/*
 * Copyright (C) 2022 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <android-base/file.h>
#include <android-base/logging.h>
#include <getopt.h>

#include <chrono>
#include <string>

#include "apex_constants.h"
#include "apex_file_repository.h"
#include "apexd_utils.h"
#include "com_android_apex.h"

using android::apex::kApexInfoList;
using android::apex::kManifestFilenamePb;
using android::apex::PathExists;
using android::apex::ReadDir;
using android::apex::ReadManifest;
using com::android::apex::ApexInfo;

void usage(const char* cmd) {
  std::cout << "Usage: " << cmd << " --root_dir=<dir>" << std::endl;
}

std::vector<ApexInfo> LoadFlattenedApexes(const std::string& root_dir);

// Create apex-info-list based on pre installed apexes
int main(int argc, char** argv) {
  android::base::InitLogging(argv, android::base::StdioLogger);
  auto severity = android::base::ERROR;
  static constexpr const char* kRootDir = "root_dir";

  static struct option long_options[] = {{kRootDir, required_argument, 0, 0},
                                         {0, 0, 0, 0}};

  std::map<std::string, std::string> opts;
  int index = 0;
  for (;;) {
    int c = getopt_long(argc, argv, "hv", long_options, &index);

    if (c == -1) {
      break;
    }
    switch (c) {
      case 0:
        opts[long_options[index].name] = optarg;
        break;
      case 'h':
        usage(argv[0]);
        return 0;
      case 'v':
        severity = android::base::VERBOSE;
        break;
      case '?':
      default:
        usage(argv[0]);
        return -1;
    }
  }

  if (opts.size() != 1) {
    usage(argv[0]);
    return -1;
  }
  android::base::SetMinimumLogSeverity(severity);
  std::string root_dir;
  if (!android::base::Realpath(opts[kRootDir], &root_dir)) {
    LOG(ERROR) << "Failed to resolve realpath for root directory "
               << opts[kRootDir];
    return -1;
  }

  const std::string apex_root =
      root_dir + std::string(::android::apex::kApexRoot);

  // Ignore duplicate definitions to support multi-installed APEXes, the first
  // found APEX package for a name is chosen.
  const bool ignore_duplicate_definitions = true;
  ::android::apex::ApexFileRepository repo(apex_root,
                                           ignore_duplicate_definitions);

  std::vector<std::string> prebuilt_dirs{
      ::android::apex::kApexPackageBuiltinDirs};

  // Add pre-installed apex directories
  for (auto& dir : prebuilt_dirs) {
    dir.insert(0, root_dir);
  }

  // Load .apex/.capex files first
  auto ret = repo.AddPreInstalledApex(prebuilt_dirs);
  if (!ret.ok()) {
    LOG(ERROR) << "Failed to add pre-installed apex directories";
    return -1;
  }

  std::vector<ApexInfo> apex_infos;
  for (const auto& [name, files] : repo.AllApexFilesByName()) {
    if (files.size() != 1) {
      LOG(ERROR) << "Multiple APEXs found for " << name;
      return -1;
    }

    const android::apex::ApexFile& apex = files[0];
    // Remove leading path (root_dir)
    const auto& path = apex.GetPath().substr(root_dir.length());
    const auto& manifest = apex.GetManifest();
    ApexInfo apex_info(manifest.name(), /* modulePath= */ path,
                       /* preinstalledModulePath= */ path, manifest.version(),
                       manifest.versionname(),
                       /* isFactory= */ true, /* isActive= */ true,
                       /*l astUpdateMillis= */ std::nullopt,
                       manifest.providesharedapexlibs());
    apex_infos.emplace_back(std::move(apex_info));
  }

  // As a second guess, try to load "flattened" apexes
  if (apex_infos.empty()) {
    apex_infos = LoadFlattenedApexes(root_dir);
  }

  std::stringstream xml;
  com::android::apex::ApexInfoList apex_info_list(apex_infos);
  com::android::apex::write(xml, apex_info_list);

  const std::string file_name = apex_root + "/" + kApexInfoList;
  android::base::unique_fd fd(TEMP_FAILURE_RETRY(
      open(file_name.c_str(), O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644)));

  if (fd.get() == -1) {
    PLOG(ERROR) << "Can't create " << file_name;
    return -1;
  }

  if (!android::base::WriteStringToFd(xml.str(), fd)) {
    PLOG(ERROR) << "Can't write to " << file_name;
    return -1;
  }

  return 0;
}

std::vector<ApexInfo> LoadFlattenedApexes(const std::string& root_dir) {
  std::vector<ApexInfo> apex_infos;

  for (const std::string& dir : ::android::apex::kApexPackageBuiltinDirs) {
    if (auto res = PathExists(root_dir + dir); !res.ok() || !*res) {
      continue;
    }

    auto dir_content = ReadDir(root_dir + dir, [](const auto& entry) {
      std::error_code ec;
      return entry.is_directory(ec);
    });

    if (!dir_content.ok()) {
      LOG(ERROR) << "Failed to scan " << dir << " : " << dir_content.error();
      continue;
    }

    // Sort to make sure that /apex/apex-info-list.xml generation doesn't depend
    // on the unstable directory scan.
    std::vector<std::string> entries = std::move(*dir_content);
    std::sort(entries.begin(), entries.end());

    for (const std::string& apex_dir : entries) {
      std::string manifest_file = apex_dir + "/" + kManifestFilenamePb;
      if (access(manifest_file.c_str(), F_OK) != 0) {
        PLOG(ERROR) << "Failed to access " << manifest_file;
        continue;
      }

      auto manifest = ReadManifest(manifest_file);
      if (!manifest.ok()) {
        LOG(ERROR) << "Failed to read apex manifest from " << manifest_file
                   << " : " << manifest.error();
        continue;
      }

      // Remove leading path (root_dir)
      const auto& path = apex_dir.substr(root_dir.length());
      apex_infos.emplace_back(manifest->name(), /* modulePath= */ path,
                              /* preinstalledModulePath= */ path,
                              /* versionCode= */ manifest->version(),
                              /* versionName= */ manifest->versionname(),
                              /* isFactory= */ true, /* isActive= */ true,
                              /* lastUpdateMillis= */ 0,
                              /* provideSharedApexLibs= */ false);
    }
  }
  return apex_infos;
}