// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/ui/elide_url.h"

#include "base/logging.h"
#include "base/strings/string_split.h"
#include "base/strings/utf_string_conversions.h"
#include "net/base/escape.h"
#include "net/base/net_util.h"
#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
#include "ui/gfx/text_elider.h"
#include "ui/gfx/text_utils.h"
#include "url/gurl.h"

using base::UTF8ToUTF16;
using gfx::ElideText;
using gfx::GetStringWidthF;
using gfx::kEllipsisUTF16;
using gfx::kForwardSlash;

namespace {

const base::char16 kDot = '.';

// Build a path from the first |num_components| elements in |path_elements|.
// Prepends |path_prefix|, appends |filename|, inserts ellipsis if appropriate.
base::string16 BuildPathFromComponents(
    const base::string16& path_prefix,
    const std::vector<base::string16>& path_elements,
    const base::string16& filename,
    size_t num_components) {
  // Add the initial elements of the path.
  base::string16 path = path_prefix;

  // Build path from first |num_components| elements.
  for (size_t j = 0; j < num_components; ++j)
    path += path_elements[j] + kForwardSlash;

  // Add |filename|, ellipsis if necessary.
  if (num_components != (path_elements.size() - 1))
    path += base::string16(kEllipsisUTF16) + kForwardSlash;
  path += filename;

  return path;
}

// Takes a prefix (Domain, or Domain+subdomain) and a collection of path
// components and elides if possible. Returns a string containing the longest
// possible elided path, or an empty string if elision is not possible.
base::string16 ElideComponentizedPath(
    const base::string16& url_path_prefix,
    const std::vector<base::string16>& url_path_elements,
    const base::string16& url_filename,
    const base::string16& url_query,
    const gfx::FontList& font_list,
    float available_pixel_width) {
  const size_t url_path_number_of_elements = url_path_elements.size();

  CHECK(url_path_number_of_elements);
  for (size_t i = url_path_number_of_elements - 1; i > 0; --i) {
    base::string16 elided_path = BuildPathFromComponents(url_path_prefix,
        url_path_elements, url_filename, i);
    if (available_pixel_width >= GetStringWidthF(elided_path, font_list))
      return ElideText(elided_path + url_query, font_list,
                       available_pixel_width, gfx::ELIDE_TAIL);
  }

  return base::string16();
}

// Splits the hostname in the |url| into sub-strings for the full hostname,
// the domain (TLD+1), and the subdomain (everything leading the domain).
void SplitHost(const GURL& url,
               base::string16* url_host,
               base::string16* url_domain,
               base::string16* url_subdomain) {
  // Get Host.
  *url_host = UTF8ToUTF16(url.host());

  // Get domain and registry information from the URL.
  *url_domain = UTF8ToUTF16(
      net::registry_controlled_domains::GetDomainAndRegistry(
          url, net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES));
  if (url_domain->empty())
    *url_domain = *url_host;

  // Add port if required.
  if (!url.port().empty()) {
    *url_host += UTF8ToUTF16(":" + url.port());
    *url_domain += UTF8ToUTF16(":" + url.port());
  }

  // Get sub domain.
  const size_t domain_start_index = url_host->find(*url_domain);
  base::string16 kWwwPrefix = UTF8ToUTF16("www.");
  if (domain_start_index != base::string16::npos)
    *url_subdomain = url_host->substr(0, domain_start_index);
  if ((*url_subdomain == kWwwPrefix || url_subdomain->empty() ||
      url.SchemeIsFile())) {
    url_subdomain->clear();
  }
}

}  // namespace

// TODO(pkasting): http://crbug.com/77883 This whole function gets
// kerning/ligatures/etc. issues potentially wrong by assuming that the width of
// a rendered string is always the sum of the widths of its substrings.  Also I
// suspect it could be made simpler.
base::string16 ElideUrl(const GURL& url,
                        const gfx::FontList& font_list,
                        float available_pixel_width,
                        const std::string& languages) {
  // Get a formatted string and corresponding parsing of the url.
  url::Parsed parsed;
  const base::string16 url_string =
      net::FormatUrl(url, languages, net::kFormatUrlOmitAll,
                     net::UnescapeRule::SPACES, &parsed, NULL, NULL);
  if (available_pixel_width <= 0)
    return url_string;

  // If non-standard, return plain eliding.
  if (!url.IsStandard())
    return ElideText(url_string, font_list, available_pixel_width,
                     gfx::ELIDE_TAIL);

  // Now start eliding url_string to fit within available pixel width.
  // Fist pass - check to see whether entire url_string fits.
  const float pixel_width_url_string = GetStringWidthF(url_string, font_list);
  if (available_pixel_width >= pixel_width_url_string)
    return url_string;

  // Get the path substring, including query and reference.
  const size_t path_start_index = parsed.path.begin;
  const size_t path_len = parsed.path.len;
  base::string16 url_path_query_etc = url_string.substr(path_start_index);
  base::string16 url_path = url_string.substr(path_start_index, path_len);

  // Return general elided text if url minus the query fits.
  const base::string16 url_minus_query =
      url_string.substr(0, path_start_index + path_len);
  if (available_pixel_width >= GetStringWidthF(url_minus_query, font_list))
    return ElideText(url_string, font_list, available_pixel_width,
                     gfx::ELIDE_TAIL);

  base::string16 url_host;
  base::string16 url_domain;
  base::string16 url_subdomain;
  SplitHost(url, &url_host, &url_domain, &url_subdomain);

  // If this is a file type, the path is now defined as everything after ":".
  // For example, "C:/aa/aa/bb", the path is "/aa/bb/cc". Interesting, the
  // domain is now C: - this is a nice hack for eliding to work pleasantly.
  if (url.SchemeIsFile()) {
    // Split the path string using ":"
    std::vector<base::string16> file_path_split;
    base::SplitString(url_path, ':', &file_path_split);
    if (file_path_split.size() > 1) {  // File is of type "file:///C:/.."
      url_host.clear();
      url_domain.clear();
      url_subdomain.clear();

      const base::string16 kColon = UTF8ToUTF16(":");
      url_host = url_domain = file_path_split.at(0).substr(1) + kColon;
      url_path_query_etc = url_path = file_path_split.at(1);
    }
  }

  // Second Pass - remove scheme - the rest fits.
  const float pixel_width_url_host = GetStringWidthF(url_host, font_list);
  const float pixel_width_url_path = GetStringWidthF(url_path_query_etc,
                                                     font_list);
  if (available_pixel_width >=
      pixel_width_url_host + pixel_width_url_path)
    return url_host + url_path_query_etc;

  // Third Pass: Subdomain, domain and entire path fits.
  const float pixel_width_url_domain = GetStringWidthF(url_domain, font_list);
  const float pixel_width_url_subdomain =
      GetStringWidthF(url_subdomain, font_list);
  if (available_pixel_width >=
      pixel_width_url_subdomain + pixel_width_url_domain +
      pixel_width_url_path)
    return url_subdomain + url_domain + url_path_query_etc;

  // Query element.
  base::string16 url_query;
  const float kPixelWidthDotsTrailer = GetStringWidthF(
      base::string16(kEllipsisUTF16), font_list);
  if (parsed.query.is_nonempty()) {
    url_query = UTF8ToUTF16("?") + url_string.substr(parsed.query.begin);
    if (available_pixel_width >=
        (pixel_width_url_subdomain + pixel_width_url_domain +
         pixel_width_url_path - GetStringWidthF(url_query, font_list))) {
      return ElideText(url_subdomain + url_domain + url_path_query_etc,
                       font_list, available_pixel_width, gfx::ELIDE_TAIL);
    }
  }

  // Parse url_path using '/'.
  std::vector<base::string16> url_path_elements;
  base::SplitString(url_path, kForwardSlash, &url_path_elements);

  // Get filename - note that for a path ending with /
  // such as www.google.com/intl/ads/, the file name is ads/.
  size_t url_path_number_of_elements = url_path_elements.size();
  DCHECK(url_path_number_of_elements != 0);
  base::string16 url_filename;
  if ((url_path_elements.at(url_path_number_of_elements - 1)).length() > 0) {
    url_filename = *(url_path_elements.end() - 1);
  } else if (url_path_number_of_elements > 1) {  // Path ends with a '/'.
    url_filename = url_path_elements.at(url_path_number_of_elements - 2) +
        kForwardSlash;
    url_path_number_of_elements--;
  }
  DCHECK(url_path_number_of_elements != 0);

  const size_t kMaxNumberOfUrlPathElementsAllowed = 1024;
  if (url_path_number_of_elements <= 1 ||
      url_path_number_of_elements > kMaxNumberOfUrlPathElementsAllowed) {
    // No path to elide, or too long of a path (could overflow in loop below)
    // Just elide this as a text string.
    return ElideText(url_subdomain + url_domain + url_path_query_etc, font_list,
                     available_pixel_width, gfx::ELIDE_TAIL);
  }

  // Start eliding the path and replacing elements by ".../".
  const base::string16 kEllipsisAndSlash =
      base::string16(kEllipsisUTF16) + kForwardSlash;
  const float pixel_width_ellipsis_slash =
      GetStringWidthF(kEllipsisAndSlash, font_list);

  // Check with both subdomain and domain.
  base::string16 elided_path =
      ElideComponentizedPath(url_subdomain + url_domain, url_path_elements,
                             url_filename, url_query, font_list,
                             available_pixel_width);
  if (!elided_path.empty())
    return elided_path;

  // Check with only domain.
  // If a subdomain is present, add an ellipsis before domain.
  // This is added only if the subdomain pixel width is larger than
  // the pixel width of kEllipsis. Otherwise, subdomain remains,
  // which means that this case has been resolved earlier.
  base::string16 url_elided_domain = url_subdomain + url_domain;
  if (pixel_width_url_subdomain > kPixelWidthDotsTrailer) {
    if (!url_subdomain.empty())
      url_elided_domain = kEllipsisAndSlash[0] + url_domain;
    else
      url_elided_domain = url_domain;

    elided_path = ElideComponentizedPath(url_elided_domain, url_path_elements,
                                         url_filename, url_query, font_list,
                                         available_pixel_width);

    if (!elided_path.empty())
      return elided_path;
  }

  // Return elided domain/.../filename anyway.
  base::string16 final_elided_url_string(url_elided_domain);
  const float url_elided_domain_width = GetStringWidthF(url_elided_domain,
                                                        font_list);

  // A hack to prevent trailing ".../...".
  if ((available_pixel_width - url_elided_domain_width) >
      pixel_width_ellipsis_slash + kPixelWidthDotsTrailer +
      GetStringWidthF(base::ASCIIToUTF16("UV"), font_list)) {
    final_elided_url_string += BuildPathFromComponents(base::string16(),
        url_path_elements, url_filename, 1);
  } else {
    final_elided_url_string += url_path;
  }

  return ElideText(final_elided_url_string, font_list, available_pixel_width,
                   gfx::ELIDE_TAIL);
}

base::string16 ElideHost(const GURL& url,
                         const gfx::FontList& font_list,
                         float available_pixel_width) {
  base::string16 url_host;
  base::string16 url_domain;
  base::string16 url_subdomain;
  SplitHost(url, &url_host, &url_domain, &url_subdomain);

  const float pixel_width_url_host = GetStringWidthF(url_host, font_list);
  if (available_pixel_width >= pixel_width_url_host)
    return url_host;

  if (url_subdomain.empty())
    return url_domain;

  const float pixel_width_url_domain = GetStringWidthF(url_domain, font_list);
  float subdomain_width = available_pixel_width - pixel_width_url_domain;
  if (subdomain_width <= 0)
    return base::string16(kEllipsisUTF16) + kDot + url_domain;

  const base::string16 elided_subdomain = ElideText(
      url_subdomain, font_list, subdomain_width, gfx::ELIDE_HEAD);
  return elided_subdomain + url_domain;
}