/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
 * 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/. */

#include "FaviconHelpers.h"

#include "nsICacheEntry.h"
#include "nsICachingChannel.h"
#include "nsIClassOfService.h"
#include "nsIAsyncVerifyRedirectCallback.h"
#include "nsIHttpChannel.h"
#include "nsIPrincipal.h"

#include "nsComponentManagerUtils.h"
#include "nsNavHistory.h"
#include "nsFaviconService.h"

#include "mozilla/dom/PlacesFavicon.h"
#include "mozilla/dom/PlacesObservers.h"
#include "mozilla/dom/Promise.h"
#include "mozilla/Base64.h"
#include "mozilla/storage.h"
#include "mozilla/ScopeExit.h"
#include "mozilla/StaticPrefs_network.h"
#include "nsNetUtil.h"
#include "nsPrintfCString.h"
#include "nsStreamUtils.h"
#include "nsStringStream.h"
#include "nsIPrivateBrowsingChannel.h"
#include "nsISupportsPriority.h"
#include <algorithm>
#include <deque>
#include "mozilla/gfx/2D.h"
#include "imgIContainer.h"
#include "ImageOps.h"
#include "imgIEncoder.h"

using namespace mozilla;
using namespace mozilla::places;
using namespace mozilla::storage;

namespace mozilla {
namespace places {

namespace {

/**
 * Fetches information about a page from the database.
 *
 * @param aDB
 *        Database connection to history tables.
 * @param _page
 *        Page that should be fetched.
 */
nsresult FetchPageInfo(const RefPtr<Database>& aDB, PageData& _page) {
  MOZ_ASSERT(_page.spec.Length(), "Must have a non-empty spec!");
  MOZ_ASSERT(!NS_IsMainThread());

  // The subquery finds the bookmarked uri we want to set the icon for,
  // walking up redirects.
  nsCString query = nsPrintfCString(
      "SELECT h.id, pi.id, h.guid, ( "
      "WITH RECURSIVE "
      "destinations(visit_type, from_visit, place_id, rev_host, bm) AS ( "
      "SELECT v.visit_type, v.from_visit, p.id, p.rev_host, b.id "
      "FROM moz_places p  "
      "LEFT JOIN moz_historyvisits v ON v.place_id = p.id  "
      "LEFT JOIN moz_bookmarks b ON b.fk = p.id "
      "WHERE p.id = h.id "
      "UNION "
      "SELECT src.visit_type, src.from_visit, src.place_id, p.rev_host, b.id "
      "FROM moz_places p "
      "JOIN moz_historyvisits src ON src.place_id = p.id "
      "JOIN destinations dest ON dest.from_visit = src.id AND dest.visit_type "
      "IN (%d, %d) "
      "LEFT JOIN moz_bookmarks b ON b.fk = src.place_id "
      "WHERE instr(p.rev_host, dest.rev_host) = 1 "
      "OR instr(dest.rev_host, p.rev_host) = 1 "
      ") "
      "SELECT url "
      "FROM moz_places p "
      "JOIN destinations r ON r.place_id = p.id "
      "WHERE bm NOTNULL "
      "LIMIT 1 "
      "), fixup_url(get_unreversed_host(h.rev_host)) AS host "
      "FROM moz_places h "
      "LEFT JOIN moz_pages_w_icons pi ON page_url_hash = hash(:page_url) AND "
      "page_url = :page_url "
      "WHERE h.url_hash = hash(:page_url) AND h.url = :page_url",
      nsINavHistoryService::TRANSITION_REDIRECT_PERMANENT,
      nsINavHistoryService::TRANSITION_REDIRECT_TEMPORARY);

  nsCOMPtr<mozIStorageStatement> stmt = aDB->GetStatement(query);
  NS_ENSURE_STATE(stmt);
  mozStorageStatementScoper scoper(stmt);

  nsresult rv = URIBinder::Bind(stmt, "page_url"_ns, _page.spec);
  NS_ENSURE_SUCCESS(rv, rv);

  bool hasResult;
  rv = stmt->ExecuteStep(&hasResult);
  NS_ENSURE_SUCCESS(rv, rv);
  if (!hasResult) {
    // The page does not exist.
    return NS_ERROR_NOT_AVAILABLE;
  }

  rv = stmt->GetInt64(0, &_page.placeId);
  NS_ENSURE_SUCCESS(rv, rv);
  // May be null, and in such a case this will be 0.
  _page.id = stmt->AsInt64(1);
  rv = stmt->GetUTF8String(2, _page.guid);
  NS_ENSURE_SUCCESS(rv, rv);
  // Bookmarked url can be nullptr.
  bool isNull;
  rv = stmt->GetIsNull(3, &isNull);
  NS_ENSURE_SUCCESS(rv, rv);
  // The page could not be bookmarked.
  if (!isNull) {
    rv = stmt->GetUTF8String(3, _page.bookmarkedSpec);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  if (_page.host.IsEmpty()) {
    rv = stmt->GetUTF8String(4, _page.host);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  if (!_page.canAddToHistory) {
    // Either history is disabled or the scheme is not supported.  In such a
    // case we want to update the icon only if the page is bookmarked.

    if (_page.bookmarkedSpec.IsEmpty()) {
      // The page is not bookmarked.  Since updating the icon with a disabled
      // history would be a privacy leak, bail out as if the page did not exist.
      return NS_ERROR_NOT_AVAILABLE;
    } else {
      // The page, or a redirect to it, is bookmarked.  If the bookmarked spec
      // is different from the requested one, use it.
      if (!_page.bookmarkedSpec.Equals(_page.spec)) {
        _page.spec = _page.bookmarkedSpec;
        rv = FetchPageInfo(aDB, _page);
        NS_ENSURE_SUCCESS(rv, rv);
      }
    }
  }

  return NS_OK;
}

/**
 * Stores information about an icon in the database.
 *
 * @param aDB
 *        Database connection to history tables.
 * @param aIcon
 *        Icon that should be stored.
 * @param aMustReplace
 *        If set to true, the function will bail out with NS_ERROR_NOT_AVAILABLE
 *        if it can't find a previous stored icon to replace.
 * @note Should be wrapped in a transaction.
 */
nsresult SetIconInfo(const RefPtr<Database>& aDB, IconData& aIcon,
                     bool aMustReplace = false) {
  MOZ_ASSERT(!NS_IsMainThread());
  MOZ_ASSERT(aIcon.payloads.Length() > 0);
  MOZ_ASSERT(!aIcon.spec.IsEmpty());
  MOZ_ASSERT(aIcon.expiration > 0);

  // There are multiple cases possible at this point:
  //   1. We must insert some payloads and no payloads exist in the table. This
  //      would be a straight INSERT.
  //   2. The table contains the same number of payloads we are inserting. This
  //      would be a straight UPDATE.
  //   3. The table contains more payloads than we are inserting. This would be
  //      an UPDATE and a DELETE.
  //   4. The table contains less payloads than we are inserting. This would be
  //      an UPDATE and an INSERT.
  // We can't just remove all the old entries and insert the new ones, cause
  // we'd lose the referential integrity with pages.  For the same reason we
  // cannot use INSERT OR REPLACE, since it's implemented as DELETE AND INSERT.
  // Thus, we follow this strategy:
  //   * SELECT all existing icon ids
  //   * For each payload, either UPDATE OR INSERT reusing icon ids.
  //   * If any previous icon ids is leftover, DELETE it.

  nsCOMPtr<mozIStorageStatement> selectStmt = aDB->GetStatement(
      "SELECT id FROM moz_icons "
      "WHERE fixed_icon_url_hash = hash(fixup_url(:url)) "
      "AND icon_url = :url ");
  NS_ENSURE_STATE(selectStmt);
  mozStorageStatementScoper scoper(selectStmt);
  nsresult rv = URIBinder::Bind(selectStmt, "url"_ns, aIcon.spec);
  NS_ENSURE_SUCCESS(rv, rv);
  std::deque<int64_t> ids;
  bool hasResult = false;
  while (NS_SUCCEEDED(selectStmt->ExecuteStep(&hasResult)) && hasResult) {
    int64_t id = selectStmt->AsInt64(0);
    MOZ_ASSERT(id > 0);
    ids.push_back(id);
  }
  if (aMustReplace && ids.empty()) {
    return NS_ERROR_NOT_AVAILABLE;
  }

  nsCOMPtr<mozIStorageStatement> insertStmt = aDB->GetStatement(
      "INSERT INTO moz_icons "
      "(icon_url, fixed_icon_url_hash, width, root, expire_ms, data, flags) "
      "VALUES (:url, hash(fixup_url(:url)), :width, :root, :expire, :data, "
      ":flags) ");
  NS_ENSURE_STATE(insertStmt);
  // ReplaceFaviconData may replace data for an already existing icon, and in
  // that case it won't have the page uri at hand, thus it can't tell if the
  // icon is a root icon or not. For that reason, never overwrite a root = 1.
  nsCOMPtr<mozIStorageStatement> updateStmt = aDB->GetStatement(
      "UPDATE moz_icons SET width = :width, "
      "expire_ms = :expire, "
      "data = :data, "
      "root = (root  OR :root), "
      "flags = :flags "
      "WHERE id = :id ");
  NS_ENSURE_STATE(updateStmt);

  for (auto& payload : aIcon.payloads) {
    // Sanity checks.
    MOZ_ASSERT(payload.mimeType.EqualsLiteral(PNG_MIME_TYPE) ||
                   payload.mimeType.EqualsLiteral(SVG_MIME_TYPE),
               "Only png and svg payloads are supported");
    MOZ_ASSERT(!payload.mimeType.EqualsLiteral(SVG_MIME_TYPE) ||
                   payload.width == UINT16_MAX,
               "SVG payloads should have max width");
    MOZ_ASSERT(payload.width > 0, "Payload should have a width");
#ifdef DEBUG
    // Done to ensure we fetch the id. See the MOZ_ASSERT below.
    payload.id = 0;
#endif
    if (!ids.empty()) {
      // Pop the first existing id for reuse.
      int64_t id = ids.front();
      ids.pop_front();
      mozStorageStatementScoper scoper(updateStmt);
      rv = updateStmt->BindInt64ByName("id"_ns, id);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = updateStmt->BindInt32ByName("width"_ns, payload.width);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = updateStmt->BindInt64ByName("expire"_ns, aIcon.expiration / 1000);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = updateStmt->BindInt32ByName("root"_ns, aIcon.rootIcon);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = updateStmt->BindBlobByName("data"_ns, TO_INTBUFFER(payload.data),
                                      payload.data.Length());
      NS_ENSURE_SUCCESS(rv, rv);
      rv = updateStmt->BindInt32ByName("flags"_ns, aIcon.flags);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = updateStmt->Execute();
      NS_ENSURE_SUCCESS(rv, rv);
      // Set the new payload id.
      payload.id = id;
    } else {
      // Insert a new entry.
      mozStorageStatementScoper scoper(insertStmt);
      rv = URIBinder::Bind(insertStmt, "url"_ns, aIcon.spec);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = insertStmt->BindInt32ByName("width"_ns, payload.width);
      NS_ENSURE_SUCCESS(rv, rv);

      rv = insertStmt->BindInt32ByName("root"_ns, aIcon.rootIcon);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = insertStmt->BindInt64ByName("expire"_ns, aIcon.expiration / 1000);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = insertStmt->BindBlobByName("data"_ns, TO_INTBUFFER(payload.data),
                                      payload.data.Length());
      NS_ENSURE_SUCCESS(rv, rv);
      rv = insertStmt->BindInt32ByName("flags"_ns, aIcon.flags);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = insertStmt->Execute();
      NS_ENSURE_SUCCESS(rv, rv);
      // Set the new payload id.
      payload.id = nsFaviconService::sLastInsertedIconId;
    }
    MOZ_ASSERT(payload.id > 0, "Payload should have an id");
  }

  if (!ids.empty()) {
    // Remove any old leftover payload.
    nsAutoCString sql("DELETE FROM moz_icons WHERE id IN (");
    for (int64_t id : ids) {
      sql.AppendInt(id);
      sql.AppendLiteral(",");
    }
    sql.AppendLiteral(" 0)");  // Non-existing id to match the trailing comma.
    nsCOMPtr<mozIStorageStatement> stmt = aDB->GetStatement(sql);
    NS_ENSURE_STATE(stmt);
    mozStorageStatementScoper scoper(stmt);
    rv = stmt->Execute();
    NS_ENSURE_SUCCESS(rv, rv);
  }

  return NS_OK;
}

/**
 * Fetches information on a icon url from the database.
 *
 * @param aDBConn
 *        Database connection to history tables.
 * @param aPreferredWidth
 *        The preferred size to fetch.
 * @param _icon
 *        Icon that should be fetched.
 */
nsresult FetchIconInfo(const RefPtr<Database>& aDB, uint16_t aPreferredWidth,
                       IconData& _icon) {
  MOZ_ASSERT(_icon.spec.Length(), "Must have a non-empty spec!");
  MOZ_ASSERT(!NS_IsMainThread());

  if (_icon.status & ICON_STATUS_CACHED) {
    // The icon data has already been set by ReplaceFaviconData.
    return NS_OK;
  }

  nsCOMPtr<mozIStorageStatement> stmt = aDB->GetStatement(
      "/* do not warn (bug no: not worth having a compound index) */ "
      "SELECT id, expire_ms, data, width, root "
      "FROM moz_icons "
      "WHERE fixed_icon_url_hash = hash(fixup_url(:url)) "
      "AND icon_url = :url "
      "ORDER BY width DESC ");
  NS_ENSURE_STATE(stmt);
  mozStorageStatementScoper scoper(stmt);

  DebugOnly<nsresult> rv = URIBinder::Bind(stmt, "url"_ns, _icon.spec);
  MOZ_ASSERT(NS_SUCCEEDED(rv));

  bool hasResult = false;
  while (NS_SUCCEEDED(stmt->ExecuteStep(&hasResult)) && hasResult) {
    IconPayload payload;
    rv = stmt->GetInt64(0, &payload.id);
    MOZ_ASSERT(NS_SUCCEEDED(rv));

    // Expiration can be nullptr.
    bool isNull;
    rv = stmt->GetIsNull(1, &isNull);
    MOZ_ASSERT(NS_SUCCEEDED(rv));
    if (!isNull) {
      int64_t expire_ms;
      rv = stmt->GetInt64(1, &expire_ms);
      MOZ_ASSERT(NS_SUCCEEDED(rv));
      _icon.expiration = expire_ms * 1000;
    }

    uint8_t* data;
    uint32_t dataLen = 0;
    rv = stmt->GetBlob(2, &dataLen, &data);
    MOZ_ASSERT(NS_SUCCEEDED(rv));
    payload.data.Adopt(TO_CHARBUFFER(data), dataLen);

    int32_t width;
    rv = stmt->GetInt32(3, &width);
    MOZ_ASSERT(NS_SUCCEEDED(rv));
    payload.width = width;
    if (payload.width == UINT16_MAX) {
      payload.mimeType.AssignLiteral(SVG_MIME_TYPE);
    } else {
      payload.mimeType.AssignLiteral(PNG_MIME_TYPE);
    }

    int32_t rootIcon;
    rv = stmt->GetInt32(4, &rootIcon);
    MOZ_ASSERT(NS_SUCCEEDED(rv));
    _icon.rootIcon = rootIcon;

    if (aPreferredWidth == 0 || _icon.payloads.Length() == 0) {
      _icon.payloads.AppendElement(payload);
    } else if (payload.width >= aPreferredWidth) {
      // Only retain the best matching payload.
      _icon.payloads.ReplaceElementAt(0, payload);
    } else {
      break;
    }
  }

  return NS_OK;
}

nsresult FetchMostFrecentSubPageIcon(const RefPtr<Database>& aDB,
                                     const nsACString& aPageRoot,
                                     const nsACString& aPageHost,
                                     IconData& aIconData) {
  nsCOMPtr<mozIStorageStatement> stmt = aDB->GetStatement(
      "SELECT i.icon_url "
      "FROM moz_pages_w_icons pwi "
      "JOIN moz_icons_to_pages itp ON pwi.id = itp.page_id "
      "JOIN moz_icons i ON itp.icon_id = i.id "
      "JOIN moz_places p ON p.url_hash = pwi.page_url_hash "
      "WHERE p.rev_host = get_unreversed_host(:pageHost || '.') || '.' "
      "AND p.url BETWEEN :pageRoot AND :pageRoot || X'FFFF' "
      "ORDER BY p.frecency DESC, i.width DESC "
      "LIMIT 1");
  NS_ENSURE_STATE(stmt);
  mozStorageStatementScoper scoperFallback(stmt);

  nsresult rv = stmt->BindUTF8StringByName("pageRoot"_ns, aPageRoot);
  NS_ENSURE_SUCCESS(rv, rv);
  rv = stmt->BindUTF8StringByName("pageHost"_ns, aPageHost);
  NS_ENSURE_SUCCESS(rv, rv);

  bool hasResult;

  if (NS_SUCCEEDED(stmt->ExecuteStep(&hasResult)) && hasResult) {
    rv = stmt->GetUTF8String(0, aIconData.spec);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  return NS_OK;
}

nsresult FetchIconPerSpec(const RefPtr<Database>& aDB,
                          const nsCOMPtr<nsIURI>& aPageURI, IconData& aIconData,
                          uint16_t aPreferredWidth) {
  MOZ_ASSERT(!NS_IsMainThread());
  MOZ_ASSERT(aPageURI, "URI must exist.");

  nsAutoCString pageSpec;
  nsresult rv = aPageURI->GetSpec(pageSpec);
  NS_ENSURE_SUCCESS(rv, rv);
  MOZ_ASSERT(!pageSpec.IsEmpty(), "Page spec must not be empty.");

  nsAutoCString pageHostAndPort;
  // It's expected that some URIs may not have a host/port.
  Unused << aPageURI->GetHostPort(pageHostAndPort);

  const uint16_t THRESHOLD_WIDTH = 64;

  // This selects both associated and root domain icons, ordered by width,
  // where an associated icon has priority over a root domain icon.
  // If the preferred width is less than or equal to THRESHOLD_WIDTH, non-rich
  // icons are prioritized over rich icons by ordering first by `isRich ASC`,
  // then by width. If the preferred width is greater than THRESHOLD_WIDTH, the
  // sorting prioritizes width, with no preference for rich or non-rich icons.
  // Regardless, note that while this way we are far more efficient, we lost
  // associations with root domain icons, so it's possible we'll return one for
  // a specific size when an associated icon for that size doesn't exist.

  nsCString query = nsPrintfCString(
      "/* do not warn (bug no: not worth having a compound index) */ "
      "SELECT width, icon_url, root, (flags & %d) as isRich "
      "FROM moz_icons i "
      "JOIN moz_icons_to_pages ON i.id = icon_id "
      "JOIN moz_pages_w_icons p ON p.id = page_id "
      "WHERE page_url_hash = hash(:url) AND page_url = :url "
      "OR (:hash_idx AND page_url_hash = hash(substr(:url, 0, :hash_idx)) "
      "AND page_url = substr(:url, 0, :hash_idx)) "
      "UNION ALL "
      "SELECT width, icon_url, root, (flags & %d) as isRich "
      "FROM moz_icons i "
      "WHERE fixed_icon_url_hash = hash(fixup_url(:hostAndPort) || "
      "'/favicon.ico') "
      "ORDER BY %s width DESC, root ASC",
      nsIFaviconService::ICONDATA_FLAGS_RICH,
      nsIFaviconService::ICONDATA_FLAGS_RICH,
      // Prefer non-rich icons for small sizes (<= 64px).
      aPreferredWidth <= THRESHOLD_WIDTH ? "isRich ASC, " : "");

  nsCOMPtr<mozIStorageStatement> stmt = aDB->GetStatement(query);

  NS_ENSURE_STATE(stmt);
  mozStorageStatementScoper scoper(stmt);

  rv = URIBinder::Bind(stmt, "url"_ns, pageSpec);
  NS_ENSURE_SUCCESS(rv, rv);
  rv = stmt->BindUTF8StringByName("hostAndPort"_ns, pageHostAndPort);
  NS_ENSURE_SUCCESS(rv, rv);
  int32_t hashIdx = PromiseFlatCString(pageSpec).RFind("#");
  rv = stmt->BindInt32ByName("hash_idx"_ns, hashIdx + 1);
  NS_ENSURE_SUCCESS(rv, rv);

  // Return the biggest icon close to the preferred width. It may be bigger
  // or smaller if the preferred width isn't found.
  // If the size difference between the bigger icon and preferred width is more
  // than 4 times greater than the difference between the preferred width and
  // the smaller icon, we prefer the smaller icon.
  // Non-rich icons are prioritized over rich ones for preferred widths <=
  // THRESHOLD_WIDTH. After the inital selection, we check if a suitable SVG
  // icon exists that could override the initial selection.

  bool hasResult;

  struct IconInfo {
    int32_t width = 0;
    int32_t isRich = 0;
    nsAutoCString spec;
    bool isSet() { return width > 0; };
  };

  IconInfo svgIcon;
  IconInfo lastIcon;
  IconInfo selectedIcon;

  bool preferNonRichIcons = aPreferredWidth <= THRESHOLD_WIDTH;

  while (NS_SUCCEEDED(stmt->ExecuteStep(&hasResult)) && hasResult) {
    int32_t width;
    rv = stmt->GetInt32(0, &width);
    if (lastIcon.width == width) {
      // If we already found an icon for this width, we always prefer the first
      // icon found, because it's a non-root icon, per the root ASC ordering.
      continue;
    }

    int32_t isRich = stmt->AsInt32(3);
    int32_t isSVG = (width == UINT16_MAX);

    nsAutoCString iconURL;
    stmt->GetUTF8String(1, iconURL);

    // If current icon is an SVG, and we haven't yet stored an SVG,
    // store the SVG when the preferred width is below
    // threshold, otherwise simply store the first SVG found regardless of
    // richness.
    if (isSVG && !svgIcon.isSet()) {
      if ((preferNonRichIcons && !isRich) || !preferNonRichIcons) {
        svgIcon = {width, isRich, iconURL};
      }
    }

    if (preferNonRichIcons && lastIcon.isSet() && isRich && !lastIcon.isRich) {
      // If we already found a non-rich icon, we prefer it to rich icons
      // for small sizes.
      break;
    }

    if (!aIconData.spec.IsEmpty() && width < aPreferredWidth) {
      // We found the best match, or we already found a match so we don't need
      // to fallback to the root domain icon.

      // If the difference between the preferred size and the previously found
      // larger icon is more than 4 times the difference between the preferred
      // size and the smaller icon, choose the smaller icon.
      if (aPreferredWidth - width < abs(lastIcon.width - aPreferredWidth) / 4) {
        selectedIcon = {width, isRich};
        rv = stmt->GetUTF8String(1, aIconData.spec);
        NS_ENSURE_SUCCESS(rv, rv);
      }
      break;
    }

    lastIcon = {width, isRich};

    selectedIcon = {width, isRich};
    rv = stmt->GetUTF8String(1, aIconData.spec);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // Check to see if we should overwrite the original icon selection with an
  // SVG. We prefer the SVG if the selected icon's width differs from the
  // preferred width. We also prefer the SVG if the selected icon is rich and
  // the preferred width is below threshold. Note that since we only store
  // non-rich SVGs for below-threshold requests, rich SVGs are not considered.
  // For above-threshold requests, any SVG would overwrite the selected icon if
  // its width differs from the requested size.
  if (svgIcon.isSet() && !svgIcon.spec.IsEmpty()) {
    if ((selectedIcon.width != aPreferredWidth) ||
        (preferNonRichIcons && selectedIcon.isRich)) {
      aIconData.spec = svgIcon.spec;
    }
  }

  // If we reached this stage without finding an icon, we can check if the
  // requested page spec is a host (no path) and if it contains any subpages
  // that have an icon associated with them. If they do, we fetch the icon
  // of the most frecent subpage.
  if (aIconData.spec.IsEmpty()) {
    nsAutoCString pageFilePath;
    rv = aPageURI->GetFilePath(pageFilePath);
    NS_ENSURE_SUCCESS(rv, rv);
    if (pageFilePath == "/"_ns) {
      nsAutoCString pageHost;
      (void)aPageURI->GetHost(pageHost);

      nsAutoCString pagePrePath;
      (void)aPageURI->GetPrePath(pagePrePath);

      if (!pageHost.IsEmpty() && !pagePrePath.IsEmpty()) {
        rv = FetchMostFrecentSubPageIcon(aDB, pagePrePath, pageHost, aIconData);
        NS_ENSURE_SUCCESS(rv, rv);
      }
    }
  }

  return NS_OK;
}

class Favicon final : public nsIFavicon {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS

  Favicon(const nsACString& aURISpec, const nsACString& aRawData,
          const nsACString& aMimeType, const uint16_t& aWidth)
      : mURISpec(aURISpec),
        mRawData(aRawData),
        mMimeType(aMimeType),
        mWidth(aWidth) {}

  NS_IMETHODIMP GetUri(nsIURI** aURI) override {
    NS_ENSURE_ARG_POINTER(aURI);
    return NS_NewURI(aURI, mURISpec);
  }

  NS_IMETHODIMP GetDataURI(nsIURI** aDataURI) override {
    NS_ENSURE_ARG_POINTER(aDataURI);

    nsAutoCString spec;
    spec.AssignLiteral("data:");
    spec.Append(mMimeType);
    spec.AppendLiteral(";base64,");
    nsresult rv = Base64EncodeAppend(mRawData, spec);
    NS_ENSURE_SUCCESS(rv, rv);

    return NS_NewURI(aDataURI, spec);
  }

  NS_IMETHOD GetRawData(nsTArray<uint8_t>& aRawData) override {
    Unused << aRawData.ReplaceElementsAt(0, aRawData.Length(),
                                         TO_INTBUFFER(mRawData),
                                         mRawData.Length(), fallible);
    return NS_OK;
  }

  NS_IMETHOD GetMimeType(nsACString& aMimeType) override {
    aMimeType.Assign(mMimeType);
    return NS_OK;
  }

  NS_IMETHOD GetWidth(uint16_t* aWidth) override {
    *aWidth = mWidth;
    return NS_OK;
  }

 private:
  ~Favicon() = default;

  nsCString mURISpec;
  nsCString mRawData;
  nsCString mMimeType;
  uint16_t mWidth;
};
NS_IMPL_ISUPPORTS(Favicon, nsIFavicon)

}  // namespace

////////////////////////////////////////////////////////////////////////////////
//// AsyncAssociateIconToPage

AsyncAssociateIconToPage::AsyncAssociateIconToPage(
    const IconData& aIcon, const PageData& aPage,
    const nsMainThreadPtrHandle<nsIFaviconDataCallback>& aCallback)
    : Runnable("places::AsyncAssociateIconToPage"),
      mCallback(aCallback),
      mIcon(aIcon),
      mPage(aPage) {
  // May be created in both threads.
}

NS_IMETHODIMP
AsyncAssociateIconToPage::Run() {
  MOZ_ASSERT(!NS_IsMainThread());
  MOZ_ASSERT(!mPage.guid.IsEmpty(),
             "Page info should have been fetched already");
  MOZ_ASSERT(mPage.canAddToHistory || !mPage.bookmarkedSpec.IsEmpty(),
             "The page should be addable to history or a bookmark");

  bool shouldUpdateIcon = mIcon.status & ICON_STATUS_CHANGED;
  if (!shouldUpdateIcon) {
    for (const auto& payload : mIcon.payloads) {
      // If the entry is missing from the database, we should add it.
      if (payload.id == 0) {
        shouldUpdateIcon = true;
        break;
      }
    }
  }

  RefPtr<Database> DB = Database::GetDatabase();
  NS_ENSURE_STATE(DB);

  mozStorageTransaction transaction(
      DB->MainConn(), false, mozIStorageConnection::TRANSACTION_IMMEDIATE);

  // XXX Handle the error, bug 1696133.
  Unused << NS_WARN_IF(NS_FAILED(transaction.Start()));

  nsresult rv;
  if (shouldUpdateIcon) {
    rv = SetIconInfo(DB, mIcon);
    if (NS_FAILED(rv)) {
      (void)transaction.Commit();
      return rv;
    }

    mIcon.status = (mIcon.status & ~(ICON_STATUS_CACHED)) | ICON_STATUS_SAVED;
  }

  // If the page does not have an id, don't try to insert a new one, cause we
  // don't know where the page comes from.  Not doing so we may end adding
  // a page that otherwise we'd explicitly ignore, like a POST or an error page.
  if (mPage.placeId == 0) {
    rv = transaction.Commit();
    NS_ENSURE_SUCCESS(rv, rv);
    return NS_OK;
  }

  // Expire old favicons to keep up with website changes. Associated icons must
  // be expired also when storing a root favicon, because a page may change to
  // only have a root favicon.
  // Note that here we could also be in the process of adding further payloads
  // to a page, and we don't want to expire just added payloads. For this
  // reason we only remove expired payloads.
  // Oprhan icons are not removed at this time because it'd be expensive. The
  // privacy implications are limited, since history removal methods also expire
  // orphan icons.
  if (mPage.id > 0) {
    nsCOMPtr<mozIStorageStatement> stmt;
    stmt = DB->GetStatement(
        "DELETE FROM moz_icons_to_pages "
        "WHERE page_id = :page_id "
        "AND expire_ms < strftime('%s','now','localtime','utc') * 1000 ");
    NS_ENSURE_STATE(stmt);
    mozStorageStatementScoper scoper(stmt);
    rv = stmt->BindInt64ByName("page_id"_ns, mPage.id);
    NS_ENSURE_SUCCESS(rv, rv);
    rv = stmt->Execute();
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // Don't associate pages to root domain icons, since those will be returned
  // regardless.  This saves a lot of work and database space since we don't
  // need to store urls and relations.
  // Though, this is possible only if both the page and the icon have the same
  // host, otherwise we couldn't relate them.
  if (!mIcon.rootIcon || !mIcon.host.Equals(mPage.host)) {
    // The page may have associated payloads already, and those could have to be
    // expired. For example at a certain point a page could decide to stop
    // serving its usual 16px and 32px pngs, and use an svg instead. On the
    // other side, we could also be in the process of adding more payloads to
    // this page, and we should not expire the payloads we just added. For this,
    // we use the expiration field as an indicator and remove relations based on
    // it being elapsed. We don't remove orphan icons at this time since it
    // would have a cost. The privacy hit is limited since history removal
    // methods already expire orphan icons.
    if (mPage.id == 0) {
      // We need to create the page entry.
      nsCOMPtr<mozIStorageStatement> stmt;
      stmt = DB->GetStatement(
          "INSERT OR IGNORE INTO moz_pages_w_icons (page_url, page_url_hash) "
          "VALUES (:page_url, hash(:page_url)) ");
      NS_ENSURE_STATE(stmt);
      mozStorageStatementScoper scoper(stmt);
      rv = URIBinder::Bind(stmt, "page_url"_ns, mPage.spec);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = stmt->Execute();
      NS_ENSURE_SUCCESS(rv, rv);
    }

    // Then we can create the relations.
    nsCOMPtr<mozIStorageStatement> stmt;
    stmt = DB->GetStatement(
        "INSERT INTO moz_icons_to_pages (page_id, icon_id, expire_ms) "
        "VALUES ((SELECT id from moz_pages_w_icons WHERE page_url_hash = "
        "hash(:page_url) AND page_url = :page_url), "
        ":icon_id, :expire) "
        "ON CONFLICT(page_id, icon_id) DO "
        "UPDATE SET expire_ms = :expire ");
    NS_ENSURE_STATE(stmt);

    // For some reason using BindingParamsArray here fails execution, so we must
    // execute the statements one by one.
    // In the future we may want to investigate the reasons, sounds like related
    // to contraints.
    for (const auto& payload : mIcon.payloads) {
      mozStorageStatementScoper scoper(stmt);
      nsCOMPtr<mozIStorageBindingParams> params;
      rv = URIBinder::Bind(stmt, "page_url"_ns, mPage.spec);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = stmt->BindInt64ByName("icon_id"_ns, payload.id);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = stmt->BindInt64ByName("expire"_ns, mIcon.expiration / 1000);
      NS_ENSURE_SUCCESS(rv, rv);
      rv = stmt->Execute();
      NS_ENSURE_SUCCESS(rv, rv);
    }
  }

  mIcon.status |= ICON_STATUS_ASSOCIATED;

  rv = transaction.Commit();
  NS_ENSURE_SUCCESS(rv, rv);

  // Finally, dispatch an event to the main thread to notify observers.
  nsCOMPtr<nsIRunnable> event =
      new NotifyIconObservers(mIcon, mPage, mCallback);
  rv = NS_DispatchToMainThread(event);
  NS_ENSURE_SUCCESS(rv, rv);

  // If there is a bookmarked page that redirects to this one, try to update its
  // icon as well.
  if (!mPage.bookmarkedSpec.IsEmpty() &&
      !mPage.bookmarkedSpec.Equals(mPage.spec)) {
    // Create a new page struct to avoid polluting it with old data.
    PageData bookmarkedPage;
    bookmarkedPage.spec = mPage.bookmarkedSpec;
    RefPtr<Database> DB = Database::GetDatabase();
    if (DB && NS_SUCCEEDED(FetchPageInfo(DB, bookmarkedPage))) {
      // This will be silent, so be sure to not pass in the current callback.
      nsMainThreadPtrHandle<nsIFaviconDataCallback> nullCallback;
      RefPtr<AsyncAssociateIconToPage> event =
          new AsyncAssociateIconToPage(mIcon, bookmarkedPage, nullCallback);
      Unused << event->Run();
    }
  }

  return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////
//// AsyncSetIconForPage

AsyncSetIconForPage::AsyncSetIconForPage(const IconData& aIcon,
                                         const PageData& aPage,
                                         dom::Promise* aPromise)
    : Runnable("places::AsyncSetIconForPage"),
      mPromise(new nsMainThreadPtrHolder<dom::Promise>(
          "AsyncSetIconForPage::Promise", aPromise, false)),
      mIcon(aIcon),
      mPage(aPage) {}

NS_IMETHODIMP
AsyncSetIconForPage::Run() {
  MOZ_ASSERT(!NS_IsMainThread());
  MOZ_ASSERT(mIcon.payloads.Length(), "The icon should have valid data");
  MOZ_ASSERT(mPage.spec.Length(), "The page should have spec");
  MOZ_ASSERT(mPage.guid.IsEmpty(), "The page should not have guid");

  nsresult rv = NS_OK;
  auto guard = MakeScopeExit([&]() {
    NS_DispatchToMainThread(NS_NewRunnableFunction(
        "AsyncSetIconForPage::Promise", [rv, promise = std::move(mPromise)]() {
          if (NS_SUCCEEDED(rv)) {
            promise->MaybeResolveWithUndefined();
          } else {
            promise->MaybeReject(rv);
          }
        }));
  });

  // Fetch the page data.
  RefPtr<Database> DB = Database::GetDatabase();
  if (MOZ_UNLIKELY(!DB)) {
    return (rv = NS_ERROR_UNEXPECTED);
  }
  rv = FetchPageInfo(DB, mPage);
  NS_ENSURE_SUCCESS(rv, rv);

  nsMainThreadPtrHandle<nsIFaviconDataCallback> nullCallback;
  AsyncAssociateIconToPage event(mIcon, mPage, nullCallback);
  return (rv = event.Run());
}

////////////////////////////////////////////////////////////////////////////////
//// AsyncGetFaviconForPageRunnable

AsyncGetFaviconForPageRunnable::AsyncGetFaviconForPageRunnable(
    const nsCOMPtr<nsIURI>& aPageURI, uint16_t aPreferredWidth,
    FaviconPromise::Private* aPromise)
    : Runnable("places::AsyncGetFaviconForPage"),
      mPageURI(aPageURI),
      mPreferredWidth(aPreferredWidth == 0 ? UINT16_MAX : aPreferredWidth),
      mPromise(new nsMainThreadPtrHolder<FaviconPromise::Private>(
          "AsyncGetFaviconForPageRunnable::Promise", aPromise, false)) {
  MOZ_ASSERT(NS_IsMainThread());
}

NS_IMETHODIMP
AsyncGetFaviconForPageRunnable::Run() {
  MOZ_ASSERT(!NS_IsMainThread());

  IconData iconData;
  nsresult rv = NS_OK;

  auto guard = MakeScopeExit([&]() {
    if (NS_FAILED(rv)) {
      mPromise->Reject(rv, __func__);
      return;
    }

    if (iconData.payloads.Length() == 0) {
      // Not found.
      mPromise->Resolve(nullptr, __func__);
      return;
    }

    IconPayload& payload = iconData.payloads[0];
    nsCOMPtr<nsIFavicon> favicon = new Favicon(iconData.spec, payload.data,
                                               payload.mimeType, payload.width);
    mPromise->Resolve(favicon.forget(), __func__);
  });

  RefPtr<Database> DB = Database::GetDatabase();
  NS_ENSURE_STATE(DB);

  rv = FetchIconPerSpec(DB, mPageURI, iconData, mPreferredWidth);
  NS_ENSURE_SUCCESS(rv, rv);

  if (iconData.spec.IsEmpty()) {
    return NS_OK;
  }

  rv = FetchIconInfo(DB, mPreferredWidth, iconData);
  NS_ENSURE_SUCCESS(rv, rv);

  return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////
//// NotifyIconObservers

NotifyIconObservers::NotifyIconObservers(
    const IconData& aIcon, const PageData& aPage,
    const nsMainThreadPtrHandle<nsIFaviconDataCallback>& aCallback)
    : Runnable("places::NotifyIconObservers"),
      mCallback(aCallback),
      mIcon(aIcon),
      mPage(aPage) {}

// MOZ_CAN_RUN_SCRIPT_BOUNDARY until Runnable::Run is marked
// MOZ_CAN_RUN_SCRIPT.  See bug 1535398.
MOZ_CAN_RUN_SCRIPT_BOUNDARY
NS_IMETHODIMP
NotifyIconObservers::Run() {
  MOZ_ASSERT(NS_IsMainThread());

  nsCOMPtr<nsIURI> iconURI;
  if (!mIcon.spec.IsEmpty()) {
    if (!NS_WARN_IF(
            NS_FAILED(NS_NewURI(getter_AddRefs(iconURI), mIcon.spec)))) {
      // Notify observers only if something changed.
      if (mIcon.status & ICON_STATUS_SAVED ||
          mIcon.status & ICON_STATUS_ASSOCIATED) {
        nsCOMPtr<nsIURI> pageURI;
        if (!NS_WARN_IF(
                NS_FAILED(NS_NewURI(getter_AddRefs(pageURI), mPage.spec)))) {
          // Invalide page-icon image cache, since the icon is about to change.
          nsFaviconService* favicons = nsFaviconService::GetFaviconService();
          MOZ_ASSERT(favicons);
          if (favicons) {
            nsCString pageIconSpec("page-icon:");
            pageIconSpec.Append(mPage.spec);
            nsCOMPtr<nsIURI> pageIconURI;
            if (NS_SUCCEEDED(
                    NS_NewURI(getter_AddRefs(pageIconURI), pageIconSpec))) {
              favicons->ClearImageCache(pageIconURI);
            }
          }

          // Notify about the favicon change.
          dom::Sequence<OwningNonNull<dom::PlacesEvent>> events;
          RefPtr<dom::PlacesFavicon> faviconEvent = new dom::PlacesFavicon();
          AppendUTF8toUTF16(mPage.spec, faviconEvent->mUrl);
          AppendUTF8toUTF16(mIcon.spec, faviconEvent->mFaviconUrl);
          faviconEvent->mPageGuid.Assign(mPage.guid);
          bool success =
              !!events.AppendElement(faviconEvent.forget(), fallible);
          MOZ_RELEASE_ASSERT(success);
          dom::PlacesObservers::NotifyListeners(events);
        }
      }
    }
  }

  if (!mCallback) {
    return NS_OK;
  }

  if (mIcon.payloads.Length() > 0) {
    IconPayload& payload = mIcon.payloads[0];
    return mCallback->OnComplete(iconURI, payload.data.Length(),
                                 TO_INTBUFFER(payload.data), payload.mimeType,
                                 payload.width);
  }
  return mCallback->OnComplete(iconURI, 0, TO_INTBUFFER(EmptyCString()), ""_ns,
                               0);
}

////////////////////////////////////////////////////////////////////////////////
//// AsyncCopyFavicons

AsyncCopyFavicons::AsyncCopyFavicons(PageData& aFromPage, PageData& aToPage,
                                     nsIFaviconDataCallback* aCallback)
    : Runnable("places::AsyncCopyFavicons"),
      mFromPage(aFromPage),
      mToPage(aToPage),
      mCallback(new nsMainThreadPtrHolder<nsIFaviconDataCallback>(
          "AsyncCopyFavicons::mCallback", aCallback)) {
  MOZ_ASSERT(NS_IsMainThread());
}

NS_IMETHODIMP
AsyncCopyFavicons::Run() {
  MOZ_ASSERT(!NS_IsMainThread());

  IconData icon;

  // Ensure we'll callback and dispatch notifications to the main-thread.
  auto cleanup = MakeScopeExit([&]() {
    // If we bailed out early, just return a null icon uri, since we didn't
    // copy anything.
    if (!(icon.status & ICON_STATUS_ASSOCIATED)) {
      icon.spec.Truncate();
    }
    nsCOMPtr<nsIRunnable> event =
        new NotifyIconObservers(icon, mToPage, mCallback);
    NS_DispatchToMainThread(event);
  });

  RefPtr<Database> DB = Database::GetDatabase();
  NS_ENSURE_STATE(DB);

  nsresult rv = FetchPageInfo(DB, mToPage);
  if (rv == NS_ERROR_NOT_AVAILABLE || !mToPage.placeId) {
    // We have never seen this page, or we can't add this page to history and
    // and it's not a bookmark. We won't add the page.
    return NS_OK;
  }
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIURI> pageURI;
  rv = NS_NewURI(getter_AddRefs(pageURI), mFromPage.spec);
  NS_ENSURE_SUCCESS(rv, rv);

  // Get just one icon, to check whether the page has any, and to notify
  // later.
  rv = FetchIconPerSpec(DB, pageURI, icon, UINT16_MAX);
  NS_ENSURE_SUCCESS(rv, rv);

  if (icon.spec.IsEmpty()) {
    // There's nothing to copy.
    return NS_OK;
  }

  // Insert an entry in moz_pages_w_icons if needed.
  if (!mToPage.id) {
    // We need to create the page entry.
    nsCOMPtr<mozIStorageStatement> stmt;
    stmt = DB->GetStatement(
        "INSERT OR IGNORE INTO moz_pages_w_icons (page_url, page_url_hash) "
        "VALUES (:page_url, hash(:page_url)) ");
    NS_ENSURE_STATE(stmt);
    mozStorageStatementScoper scoper(stmt);
    rv = URIBinder::Bind(stmt, "page_url"_ns, mToPage.spec);
    NS_ENSURE_SUCCESS(rv, rv);
    rv = stmt->Execute();
    NS_ENSURE_SUCCESS(rv, rv);
    // Required to to fetch the id and the guid.
    rv = FetchPageInfo(DB, mToPage);
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // Create the relations.
  nsCOMPtr<mozIStorageStatement> stmt = DB->GetStatement(
      "INSERT OR IGNORE INTO moz_icons_to_pages (page_id, icon_id, expire_ms) "
      "SELECT :id, icon_id, expire_ms "
      "FROM moz_icons_to_pages "
      "WHERE page_id = (SELECT id FROM moz_pages_w_icons WHERE page_url_hash = "
      "hash(:url) AND page_url = :url) ");
  NS_ENSURE_STATE(stmt);
  mozStorageStatementScoper scoper(stmt);
  rv = stmt->BindInt64ByName("id"_ns, mToPage.id);
  NS_ENSURE_SUCCESS(rv, rv);
  rv = URIBinder::Bind(stmt, "url"_ns, mFromPage.spec);
  NS_ENSURE_SUCCESS(rv, rv);
  rv = stmt->Execute();
  NS_ENSURE_SUCCESS(rv, rv);

  // Setting this will make us send pageChanged notifications.
  // The scope exit will take care of the callback and notifications.
  icon.status |= ICON_STATUS_ASSOCIATED;

  return NS_OK;
}

}  // namespace places
}  // namespace mozilla