using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;

namespace Nuclex.NAnt.Tasks {

  /// <summary>Invokes the Subversion command line client executable</summary>
  public static class Subversion {

    #region class ErrorCapturer

    /// <summary>Captures the error message reported by Subversion, if any</summary>
    private class ErrorCapturer {

      /// <summary>Called when Subversion outputs data to the stderr stream</summary>
      /// <param name="sender">Process that is outputting data</param>
      /// <param name="arguments">Contains the data that was sent to stderr</param>
      public void SubversionErrorDataReceived(
        object sender, DataReceivedEventArgs arguments
      ) {
        if(this.errorMessageBuilder == null) {
          this.errorMessageBuilder = new StringBuilder();
          this.errorMessageBuilder.AppendLine();
        }
        if(!string.IsNullOrEmpty(arguments.Data)) {
          this.errorMessageBuilder.AppendLine(arguments.Data);
          this.gotError = true;
        }
      }

      /// <summary>Called when Subversion outputs data to the stderr stream</summary>
      /// <param name="sender">Process that is outputting data</param>
      /// <param name="arguments">Contains the data that was sent to stderr</param>
      public void SubversionOutputDataReceived(
        object sender, DataReceivedEventArgs arguments
      ) {
        Debug.WriteLine("stdout: " + arguments.Data);
      }

      /// <summary>The error message if an error has occured</summary>
      public string ErrorMessage {
        get { return this.errorMessageBuilder.ToString(); }
      }

      /// <summary>Whether an error has occured at all</summary>
      public bool ErrorOccured {
        get { return this.gotError; }
      }

      /// <summary>True if an error has occured</summary>
      private bool gotError;
      /// <summary>The suspected error message from Subversion</summary>
      private StringBuilder errorMessageBuilder;

    }

    #endregion // class ErrorCapturer

    /// <summary>Quotes an argument for the subversion executable</summary>
    /// <param name="argument">Argument that will be quoted</param>
    /// <returns>The quoted argument</returns>
    public static string QuoteArgument(string argument) {
      int additional = Math.Max(argument.Length / 2, 3);
      StringBuilder builder = new StringBuilder(argument.Length + additional);

      builder.Append('"');
      //argument.IndexOf('"');
      builder.Append('"');

      return builder.ToString();
    }

    /// <summary>Runs the Subversion executable</summary>
    /// <param name="workingDirectory">Working directory in which to start Subversion</param>
    /// <param name="commandLine">Command line arguments to pass to Subversion</param>
    public static void Run(string workingDirectory, string commandLine) {

      ErrorCapturer errorCapturer = new ErrorCapturer();

      // Configure the startup options for the Subversion process
      Process subversion = new Process();
      subversion.StartInfo.Arguments = commandLine;
      subversion.StartInfo.CreateNoWindow = true;
      subversion.StartInfo.FileName = Helpers.SubversionLocator.Location;
      subversion.StartInfo.WorkingDirectory = workingDirectory;
      subversion.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
      subversion.StartInfo.RedirectStandardOutput = true;
      subversion.StartInfo.RedirectStandardError = true;
      subversion.StartInfo.UseShellExecute = false;
      subversion.OutputDataReceived += new DataReceivedEventHandler(
        errorCapturer.SubversionOutputDataReceived
      );
      subversion.ErrorDataReceived += new DataReceivedEventHandler(
        errorCapturer.SubversionErrorDataReceived
      );

      // Start the Subversion process and wait for it to end
      subversion.Start();
      subversion.BeginOutputReadLine();
      subversion.BeginErrorReadLine();
      subversion.WaitForExit();

      // Check if Subversion failed and throw an exception if it did
      int exitCode = subversion.ExitCode;
      if(exitCode != 0) {
        throw new InvalidOperationException(errorCapturer.ErrorMessage ?? "unknown error");
      }

    }

  }

} // namespace Nuclex.NAnt.Tasks