/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * Search service utilities for urlbar.  The only reason these functions aren't
 * a part of UrlbarUtils is that we want O(1) case-insensitive lookup for search
 * aliases, and to do that we need to observe the search service, persistent
 * state, and an init method.  A separate object is easier.
 */

"use strict";

var EXPORTED_SYMBOLS = ["UrlbarSearchUtils"];

const { XPCOMUtils } = ChromeUtils.import(
  "resource://gre/modules/XPCOMUtils.jsm"
);
const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");

const SEARCH_ENGINE_TOPIC = "browser-search-engine-modified";

/**
 * Search service utilities for urlbar.
 */
class SearchUtils {
  constructor() {
    this._refreshEnginesByAliasPromise = Promise.resolve();
    this.QueryInterface = ChromeUtils.generateQI([
      "nsIObserver",
      "nsISupportsWeakReference",
    ]);
    XPCOMUtils.defineLazyPreferenceGetter(
      this,
      "separatePrivateDefaultUIEnabled",
      "browser.search.separatePrivateDefault.ui.enabled",
      false
    );
    XPCOMUtils.defineLazyPreferenceGetter(
      this,
      "separatePrivateDefault",
      "browser.search.separatePrivateDefault",
      false
    );
  }

  /**
   * Initializes the instance and also Services.search.
   */
  async init() {
    if (!this._initPromise) {
      this._initPromise = this._initInternal();
    }
    await this._initPromise;
  }

  /**
   * Gets the engines whose domains match a given prefix.
   *
   * @param {string} prefix
   *   String containing the first part of the matching domain name(s).
   * @param {object} [options]
   * @param {boolean} [options.matchAllDomainLevels]
   *   Match at each sub domain, for example "a.b.c.com" will be matched at
   *   "a.b.c.com", "b.c.com", and "c.com". Partial matches are always returned
   *   after perfect matches.
   * @param {boolean} [options.onlyEnabled]
   *   Match only engines that have not been disabled on the Search Preferences
   *   list.
   * @returns {Array<nsISearchEngine>}
   *   An array of all matching engines. An empty array if there are none.
   */
  async enginesForDomainPrefix(
    prefix,
    { matchAllDomainLevels = false, onlyEnabled = false } = {}
  ) {
    await this.init();
    prefix = prefix.toLowerCase();

    let disabledEngines = onlyEnabled
      ? Services.prefs
          .getStringPref("browser.search.hiddenOneOffs", "")
          .split(",")
          .filter(e => !!e)
      : [];

    // Array of partially matched engines, added through matchPrefix().
    let partialMatchEngines = [];
    function matchPrefix(engine, engineHost) {
      let parts = engineHost.split(".");
      for (let i = 1; i < parts.length - 1; ++i) {
        if (
          parts
            .slice(i)
            .join(".")
            .startsWith(prefix)
        ) {
          partialMatchEngines.push(engine);
        }
      }
    }

    // Array of fully matched engines.
    let engines = [];
    for (let engine of await Services.search.getVisibleEngines()) {
      if (disabledEngines.includes(engine.name)) {
        continue;
      }
      let domain = engine.getResultDomain();
      if (domain.startsWith(prefix) || domain.startsWith("www." + prefix)) {
        engines.push(engine);
      }

      if (matchAllDomainLevels) {
        // The prefix may or may not contain part of the public suffix. If
        // it contains a dot, we must match with and without the public suffix,
        // otherwise it's sufficient to just match without it.
        if (prefix.includes(".")) {
          matchPrefix(engine, domain);
        }
        matchPrefix(
          engine,
          domain.substr(0, domain.length - engine.searchUrlPublicSuffix.length)
        );
      }
    }

    // Partial matches come after perfect matches.
    return [...engines, ...partialMatchEngines];
  }

  /**
   * Gets the engine with a given alias.
   *
   * @param {string} alias
   *   A search engine alias.  The alias string comparison is case insensitive.
   * @returns {nsISearchEngine}
   *   The matching engine or null if there isn't one.
   */
  async engineForAlias(alias) {
    await Promise.all([this.init(), this._refreshEnginesByAliasPromise]);
    return this._enginesByAlias.get(alias.toLocaleLowerCase()) || null;
  }

  /**
   * The list of engines with token ("@") aliases.
   *
   * @returns {array}
   *   Array of objects { engine, tokenAliases } for token alias engines.
   */
  async tokenAliasEngines() {
    await this.init();
    let tokenAliasEngines = [];
    for (let engine of await Services.search.getVisibleEngines()) {
      let tokenAliases = this._aliasesForEngine(engine).filter(a =>
        a.startsWith("@")
      );
      if (tokenAliases.length) {
        tokenAliasEngines.push({ engine, tokenAliases });
      }
    }
    return tokenAliasEngines;
  }

  /**
   * @param {nsISearchEngine} engine
   * @returns {string}
   *   The root domain of a search engine. e.g. If `engine` has the domain
   *   www.subdomain.rootdomain.com, `rootdomain` is returned. Returns the
   *   engine's domain if the engine's URL does not have a valid TLD.
   */
  getRootDomainFromEngine(engine) {
    let domain = engine.getResultDomain();
    let suffix = engine.searchUrlPublicSuffix;
    if (!suffix) {
      if (domain.endsWith(".test")) {
        suffix = "test";
      } else {
        return domain;
      }
    }
    domain = domain.substr(
      0,
      // -1 to remove the trailing dot.
      domain.length - suffix.length - 1
    );
    let domainParts = domain.split(".");
    return domainParts.pop();
  }

  getDefaultEngine(isPrivate = false) {
    return this.separatePrivateDefaultUIEnabled &&
      this.separatePrivateDefault &&
      isPrivate
      ? Services.search.defaultPrivateEngine
      : Services.search.defaultEngine;
  }

  async _initInternal() {
    await Services.search.init();
    await this._refreshEnginesByAlias();
    Services.obs.addObserver(this, SEARCH_ENGINE_TOPIC, true);
  }

  async _refreshEnginesByAlias() {
    // See the comment at the top of this file.  The only reason we need this
    // class is for O(1) case-insensitive lookup for search aliases, which is
    // facilitated by _enginesByAlias.
    this._enginesByAlias = new Map();
    for (let engine of await Services.search.getVisibleEngines()) {
      if (!engine.hidden) {
        for (let alias of this._aliasesForEngine(engine)) {
          this._enginesByAlias.set(alias, engine);
        }
      }
    }
  }

  /**
   * Compares the query parameters of two SERPs to see if one is equivalent to
   * the other. URL `x` is equivalent to URL `y` if
   *   (a) `y` contains at least all the query parameters contained in `x`, and
   *   (b) The values of the query parameters contained in both `x` and `y `are
   *       the same.
   *
   * @param {string} historySerp
   *   The SERP from history whose params should be contained in
   *   `generatedSerp`.
   * @param {string} generatedSerp
   *   The search URL we would generate for a search result with the same search
   *   string used in `historySerp`.
   * @param {array} [ignoreParams]
   *   A list of params to ignore in the matching, i.e. params that can be
   *   contained in `historySerp` but not be in `generatedSerp`.
   * @returns {boolean} True if `historySerp` can be deduped by `generatedSerp`.
   *
   * @note This function does not compare the SERPs' origins or pathnames.
   *   `historySerp` can have a different origin and/or pathname than
   *   `generatedSerp` and still be considered equivalent.
   */
  serpsAreEquivalent(historySerp, generatedSerp, ignoreParams = []) {
    let historyParams = new URL(historySerp).searchParams;
    let generatedParams = new URL(generatedSerp).searchParams;
    if (
      !Array.from(historyParams.entries()).every(
        ([key, value]) =>
          ignoreParams.includes(key) || value === generatedParams.get(key)
      )
    ) {
      return false;
    }

    return true;
  }

  /**
   * Gets the aliases of an engine.  For the user's convenience, we recognize
   * token versions of all non-token aliases.  For example, if the user has an
   * alias of "foo", then we recognize both "foo" and "@foo" as aliases for
   * foo's engine.  The returned list is therefore a superset of
   * `engine.aliases`.  Additionally, the returned aliases will be lower-cased
   * to make lookups and comparisons easier.
   *
   * @param {nsISearchEngine} engine
   *   The aliases of this search engine will be returned.
   * @returns {array}
   *   An array of lower-cased string aliases as described above.
   */
  _aliasesForEngine(engine) {
    return engine.aliases.reduce((aliases, aliasWithCase) => {
      // We store lower-cased aliases to make lookups and comparisons easier.
      let alias = aliasWithCase.toLocaleLowerCase();
      aliases.push(alias);
      if (!alias.startsWith("@")) {
        aliases.push("@" + alias);
      }
      return aliases;
    }, []);
  }

  observe(subject, topic, data) {
    switch (data) {
      case "engine-added":
      case "engine-changed":
      case "engine-removed":
      case "engine-default":
        this._refreshEnginesByAliasPromise = this._refreshEnginesByAlias();
        break;
    }
  }
}

var UrlbarSearchUtils = new SearchUtils();