// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <optional>
#include <string>
#include <vector>

#include "base/containers/to_vector.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/files/safe_base_name.h"
#include "base/strings/string_split.h"
#include "chrome/updater/activity_impl_util_posix.h"
#include "chrome/updater/updater_branding.h"
#include "chrome/updater/updater_scope.h"

namespace updater {
namespace {

// Discovers all system home directories by parsing /etc/passwd.
std::vector<base::FilePath> ReadHomeDirsFromPasswd() {
  std::string passwd_contents;
  if (!base::ReadFileToString(base::FilePath("/etc/passwd"),
                              &passwd_contents)) {
    return {};
  }

  // /etc/passwd has one line per user account, with seven colon-delimited
  // fields.
  std::vector<base::FilePath> home_dirs = base::ToVector(
      base::SplitString(passwd_contents, "\n",
                        base::WhitespaceHandling::TRIM_WHITESPACE,
                        base::SplitResult::SPLIT_WANT_NONEMPTY),
      [](const std::string& line) {
        std::vector<std::string> entries = base::SplitString(
            line, ":", base::WhitespaceHandling::KEEP_WHITESPACE,
            base::SplitResult::SPLIT_WANT_ALL);
        // The sixth field (index 5) is the user's home directory.
        return entries.size() == 7 ? base::FilePath(entries[5])
                                   : base::FilePath();
      });

  // Remove invalid paths.
  std::erase(home_dirs, base::FilePath());
  return home_dirs;
}
}  // namespace

std::vector<base::FilePath> GetHomeDirPaths(UpdaterScope scope) {
  switch (scope) {
    case UpdaterScope::kUser: {
      const base::FilePath path = base::GetHomeDir();
      if (path.empty()) {
        return {};
      }
      return {path};
    }
    case UpdaterScope::kSystem: {
      return ReadHomeDirsFromPasswd();
    }
  }
  return {};
}

std::optional<base::FilePath> GetActiveFile(const base::FilePath& home_dir,
                                            const std::string& id) {
  std::optional<base::SafeBaseName> basename = base::SafeBaseName::Create(id);
  if (!basename || basename->path() != base::FilePath(id) ||
      basename->empty() || basename->path() == base::FilePath(".")) {
    return std::nullopt;
  }
  return home_dir.Append(".local")
      .Append(COMPANY_SHORTNAME_STRING)
      .Append(PRODUCT_FULLNAME_STRING)
      .Append("Actives")
      .Append(*basename);
}

}  // namespace updater