package emissary.util.os;
   
   import org.apache.commons.exec.OS;
   import org.apache.commons.lang3.StringUtils;
   
   import java.io.IOException;
   import java.nio.file.Files;
   import java.nio.file.Path;
   import java.util.Optional;
  import java.util.stream.Stream;
  
  public class OSReleaseUtil {
  
      private static final Path OS_RELEASE_PATH = Path.of("/etc/os-release");
  
      private OSReleaseUtil() {}
  
      /**
       * Finds and parses the VERSION_ID entry in the /etc/os-release file
       *
       * @return the VERSION_ID value
       */
      public static String getVersionId() {
          return getVersionId(OS_RELEASE_PATH);
      }
  
      static String getVersionId(Path osReleasePath) {
          String versionId = "UNKNOWN";
  
          if (Files.exists(osReleasePath)) {
              try (Stream<String> lines = Files.lines(osReleasePath)) {
                  Optional<String> versionIdOptional = lines.filter(line -> StringUtils.startsWith(line, "VERSION_ID")).findFirst();
                  if (versionIdOptional.isPresent()) {
                      String versionIdLine = versionIdOptional.get().replace("\"", "");
                      versionId = versionIdLine.substring(versionIdLine.indexOf("=") + 1);
                  }
              } catch (Exception ignored) {
                  // ignore
              }
          } else {
              // fallback to the os.version system property for mac support
              versionId = StringUtils.defaultIfBlank(System.getProperty("os.version"), versionId);
          }
          return versionId;
      }
  
      /**
       * Uses the VERSION_ID entry in the /etc/os-release file to determine the major OS version
       *
       * @return the major OS version
       */
      public static String getMajorReleaseVersion() {
          return getMajorReleaseVersion(OS_RELEASE_PATH);
      }
  
      static String getMajorReleaseVersion(Path osReleasePath) {
          try {
              return String.format("%.0f", Float.parseFloat(getVersionId(osReleasePath)));
          } catch (NumberFormatException e) {
              // support x.y.z format
              return StringUtils.substringBefore(getVersionId(osReleasePath), ".");
          }
      }
  
      /**
       * Use the /etc/os-release file to determine if the OS is Ubuntu
       *
       * @return true if ubuntu is found, false otherwise
       */
      public static boolean isUbuntu() {
          return isUbuntu(OS_RELEASE_PATH);
      }
  
      static boolean isUbuntu(Path osReleasePath) {
          return isOsName(osReleasePath, "ubuntu") || isOsLike(osReleasePath, "ubuntu");
      }
  
      /**
       * Use the /etc/os-release file to determine if the OS is CentOS
       *
       * @return true if CentOS is found, false otherwise
       */
      public static boolean isCentOs() {
          return isCentOs(OS_RELEASE_PATH);
      }
  
      static boolean isCentOs(Path osReleasePath) {
          return isOsName(osReleasePath, "centos");
      }
  
      /**
       * Use the /etc/os-release file to determine if the OS is RHEL
       *
       * @return true if RHEL is found, false otherwise
       */
      public static boolean isRhel() {
          return isRhel(OS_RELEASE_PATH);
      }
  
     static boolean isRhel(Path osReleasePath) {
         return isOsName(osReleasePath, "rhel");
     }
 
     /**
      * Determine if the OS is macos
      *
      * @return true if mac, false otherwise
      */
     public static boolean isMac() {
         return OS.isFamilyMac();
     }
 
     // checks against ID in /etc/os-release
     private static boolean isOsName(Path osReleasePath, String osName) {
         if (Files.exists(osReleasePath)) {
             try (Stream<String> lines = Files.lines(osReleasePath)) {
                 return lines.filter(line -> line.startsWith("ID=")).anyMatch(entry -> StringUtils.containsIgnoreCase(entry, osName));
             } catch (IOException ignored) {
                 // ignore
             }
         }
         return false;
     }
 
     // checks against ID_LIKE in /etc/os-release
     private static boolean isOsLike(Path osReleasePath, String osName) {
         if (Files.exists(osReleasePath)) {
             try (Stream<String> lines = Files.lines(osReleasePath)) {
                 return lines.filter(line -> line.startsWith("ID_LIKE=")).anyMatch(entry -> StringUtils.containsIgnoreCase(entry, osName));
             } catch (IOException ignored) {
                 // ignore
             }
         }
         return false;
     }
 }