== 'auto') {
    const PALETTES = { dark: 'dark palette, deep blues and blacks, bright highlights', light: 'light palette, soft whites, pastels', warm: 'warm palette, oranges, reds, gold', cool: 'cool palette, blues, teals, purples', mono: 'monochromatic, single hue with shades', vibrant: 'vibrant saturated colors, high energy' };
    paletteDesc = PALETTES[channelStyle.image_palette] || null;
  }

  return `Abstract editorial cover illustration for an article titled "${subject}".

Style: ${styleDesc}.
${paletteDesc ? `Color palette: ${paletteDesc}.` : ''}
Mood: ${moodDesc}.
Composition: ${compositionDesc}
${tagHint ? `Theme cues (subtle, abstract): ${tagHint}.` : ''}
${channelStyle?.image_prompt_instructions ? `\nChannel visual guidelines: ${channelStyle.image_prompt_instructions}` : ''}

Strictly: no text, no letters, no logos, no identifiable real human faces.`;
}

/**
 * Генерирует картинку через /v1/responses + image_generation tool на GPT-5.
 * Это работает даже когда /v1/images/generations отдаёт unavailable.
 */
async function generateCoverViaResponses({ prompt }) {
  const model = config.ai.imageModelViaResponses || 'gpt-5.2';
  // GPT-5 иногда не вызывает инструмент сама — даём явную инструкцию
  const wrappedInput = `Use the image_generation tool to create the following illustration. Do not write any text response, only call the tool.\n\n${prompt}`;

  const started = Date.now();
  let res;
  try {
    res = await axios.post(
      `${config.ai.baseUrl}/responses`,
      {
        model,
        input: wrappedInput,
        tools: [{ type: 'image_generation' }],
        tool_choice: { type: 'image_generation' },
      },
      {
        headers: { Authorization: `Bearer ${config.ai.apiKey}` },
        timeout: 300_000, // GPT-5 reasoning + image — медленно, до 5 минут
      }
    );
  } catch (err) {
    aiUsage.log({
      provider: aiUsage.providerFromBaseUrl(config.ai.baseUrl),
      requestType: 'image_via_responses',
      model, imageCount: 1,
      durationMs: Date.now() - started, succeeded: false,
      errorMessage: (err.response?.data?.error?.message || err.message || '').slice(0, 500),
    }).catch(() => {});
    throw err;
  }

  const output = res.data?.output || [];
  const imgCall = output.find(o => o.type === 'image_generation_call');
  if (!imgCall) {
    aiUsage.log({
      provider: aiUsage.providerFromBaseUrl(config.ai.baseUrl),
      requestType: 'image_via_responses', model, imageCount: 1,
      durationMs: Date.now() - started, succeeded: false,
      errorMessage: 'No image_generation_call in response output',
    }).catch(() => {});
    throw new Error('No image_generation_call in response output');
  }
  if (!imgCall.result) {
    aiUsage.log({
      provider: aiUsage.providerFromBaseUrl(config.ai.baseUrl),
      requestType: 'image_via_responses', model, imageCount: 1,
      durationMs: Date.now() - started, succeeded: false,
      errorMessage: `image_generation_call without result, status=${imgCall.status}`,
    }).catch(() => {});
    throw new Error(`image_generation_call without result, status=${imgCall.status}`);
  }

  aiUsage.log({
    provider: aiUsage.providerFromBaseUrl(config.ai.baseUrl),
    requestType: 'image_via_responses', model, imageCount: 1,
    requestId: res.data?.id,
    durationMs: Date.now() - started, succeeded: true,
  }).catch(() => {});

  const bytes = Buffer.from(imgCall.result, 'base64');
  return {
    bytes,
    format: imgCall.output_format || 'png',
    size: imgCall.size,
    revisedPrompt: imgCall.revised_prompt,
  };
}

/**
 * Старый путь — на случай если шлюз внезапно починят и захотим вернуться.
 */
async function generateCoverViaImagesEndpoint({ prompt }) {
  const model = config.ai.models?.image || 'gpt-image-1';
  const started = Date.now();
  let res;
  try {
    res = await axios.post(
      `${config.ai.baseUrl}/images/generations`,
      { model, prompt, n: 1, size: '1536x1024' },
      {
        headers: { Authorization: `Bearer ${config.ai.apiKey}` },
        timeout: 120_000,
      }
    );
  } catch (err) {
    aiUsage.log({
      provider: aiUsage.providerFromBaseUrl(config.ai.baseUrl),
      requestType: 'image', model, imageCount: 1,
      durationMs: Date.now() - started, succeeded: false,
      errorMessage: (err.response?.data?.error?.message || err.message || '').slice(0, 500),
    }).catch(() => {});
    throw err;
  }
  const item = res.data?.data?.[0];
  if (!item) {
    aiUsage.log({
      provider: aiUsage.providerFromBaseUrl(config.ai.baseUrl),
      requestType: 'image', model, imageCount: 1,
      durationMs: Date.now() - started, succeeded: false,
      errorMessage: 'Empty image response',
    }).catch(() => {});
    throw new Error('Empty image response');
  }
  aiUsage.log({
    provider: aiUsage.providerFromBaseUrl(config.ai.baseUrl),
    requestType: 'image', model, imageCount: 1,
    durationMs: Date.now() - started, succeeded: true,
  }).catch(() => {});
  if (item.b64_json) return { bytes: Buffer.from(item.b64_json, 'base64'), format: 'png' };
  if (item.url) {
    const r = await axios.get(item.url, { responseType: 'arraybuffer', timeout: 60_000 });
    return { bytes: Buffer.from(r.data), format: 'png' };
  }
  throw new Error('No image data');
}

/**
 * Основной путь — /images/generations (aiguoguo199.com или любой OpenAI-совместимый).
 * Более стабильный чем /responses, поддерживает gpt-image-1-mini/gpt-image-2.
 */
/**
 * RouterAI — стабильный провайдер через /responses + image_generation tool.
 * Используется как третий fallback когда aiguoguo и Nyxos недоступны.
 */
async function generateCoverViaRouterAI({ prompt }) {
  const base  = config.ai.routeraiBaseUrl;
  const key   = config.ai.routeraiApiKey;
  const model = config.ai.routeraiImageModel || 'openai/gpt-5-image-mini';
  const started = Date.now();
  try {
    const res = await axios.post(`${base}/responses`, {
      model,
      input: `Use the image_generation tool to create this illustration. Only call the tool, no text.\n\n${prompt.slice(0, 3000)}`,
      tools: [{ type: 'image_generation' }],
      tool_choice: { type: 'image_generation' },
    }, {
      headers: { Authorization: `Bearer ${key}` },
      timeout: 120_000,
    });
    const imgCall = (res.data?.output || []).find(o => o.type === 'image_generation_call');
    if (!imgCall?.result) throw new Error('No image in RouterAI response');
    aiUsage.log({ provider: 'routerai', requestType: 'image_via_responses', model, imageCount: 1, durationMs: Date.now()-started, succeeded: true }).catch(() => {});
    return { bytes: Buffer.from(imgCall.result, 'base64'), format: imgCall.output_format || 'png' };
  } catch (err) {
    aiUsage.log({ provider: 'routerai', requestType: 'image_via_responses', model, imageCount: 1, durationMs: Date.now()-started, succeeded: false, errorMessage: (err.response?.data?.error?.message || err.message || '').slice(0,500) }).catch(() => {});
    throw err;
  }
}

async function generateCoverViaImageGenerations({ prompt }) {
  const model = config.ai.imageModel || 'gpt-image-2';

  async function tryProvider(baseUrl, apiKey) {
    const started = Date.now();
    try {
      const res = await axios.post(
        `${baseUrl}/images/generations`,
        { model, prompt: prompt.slice(0, 4000), n: 1, size: '1024x1024', response_format: 'url' },
        { headers: { Authorization: `Bearer ${apiKey}` }, timeout: 45_000 }
      );
      const item = res.data?.data?.[0];
      if (!item) throw new Error('No image data in response');
      aiUsage.log({ provider: aiUsage.providerFromBaseUrl(baseUrl), requestType: 'image', model, imageCount: 1, durationMs: Date.now()-started, succeeded: true }).catch(() => {});
      if (item.url) {
        const r = await axios.get(item.url, { responseType: 'arraybuffer', timeout: 60_000 });
        return { bytes: Buffer.from(r.data), format: 'png' };
      }
      if (item.b64_json) return { bytes: Buffer.from(item.b64_json, 'base64'), format: 'png' };
      throw new Error('No url or b64_json in response');
    } catch (err) {
      aiUsage.log({ provider: aiUsage.providerFromBaseUrl(baseUrl), requestType: 'image', model, imageCount: 1, durationMs: Date.now()-started, succeeded: false, errorMessage: (err.response?.data?.error?.message || err.message || '').slice(0, 500) }).catch(() => {});
      throw err;
    }
  }

  // Основной: RouterAI /responses (стабильный)
  try {
    return await generateCoverViaRouterAI({ prompt });
  } catch (err) {
    const status = err.response?.status;
    if (!status || status >= 500) {
      console.warn(`[Cover] RouterAI failed (${status||'timeout'}), trying Nyxos fallback...`);
      return await tryProvider(config.ai.imageFallbackBaseUrl, config.ai.imageFallbackApiKey);
    }
    throw err;
  }
}

/**
 * Резервный путь — Pollinations.AI (https://pollinations.ai).
 * 100% бесплатно, без API ключа, без регистрации.
 * GET запрос → JPEG обложка за ~1-2 секунды.
 * Используется только когда aiprimetech.io недоступен.
 */
async function generateCoverViaPollinations({ prompt }) {
  // Pollinations: простой GET по URL, сразу возвращает бинарный JPEG
  const encoded = encodeURIComponent(prompt.slice(0, 1000)); // лимит на длину URL
  const url = `https://image.pollinations.ai/prompt/${encoded}?width=1600&height=900&model=flux&nologo=true`;
  const res = await axios.get(url, {
    responseType: 'arraybuffer',
    timeout: 90_000, // Pollinations иногда медленный при нагрузке
    headers: { 'User-Agent': 'ZeroPost/1.0 blog-cover-generator' },
  });
  if (!res.data || res.data.byteLength < 5000) {
    throw new Error(`Pollinations returned too small response: ${res.data?.byteLength} bytes`);
  }
  return {
    bytes: Buffer.from(res.data),
    format: 'jpg',
  };
}

/**
 * Главный путь генерации. Использует /v1/responses, при ошибке падает в legacy.
 */

/**
 * Выбирает наиболее подходящую рубрику для обложки статьи.
 * Дешёвый haiku-вызов: ~50 токенов. При ошибке — случайная рубрика.
 */
async function selectRubric({ title, tags = [], rubrics }) {
  if (!rubrics || rubrics.length === 0) return null;
  if (rubrics.length === 1) return rubrics[0];

  const rubricList = rubrics.map((r, i) => `${i}. ${r.id}: ${r.desc}`).join('\n');
  const userMsg = `Article title: "${title}"\nTags: ${tags.join(', ') || 'none'}\n\nRubrics:\n${rubricList}\n\nRespond with ONLY the index number (0-${rubrics.length - 1}) of the best matching rubric.`;

  try {
    const res = await axios.post(
      `${config.ai.baseUrl}/chat/completions`,
      {
        model: config.ai.models.post || 'claude-haiku-4-5-20251001',
        max_tokens: 5,
        temperature: 0,
        messages: [
          { role: 'system', content: 'You select a visual style for article cover images. Reply with only a single digit index number.' },
          { role: 'user', content: userMsg },
        ],
      },
      { headers: { Authorization: `Bearer ${config.ai.apiKey}` }, timeout: 10000 }
    );
    const raw = res.data?.choices?.[0]?.message?.content?.trim() || '0';
    const idx = parseInt(raw.replace(/\D/g, '')) || 0;
    const safeIdx = Math.min(Math.max(idx, 0), rubrics.length - 1);
    return rubrics[safeIdx];
  } catch (err) {
    console.warn('[Cover] selectRubric failed, using random:', err.message.slice(0, 80));
    return rubrics[Math.floor(Math.random() * rubrics.length)];
  }
}

async function generateCover({ articleId, title, tags = [], channelId = null }) {
  // Подгружаем настройки канала включая рубрики
  let channelStyle = null;
  if (channelId) {
    try {
      const r = await query('SELECT image_style, image_palette, image_custom_colors, image_prompt_instructions, image_rubrics FROM channel_style WHERE channel_id = $1', [channelId]);
      channelStyle = r.rows[0] || null;
    } catch (err) {
      console.warn('[Cover] channel_style load failed, using defaults:', err.message);
    }
  }

  // Выбираем рубрику если они заданы
  let selectedRubric = null;
  let styleName;
  const rubrics = channelStyle?.image_rubrics;
  if (Array.isArray(rubrics) && rubrics.length > 0) {
    selectedRubric = await selectRubric({ title, tags, rubrics });
    styleName = selectedRubric?.id || 'rubric';
    console.log(`[Cover] article=${articleId} channel=${channelId} rubric=${styleName}`);
  } else {
    const styleIdx = pickStyleIndex(articleId);
    styleName = channelStyle?.image_style || COVER_STYLES[styleIdx].name;
    console.log(`[Cover] article=${articleId} channel=${channelId || 'none'} style=${styleName}`);
  }

  const prompt = buildCoverPrompt({ title, tags, articleId, channelStyle, rubric: selectedRubric });

  let img;
  let usedPath = 'images-generations';

  // Цепочка: 1) aiguoguo /images/generations (2 попытки) → 2) aiprimetech /responses → 3) legacy → 4) local SVG
  try {
    try {
      try {
        img = await generateCoverViaImageGenerations({ prompt });
      } catch (err) {
        // Ретрай только при временных ошибках провайдера (5xx)
        const status = err.response?.status;
        if (status >= 500 && status < 600) {
          console.warn(`[Cover] /images/generations ${status} — retry in 12s...`);
          await new Promise(r => setTimeout(r, 12000));
          img = await generateCoverViaImageGenerations({ prompt });
        } else {
          throw err;
        }
      }
    } catch (err) {
      console.warn(`[Cover] /images/generations failed: ${(err.response?.data?.error?.message || err.message).slice(0, 150)}`);
      try {
        img = await generateCoverViaResponses({ prompt });
        usedPath = 'responses';
      } catch (err2) {
        console.warn(`[Cover] /responses failed: ${(err2.response?.data?.error?.message || err2.message).slice(0, 150)}`);
        try {
          img = await generateCoverViaImagesEndpoint({ prompt });
          usedPath = 'images-legacy';
        } catch (err3) {
          console.warn(`[Cover] legacy failed: ${(err3.response?.data?.error?.message || err3.message).slice(0, 150)}`);
          throw new Error('all_external_failed');
        }
      }
    }
  } catch (outerErr) {
    // Все внешние API упали — local SVG
    console.log(`[Cover] article=${articleId} → local SVG (all external APIs unavailable)`);
    const localUrl = await localGen.generateLocalCover({ articleId, title, category: tags?.[0] || '' });
    await query('UPDATE articles SET cover_url=$1, updated_at=NOW() WHERE id=$2', [localUrl, articleId]);
    return localUrl;
  }

  // Сохраняем оригинал
  const tsKey = `${articleId}-${Date.now()}`;
  const ext = img.format || 'png';
  const originalName = `cover-${tsKey}.${ext}`;
  const originalPath = path.join(UPLOADS_DIR, originalName);
  fs.writeFileSync(originalPath, img.bytes);

  // Оптимизация — если sharp есть, делаем WebP в подходящем размере
  let publicUrl = `/uploads/${originalName}`;
  let optimizedSize = null;
  if (sharp) {
    try {
      const webpName = `cover-${tsKey}.webp`;
      const webpPath = path.join(UPLOADS_DIR, webpName);
      await sharp(img.bytes)
        .resize(1600, null, { withoutEnlargement: true })
        .webp({ quality: 84 })
        .toFile(webpPath);
      const stat = fs.statSync(webpPath);
      optimizedSize = stat.size;
      publicUrl = `/uploads/${webpName}`;
    } catch (e) {
      console.warn(`[Cover] sharp optimization skipped: ${e.message}`);
    }
  }

  await query(`UPDATE articles SET cover_url=$1, updated_at=NOW() WHERE id=$2`, [publicUrl, articleId]);

  console.log(`[Cover] saved ${publicUrl} via ${usedPath} style=${styleName} (${(img.bytes.length / 1024).toFixed(0)}KB original, ${optimizedSize ? (optimizedSize / 1024).toFixed(0) + 'KB optimized' : 'no opt'})`);
  return publicUrl;
}

/**
 * Дофоновая попытка сгенерировать обложки для статей без cover_url.
 */
async function backfillCovers({ limit = 3 } = {}) {
  const { rows } = await query(
    `SELECT id, title, tags FROM articles
     WHERE cover_url IS NULL AND status='published'
     ORDER BY published_at DESC LIMIT $1`,
    [limit]
  );
  let ok = 0, fail = 0;
  const results = [];
  for (const a of rows) {
    try {
      const url = await generateCover({ articleId: a.id, title: a.title, tags: a.tags || [] });
      ok++;
      results.push({ id: a.id, status: 'ok', url });
    } catch (err) {
      fail++;
      results.push({ id: a.id, status: 'fail', error: err.message.slice(0, 150) });
    }
  }
  return { processed: rows.length, ok, fail, results };
}

module.exports = { generateCover, backfillCovers, buildCoverPrompt, pickStyleIndex, COVER_STYLES, UPLOADS_DIR };