/*
 * Copyright 2023 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 "widevine_apex_info.h"

#include <android-base/file.h>
#include <android-base/strings.h>

#include "apex_manifest_minimal.pb.h"

using android::base::ConsumePrefix;
using android::base::ErrnoError;
using android::base::Error;
using android::base::GetExecutablePath;
using android::base::ReadFileToString;
using android::base::Result;
using apex::proto::ApexManifest;

namespace widevine::apex {

namespace {

Result<std::string> GetApexNameFromPath(const std::string& path) {
  std::string_view sv{path};
  if (!ConsumePrefix(&sv, "/apex/")) {
    return Error() << "Not found an apex name: " << path;
  }
  return std::string{sv.substr(0, sv.find('/'))};
}

Result<ApexManifest> ParseApexManifest(const std::string& manifest_path) {
  std::string content;
  if (!ReadFileToString(manifest_path, &content)) {
    return ErrnoError() << "Failed to read manifest file: " << manifest_path;
  }
  ApexManifest manifest;
  if (!manifest.ParseFromString(content)) {
    return Error() << "Can't parse APEX manifest: " << manifest_path;
  }
  return manifest;
}

}

Result<ApexInfo> GetApexInfo() {
  auto exe_path = GetExecutablePath();
  auto apex_name = GetApexNameFromPath(exe_path);
  if (!apex_name.ok()) {
    return apex_name.error();
  }
  auto manifest_path = fmt::format("/apex/{}/apex_manifest.pb", *apex_name);
  auto apex_manifest = ParseApexManifest(manifest_path);
  if (!apex_manifest.ok()) {
    return apex_manifest.error();
  }
  return ApexInfo {
    apex_manifest->name(),
    apex_manifest->version(),
  };
}

}  // namespace widevine::apex