using System;
using System.Collections.ObjectModel;
using System.IO;
using System.Reflection;

using Unosquare.WiringPi.Native;

namespace Unosquare.WiringPi.Resources {
  /// <summary>
  /// Provides access to embedded assembly files.
  /// </summary>
  internal static class EmbeddedResources {
    /// <summary>
    /// Initializes static members of the <see cref="EmbeddedResources"/> class.
    /// </summary>
    static EmbeddedResources() => ResourceNames = new ReadOnlyCollection<String>(typeof(EmbeddedResources).Assembly.GetManifestResourceNames());

    /// <summary>
    /// Gets the resource names.
    /// </summary>
    /// <value>
    /// The resource names.
    /// </value>
    public static ReadOnlyCollection<String> ResourceNames {
      get;
    }

    /// <summary>
    /// Extracts all the file resources to the specified base path.
    /// </summary>
    public static void ExtractAll() {
      String basePath = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);
      Int32 executablePermissions = SysCall.StringToInteger("0777", IntPtr.Zero, 8);

      foreach(String resourceName in ResourceNames) {
        String filename = resourceName.Substring($"{typeof(EmbeddedResources).Namespace}.".Length);
        String targetPath = Path.Combine(basePath, filename);
        if(File.Exists(targetPath)) {
          return;
        }

        using(Stream stream = typeof(EmbeddedResources).Assembly.GetManifestResourceStream(resourceName)) {
          using(FileStream outputStream = File.OpenWrite(targetPath)) {
            stream?.CopyTo(outputStream);
          }

          try {
            _ = SysCall.Chmod(targetPath, (UInt32)executablePermissions);
          } catch {
            /* Ignore */
          }
        }
      }
    }
  }
}