// ****************************************************************

// Copyright 2008, Charlie Poole

// This is free software licensed under the NUnit license. You may

// obtain a copy of the license at http://nunit.org.

// ****************************************************************



using System.IO;



namespace NUnit.Core

{

    /// <summary>

    /// Abstract base for classes that capture text output

    /// and redirect it to a TextWriter.

    /// </summary>

    public abstract class TextCapture

    {

        #region Private Fields

        /// <summary>

        /// True if capture is enabled

        /// </summary>

        private bool enabled;



        /// <summary>

        /// The TextWriter to which text is redirected

        /// </summary>

        private TextWriter writer;

        #endregion



        #region Properties

        /// <summary>

        /// The TextWriter to which text is redirected

        /// </summary>

        public TextWriter Writer

        {

            get { return writer; }

            set

            {

                writer = value;



                if (writer != null && enabled)

                    StartCapture();

            }

        }



        /// <summary>

        /// Controls whether text is captured or not

        /// </summary>

        public bool Enabled

        {

            get { return enabled; }

            set

            {

                if (enabled != value)

                {

                    if (writer != null && enabled)

                        StopCapture();



                    enabled = value;



                    if (writer != null && enabled && DefaultThreshold != "Off")

                        StartCapture();

                }

            }

        }



        /// <summary>

        /// Returns the default threshold value, which represents

        /// the degree of verbosity of the output text stream.

        /// Returns "None" in the base class. Derived classes that

        /// support verbosity levels should override it.

        /// </summary>

        public virtual string DefaultThreshold

        {

            get { return "None"; }

        }

        #endregion



        #region Abstract Members

        /// <summary>

        /// Override this to perform whatever actions are needed

        /// to start capturing text and sending it to the Writer.

        /// </summary>

        protected abstract void StartCapture();



        /// <summary>

        /// Override this to perform whatever actions are needed

        /// to flush remaining output and stop capturing text.

        /// The Writer should not be changed, allowing capture

        /// to be restarted at a future point.

        /// </summary>

        protected abstract void StopCapture();

        #endregion

    }



}