stylus/background/style-manager.js

/* eslint no-eq-null: 0, eqeqeq: [2, "smart"] */
/* global createCache db calcStyleDigest db tryRegExp styleCodeEmpty
  getStyleWithNoCode msg */
/* exported styleManager */
'use strict';

/*
This style manager is a layer between content script and the DB. When a style
is added/updated, it broadcast a message to content script and the content
script would try to fetch the new code.

The live preview feature relies on `runtime.connect` and `port.onDisconnect`
to cleanup the temporary code. See /edit/live-preview.js.
*/
const styleManager = (() => {
  const preparing = prepare();

  /* styleId => {
    data: styleData,
    preview: styleData,
    appliesTo: Set<url>
  } */
  const styles = new Map();

  /* url => {
    maybeMatch: Set<styleId>,
    sections: Object<styleId => {
      id: styleId,
      code: Array<String>
    }>
  } */
  const cachedStyleForUrl = createCache({
    onDeleted: (url, cache) => {
      for (const section of Object.values(cache.sections)) {
        const style = styles.get(section.id);
        if (style) {
          style.appliesTo.delete(url);
        }
      }
    }
  });

  const BAD_MATCHER = {test: () => false};
  const compileRe = createCompiler(text => `^(${text})$`);
  const compileSloppyRe = createCompiler(text => `^${text}$`);
  const compileExclusion = createCompiler(buildGlob);

  handleLivePreviewConnections();

  return ensurePrepared({
    get,
    getSectionsByUrl,
    installStyle,
    deleteStyle,
    editSave,
    findStyle,
    importStyle,
    toggleStyle,
    setStyleExclusions,
    getAllStyles, // used by import-export
    getStylesByUrl, // used by popup
    styleExists,
  });

  function handleLivePreviewConnections() {
    chrome.runtime.onConnect.addListener(port => {
      if (port.name !== 'livePreview') {
        return;
      }
      let id;
      port.onMessage.addListener(data => {
        if (!id) {
          id = data.id;
        }
        const style = styles.get(id);
        style.preview = data;
        broadcastStyleUpdated(style.preview, 'editPreview');
      });
      port.onDisconnect.addListener(() => {
        port = null;
        if (id) {
          const style = styles.get(id);
          if (!style) {
            // maybe deleted
            return;
          }
          style.preview = null;
          broadcastStyleUpdated(style.data, 'editPreviewEnd');
        }
      });
    });
  }

  function get(id, noCode = false) {
    const data = styles.get(id).data;
    return noCode ? getStyleWithNoCode(data) : data;
  }

  function getAllStyles(noCode = false) {
    const datas = [...styles.values()].map(s => s.data);
    return noCode ? datas.map(getStyleWithNoCode) : datas;
  }

  function toggleStyle(id, enabled) {
    const style = styles.get(id);
    const data = Object.assign({}, style.data, {enabled});
    return saveStyle(data)
      .then(newData => handleSave(newData, 'toggle', false))
      .then(() => id);
  }

  // used by install-hook-userstyles.js
  function findStyle(filter, noCode = false) {
    for (const style of styles.values()) {
      if (filterMatch(filter, style.data)) {
        return noCode ? getStyleWithNoCode(style.data) : style.data;
      }
    }
    return null;
  }

  function styleExists(filter) {
    return [...styles.values()].some(s => filterMatch(filter, s.data));
  }

  function filterMatch(filter, target) {
    for (const key of Object.keys(filter)) {
      if (filter[key] !== target[key]) {
        return false;
      }
    }
    return true;
  }

  function importStyle(data) {
    // FIXME: is it a good idea to save the data directly?
    return saveStyle(data)
      .then(newData => handleSave(newData, 'import'));
  }

  function installStyle(data, reason = null) {
    const style = styles.get(data.id);
    if (!style) {
      data = Object.assign(createNewStyle(), data);
    } else {
      data = Object.assign({}, style.data, data);
    }
    if (!reason) {
      reason = style ? 'update' : 'install';
    }
    // FIXME: update updateDate? what about usercss config?
    return calcStyleDigest(data)
      .then(digest => {
        data.originalDigest = digest;
        return saveStyle(data);
      })
      .then(newData => handleSave(newData, reason));
  }

  function editSave(data) {
    const style = styles.get(data.id);
    if (style) {
      data = Object.assign({}, style.data, data);
    } else {
      data = Object.assign(createNewStyle(), data);
    }
    return saveStyle(data)
      .then(newData => handleSave(newData, 'editSave'));
  }

  function setStyleExclusions(id, exclusions) {
    const data = Object.assign({}, styles.get(id).data, {exclusions});
    return saveStyle(data)
      .then(newData => handleSave(newData, 'exclusions'));
  }

  function deleteStyle(id) {
    const style = styles.get(id);
    return db.exec('delete', id)
      .then(() => {
        for (const url of style.appliesTo) {
          const cache = cachedStyleForUrl.get(url);
          if (cache) {
            delete cache.sections[id];
          }
        }
        styles.delete(id);
        return msg.broadcast({
          method: 'styleDeleted',
          style: {id}
        });
      })
      .then(() => id);
  }

  function ensurePrepared(methods) {
    const prepared = {};
    for (const [name, fn] of Object.entries(methods)) {
      prepared[name] = (...args) =>
        preparing.then(() => fn(...args));
    }
    return prepared;
  }

  function createNewStyle() {
    return {
      enabled: true,
      updateUrl: null,
      md5Url: null,
      url: null,
      originalMd5: null,
      installDate: Date.now()
    };
  }

  function broadcastStyleUpdated(data, reason, method = 'styleUpdated', codeIsUpdated = true) {
    const style = styles.get(data.id);
    const excluded = new Set();
    const updated = new Set();
    for (const [url, cache] of cachedStyleForUrl.entries()) {
      if (!style.appliesTo.has(url)) {
        cache.maybeMatch.add(data.id);
        continue;
      }
      const code = getAppliedCode(url, data);
      if (!code) {
        excluded.add(url);
        delete cache.sections[data.id];
      } else {
        updated.add(url);
        cache.sections[data.id] = {
          id: data.id,
          code
        };
      }
    }
    style.appliesTo = updated;
    return msg.broadcast({
      method,
      style: {
        id: data.id,
        enabled: data.enabled
      },
      reason,
      codeIsUpdated
    });
  }

  function saveStyle(style) {
    if (!style.name) {
      throw new Error('style name is empty');
    }
    if (style.id == null) {
      delete style.id;
    }
    fixUsoMd5Issue(style);
    return db.exec('put', style)
      .then(event => {
        if (style.id == null) {
          style.id = event.target.result;
        }
        return style;
      });
  }

  function handleSave(data, reason, codeIsUpdated) {
    const style = styles.get(data.id);
    let method;
    if (!style) {
      styles.set(data.id, {
        appliesTo: new Set(),
        data
      });
      method = 'styleAdded';
    } else {
      style.data = data;
      method = 'styleUpdated';
    }
    return broadcastStyleUpdated(data, reason, method, codeIsUpdated)
      .then(() => data);
  }

  // get styles matching a URL, including sloppy regexps and excluded items.
  function getStylesByUrl(url, id = null) {
    // FIXME: do we want to cache this? Who would like to open popup rapidly
    // or search the DB with the same URL?
    const result = [];
    const datas = !id ? [...styles.values()].map(s => s.data) :
      styles.has(id) ? [styles.get(id).data] : [];
    for (const data of datas) {
      let excluded = false;
      let sloppy = false;
      let sectionMatched = false;
      const match = urlMatchStyle(url, data);
      // TODO: enable this when the function starts returning false
      // if (match === false) {
        // continue;
      // }
      if (match === 'excluded') {
        excluded = true;
      }
      for (const section of data.sections) {
        if (styleCodeEmpty(section.code)) {
          continue;
        }
        const match = urlMatchSection(url, section);
        if (match) {
          if (match === 'sloppy') {
            sloppy = true;
          }
          sectionMatched = true;
          break;
        }
      }
      if (sectionMatched) {
        result.push({
          data: getStyleWithNoCode(data),
          excluded,
          sloppy
        });
      }
    }
    return result;
  }

  function getSectionsByUrl(url, id) {
    let cache = cachedStyleForUrl.get(url);
    if (!cache) {
      cache = {
        sections: {},
        maybeMatch: new Set()
      };
      buildCache(styles.values());
      cachedStyleForUrl.set(url, cache);
    } else if (cache.maybeMatch.size) {
      buildCache(
        [...cache.maybeMatch]
          .filter(i => styles.has(i))
          .map(i => styles.get(i))
      );
    }
    if (id) {
      if (cache.sections[id]) {
        return {[id]: cache.sections[id]};
      }
      return {};
    }
    return cache.sections;

    function buildCache(styleList) {
      for (const {appliesTo, data, preview} of styleList) {
        const code = getAppliedCode(url, preview || data);
        if (code) {
          cache.sections[data.id] = {
            id: data.id,
            code
          };
          appliesTo.add(url);
        }
      }
    }
  }

  function getAppliedCode(url, data) {
    if (urlMatchStyle(url, data) !== true) {
      return;
    }
    const code = [];
    for (const section of data.sections) {
      if (urlMatchSection(url, section) === true && !styleCodeEmpty(section.code)) {
        code.push(section.code);
      }
    }
    return code.length && code;
  }

  function prepare() {
    return db.exec('getAll').then(event => {
      const styleList = event.target.result;
      if (!styleList) {
        return;
      }
      for (const style of styleList) {
        fixUsoMd5Issue(style);
        styles.set(style.id, {
          appliesTo: new Set(),
          data: style
        });
        if (!style.name) {
          style.name = 'ID: ' + style.id;
        }
      }
    });
  }

  function urlMatchStyle(url, style) {
    if (style.exclusions && style.exclusions.some(e => compileExclusion(e).test(url))) {
      return 'excluded';
    }
    if (!style.enabled) {
      return 'disabled';
    }
    return true;
  }

  function urlMatchSection(url, section) {
    const domain = getDomain(url);
    if (section.domains && section.domains.some(d => d === domain || domain.endsWith(`.${d}`))) {
      return true;
    }
    if (section.urlPrefixes && section.urlPrefixes.some(p => url.startsWith(p))) {
      return true;
    }
    // as per spec the fragment portion is ignored in @-moz-document:
    // https://www.w3.org/TR/2012/WD-css3-conditional-20120911/#url-of-doc
    // but the spec is outdated and doesn't account for SPA sites
    // so we only respect it for `url()` function
    if (section.urls && (
      section.urls.includes(url) ||
      section.urls.includes(getUrlNoHash(url))
    )) {
      return true;
    }
    if (section.regexps && section.regexps.some(r => compileRe(r).test(url))) {
      return true;
    }
    /*
    According to CSS4 @document specification the entire URL must match.
    Stylish-for-Chrome implemented it incorrectly since the very beginning.
    We'll detect styles that abuse the bug by finding the sections that
    would have been applied by Stylish but not by us as we follow the spec.
    */
    if (section.regexps && section.regexps.some(r => compileSloppyRe(r).test(url))) {
      return 'sloppy';
    }
    // TODO: check for invalid regexps?
    if (
      (!section.regexps || !section.regexps.length) &&
      (!section.urlPrefixes || !section.urlPrefixes.length) &&
      (!section.urls || !section.urls.length) &&
      (!section.domains || !section.domains.length)
    ) {
      return true;
    }
    return false;
  }

  function createCompiler(compile) {
    // FIXME: FIFO cache doesn't work well here, if we want to match many
    // regexps more than the cache size, we will never hit the cache because
    // the first cache is deleted. So we use a simple map but it leaks memory.
    const cache = new Map();
    return text => {
      let re = cache.get(text);
      if (!re) {
        re = tryRegExp(compile(text));
        if (!re) {
          re = BAD_MATCHER;
        }
        cache.set(text, re);
      }
      return re;
    };
  }

  function buildGlob(text) {
    const prefix = text[0] === '^' ? '' : '\\b';
    const suffix = text[text.length - 1] === '$' ? '' : '\\b';
    return `${prefix}${escape(text)}${suffix}`;

    function escape(text) {
      // FIXME: using .* everywhere is slow
      return text.replace(/[.*]/g, m => m === '.' ? '\\.' : '.*');
    }
  }

  function getDomain(url) {
    return url.match(/^[\w-]+:\/+(?:[\w:-]+@)?([^:/#]+)/)[1];
  }

  function getUrlNoHash(url) {
    return url.split('#')[0];
  }

  // The md5Url provided by USO includes a duplicate "update" subdomain (see #523),
  // This fixes any already installed styles containing this error
  function fixUsoMd5Issue(style) {
    if (style && style.md5Url && style.md5Url.includes('update.update.userstyles')) {
      style.md5Url = style.md5Url.replace('update.update.userstyles', 'update.userstyles');
    }
  }
})();