components/autofill/core/browser/legal_message_line.cc

// Copyright 2016 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 "components/autofill/core/browser/legal_message_line.h"

#include "base/i18n/message_formatter.h"
#include "base/logging.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/values.h"

namespace autofill {
namespace {

// Replace "{0}", "{1}", ... in |template_icu| with corresponding strings
// from |display_texts|. Sets |out_message| to the resulting string, with
// start position of each replacement in |out_offsets|.
// Return false on failure. If false is returned then contents of |out_message|
// and |out_offsets| are undefined.
bool ReplaceTemplatePlaceholders(
    const base::string16& template_icu,
    const std::vector<base::string16>& display_texts,
    base::string16* out_message,
    std::vector<size_t>* out_offsets) {
  // Escape "$" -> "$$" for ReplaceStringPlaceholders().
  //
  // Edge cases:
  // 1. Two or more consecutive $ characters will be incorrectly expanded
  //    ("$$" -> "$$$$", which ReplaceStringPlaceholders() then turns into
  //    "$$$").
  //
  // 2. "${" will cause false to be returned. "${0}" will expand to "$${0}".
  //    FormatWithNumberedArgs() turns it into "$$$1", which
  //    ReplaceStringPlaceholders() then turns into "$$1" without doing the
  //    parameter replacement. This causes false to be returned because each
  //    parameter is not used exactly once.
  //
  // Both of these cases are noted in the header file, and are unlikely to
  // occur in any actual legal message.
  base::string16 template_icu_escaped;
  base::ReplaceChars(template_icu, base::ASCIIToUTF16("$"),
                     base::ASCIIToUTF16("$$"), &template_icu_escaped);

  // Replace "{0}" -> "$1", "{1}" -> "$2", ... to prepare |template_dollars|
  // for ReplaceStringPlaceholders().
  base::string16 template_dollars =
      base::i18n::MessageFormatter::FormatWithNumberedArgs(
          template_icu_escaped, "$1", "$2", "$3", "$4", "$5", "$6", "$7");

  // FormatWithNumberedArgs() returns an empty string on failure.
  if (template_dollars.empty() && !template_icu.empty())
    return false;

  // Replace "$1", "$2", ... with the display text of each parameter.
  *out_message = base::ReplaceStringPlaceholders(template_dollars,
                                                 display_texts, out_offsets);

  // Each parameter must be used exactly once. If a parameter is unused or
  // used more than once then it can't be determined which |offsets| entry
  // corresponds to which parameter.
  return out_offsets->size() == display_texts.size();
}

}  // namespace

LegalMessageLine::Link::Link(size_t start,
                             size_t end,
                             const std::string& url_spec)
    : range(start, end), url(url_spec) {}

LegalMessageLine::Link::~Link() {}

LegalMessageLine::LegalMessageLine() {}

LegalMessageLine::LegalMessageLine(const LegalMessageLine& other) = default;

LegalMessageLine::~LegalMessageLine() {}

// static
bool LegalMessageLine::Parse(const base::DictionaryValue& legal_message,
                             LegalMessageLines* out,
                             bool escape_apostrophes) {
  const base::ListValue* lines_list = nullptr;
  if (legal_message.GetList("line", &lines_list)) {
    LegalMessageLines lines;
    lines.reserve(lines_list->GetSize());
    for (size_t i = 0; i < lines_list->GetSize(); ++i) {
      lines.emplace_back(LegalMessageLine());
      const base::DictionaryValue* single_line;
      if (!lines_list->GetDictionary(i, &single_line) ||
          !lines.back().ParseLine(*single_line, escape_apostrophes))
        return false;
    }

    out->swap(lines);
  }

  return true;
}

bool LegalMessageLine::ParseLine(const base::DictionaryValue& line,
                                 bool escape_apostrophes) {
  DCHECK(text_.empty());
  DCHECK(links_.empty());

  // |display_texts| elements are the strings that will be substituted for
  // "{0}", "{1}", etc. in the template string.
  std::vector<base::string16> display_texts;

  // Process all the template parameters.
  const base::ListValue* template_parameters = nullptr;
  if (line.GetList("template_parameter", &template_parameters)) {
    display_texts.resize(template_parameters->GetSize());
    links_.reserve(template_parameters->GetSize());

    for (size_t parameter_index = 0;
         parameter_index < template_parameters->GetSize(); ++parameter_index) {
      const base::DictionaryValue* single_parameter;
      std::string url;
      if (!template_parameters->GetDictionary(parameter_index,
                                              &single_parameter) ||
          !single_parameter->GetString("display_text",
                                       &display_texts[parameter_index]) ||
          !single_parameter->GetString("url", &url))
        return false;

      links_.emplace_back(0, 0, url);
    }
  }

  // Read the template string. It's a small subset of the ICU message format
  // syntax.
  base::string16 template_icu;
  if (!line.GetString("template", &template_icu))
    return false;

  if (escape_apostrophes) {
    // The ICU standard counts "'{" as beginning an escaped string literal, even
    // if there's no closing apostrophe.  This fails legal message templates
    // where an apostrophe precedes the template parameter, like "l'{1}" in
    // Italian.  Therefore, when |escape_apostrophes| is true, escape all
    // apostrophes in the string by doubling them up.
    // http://www.icu-project.org/apiref/icu4c/messagepattern_8h.html#af6e0757e0eb81c980b01ee5d68a9978b
    base::ReplaceChars(template_icu, base::ASCIIToUTF16("'"),
                       base::ASCIIToUTF16("''"), &template_icu);
  }

  // Replace the placeholders in |template_icu| with strings from
  // |display_texts|, and store the start position of each replacement in
  // |offsets|.
  std::vector<size_t> offsets;
  if (!ReplaceTemplatePlaceholders(template_icu, display_texts, &text_,
                                   &offsets))
    return false;

  // Fill in range values for all links.
  for (size_t offset_index = 0; offset_index < offsets.size(); ++offset_index) {
    size_t range_start = offsets[offset_index];
    links_[offset_index].range = gfx::Range(
        range_start, range_start + display_texts[offset_index].size());
  }

  return true;
}

}  // namespace autofill