/*
 * Content script (classic script, single file).
 *
 * Sections:
 *   1. constants (mirrored from src/shared/constants.js - keep in sync,
 *      enforced by unit tests)
 *   2. selection controller
 *   3. action button (Shadow DOM)
 *   4. translation popover (Shadow DOM, state machine)
 *   5. port client (runtime.Port to background)
 *   6. entry point
 *
 * Security rules (Security.md):
 *   - never call Ollama directly;
 *   - all dynamic text is rendered with textContent;
 *   - no eval / new Function / remote code.
 */
(() => {
  'use strict';

  // ---------------------------------------------------------------------
  // 1. Constants (mirrored from src/shared/constants.js)
  // ---------------------------------------------------------------------

  const PORT_NAME = 'translation-stream';
  const MAX_SELECTION_LENGTH = 20000;
  const ERROR_CODES = {
    INVALID_REQUEST: 'INVALID_REQUEST',
    TEXT_EMPTY: 'TEXT_EMPTY',
    TEXT_TOO_LONG: 'TEXT_TOO_LONG',
    OLLAMA_UNAVAILABLE: 'OLLAMA_UNAVAILABLE',
    MODEL_NOT_FOUND: 'MODEL_NOT_FOUND',
    INVALID_SETTINGS: 'INVALID_SETTINGS',
    REQUEST_ABORTED: 'REQUEST_ABORTED',
    STREAM_ERROR: 'STREAM_ERROR',
    UNKNOWN_ERROR: 'UNKNOWN_ERROR'
  };
  const CONTENT_TO_BG = { TRANSLATE: 'translate', CANCEL: 'cancel' };
  const BG_TO_CONTENT = { STARTED: 'started', CHUNK: 'chunk', COMPLETED: 'completed', ERROR: 'error' };

  const POPOVER_STATES = {
    HIDDEN: 'HIDDEN',
    LOADING: 'LOADING',
    STREAMING: 'STREAMING',
    COMPLETED: 'COMPLETED',
    ERROR: 'ERROR'
  };

  // ---------------------------------------------------------------------
  // State
  // ---------------------------------------------------------------------

  /** @type {boolean} */
  let enabled = true;
  /** @type {DOMRect|null} rect of the latest stable selection */
  let currentSelectionRect = null;
  /** @type {string|null} id of the request the popover currently shows */
  let activeRequestId = null;

  // ---------------------------------------------------------------------
  // 2. Selection controller
  // ---------------------------------------------------------------------

  /**
   * Read the current selection. Returns null when there is nothing to show.
   * Top-level document only (SEL-05).
   * @returns {{text: string, rect: DOMRect}|null}
   */
  function readSelection() {
    const selection = window.getSelection();
    if (!selection || selection.rangeCount === 0 || selection.isCollapsed) {
      return null;
    }
    const text = selection.toString().trim();
    if (!text) return null;
    if (text.length > MAX_SELECTION_LENGTH) return null;
    const range = selection.getRangeAt(0);
    const rect = range.getBoundingClientRect();
    if (!rect || (rect.width === 0 && rect.height === 0)) return null;
    return { text, rect };
  }

  /**
   * Debounce helper.
   * @param {Function} fn
   * @param {number} wait ms
   */
  function debounce(fn, wait) {
    let timer = 0;
    return (...args) => {
      window.clearTimeout(timer);
      timer = window.setTimeout(() => fn(...args), wait);
    };
  }

  const scheduleUpdate = debounce(() => {
    const selection = readSelection();
    if (selection) {
      currentSelectionRect = selection.rect;
      actionButton.show(selection.rect);
      if (popover.isVisible()) {
        // Follow the newest selection rect while visible (ACT-05).
        popover.repositionTo(selection.rect);
      }
    } else {
      currentSelectionRect = null;
      actionButton.hide();
      // Selection cleared: hide the popover too (SEL-03), cancelling any
      // in-flight request.
      if (popover.isVisible()) {
        popover.close();
      }
    }
  }, 150);

  function onSelectionEvent() {
    if (!enabled) return;
    scheduleUpdate();
  }

  // ---------------------------------------------------------------------
  // 3. Action button (Shadow DOM)
  // ---------------------------------------------------------------------

  const actionButton = (() => {
    let host = null;
    let shadow = null;
    let wrap = null;
    let button = null;

    function ensureDom() {
      if (host) return;
      host = document.createElement('div');
      host.id = 'ollama-translations-action-host';
      host.className = 'ollama-translations-host';
      document.documentElement.appendChild(host);
      shadow = host.attachShadow({ mode: 'open' });

      const style = document.createElement('style');
      style.textContent = `
        :host { all: initial; display: block; }
        .wrap {
          position: fixed;
          z-index: 2147483647;
          display: none;
          width: 28px;
          height: 28px;
        }
        /* The clickable element is the SVG itself with explicit width/height
           attributes. A <button> wrapper with flex centering renders as a
           collapsed bar in some Firefox versions, so we avoid it here. */
        .btn {
          display: block;
          border-radius: 50%;
          background: #ffffff;
          box-shadow: 0 1px 4px rgba(0,0,0,.35);
          cursor: pointer;
          padding: 2px;
        }
        .btn:hover { background: #eef3ff; }
      `;
      shadow.append(style);

      button = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
      button.setAttribute('role', 'button');
      button.setAttribute('tabindex', '0');
      button.setAttribute('title', '選択範囲を翻訳');
      // Explicit width/height attributes: CSS-only sizing of SVG in a shadow
      // root collapsed to a thin bar in the user's Firefox.
      button.setAttribute('width', '28');
      button.setAttribute('height', '28');
      button.setAttribute('aria-label', '選択範囲を翻訳');
      button.setAttribute('class', 'btn');
      button.setAttribute('viewBox', '0 0 24 24');
      button.setAttribute('aria-hidden', 'false');

      // White circle background so the glyph reads on dark pages.
      const circle = document.createElementNS('http://www.w3.org/2000/svg', 'circle');
      circle.setAttribute('cx', '12');
      circle.setAttribute('cy', '12');
      circle.setAttribute('r', '11');
      circle.setAttribute('fill', '#ffffff');
      circle.setAttribute('stroke', 'rgba(0,0,0,.25)');
      circle.setAttribute('stroke-width', '1');
      button.append(circle);

      // Project-owned inline SVG (no external resources).
      const path = document.createElementNS('http://www.w3.org/2000/svg', 'path');
      path.setAttribute(
        'd',
        'M12.87 15.07 10.33 12.56 10.36 12.53C12.1 10.59 13.27 8.36 13.93 6.26H16V4.26H9V2.26H7V4.26H0V6.24H12.17 ' +
          'C11.5 8 10.44 9.65 9 11.16 8.07 10.18 7.3 9.11 6.69 8H4.69C5.42 9.63 6.42 11.16 7.67 12.53L2.63 17.54 4.05 ' +
          '18.96 9.5 13.51 12.87 15.07M17.5 10H15.5L11 22H13L14.12 19H18.88L20 22H22L17.5 10M14.88 17 16.5 12.66 18.12 ' +
          '17H14.88Z'
      );
      path.setAttribute('fill', '#1a73e8');
      button.append(path);

      button.addEventListener('click', (event) => {
        event.preventDefault();
        event.stopPropagation();
        onTranslateClicked();
      });

      wrap = document.createElement('div');
      wrap.className = 'wrap';
      wrap.append(button);
      shadow.append(wrap);
    }

    /**
     * Show the button near the selection rect.
     * @param {DOMRect} rect
     */
    function show(rect) {
      if (!enabled) return;
      ensureDom();
      const margin = 6;
      const size = 28;
      let left = rect.right + margin;
      let top = rect.top;
      if (left + size > window.innerWidth - 4) left = rect.left - size - margin;
      if (left + size > window.innerWidth - 4) left = window.innerWidth - size - 4;
      if (left < 4) left = 4;
      if (top + size > window.innerHeight - 4) top = window.innerHeight - size - 4;
      if (top < 4) top = 4;
      wrap.style.left = `${Math.round(left)}px`;
      wrap.style.top = `${Math.round(top)}px`;
      wrap.style.display = 'block';
    }

    function hide() {
      if (wrap) wrap.style.display = 'none';
    }

    return { show, hide };
  })();

  // ---------------------------------------------------------------------
  // 4. Translation popover (Shadow DOM)
  // ---------------------------------------------------------------------

  const popover = (() => {
    let host = null;
    let shadow = null;
    let panel = null;
    let body = null;
    let meta = null;
    let status = null;
    let copyButton = null;
    let regenerateButton = null;
    let closeButton = null;
    let currentRect = null;

    let state = POPOVER_STATES.HIDDEN;
    /** @type {string} accumulated translation text of the current request */
    let text = '';
    /** @type {string|null} text of the last requested translation */
    let localLastSourceText = null;

    function ensureDom() {
      if (host) return;
      host = document.createElement('div');
      host.id = 'ollama-translations-popover-host';
      host.className = 'ollama-translations-host';
      document.documentElement.append(host);
      shadow = host.attachShadow({ mode: 'open' });

      const style = document.createElement('style');
      style.textContent = `
        :host { all: initial; }
        .panel {
          position: fixed;
          z-index: 2147483647;
          width: 340px;
          max-width: calc(100vw - 16px);
          max-height: 320px;
          display: none;
          flex-direction: column;
          background: #ffffff;
          color: #1f1f1f;
          border: 1px solid rgba(0,0,0,.28);
          border-radius: 8px;
          box-shadow: 0 4px 16px rgba(0,0,0,.3);
          font-family: system-ui, sans-serif;
          font-size: 13px;
          line-height: 1.5;
        }
        .header {
          display: flex;
          align-items: center;
          gap: 6px;
          padding: 6px 10px;
          border-bottom: 1px solid rgba(0,0,0,.12);
          background: #f6f8fa;
          border-radius: 8px 8px 0 0;
        }
        .title { font-weight: 600; flex: 1; }
        .meta { color: #5f6368; font-size: 11px; }
        .close {
          border: none; background: transparent; cursor: pointer;
          font-size: 14px; line-height: 1; padding: 2px 4px; color: #444;
        }
        .body {
          padding: 8px 10px;
          overflow-y: auto;
          white-space: pre-wrap;
          word-break: break-word;
          min-height: 24px;
          user-select: text;
        }
        .footer {
          display: flex; gap: 6px; padding: 6px 10px;
          border-top: 1px solid rgba(0,0,0,.12);
        }
        .btn {
          border: 1px solid rgba(0,0,0,.25);
          background: #fff; border-radius: 4px;
          padding: 3px 10px; cursor: pointer; font-size: 12px;
          font-family: system-ui, sans-serif;
        }
        .btn:hover { background: #f0f4ff; }
        .btn[disabled] { opacity: .5; cursor: default; }
        .status { color: #5f6368; font-size: 11px; padding: 0 10px 6px; }
        .state-ERROR .status { color: #c5221f; }
        .state-COMPLETED .status { color: #188038; }
      `;
      shadow.append(style);

      panel = document.createElement('div');
      panel.className = 'panel';

      const header = document.createElement('div');
      header.className = 'header';
      const title = document.createElement('span');
      title.className = 'title';
      title.textContent = '翻訳';
      meta = document.createElement('span');
      meta.className = 'meta';
      closeButton = document.createElement('button');
      closeButton.type = 'button';
      closeButton.className = 'close';
      closeButton.textContent = '✕';
      closeButton.title = '閉じる';
      closeButton.setAttribute('aria-label', '閉じる');
      header.append(title, meta, closeButton);

      body = document.createElement('div');
      body.className = 'body';

      status = document.createElement('div');
      status.className = 'status';

      const footer = document.createElement('div');
      footer.className = 'footer';
      copyButton = document.createElement('button');
      copyButton.type = 'button';
      copyButton.className = 'btn';
      copyButton.textContent = 'コピー';
      regenerateButton = document.createElement('button');
      regenerateButton.type = 'button';
      regenerateButton.className = 'btn';
      regenerateButton.textContent = '再生成';
      footer.append(copyButton, regenerateButton);

      panel.append(header, body, status, footer);
      shadow.append(panel);

      closeButton.addEventListener('click', () => {
        close();
      });
      copyButton.addEventListener('click', () => {
        void copyToClipboard();
      });
      regenerateButton.addEventListener('click', () => {
        if (localLastSourceText) {
          portClient.translate(localLastSourceText);
        }
      });
    }

    function setState(next) {
      state = next;
      if (panel) {
        panel.className = `panel state-${next}`;
      }
      updateControls();
    }

    function updateControls() {
      const busy = state === POPOVER_STATES.LOADING || state === POPOVER_STATES.STREAMING;
      copyButton.disabled = busy || text.length === 0;
      regenerateButton.disabled = busy || !localLastSourceText;
      if (state === POPOVER_STATES.LOADING) status.textContent = '翻訳中…';
      else if (state === POPOVER_STATES.STREAMING) status.textContent = '受信中…';
      else if (state === POPOVER_STATES.COMPLETED) status.textContent = '完了';
      else if (state === POPOVER_STATES.ERROR) status.textContent = 'エラー';
      else status.textContent = '';
    }

    /**
     * Show the popover near the given rect.
     * @param {DOMRect|{left:number,top:number,bottom:number,right:number}} rect
     */
    function show(rect) {
      ensureDom();
      currentRect = rect;
      panel.style.display = 'flex';
      reposition();
    }

    function reposition() {
      if (!currentRect || !panel) return;
      const width = 340;
      const max = window.innerWidth - 8;
      let left = currentRect.left;
      if (left + width > max) left = Math.max(4, max - width);
      if (left < 4) left = 4;
      let top = currentRect.bottom + 8;
      // If it would overflow the bottom, place it above the selection.
      const approxHeight = Math.min(320, Math.max(80, panel.getBoundingClientRect().height || 120));
      if (top + approxHeight > window.innerHeight - 4) {
        top = Math.max(4, currentRect.top - approxHeight - 8);
      }
      panel.style.left = `${Math.round(left)}px`;
      panel.style.top = `${Math.round(top)}px`;
    }

    function isVisible() {
      return Boolean(panel && panel.style.display !== 'none' && state !== POPOVER_STATES.HIDDEN);
    }

    function repositionTo(rect) {
      currentRect = rect;
      reposition();
    }

    function hideInternal() {
      if (panel) panel.style.display = 'none';
      setState(POPOVER_STATES.HIDDEN);
      text = '';
      activeRequestId = null;
    }

    function close() {
      if (activeRequestId) {
        portClient.cancel(activeRequestId);
      }
      hideInternal();
    }

    /**
     * Begin a new translation request.
     * @param {string} sourceText
     * @param {DOMRect|{left:number,top:number,bottom:number,right:number}} rect
     */
    function beginRequest(sourceText, rect) {
      ensureDom();
      localLastSourceText = sourceText;
      text = '';
      body.textContent = '';
      show(rect);
      setState(POPOVER_STATES.LOADING);
    }

    /** @param {string} modelName */
    function setModel(modelName) {
      if (meta) meta.textContent = modelName ? `Ollama / ${modelName}` : 'Ollama';
    }

    /** @param {string} partial */
    function appendChunk(partial) {
      if (!partial) return;
      text += partial;
      // Plain text rendering only (UI-04 / SEC-03).
      body.textContent = text;
      if (state !== POPOVER_STATES.STREAMING) setState(POPOVER_STATES.STREAMING);
    }

    function complete() {
      setState(POPOVER_STATES.COMPLETED);
    }

    /** @param {string} message */
    function showError(message) {
      setState(POPOVER_STATES.ERROR);
      status.textContent = message || 'エラーが発生しました。';
    }

    async function copyToClipboard() {
      if (!text) return;
      try {
        await navigator.clipboard.writeText(text);
        status.textContent = 'コピーしました';
      } catch {
        // No execCommand fallback (deprecated): show failure only (Design §20).
        status.textContent = 'コピーできませんでした';
      }
    }

    return {
      get state() {
        return state;
      },
      isVisible,
      repositionTo,
      close,
      beginRequest,
      setModel,
      appendChunk,
      complete,
      showError
    };
  })();

  // ---------------------------------------------------------------------
  // 5. Port client
  // ---------------------------------------------------------------------

  const portClient = (() => {
    /** @type {object|null} */
    let port = null;

    function connect() {
      if (port) return port;
      port = browser.runtime.connect({ name: PORT_NAME });
      port.onMessage.addListener((message) => {
        if (!message || typeof message !== 'object' || typeof message.requestId !== 'string') return;
        if (message.requestId !== activeRequestId) return; // stale chunk
        switch (message.type) {
          case BG_TO_CONTENT.STARTED:
            popover.setModel(typeof message.model === 'string' ? message.model : '');
            break;
          case BG_TO_CONTENT.CHUNK:
            if (typeof message.text === 'string') popover.appendChunk(message.text);
            break;
          case BG_TO_CONTENT.COMPLETED:
            popover.complete();
            break;
          case BG_TO_CONTENT.ERROR:
            if (message.code !== ERROR_CODES.REQUEST_ABORTED) {
              popover.showError(typeof message.message === 'string' ? message.message : '');
            }
            break;
          default:
            break;
        }
      });
      port.onDisconnect.addListener(() => {
        port = null;
      });
      return port;
    }

    return {
      /**
       * Start a translation request for the given text, showing the popover.
       * @param {string} text
       */
      translate(text) {
        const p = connect();
        const requestId = generateRequestId();
        activeRequestId = requestId;
        popover.beginRequest(text, currentSelectionRect || { left: 16, top: 16, bottom: 40, right: 356 });
        p.postMessage({ type: CONTENT_TO_BG.TRANSLATE, requestId, text });
      },
      /**
       * @param {string} requestId
       */
      cancel(requestId) {
        const p = port || connect();
        p.postMessage({ type: CONTENT_TO_BG.CANCEL, requestId });
      }
    };
  })();

  /** @returns {string} random request id */
  function generateRequestId() {
    if (globalThis.crypto && typeof globalThis.crypto.randomUUID === 'function') {
      return globalThis.crypto.randomUUID();
    }
    const bytes = new Uint8Array(16);
    globalThis.crypto.getRandomValues(bytes);
    return Array.from(bytes, (b) => b.toString(16).padStart(2, '0')).join('');
  }

  // ---------------------------------------------------------------------
  // Flow: icon click -> translate, regenerate
  // ---------------------------------------------------------------------

  function onTranslateClicked() {
    if (!enabled) return;
    const selection = readSelection();
    if (!selection) return;
    currentSelectionRect = selection.rect;
    portClient.translate(selection.text);
  }

  // ---------------------------------------------------------------------
  // Enabled state (storage.local, EN-01/EN-02)
  // ---------------------------------------------------------------------

  function applyEnabled(next) {
    enabled = typeof next === 'boolean' ? next : true;
    if (!enabled) {
      actionButton.hide();
      if (popover.state !== POPOVER_STATES.HIDDEN) {
        popover.close();
      }
    }
  }

  function readEnabled() {
    try {
      browser.storage.local
        .get({ settings: null })
        .then((result) => {
          const settings = result && result.settings;
          applyEnabled(settings && typeof settings.enabled === 'boolean' ? settings.enabled : true);
        })
        .catch(() => {});
    } catch {
      // storage may be unavailable early; default stays enabled
    }
  }

  try {
    browser.storage.onChanged.addListener((changes, areaName) => {
      if (areaName !== 'local' || !changes.settings) return;
      const next = changes.settings.newValue;
      applyEnabled(next && typeof next.enabled === 'boolean' ? next.enabled : true);
    });
  } catch {
    // ignore
  }

  // ---------------------------------------------------------------------
  // 6. Entry point
  // ---------------------------------------------------------------------

  window.addEventListener('selectionchange', onSelectionEvent, { passive: true });
  document.addEventListener('mouseup', onSelectionEvent, { passive: true });
  document.addEventListener('keyup', onSelectionEvent, { passive: true });

  // Reposition the UI while the viewport changes (Design 5.4). Keep the
  // icon visible whenever a selection exists - hiding it on scroll left
  // users without any way to translate until they re-selected.
  window.addEventListener(
    'scroll',
    () => {
      if (popover.state === POPOVER_STATES.HIDDEN) {
        const selection = readSelection();
        if (selection) {
          currentSelectionRect = selection.rect;
          actionButton.show(selection.rect);
        } else {
          actionButton.hide();
        }
        return;
      }
      const selection = readSelection();
      if (selection) {
        currentSelectionRect = selection.rect;
        actionButton.show(selection.rect);
        popover.repositionTo(selection.rect);
      } else {
        actionButton.hide();
      }
    },
    { passive: true, capture: true }
  );

  window.addEventListener(
    'resize',
    () => {
      if (popover.state !== POPOVER_STATES.HIDDEN) {
        const selection = readSelection();
        if (selection) popover.repositionTo(selection.rect);
      }
    },
    { passive: true }
  );

  readEnabled();
})();