// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/command_line.h"

#include <algorithm>
#include <array>
#include <ostream>
#include <string_view>

#include "base/check_op.h"
#include "base/compiler_specific.h"
#include "base/containers/contains.h"
#include "base/containers/span.h"
#include "base/debug/debugging_buildflags.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/notreached.h"
#include "base/numerics/checked_math.h"
#include "base/strings/strcat.h"
#include "base/strings/string_split.h"
#include "base/strings/string_tokenizer.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "build/build_config.h"

#if BUILDFLAG(IS_WIN)
#include <windows.h>

#include <shellapi.h>

#include "base/strings/string_util_win.h"
#endif  // BUILDFLAG(IS_WIN)

namespace base {

CommandLine* CommandLine::current_process_commandline_ = nullptr;

namespace {

DuplicateSwitchHandler* g_duplicate_switch_handler = nullptr;

constexpr CommandLine::CharType kSwitchTerminator[] = FILE_PATH_LITERAL("--");
constexpr CommandLine::CharType kSwitchValueSeparator[] =
    FILE_PATH_LITERAL("=");

// Since we use a lazy match, make sure that longer versions (like "--") are
// listed before shorter versions (like "-") of similar prefixes.
#if BUILDFLAG(IS_WIN)
// By putting slash last, we can control whether it is treaded as a switch
// value by changing the value of switch_prefix_count to be one less than
// the array size.
constexpr auto kSwitchPrefixes = std::to_array<CommandLine::StringViewType>({
    L"--",
    L"-",
    L"/",
});
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
// Unixes don't use slash as a switch.
constexpr auto kSwitchPrefixes = std::to_array<CommandLine::StringViewType>({
    "--",
    "-",
});
#endif
size_t switch_prefix_count = std::size(kSwitchPrefixes);

bool IsSwitchNameValid(std::string_view switch_name) {
  return ToLowerASCII(switch_name) == switch_name;
}

#if BUILDFLAG(IS_WIN)
// Switch string that specifies the single argument to the command line.
// If present, everything after this switch is interpreted as a single
// argument regardless of whitespace, quotes, etc. Used for launches from the
// Windows shell, which may have arguments with unencoded quotes that could
// otherwise unexpectedly be split into multiple arguments
// (https://crbug.com/937179).
constexpr CommandLine::CharType kSingleArgument[] =
    FILE_PATH_LITERAL("single-argument");
#endif  // BUILDFLAG(IS_WIN)

size_t GetSwitchPrefixLength(CommandLine::StringViewType string) {
  for (size_t i = 0; i < switch_prefix_count; ++i) {
    CommandLine::StringType prefix(kSwitchPrefixes[i]);
    if (string.substr(0, prefix.length()) == prefix) {
      return prefix.length();
    }
  }
  return 0;
}

// Fills in |switch_string| and |switch_value| if |string| is a switch.
// This will preserve the input switch prefix in the output |switch_string|.
bool IsSwitch(const CommandLine::StringType& string,
              CommandLine::StringType* switch_string,
              CommandLine::StringType* switch_value) {
  switch_string->clear();
  switch_value->clear();
  size_t prefix_length = GetSwitchPrefixLength(string);
  if (prefix_length == 0 || prefix_length == string.length()) {
    return false;
  }

  const size_t equals_position = string.find(kSwitchValueSeparator);
  *switch_string = string.substr(0, equals_position);
  if (equals_position != CommandLine::StringType::npos) {
    *switch_value = string.substr(equals_position + 1);
  }
  return true;
}

// Returns true iff |string| represents a switch with key
// |switch_key_without_prefix|, regardless of value.
bool IsSwitchWithKey(CommandLine::StringViewType string,
                     CommandLine::StringViewType switch_key_without_prefix) {
  size_t prefix_length = GetSwitchPrefixLength(string);
  if (prefix_length == 0 || prefix_length == string.length()) {
    return false;
  }

  const size_t equals_position = string.find(kSwitchValueSeparator);
  return string.substr(prefix_length, equals_position - prefix_length) ==
         switch_key_without_prefix;
}

#if BUILDFLAG(IS_WIN)
// Quotes a string as necessary for CommandLineToArgvW compatibility *on
// Windows*.
// http://msdn.microsoft.com/en-us/library/17w5ykft.aspx#parsing-c-command-line-arguments.
std::wstring QuoteForCommandLineToArgvWInternal(
    const std::wstring& arg,
    bool allow_unsafe_insert_sequences) {
  // Ensures that GetCommandLineString isn't used to generate command-line
  // strings for the Windows shell by checking for Windows insert sequences like
  // "%1". GetCommandLineStringForShell should be used instead to get a string
  // with the correct placeholder format for the shell.
  DCHECK(arg.size() != 2 || arg[0] != L'%' || allow_unsafe_insert_sequences);

  constexpr wchar_t kQuotableCharacters[] = L" \t\\\"";
  if (arg.find_first_of(kQuotableCharacters) == std::wstring::npos) {
    return arg;
  }

  std::wstring out(1, L'"');
  for (size_t i = 0; i < arg.size(); ++i) {
    if (arg[i] == L'\\') {
      // Finds the extent of this run of backslashes.
      size_t end = i + 1;
      while (end < arg.size() && arg[end] == L'\\') {
        ++end;
      }

      const size_t backslash_count = end - i;

      // Backslashes are escaped only if the run is followed by a double quote.
      // Since we also will end the string with a double quote, we escape for
      // either a double quote or the end of the string.
      const size_t backslash_multiplier =
          (end == arg.size() || arg[end] == L'"') ? 2 : 1;

      out.append(std::wstring(backslash_count * backslash_multiplier, L'\\'));

      // Advances `i` to one before `end` to balance `++i` in loop.
      i = end - 1;
    } else if (arg[i] == L'"') {
      out.append(LR"(\")");
    } else {
      out.push_back(arg[i]);
    }
  }

  out.push_back(L'"');

  return out;
}
#endif  // BUILDFLAG(IS_WIN)

}  // namespace

// static
void CommandLine::SetDuplicateSwitchHandler(
    std::unique_ptr<DuplicateSwitchHandler> new_duplicate_switch_handler) {
  delete g_duplicate_switch_handler;
  g_duplicate_switch_handler = new_duplicate_switch_handler.release();
}

CommandLine::CommandLine(NoProgram no_program) : argv_(1), begin_args_(1) {}

CommandLine::CommandLine(const FilePath& program) : argv_(1), begin_args_(1) {
  SetProgram(program);
}

CommandLine::CommandLine(int argc, const CommandLine::CharType* const* argv)
    : argv_(1), begin_args_(1) {
  // SAFETY: required from caller.
  UNSAFE_BUFFERS(InitFromArgv(argc, argv));
}

CommandLine::CommandLine(const StringVector& argv) : argv_(1), begin_args_(1) {
  InitFromArgv(argv);
}

CommandLine::CommandLine(const CommandLine& other) = default;
CommandLine::CommandLine(CommandLine&& other) noexcept
    :
#if BUILDFLAG(IS_WIN)
      raw_command_line_string_(
          std::exchange(other.raw_command_line_string_, StringViewType())),
      has_single_argument_switch_(
          std::exchange(other.has_single_argument_switch_, false)),
#endif  // BUILDFLAG(IS_WIN)
      argv_(std::exchange(other.argv_, StringVector(1))),
      switches_(std::move(other.switches_)),
      begin_args_(std::exchange(other.begin_args_, 1)) {
#if BUILDFLAG(ENABLE_COMMANDLINE_SEQUENCE_CHECKS)
  other.sequence_checker_.Detach();
#endif
}
CommandLine& CommandLine::operator=(const CommandLine& other) = default;
CommandLine& CommandLine::operator=(CommandLine&& other) noexcept {
#if BUILDFLAG(IS_WIN)
  raw_command_line_string_ =
      std::exchange(other.raw_command_line_string_, StringViewType());
  has_single_argument_switch_ =
      std::exchange(other.has_single_argument_switch_, false);
#endif  // BUILDFLAG(IS_WIN)
  argv_ = std::exchange(other.argv_, StringVector(1));
  switches_ = std::move(other.switches_);
  begin_args_ = std::exchange(other.begin_args_, 1);
#if BUILDFLAG(ENABLE_COMMANDLINE_SEQUENCE_CHECKS)
  other.sequence_checker_.Detach();
#endif
  return *this;
}
CommandLine::~CommandLine() = default;

#if BUILDFLAG(IS_WIN)
// static
void CommandLine::set_slash_is_not_a_switch() {
  // The last switch prefix should be slash, so adjust the size to skip it.
  static_assert(base::span(kSwitchPrefixes).back() == L"/",
                "Error: Last switch prefix is not a slash.");
  switch_prefix_count = std::size(kSwitchPrefixes) - 1;
}

// static
void CommandLine::InitUsingArgvForTesting(int argc, const char* const* argv) {
  DCHECK(!current_process_commandline_);
  current_process_commandline_ = new CommandLine(NO_PROGRAM);
  // On Windows we need to convert the command line arguments to std::wstring.
  CommandLine::StringVector argv_vector;
  for (int i = 0; i < argc; ++i) {
    // SAFETY: required from caller.
    argv_vector.push_back(UTF8ToWide(UNSAFE_BUFFERS(argv[i])));
  }
  current_process_commandline_->InitFromArgv(argv_vector);
}
#endif  // BUILDFLAG(IS_WIN)

// static
bool CommandLine::Init(int argc, const char* const* argv) {
  if (current_process_commandline_) {
    // If this is intentional, Reset() must be called first. If we are using
    // the shared build mode, we have to share a single object across multiple
    // shared libraries.
    return false;
  }

  current_process_commandline_ = new CommandLine(NO_PROGRAM);
#if BUILDFLAG(IS_WIN)
  current_process_commandline_->ParseFromString(::GetCommandLineW());
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  // SAFETY: required from caller.
  UNSAFE_BUFFERS(current_process_commandline_->InitFromArgv(argc, argv));
#else
#error Unsupported platform
#endif

  return true;
}

// static
void CommandLine::Reset() {
  DCHECK(current_process_commandline_);
  delete current_process_commandline_;
  current_process_commandline_ = nullptr;
}

// static
CommandLine* CommandLine::ForCurrentProcess() {
  DCHECK(current_process_commandline_);
  return current_process_commandline_;
}

// static
bool CommandLine::InitializedForCurrentProcess() {
  return !!current_process_commandline_;
}

// static
CommandLine CommandLine::FromArgvWithoutProgram(const StringVector& argv) {
  CommandLine cmd(NO_PROGRAM);
  cmd.AppendSwitchesAndArguments(argv);
  return cmd;
}

#if BUILDFLAG(IS_WIN)
// static
CommandLine CommandLine::FromString(StringViewType command_line) {
  CommandLine cmd(NO_PROGRAM);
  cmd.ParseFromString(command_line);
  return cmd;
}
#endif  // BUILDFLAG(IS_WIN)

void CommandLine::InitFromArgv(int argc,
                               const CommandLine::CharType* const* argv) {
  StringVector new_argv;
  for (int i = 0; i < argc; ++i) {
    // SAFETY: required from caller.
    new_argv.push_back(UNSAFE_BUFFERS(argv[i]));
  }
  InitFromArgv(new_argv);
}

void CommandLine::InitFromArgv(const StringVector& argv) {
  argv_ = StringVector(1);
  switches_.clear();
  begin_args_ = 1;
  SetProgram(argv.empty() ? FilePath() : FilePath(argv[0]));
  if (!argv.empty()) {
    AppendSwitchesAndArguments(span(argv).subspan<1>());
  }
}

FilePath CommandLine::GetProgram() const {
  return FilePath(argv_[0]);
}

void CommandLine::SetProgram(const FilePath& program) {
#if BUILDFLAG(ENABLE_COMMANDLINE_SEQUENCE_CHECKS)
  sequence_checker_.Check();
#endif
#if BUILDFLAG(IS_WIN)
  argv_[0] = StringType(TrimWhitespace(program.value(), TRIM_ALL));
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  TrimWhitespaceASCII(program.value(), TRIM_ALL, &argv_[0]);
#else
#error Unsupported platform
#endif
}

bool CommandLine::HasSwitch(std::string_view switch_string) const {
  CHECK(IsSwitchNameValid(switch_string));
  return Contains(switches_, switch_string);
}

bool CommandLine::HasSwitch(const char switch_constant[]) const {
  return HasSwitch(std::string_view(switch_constant));
}

std::string CommandLine::GetSwitchValueASCII(
    std::string_view switch_string) const {
  StringType value = GetSwitchValueNative(switch_string);
#if BUILDFLAG(IS_WIN)
  if (!IsStringASCII(base::AsStringPiece16(value))) {
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  if (!IsStringASCII(value)) {
#endif
    DLOG(WARNING) << "Value of switch (" << switch_string << ") must be ASCII.";
    return std::string();
  }
#if BUILDFLAG(IS_WIN)
  return WideToUTF8(value);
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  return value;
#endif
}

std::string CommandLine::GetSwitchValueUTF8(
    std::string_view switch_string) const {
  StringType value = GetSwitchValueNative(switch_string);

#if BUILDFLAG(IS_WIN)
  const std::string maybe_utf8_value = WideToUTF8(value);
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  const std::string maybe_utf8_value = value;
#endif

  if (!IsStringUTF8(maybe_utf8_value)) {
    DLOG(WARNING) << "Value of switch (" << switch_string << ") is not UTF8.";
    return {};
  }
  return maybe_utf8_value;
}

FilePath CommandLine::GetSwitchValuePath(std::string_view switch_string) const {
  return FilePath(GetSwitchValueNative(switch_string));
}

CommandLine::StringType CommandLine::GetSwitchValueNative(
    std::string_view switch_string) const {
  CHECK(IsSwitchNameValid(switch_string));

  auto result = switches_.find(switch_string);
  return result == switches_.end() ? StringType() : result->second;
}

void CommandLine::AppendSwitch(std::string_view switch_string) {
  AppendSwitchNative(switch_string, StringType());
}

void CommandLine::AppendSwitchPath(std::string_view switch_string,
                                   const FilePath& path) {
  AppendSwitchNative(switch_string, path.value());
}

void CommandLine::AppendSwitchNative(std::string_view switch_string,
                                     CommandLine::StringViewType value) {
#if BUILDFLAG(ENABLE_COMMANDLINE_SEQUENCE_CHECKS)
  sequence_checker_.Check();
#endif
#if BUILDFLAG(IS_WIN)
  const std::string switch_key = ToLowerASCII(switch_string);
  StringType combined_switch_string(UTF8ToWide(switch_key));
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  std::string_view switch_key = switch_string;
  StringType combined_switch_string(switch_key);
#endif
  size_t prefix_length = GetSwitchPrefixLength(combined_switch_string);
  auto key = switch_key.substr(prefix_length);
  if (g_duplicate_switch_handler) {
    g_duplicate_switch_handler->ResolveDuplicate(key, value,
                                                 switches_[std::string(key)]);
  } else {
    switches_[std::string(key)] = StringType(value);
  }

  // Preserve existing switch prefixes in |argv_|; only append one if necessary.
  if (prefix_length == 0) {
    combined_switch_string.insert(0, kSwitchPrefixes[0].data(),
                                  kSwitchPrefixes[0].size());
  }
  if (!value.empty()) {
    base::StrAppend(&combined_switch_string, {kSwitchValueSeparator, value});
  }
  // Append the switch and update the switches/arguments divider |begin_args_|.
  argv_.insert(argv_.begin() + begin_args_, combined_switch_string);
  begin_args_ = (CheckedNumeric(begin_args_) + 1).ValueOrDie();
}

void CommandLine::AppendSwitchASCII(std::string_view switch_string,
                                    std::string_view value_string) {
  AppendSwitchUTF8(switch_string, value_string);
}

void CommandLine::AppendSwitchUTF8(std::string_view switch_string,
                                   std::string_view value_string) {
  DCHECK(IsStringUTF8(value_string))
      << "Switch (" << switch_string << ") value (" << value_string
      << ") is not UTF8.";
#if BUILDFLAG(IS_WIN)
  AppendSwitchNative(switch_string, UTF8ToWide(value_string));
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  AppendSwitchNative(switch_string, value_string);
#else
#error Unsupported platform
#endif
}

void CommandLine::RemoveSwitch(std::string_view switch_key_without_prefix) {
#if BUILDFLAG(ENABLE_COMMANDLINE_SEQUENCE_CHECKS)
  sequence_checker_.Check();
#endif
  CHECK(IsSwitchNameValid(switch_key_without_prefix));

#if BUILDFLAG(IS_WIN)
  StringType switch_key_native = UTF8ToWide(switch_key_without_prefix);
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  StringType switch_key_native(switch_key_without_prefix);
#endif

  DCHECK_EQ(0u, GetSwitchPrefixLength(switch_key_native));
  auto it = switches_.find(switch_key_without_prefix);
  if (it == switches_.end()) {
    return;
  }
  switches_.erase(it);
  // Also erase from the switches section of |argv_| and update |begin_args_|
  // accordingly.
  // Switches in |argv_| have indices [1, begin_args_).
  auto argv_switches_begin = argv_.begin() + 1;
  auto argv_switches_end = argv_.begin() + begin_args_;
  DCHECK(argv_switches_begin <= argv_switches_end);
  DCHECK(argv_switches_end <= argv_.end());
  auto expell = std::remove_if(argv_switches_begin, argv_switches_end,
                               [&switch_key_native](const StringType& arg) {
                                 return IsSwitchWithKey(arg, switch_key_native);
                               });
  if (expell == argv_switches_end) {
    NOTREACHED();
  }
  begin_args_ -= argv_switches_end - expell;
  argv_.erase(expell, argv_switches_end);
}

void CommandLine::CopySwitchesFrom(const CommandLine& source,
                                   span<const char* const> switches) {
  for (const char* entry : switches) {
    if (source.HasSwitch(entry)) {
      AppendSwitchNative(entry, source.GetSwitchValueNative(entry));
    }
  }
}

CommandLine::StringVector CommandLine::GetArgs() const {
  // Gather all arguments after the last switch (may include kSwitchTerminator).
  StringVector args(argv_.begin() + begin_args_, argv_.end());
  // Erase only the first kSwitchTerminator (maybe "--" is a legitimate page?)
  auto switch_terminator = std::ranges::find(args, kSwitchTerminator);
  if (switch_terminator != args.end()) {
    args.erase(switch_terminator);
  }
  return args;
}

void CommandLine::AppendArg(std::string_view value) {
#if BUILDFLAG(IS_WIN)
  DCHECK(IsStringUTF8(value));
  AppendArgNative(UTF8ToWide(value));
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
  AppendArgNative(value);
#else
#error Unsupported platform
#endif
}

void CommandLine::AppendArgPath(const FilePath& path) {
  AppendArgNative(path.value());
}

void CommandLine::AppendArgNative(StringViewType value) {
#if BUILDFLAG(ENABLE_COMMANDLINE_SEQUENCE_CHECKS)
  sequence_checker_.Check();
#endif
  argv_.emplace_back(value);
}

void CommandLine::AppendArguments(const CommandLine& other,
                                  bool include_program) {
  if (include_program) {
    SetProgram(other.GetProgram());
  }
  if (!other.argv().empty()) {
    AppendSwitchesAndArguments(span(other.argv()).subspan<1>());
  }
}

void CommandLine::PrependWrapper(StringViewType wrapper) {
#if BUILDFLAG(ENABLE_COMMANDLINE_SEQUENCE_CHECKS)
  sequence_checker_.Check();
#endif
  if (wrapper.empty()) {
    return;
  }
  // Split the wrapper command based on whitespace (with quoting).
  // StringViewType does not currently work directly with StringTokenizerT.
  using CommandLineTokenizer =
      StringTokenizerT<StringType, StringType::const_iterator>;
  StringType wrapper_string(wrapper);
  CommandLineTokenizer tokenizer(wrapper_string, FILE_PATH_LITERAL(" "));
  tokenizer.set_quote_chars(FILE_PATH_LITERAL("'\""));
  std::vector<StringType> wrapper_argv;
  while (std::optional<StringViewType> token = tokenizer.GetNextTokenView()) {
    wrapper_argv.emplace_back(token.value());
  }

  // Prepend the wrapper and update the switches/arguments |begin_args_|.
  argv_.insert(argv_.begin(), wrapper_argv.begin(), wrapper_argv.end());
  begin_args_ += wrapper_argv.size();
}

#if BUILDFLAG(IS_WIN)
void CommandLine::ParseFromString(StringViewType command_line) {
  command_line = TrimWhitespace(command_line, TRIM_ALL);
  if (command_line.empty()) {
    return;
  }
  raw_command_line_string_ = command_line;

  int num_args = 0;
  wchar_t** args = NULL;
  // When calling CommandLineToArgvW, use the apiset if available.
  // Doing so will bypass loading shell32.dll on Windows.
  HMODULE downlevel_shell32_dll =
      ::LoadLibraryEx(L"api-ms-win-downlevel-shell32-l1-1-0.dll", nullptr,
                      LOAD_LIBRARY_SEARCH_SYSTEM32);
  if (downlevel_shell32_dll) {
    auto command_line_to_argv_w_proc =
        reinterpret_cast<decltype(::CommandLineToArgvW)*>(
            ::GetProcAddress(downlevel_shell32_dll, "CommandLineToArgvW"));
    if (command_line_to_argv_w_proc) {
      args = command_line_to_argv_w_proc(command_line.data(), &num_args);
    }
  } else {
    // Since the apiset is not available, allow the delayload of shell32.dll
    // to take place.
    args = ::CommandLineToArgvW(command_line.data(), &num_args);
  }

  DPLOG_IF(FATAL, !args) << "CommandLineToArgvW failed on command line: "
                         << command_line;
  StringVector argv(args, UNSAFE_TODO(args + num_args));
  InitFromArgv(argv);
  raw_command_line_string_ = StringViewType();
  LocalFree(args);

  if (downlevel_shell32_dll) {
    ::FreeLibrary(downlevel_shell32_dll);
  }
}

#endif  // BUILDFLAG(IS_WIN)

void CommandLine::AppendSwitchesAndArguments(span<const StringType> argv) {
  bool parse_switches = true;
#if BUILDFLAG(IS_WIN)
  const bool is_parsed_from_string = !raw_command_line_string_.empty();
#endif
  for (StringType arg : argv) {
#if BUILDFLAG(IS_WIN)
    arg = CommandLine::StringType(TrimWhitespace(arg, TRIM_ALL));
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
    TrimWhitespaceASCII(arg, TRIM_ALL, &arg);
#endif

    CommandLine::StringType switch_string;
    CommandLine::StringType switch_value;
    parse_switches &= (arg != kSwitchTerminator);
    if (parse_switches && IsSwitch(arg, &switch_string, &switch_value)) {
#if BUILDFLAG(IS_WIN)
      if (is_parsed_from_string &&
          IsSwitchWithKey(switch_string, kSingleArgument)) {
        ParseAsSingleArgument(switch_string);
        return;
      }
      AppendSwitchNative(WideToUTF8(switch_string), switch_value);
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
      AppendSwitchNative(switch_string, switch_value);
#else
#error Unsupported platform
#endif
    } else {
      AppendArgNative(arg);
    }
  }
}

CommandLine::StringType CommandLine::GetArgumentsStringInternal(
    bool allow_unsafe_insert_sequences) const {
  StringType params;
  // Append switches and arguments.
  bool parse_switches = true;
#if BUILDFLAG(IS_WIN)
  bool appended_single_argument_switch = false;
#endif

  for (size_t i = 1; i < argv_.size(); ++i) {
    StringType arg = argv_[i];
    StringType switch_string;
    StringType switch_value;
    parse_switches &= arg != kSwitchTerminator;
    if (i > 1) {
      params.append(FILE_PATH_LITERAL(" "));
    }
    if (parse_switches && IsSwitch(arg, &switch_string, &switch_value)) {
      params.append(switch_string);
      if (!switch_value.empty()) {
#if BUILDFLAG(IS_WIN)
        switch_value = QuoteForCommandLineToArgvWInternal(
            switch_value, allow_unsafe_insert_sequences);
#endif
        params.append(kSwitchValueSeparator + switch_value);
      }
    } else {
#if BUILDFLAG(IS_WIN)
      if (has_single_argument_switch_) {
        // Check that we don't have multiple arguments when
        // `has_single_argument_switch_` is true.
        DCHECK(!appended_single_argument_switch);
        appended_single_argument_switch = true;
        params.append(base::StrCat(
            {kSwitchPrefixes[0], kSingleArgument, FILE_PATH_LITERAL(" ")}));
      } else {
        arg = QuoteForCommandLineToArgvWInternal(arg,
                                                 allow_unsafe_insert_sequences);
      }
#endif
      params.append(arg);
    }
  }
  return params;
}

CommandLine::StringType CommandLine::GetCommandLineString() const {
  StringType string(argv_[0]);
#if BUILDFLAG(IS_WIN)
  string = QuoteForCommandLineToArgvWInternal(
      string,
      /*allow_unsafe_insert_sequences=*/false);
#endif
  StringType params(GetArgumentsString());
  if (!params.empty()) {
    string.append(FILE_PATH_LITERAL(" "));
    string.append(params);
  }
  return string;
}

#if BUILDFLAG(IS_WIN)
// static
std::wstring CommandLine::QuoteForCommandLineToArgvW(const std::wstring& arg) {
  return QuoteForCommandLineToArgvWInternal(
      arg, /*allow_unsafe_insert_sequences=*/false);
}

// NOTE: this function is used to set Chrome's open command in the registry
// during update. Any change to the syntax must be compatible with the prior
// version (i.e., any new syntax must be understood by older browsers expecting
// the old syntax, and the new browser must still handle the old syntax), as
// old versions are likely to persist, e.g., immediately after background
// update, when parsing command lines for other channels, when uninstalling web
// applications installed using the old syntax, etc.
CommandLine::StringType CommandLine::GetCommandLineStringForShell() const {
  DCHECK(GetArgs().empty());
  StringType command_line_string = GetCommandLineString();
  return command_line_string + FILE_PATH_LITERAL(" ") +
         StringType(kSwitchPrefixes[0]) + kSingleArgument +
         FILE_PATH_LITERAL(" %1");
}

CommandLine::StringType
CommandLine::GetCommandLineStringWithUnsafeInsertSequences() const {
  StringType string(argv_[0]);
  string = QuoteForCommandLineToArgvWInternal(
      string,
      /*allow_unsafe_insert_sequences=*/true);
  StringType params(
      GetArgumentsStringInternal(/*allow_unsafe_insert_sequences=*/true));
  if (!params.empty()) {
    string.append(FILE_PATH_LITERAL(" "));
    string.append(params);
  }
  return string;
}
#endif  // BUILDFLAG(IS_WIN)

CommandLine::StringType CommandLine::GetArgumentsString() const {
  return GetArgumentsStringInternal(/*allow_unsafe_insert_sequences=*/false);
}

#if BUILDFLAG(IS_WIN)
void CommandLine::ParseAsSingleArgument(
    const CommandLine::StringType& single_arg_switch) {
  DCHECK(!raw_command_line_string_.empty());

  // Remove any previously parsed arguments.
  argv_.resize(static_cast<size_t>(begin_args_));

  // Locate "--single-argument" in the process's raw command line. Results are
  // unpredictable if "--single-argument" appears as part of a previous
  // argument or switch.
  const size_t single_arg_switch_position =
      raw_command_line_string_.find(single_arg_switch);
  DCHECK_NE(single_arg_switch_position, StringType::npos);

  // Append the portion of the raw command line that starts one character past
  // "--single-argument" as the one and only argument, or return if no
  // argument is present.
  const size_t arg_position =
      single_arg_switch_position + single_arg_switch.length() + 1;
  if (arg_position >= raw_command_line_string_.length()) {
    return;
  }
  has_single_argument_switch_ = true;
  const StringViewType arg = raw_command_line_string_.substr(arg_position);
  if (!arg.empty()) {
    AppendArgNative(arg);
  }
}
#endif  // BUILDFLAG(IS_WIN)

void CommandLine::DetachFromCurrentSequence() {
#if BUILDFLAG(ENABLE_COMMANDLINE_SEQUENCE_CHECKS)
  sequence_checker_.Detach();
#endif  // BUILDFLAG(ENABLE_COMMANDLINE_SEQUENCE_CHECKS)
}

}  // namespace base