/* global cachedStyles: true */
'use strict';

const RX_NAMESPACE = new RegExp([/[\s\r\n]*/,
  /(@namespace[\s\r\n]+(?:[^\s\r\n]+[\s\r\n]+)?url\(http:\/\/.*?\);)/,
  /[\s\r\n]*/].map(rx => rx.source).join(''), 'g');
const RX_CSS_COMMENTS = /\/\*[\s\S]*?\*\//g;
const SLOPPY_REGEXP_PREFIX = '\0';

// Note, only 'var'-declared variables are visible from another extension page
// eslint-disable-next-line no-var
var cachedStyles = {
  list: null,            // array of all styles
  byId: new Map(),       // all styles indexed by id
  filters: new Map(),    // filterStyles() parameters mapped to the returned results, 10k max
  regexps: new Map(),    // compiled style regexps
  urlDomains: new Map(), // getDomain() results for 100 last checked urls
  emptyCode: new Map(),  // entire code is comments/whitespace/@namespace
  mutex: {
    inProgress: false,   // while getStyles() is reading IndexedDB all subsequent calls
    onDone: [],          // to getStyles() are queued and resolved when the first one finishes
  },
};


function getDatabase(ready, error) {
  const dbOpenRequest = window.indexedDB.open('stylish', 2);
  dbOpenRequest.onsuccess = event => {
    ready(event.target.result);
  };
  dbOpenRequest.onerror = event => {
    console.warn(event.target.errorCode);
    if (error) {
      error(event);
    }
  };
  dbOpenRequest.onupgradeneeded = event => {
    if (event.oldVersion == 0) {
      event.target.result.createObjectStore('styles', {
        keyPath: 'id',
        autoIncrement: true,
      });
    }
  };
}


function getStyles(options, callback) {
  if (cachedStyles.list) {
    callback(filterStyles(options));
    return;
  }
  if (cachedStyles.mutex.inProgress) {
    cachedStyles.mutex.onDone.push({options, callback});
    return;
  }
  cachedStyles.mutex.inProgress = true;

  getDatabase(db => {
    const tx = db.transaction(['styles'], 'readonly');
    const os = tx.objectStore('styles');
    os.getAll().onsuccess = event => {
      cachedStyles.list = event.target.result || [];
      cachedStyles.byId.clear();
      for (const style of cachedStyles.list) {
        cachedStyles.byId.set(style.id, style);
        compileStyleRegExps({style});
      }
      callback(filterStyles(options));

      cachedStyles.mutex.inProgress = false;
      for (const {options, callback} of cachedStyles.mutex.onDone) {
        callback(filterStyles(options));
      }
      cachedStyles.mutex.onDone = [];
    };
  }, null);
}


function filterStyles({
  enabled,
  url = null,
  id = null,
  matchUrl = null,
  asHash = null,
  strictRegexp = true, // used by the popup to detect bad regexps
} = {}) {
  enabled = fixBoolean(enabled);
  id = id === null ? null : Number(id);

  if (enabled === null
  && url === null
  && id === null
  && matchUrl === null
  && asHash != true) {
    return cachedStyles.list;
  }
  const disableAll = asHash && prefs.get('disableAll', false);

  if (matchUrl && matchUrl.startsWith(URLS.chromeWebStore)) {
    // CWS cannot be scripted in chromium, see ChromeExtensionsClient::IsScriptableURL
    // https://cs.chromium.org/chromium/src/chrome/common/extensions/chrome_extensions_client.cc
    return asHash ? {} : [];
  }

  // add \t after url to prevent collisions (not sure it can actually happen though)
  const cacheKey = ' ' + enabled + url + '\t' + id + matchUrl + '\t' + asHash + strictRegexp;
  const cached = cachedStyles.filters.get(cacheKey);
  if (cached) {
    cached.hits++;
    cached.lastHit = Date.now();
    return asHash
      ? Object.assign({disableAll}, cached.styles)
      : cached.styles;
  }

  return filterStylesInternal({
    enabled,
    url,
    id,
    matchUrl,
    asHash,
    strictRegexp,
    disableAll,
    cacheKey,
  });
}


function filterStylesInternal({
  // js engines don't like big functions (V8 often deoptimized the original filterStyles)
  // it also makes sense to extract the less frequently executed code
  enabled,
  url,
  id,
  matchUrl,
  asHash,
  strictRegexp,
  disableAll,
  cacheKey,
}) {
  if (matchUrl && !cachedStyles.urlDomains.has(matchUrl)) {
    cachedStyles.urlDomains.set(matchUrl, getDomains(matchUrl));
    for (let i = cachedStyles.urlDomains.size - 100; i > 0; i--) {
      const firstKey = cachedStyles.urlDomains.keys().next().value;
      cachedStyles.urlDomains.delete(firstKey);
    }
  }

  const styles = id === null
    ? cachedStyles.list
    : [cachedStyles.byId.get(id)];
  const filtered = asHash ? {} : [];
  if (!styles) {
    // may happen when users [accidentally] reopen an old URL
    // of edit.html with a non-existent style id parameter
    return filtered;
  }

  const needSections = asHash || matchUrl !== null;

  for (let i = 0, style; (style = styles[i]); i++) {
    if ((enabled === null || style.enabled == enabled)
    && (url === null || style.url == url)
    && (id === null || style.id == id)) {
      const sections = needSections &&
        getApplicableSections({style, matchUrl, strictRegexp, stopOnFirst: !asHash});
      if (asHash) {
        if (sections.length) {
          filtered[style.id] = sections;
        }
      } else if (matchUrl === null || sections.length) {
        filtered.push(style);
      }
    }
  }

  cachedStyles.filters.set(cacheKey, {
    styles: filtered,
    lastHit: Date.now(),
    hits: 1,
  });
  if (cachedStyles.filters.size > 10000) {
    cleanupCachedFilters();
  }

  return asHash
    ? Object.assign({disableAll}, filtered)
    : filtered;
}


function saveStyle(style) {
  return new Promise(resolve => {
    getDatabase(db => {
      const tx = db.transaction(['styles'], 'readwrite');
      const os = tx.objectStore('styles');

      const id = style.id !== undefined && style.id !== null ? Number(style.id) : null;
      const reason = style.reason;
      const notify = style.notify !== false;
      delete style.method;
      delete style.reason;
      delete style.notify;
      if (!style.name) {
        delete style.name;
      }

      if (id !== null) {
        // Update or create
        style.id = id;
        os.get(id).onsuccess = eventGet => {
          const existed = Boolean(eventGet.target.result);
          const oldStyle = Object.assign({}, eventGet.target.result);
          const codeIsUpdated = 'sections' in style && !styleSectionsEqual(style, oldStyle);
          write(Object.assign(oldStyle, style), {existed, codeIsUpdated});
        };
      } else {
        // Create
        delete style.id;
        write(Object.assign({
          // Set optional things if they're undefined
          enabled: true,
          updateUrl: null,
          md5Url: null,
          url: null,
          originalMd5: null,
        }, style));
      }

      function write(style, {existed, codeIsUpdated} = {}) {
        style.sections = (style.sections || []).map(section =>
          Object.assign({
            urls: [],
            urlPrefixes: [],
            domains: [],
            regexps: [],
          }, section)
        );
        os.put(style).onsuccess = event => {
          style.id = style.id || event.target.result;
          invalidateCache(existed ? {updated: style} : {added: style});
          compileStyleRegExps({style});
          if (notify) {
            notifyAllTabs({
              method: existed ? 'styleUpdated' : 'styleAdded',
              style, codeIsUpdated, reason,
            });
          }
          resolve(style);
        };
      }
    });
  });
}


function deleteStyle({id, notify = true}) {
  return new Promise(resolve =>
    getDatabase(db => {
      const tx = db.transaction(['styles'], 'readwrite');
      const os = tx.objectStore('styles');
      os.delete(Number(id)).onsuccess = () => {
        invalidateCache({deletedId: id});
        if (notify) {
          notifyAllTabs({method: 'styleDeleted', id});
        }
        resolve(id);
      };
    }));
}


function getApplicableSections({style, matchUrl, strictRegexp = true, stopOnFirst}) {
  if (!matchUrl.startsWith('http')
  && !matchUrl.startsWith('ftp')
  && !matchUrl.startsWith('file')
  && !matchUrl.startsWith(URLS.ownOrigin)) {
    return [];
  }
  const sections = [];
  for (const section of style.sections) {
    const {urls, domains, urlPrefixes, regexps, code} = section;
    if ((!urls.length && !urlPrefixes.length && !domains.length && !regexps.length
      || urls.length && urls.indexOf(matchUrl) >= 0
      || urlPrefixes.length && arraySomeIsPrefix(urlPrefixes, matchUrl)
      || domains.length && arraySomeIn(cachedStyles.urlDomains.get(matchUrl) || getDomains(matchUrl), domains)
      || regexps.length && arraySomeMatches(regexps, matchUrl, strictRegexp)
    ) && !styleCodeEmpty(code)) {
      sections.push(section);
      if (stopOnFirst) {
        break;
      }
    }
  }
  return sections;

  function arraySomeIsPrefix(array, string) {
    for (const prefix of array) {
      if (string.startsWith(prefix)) {
        return true;
      }
    }
    return false;
  }

  function arraySomeIn(array, haystack) {
    for (const el of array) {
      if (haystack.indexOf(el) >= 0) {
        return true;
      }
    }
    return false;
  }

  function arraySomeMatches(array, matchUrl, strictRegexp) {
    for (const regexp of array) {
      for (let pass = 1; pass <= (strictRegexp ? 1 : 2); pass++) {
        const cacheKey = pass == 1 ? regexp : SLOPPY_REGEXP_PREFIX + regexp;
        let rx = cachedStyles.regexps.get(cacheKey);
        if (rx == false) {
          // invalid regexp
          break;
        }
        if (!rx) {
          const anchored = pass == 1 ? '^(?:' + regexp + ')$' : '^' + regexp + '$';
          rx = tryRegExp(anchored);
          cachedStyles.regexps.set(cacheKey, rx || false);
          if (!rx) {
            // invalid regexp
            break;
          }
        }
        if (rx.test(matchUrl)) {
          return true;
        }
      }
    }
    return false;
  }
}


function styleCodeEmpty(code) {
  // Collect the section if not empty or namespace-only.
  // We don't check long code as it's slow both for emptyCode declared as Object
  // and as Map in case the string is not the same reference used to add the item
  let isEmpty = code !== null &&
    code.length < 1000 &&
    cachedStyles.emptyCode.get(code);
  if (isEmpty !== undefined) {
    return isEmpty;
  }
  isEmpty = !code || !code.trim()
    || code.indexOf('@namespace') >= 0
    && code.replace(RX_CSS_COMMENTS, '').replace(RX_NAMESPACE, '').trim() == '';
  cachedStyles.emptyCode.set(code, isEmpty);
  return isEmpty;
}


function styleSectionsEqual({sections: a}, {sections: b}) {
  if (!a || !b) {
    return undefined;
  }
  if (a.length != b.length) {
    return false;
  }
  const checkedInB = [];
  return a.every(sectionA => b.some(sectionB => {
    if (!checkedInB.includes(sectionB) && propertiesEqual(sectionA, sectionB)) {
      checkedInB.push(sectionB);
      return true;
    }
  }));

  function propertiesEqual(secA, secB) {
    for (const name of ['urlPrefixes', 'urls', 'domains', 'regexps']) {
      if (!equalOrEmpty(secA[name], secB[name], 'every', arrayMirrors)) {
        return false;
      }
    }
    return equalOrEmpty(secA.code, secB.code, 'substr', (a, b) => a == b);
  }

  function equalOrEmpty(a, b, telltale, comparator) {
    const typeA = a && typeof a[telltale] == 'function';
    const typeB = b && typeof b[telltale] == 'function';
    return (
      (a === null || a === undefined || (typeA && !a.length)) &&
      (b === null || b === undefined || (typeB && !b.length))
    ) || typeA && typeB && a.length == b.length && comparator(a, b);
  }

  function arrayMirrors(array1, array2) {
    for (const el of array1) {
      if (array2.indexOf(el) < 0) {
        return false;
      }
    }
    for (const el of array2) {
      if (array1.indexOf(el) < 0) {
        return false;
      }
    }
    return true;
  }
}


function compileStyleRegExps({style, compileAll}) {
  const t0 = performance.now();
  for (const section of style.sections || []) {
    for (const regexp of section.regexps) {
      for (let pass = 1; pass <= (compileAll ? 2 : 1); pass++) {
        const cacheKey = pass == 1 ? regexp : SLOPPY_REGEXP_PREFIX + regexp;
        if (cachedStyles.regexps.has(cacheKey)) {
          continue;
        }
        // according to CSS4 @document specification the entire URL must match
        const anchored = pass == 1 ? '^(?:' + regexp + ')$' : '^' + regexp + '$';
        const rx = tryRegExp(anchored);
        cachedStyles.regexps.set(cacheKey, rx || false);
        if (!compileAll && performance.now() - t0 > 100) {
          return;
        }
      }
    }
  }
}


function invalidateCache({added, updated, deletedId} = {}) {
  // prevent double-add on echoed invalidation
  const cached = added && cachedStyles.byId.get(added.id);
  if (cached) {
    return;
  }
  if (!cachedStyles.list) {
    return;
  }
  if (updated) {
    const cached = cachedStyles.byId.get(updated.id);
    if (cached) {
      Object.assign(cached, updated);
    }
    cachedStyles.filters.clear();
    return;
  }
  if (added) {
    cachedStyles.list.push(added);
    cachedStyles.byId.set(added.id, added);
    cachedStyles.filters.clear();
    return;
  }
  if (deletedId != undefined) {
    const deletedStyle = (cachedStyles.byId.get(deletedId) || {}).style;
    if (deletedStyle) {
      const cachedIndex = cachedStyles.list.indexOf(deletedStyle);
      cachedStyles.list.splice(cachedIndex, 1);
      cachedStyles.byId.delete(deletedId);
      cachedStyles.filters.clear();
      return;
    }
  }
  cachedStyles.list = null;
  cachedStyles.filters.clear();
}


function cleanupCachedFilters({force = false} = {}) {
  if (!force) {
    debounce(cleanupCachedFilters, 1000, {force: true});
    return;
  }
  const size = cachedStyles.filters.size;
  const oldestHit = cachedStyles.filters.values().next().value.lastHit;
  const now = Date.now();
  const timeSpan = now - oldestHit;
  const recencyWeight = 5 / size;
  const hitWeight = 1 / 4; // we make ~4 hits per URL
  const lastHitWeight = 10;
  // delete the oldest 10%
  [...cachedStyles.filters.entries()]
    .map(([id, v], index) => ({
      id,
      weight:
        index * recencyWeight +
        v.hits * hitWeight +
        (v.lastHit - oldestHit) / timeSpan * lastHitWeight,
    }))
    .sort((a, b) => a.weight - b.weight)
    .slice(0, size / 10 + 1)
    .forEach(({id}) => cachedStyles.filters.delete(id));
}


function reportError(...args) {
  for (const arg of args) {
    if ('message' in arg) {
      console.log(arg.message);
    }
  }
}


function fixBoolean(b) {
  if (typeof b != 'undefined') {
    return b != 'false';
  }
  return null;
}


function getDomains(url) {
  if (url.indexOf('file:') == 0) {
    return [];
  }
  let d = /.*?:\/*([^/:]+)/.exec(url)[1];
  const domains = [d];
  while (d.indexOf('.') != -1) {
    d = d.substring(d.indexOf('.') + 1);
    domains.push(d);
  }
  return domains;
}