/**
 * AuthorBot Chat Widget — widget.js
 * Vanilla JS, zero dependencies.
 * Embeds as a floating chat bubble on any author website.
 *
 * One-line install (recommended):
 *   <script src="https://YOUR-BACKEND/static/widget.js" defer
 *     data-authorbot-token="TOKEN"
 *     data-authorbot-slug="AUTHOR_ID"
 *     data-authorbot-api="https://YOUR-BACKEND/api"
 *     data-authorbot-theme="midnight"
 *     data-authorbot-position="bottom-right"></script>
 */

(function() {
  'use strict';

  if (window.__authorBotMounted) return;

  function readConfig() {
    const script = document.currentScript;
    const fromData = script ? {
      token: script.getAttribute('data-authorbot-token') || '',
      slug: script.getAttribute('data-authorbot-slug') || '',
      apiBase: script.getAttribute('data-authorbot-api') || '',
      theme: script.getAttribute('data-authorbot-theme') || '',
      position: script.getAttribute('data-authorbot-position') || '',
      autoOpenDelay: Number(script.getAttribute('data-authorbot-auto-open') || 0),
    } : {};

    return Object.assign({
      theme: 'midnight',
      position: 'bottom-right',
      autoOpenDelay: 0,
      apiBase: '',
      slug: '',
      token: '',
    }, window.AuthorBotConfig || {}, fromData);
  }

  function mount() {
    if (window.__authorBotMounted) return;
    if (!document.body) return;

    const CONFIG = readConfig();

    if (!CONFIG.token) {
      console.warn('[AuthorBot] No token provided. Widget disabled.');
      return;
    }

    window.__authorBotMounted = true;

    // ── Theme Definitions ──────────────────────────────────────
    const THEMES = {
      midnight: { bg: '#0d0f1a', surface: '#13161f', border: '#ffffff0f', brand: '#6366f1', text: '#e2e8f0', sub: '#94a3b8' },
      ocean:    { bg: '#0a1628', surface: '#0f1e38', border: '#ffffff0f', brand: '#0ea5e9', text: '#e0f2fe', sub: '#7dd3fc' },
      forest:   { bg: '#0a1a0f', surface: '#0f2416', border: '#ffffff0f', brand: '#22c55e', text: '#dcfce7', sub: '#86efac' },
      sunset:   { bg: '#1a0d0a', surface: '#261510', border: '#ffffff0f', brand: '#f97316', text: '#fff7ed', sub: '#fdba74' },
      minimal:  { bg: '#ffffff', surface: '#f8fafc', border: '#e2e8f0',   brand: '#4f46e5', text: '#1e293b', sub: '#64748b' },
    };

    const T = THEMES[CONFIG.theme] || THEMES.midnight;

    // ── State ───────────────────────────────────────────────────
    let sessionId = null;
    let isOpen = false;
    let isLoading = false;
    let selectedBookId = null;
    let books = [];
    let purchaseUrls = {};
    let turnCount = 0;
    let farewellShown = false;

    const POS = CONFIG.position.split('-');
    const vPos = POS[0];
    const hPos = POS[1];

    const style = document.createElement('style');
    style.textContent = `
    #ab-root * { box-sizing: border-box; font-family: -apple-system, 'Inter', BlinkMacSystemFont, sans-serif; }
    #ab-root { position: fixed; ${vPos}: 24px; ${hPos}: 24px; z-index: 2147483647; display: flex; flex-direction: column; align-items: ${hPos === 'right' ? 'flex-end' : 'flex-start'}; gap: 12px; }

    #ab-bubble {
      width: 56px; height: 56px; border-radius: 50%;
      background: linear-gradient(135deg, ${T.brand}, ${T.brand}cc);
      cursor: pointer; display: flex; align-items: center; justify-content: center;
      font-size: 24px; border: none; outline: none;
      box-shadow: 0 4px 20px ${T.brand}55;
      transition: transform 0.25s cubic-bezier(0.34,1.56,0.64,1), box-shadow 0.2s;
      animation: ab-float 4s ease-in-out infinite;
    }
    #ab-bubble:hover { transform: scale(1.1); box-shadow: 0 6px 28px ${T.brand}80; }

    #ab-window {
      width: 370px; max-height: 560px;
      background: ${T.bg}; border: 1px solid ${T.border};
      border-radius: 20px; display: flex; flex-direction: column;
      box-shadow: 0 24px 80px rgba(0,0,0,0.6);
      overflow: hidden;
      transform-origin: ${hPos === 'right' ? 'bottom right' : 'bottom left'};
      transition: transform 0.3s cubic-bezier(0.34,1.56,0.64,1), opacity 0.2s;
    }
    #ab-window.ab-hidden { transform: scale(0.85); opacity: 0; pointer-events: none; }

    #ab-header {
      background: ${T.surface}; padding: 14px 16px;
      border-bottom: 1px solid ${T.border};
      display: flex; align-items: center; gap: 10px; flex-shrink: 0;
    }
    #ab-avatar {
      width: 36px; height: 36px; border-radius: 50%;
      background: linear-gradient(135deg, ${T.brand}, ${T.brand}99);
      display: flex; align-items: center; justify-content: center; font-size: 18px; flex-shrink: 0;
    }
    #ab-bot-name { font-weight: 700; font-size: 14px; color: ${T.text}; }
    #ab-status   { font-size: 11px; color: #22c55e; display: flex; align-items: center; gap: 4px; }
    #ab-status::before { content: ''; width: 6px; height: 6px; border-radius: 50%; background: #22c55e; box-shadow: 0 0 6px #22c55e; }
    #ab-close-btn { margin-left: auto; background: none; border: none; cursor: pointer; color: ${T.sub}; font-size: 18px; line-height: 1; padding: 2px; }

    #ab-messages {
      flex: 1; overflow-y: auto; padding: 16px; display: flex; flex-direction: column; gap: 10px;
      scrollbar-width: thin; scrollbar-color: ${T.border} transparent;
    }

    .ab-msg { display: flex; flex-direction: column; max-width: 85%; animation: ab-slide-up 0.2s ease; }
    .ab-msg.ab-bot { align-self: flex-start; }
    .ab-msg.ab-user { align-self: flex-end; }

    .ab-bubble-text {
      padding: 10px 14px; border-radius: 16px; font-size: 13.5px; line-height: 1.55;
      white-space: pre-wrap; word-break: break-word;
    }
    .ab-bot .ab-bubble-text {
      background: ${T.surface}; border: 1px solid ${T.border}; color: ${T.text};
      border-bottom-left-radius: 4px;
    }
    .ab-user .ab-bubble-text {
      background: ${T.brand}; color: #fff; border-bottom-right-radius: 4px;
    }

    .ab-links { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 6px; }
    .ab-link-btn {
      display: inline-flex; align-items: center; gap: 5px;
      padding: 6px 12px; border-radius: 20px; font-size: 12px; font-weight: 600;
      background: ${T.brand}22; color: ${T.brand}; border: 1px solid ${T.brand}44;
      cursor: pointer; text-decoration: none; transition: all 0.15s;
    }
    .ab-link-btn:hover { background: ${T.brand}; color: #fff; }

    .ab-book-selector { display: flex; flex-direction: column; gap: 6px; margin-top: 4px; }
    .ab-book-btn {
      display: flex; align-items: center; gap: 10px;
      padding: 10px 12px; border-radius: 12px; cursor: pointer;
      background: ${T.surface}; border: 1px solid ${T.border};
      transition: all 0.15s; font-size: 13px; color: ${T.text};
      text-align: left; width: 100%;
    }
    .ab-book-btn:hover { border-color: ${T.brand}; background: ${T.brand}15; }
    .ab-book-btn.ab-selected { border-color: ${T.brand}; background: ${T.brand}15; opacity: 1 !important; }
    .ab-book-btn:disabled { opacity: 0.45; cursor: default; }
    .ab-book-thumb { font-size: 20px; flex-shrink: 0; width: 28px; text-align: center; }
    .ab-book-title { font-weight: 600; font-size: 13px; line-height: 1.3; }
    .ab-book-tagline { font-size: 11px; opacity: 0.75; margin-top: 2px; line-height: 1.35; }

    .ab-typing { display: flex; gap: 4px; padding: 12px 14px; }
    .ab-dot {
      width: 6px; height: 6px; border-radius: 50%;
      background: ${T.sub}; animation: ab-bounce 1.2s ease infinite;
    }
    .ab-dot:nth-child(2) { animation-delay: 0.2s; }
    .ab-dot:nth-child(3) { animation-delay: 0.4s; }

    #ab-input-bar {
      padding: 12px 14px; border-top: 1px solid ${T.border};
      display: flex; gap: 8px; flex-shrink: 0; background: ${T.surface};
    }
    #ab-input {
      flex: 1; background: ${T.bg}; border: 1px solid ${T.border};
      border-radius: 20px; padding: 8px 14px; font-size: 13px; color: ${T.text};
      outline: none; resize: none; font-family: inherit;
      transition: border-color 0.15s;
    }
    #ab-input::placeholder { color: ${T.sub}; }
    #ab-input:focus { border-color: ${T.brand}; }
    #ab-send {
      width: 36px; height: 36px; border-radius: 50%; border: none; cursor: pointer;
      background: linear-gradient(135deg, ${T.brand}, ${T.brand}cc);
      color: #fff; font-size: 16px; display: flex; align-items: center; justify-content: center;
      transition: all 0.2s; flex-shrink: 0; align-self: flex-end;
    }
    #ab-send:hover { transform: scale(1.1); }
    #ab-send:disabled { opacity: 0.4; cursor: not-allowed; transform: none; }

    #ab-branding {
      text-align: center; padding: 6px; font-size: 10px; color: ${T.sub}; opacity: 0.6;
      background: ${T.surface}; border-top: 1px solid ${T.border};
    }

    @keyframes ab-float { 0%,100%{transform:translateY(0)} 50%{transform:translateY(-5px)} }
    @keyframes ab-slide-up { from{opacity:0;transform:translateY(8px)} to{opacity:1;transform:translateY(0)} }
    @keyframes ab-bounce { 0%,100%{transform:translateY(0)} 50%{transform:translateY(-4px)} }
  `;
    (document.head || document.documentElement).appendChild(style);

    const root = document.createElement('div');
    root.id = 'ab-root';
    root.innerHTML = `
    <div id="ab-window" class="ab-hidden">
      <div id="ab-header">
        <div id="ab-avatar">🤖</div>
        <div>
          <div id="ab-bot-name">Book Advisor</div>
          <div id="ab-status">Online</div>
        </div>
        <button id="ab-close-btn" aria-label="Close chat">×</button>
      </div>
      <div id="ab-messages" role="log" aria-live="polite"></div>
      <div id="ab-input-bar">
        <textarea id="ab-input" rows="1" placeholder="Ask me anything about the books..." aria-label="Chat input"></textarea>
        <button id="ab-send" aria-label="Send message">↑</button>
      </div>
      <div id="ab-branding">Powered by AuthorBot</div>
    </div>
    <button id="ab-bubble" aria-label="Open book advisor chat">💬</button>
  `;

    if (vPos === 'bottom') {
      root.style.flexDirection = 'column-reverse';
    }

    document.body.appendChild(root);

    const $window   = root.querySelector('#ab-window');
    const $messages = root.querySelector('#ab-messages');
    const $input    = root.querySelector('#ab-input');
    const $send     = root.querySelector('#ab-send');
    const $bubble   = root.querySelector('#ab-bubble');
    const $close    = root.querySelector('#ab-close-btn');
    const $botName  = root.querySelector('#ab-bot-name');

    function openChat() {
      isOpen = true;
      $window.classList.remove('ab-hidden');
      $bubble.style.display = 'none';
      if (!sessionId) initSession();
      else $input.focus();
    }

    async function showFarewell() {
      farewellShown = true;
      try {
        const res = await apiPost(`/chat/${CONFIG.slug}/session/farewell`, {
          session_id: sessionId,
          selected_book_id: selectedBookId,
        }, { 'X-Subscription-Token': CONFIG.token });
        addBotMessage(res.text, res.links || [], null);
      } catch (e) {
        const title = books.find(b => b.id === selectedBookId)?.title || 'this book';
        const url = purchaseUrls[selectedBookId];
        const links = url ? [{ label: 'Buy Book', url, type: 'purchase', icon: '🛒' }] : [];
        addBotMessage(`Glad we chatted! If ${title} speaks to you, grab your copy below.`, links, null);
      }
      // Keep chat open so the visitor can tap Buy Book; they close with X again
    }

    function closeChat() {
      if (isOpen && farewellShown) {
        isOpen = false;
        $window.classList.add('ab-hidden');
        $bubble.style.display = '';
        return;
      }
      if (isOpen && !farewellShown && sessionId && selectedBookId && turnCount >= 1) {
        showFarewell();
        return;
      }
      isOpen = false;
      $window.classList.add('ab-hidden');
      $bubble.style.display = '';
    }

    $bubble.addEventListener('click', openChat);
    $close.addEventListener('click', closeChat);

    function mapBooks(rawBooks) {
      purchaseUrls = {};
      return (rawBooks || []).map(b => {
        if (b.purchase_url) purchaseUrls[b.id] = b.purchase_url;
        return {
          id: b.id,
          title: b.title,
          tagline: b.tagline || '',
        };
      });
    }

    async function initSession() {
      try {
        const res = await apiPost(`/chat/${CONFIG.slug}/session/init`, {}, { 'X-Subscription-Token': CONFIG.token });
        sessionId = res.session_id;
        books = mapBooks(res.books);
        farewellShown = false;
        $botName.textContent = res.bot_name || 'Book Advisor';
        const welcome = res.welcome_message || `Hello!\n\nSelect a book below to ask about it.`;
        addBotMessage(welcome, [], books.length ? books : null);
        $input.focus();
      } catch (e) {
        addBotMessage("Sorry, I'm having trouble starting. Please refresh and try again.", [], null);
      }
    }

    async function sendMessage() {
      const text = $input.value.trim();
      if (!text || isLoading || !sessionId) return;

      addUserMessage(text);
      $input.value = '';
      resizeInput();

      const typingEl = addTypingIndicator();
      isLoading = true;
      $send.disabled = true;
      turnCount++;

      try {
        const res = await apiPost(`/chat/${CONFIG.slug}`, {
          session_id: sessionId,
          message: text,
          selected_book_id: selectedBookId,
        }, { 'X-Subscription-Token': CONFIG.token });

        typingEl.remove();
        addBotMessage(res.text, res.links || [], mapBooks(res.book_selector));
        if (res.links && res.links.length) {
          res.links.forEach(l => {
            if (l.type === 'purchase' && selectedBookId) purchaseUrls[selectedBookId] = l.url;
          });
        }
      } catch (e) {
        typingEl.remove();
        turnCount = Math.max(0, turnCount - 1);
        addBotMessage(chatErrorMessage(e, "Sorry, something went wrong. Please try again."), [], null);
      } finally {
        isLoading = false;
        $send.disabled = false;
        $input.focus();
      }
    }

    function formatBotText(text) {
      return escHtml(text);
    }

    function addUserMessage(text) {
      const el = document.createElement('div');
      el.className = 'ab-msg ab-user';
      el.innerHTML = `<div class="ab-bubble-text">${formatBotText(text)}</div>`;
      $messages.appendChild(el);
      scrollToBottom();
    }

    function addBotMessage(text, links, bookSelector) {
      const el = document.createElement('div');
      el.className = 'ab-msg ab-bot';

      let html = `<div class="ab-bubble-text">${formatBotText(text)}</div>`;

      if (links && links.length) {
        html += `<div class="ab-links">`;
        links.forEach(l => {
          html += `<a class="ab-link-btn" href="${escAttr(l.url)}" target="_blank" rel="noopener" data-type="${escAttr(l.type)}">${escHtml(l.icon)} ${escHtml(l.label)}</a>`;
        });
        html += `</div>`;
      }

      if (bookSelector && bookSelector.length) {
        html += `<div class="ab-book-selector">`;
        bookSelector.forEach(b => {
          const selected = selectedBookId === b.id;
          html += `<button type="button" class="ab-book-btn${selected ? ' ab-selected' : ''}" data-book-id="${escAttr(b.id)}"${selected ? ' disabled' : ''}>
          <span class="ab-book-thumb">📖</span>
          <div>
            <div class="ab-book-title">${escHtml(b.title)}</div>
            ${b.tagline ? `<div class="ab-book-tagline">${escHtml(b.tagline)}</div>` : ''}
          </div>
        </button>`;
        });
        html += `</div>`;
      }

      el.innerHTML = html;

      el.querySelectorAll('.ab-book-btn').forEach(btn => {
        btn.addEventListener('click', () => selectBook(btn, bookSelector));
      });

      el.querySelectorAll('.ab-link-btn').forEach(a => {
        a.addEventListener('click', () => {
          try {
            apiPost(`/chat/${CONFIG.slug}/track-click`, {
              session_id: sessionId,
              link_type: a.getAttribute('data-type'),
            }, { 'X-Subscription-Token': CONFIG.token }).catch(() => {});
          } catch {}
        });
      });

      $messages.appendChild(el);
      scrollToBottom();
    }

    async function selectBook(btn, bookSelector) {
      if (isLoading || btn.disabled) return;

      const bookId = btn.getAttribute('data-book-id');
      const book = bookSelector.find(b => b.id === bookId);
      if (!book) return;

      selectedBookId = bookId;
      addUserMessage(book.title);

      btn.closest('.ab-book-selector')?.querySelectorAll('.ab-book-btn').forEach(b => {
        b.disabled = true;
        b.style.opacity = '0.45';
      });
      btn.classList.add('ab-selected');
      btn.style.opacity = '1';

      const typingEl = addTypingIndicator();
      isLoading = true;
      $send.disabled = true;

      try {
        const res = await apiPost(`/chat/${CONFIG.slug}`, {
          session_id: sessionId,
          message: book.title,
          selected_book_id: bookId,
        }, { 'X-Subscription-Token': CONFIG.token });
        typingEl.remove();
        addBotMessage(res.text, res.links || [], null);
        turnCount++;
        if (res.links && res.links.length) {
          res.links.forEach(l => {
            if (l.type === 'purchase') purchaseUrls[bookId] = l.url;
          });
        }
      } catch (e) {
        typingEl.remove();
        addBotMessage(chatErrorMessage(e, "Sorry, something went wrong. Please try again."), [], null);
      } finally {
        isLoading = false;
        $send.disabled = false;
        $input.focus();
      }
    }

    function addTypingIndicator() {
      const el = document.createElement('div');
      el.className = 'ab-msg ab-bot';
      el.innerHTML = `<div class="ab-bubble-text ab-typing"><div class="ab-dot"></div><div class="ab-dot"></div><div class="ab-dot"></div></div>`;
      $messages.appendChild(el);
      scrollToBottom();
      return el;
    }

    function resizeInput() {
      $input.style.height = 'auto';
      $input.style.height = Math.min($input.scrollHeight, 100) + 'px';
    }

    $input.addEventListener('input', resizeInput);
    $input.addEventListener('keydown', e => {
      if (e.key === 'Enter' && !e.shiftKey) { e.preventDefault(); sendMessage(); }
    });
    $send.addEventListener('click', sendMessage);

    function scrollToBottom() {
      requestAnimationFrame(() => {
        $messages.scrollTop = $messages.scrollHeight;
      });
    }

    function escHtml(str) {
      return String(str || '').replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;').replace(/"/g,'&quot;').replace(/'/g,'&#39;');
    }

    function escAttr(str) {
      return String(str || '').replace(/"/g, '&quot;');
    }

    async function apiPost(path, body, headers) {
      const base = CONFIG.apiBase || window.location.origin + '/api';
      const res = await fetch(`${base}${path}`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json', ...headers },
        body: JSON.stringify(body),
      });
      if (!res.ok) {
        let detail = '';
        try {
          const err = await res.json();
          detail = err.detail || err.message || '';
        } catch (_) { /* non-JSON body */ }
        const err = new Error(detail || `HTTP ${res.status}`);
        err.status = res.status;
        err.detail = detail;
        throw err;
      }
      return res.json();
    }

    function chatErrorMessage(err, fallback) {
      if (err && err.status === 429) {
        return err.detail || "You're sending messages quickly — take a short break and try again.";
      }
      if (err && err.status === 401) {
        return "This chat session expired. Please refresh the page.";
      }
      if (err && err.status === 413) {
        return "That message is too long. Try asking one question at a time.";
      }
      if (err && err.detail) return err.detail;
      return fallback || "Sorry, something went wrong. Please try again.";
    }

    if (CONFIG.autoOpenDelay > 0) {
      setTimeout(openChat, CONFIG.autoOpenDelay * 1000);
    }

    window.AuthorBot = {
      open: openChat,
      close: closeChat,
      toggle: () => isOpen ? closeChat() : openChat(),
    };
  }

  function boot() {
    if (document.readyState === 'loading') {
      document.addEventListener('DOMContentLoaded', mount);
    } else {
      mount();
    }
  }

  boot();
})();