// ****************************************************************
// Copyright 2007, 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;
using System.Collections.Specialized;
using System.Configuration;
using System.IO;
using System.Diagnostics;
using System.Globalization;
using System.Security.Principal;
using System.Threading;

namespace NUnit.Core
{
	/// <summary>
	/// Helper class used to save and restore certain static or
	/// singleton settings in the environment that affect tests 
	/// or which might be changed by the user tests.
	/// 
	/// An internal class is used to hold settings and a stack
	/// of these objects is pushed and popped as Save and Restore
	/// are called.
	/// 
	/// Static methods for each setting forward to the internal 
	/// object on the top of the stack.
	/// </summary>
	public class TestExecutionContext
	{
		#region Static Fields

		/// <summary>
		/// The current context, head of the list of saved contexts.
		/// </summary>
        private static TestExecutionContext current = new TestExecutionContext();

        #endregion

        #region Instance Fields

        /// <summary>
        /// Indicates whether trace is enabled
        /// </summary>
        private bool tracing;

        /// <summary>
        /// Indicates whether logging is enabled
        /// </summary>
        //private bool logging;

        /// <summary>
        /// Destination for standard output
        /// </summary>
        private TextWriter outWriter;

        /// <summary>
        /// Destination for standard error
        /// </summary>
        private TextWriter errorWriter;

        /// <summary>
        /// Destination for Trace output
        /// </summary>
        private TextWriter traceWriter;

        /// <summary>
        /// Default timeout for test cases
        /// </summary>
        private int testCaseTimeout;

        private Log4NetCapture logCapture;

        /// <summary>
        /// The current working directory
        /// </summary>
        private string currentDirectory;

        /// <summary>
        /// The current culture
        /// </summary>
        private CultureInfo currentCulture;

        /// <summary>
        /// The current UI culture
        /// </summary>
        private CultureInfo currentUICulture;

        /// <summary>
        /// The current Principal.
        /// </summary>
        private IPrincipal currentPrincipal;

        /// <summary>
        /// The currently executing test
        /// </summary>
        private Test currentTest;

        /// <summary>
        /// The active TestResult for the current test
        /// </summary>
        private TestResult currentResult;

        /// <summary>
        /// The TestPackage being executed
        /// </summary>
        private TestPackage testPackage;

        /// <summary>
        /// Link to a prior saved context
        /// </summary>
        public TestExecutionContext prior;

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="TestExecutionContext"/> class.
        /// </summary>
        public TestExecutionContext()
        {
            this.prior = null;
            this.tracing = false;
            //this.logging = false;
            this.outWriter = Console.Out;
            this.errorWriter = Console.Error;
            this.traceWriter = null;
            this.logCapture = new Log4NetCapture();
            this.testCaseTimeout = 0;

            this.currentDirectory = Environment.CurrentDirectory;
            this.currentCulture = CultureInfo.CurrentCulture;
            this.currentUICulture = CultureInfo.CurrentUICulture;
            this.currentPrincipal = Thread.CurrentPrincipal;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="TestExecutionContext"/> class.
        /// </summary>
        /// <param name="other">An existing instance of TestExecutionContext.</param>
        public TestExecutionContext(TestExecutionContext other)
        {
            this.prior = other;
            this.tracing = other.tracing;
            //this.logging = other.logging;
            this.outWriter = other.outWriter;
            this.errorWriter = other.errorWriter;
            this.traceWriter = other.traceWriter;
            this.logCapture = other.logCapture;
            this.testCaseTimeout = other.testCaseTimeout;

            this.currentTest = other.currentTest;
            this.currentResult = other.currentResult;
            this.testPackage = other.testPackage;

            this.currentDirectory = Environment.CurrentDirectory;
            this.currentCulture = CultureInfo.CurrentCulture;
            this.currentUICulture = CultureInfo.CurrentUICulture;
            this.currentPrincipal = Thread.CurrentPrincipal;
        }

        #endregion

        #region Static Singleton Instance

        /// <summary>
        /// Gets the current context.
        /// </summary>
        /// <value>The current context.</value>
        public static TestExecutionContext CurrentContext
        {
            get { return current; }
        }

        #endregion

        #region Properties

        /// <summary>
        /// Controls whether trace and debug output are written
        /// to the standard output.
        /// </summary>
        public bool Tracing
        {
            get { return tracing; }
            set
            {
                if (tracing != value)
                {
                    if (traceWriter != null && tracing)
                        StopTracing();

                    tracing = value;

                    if (traceWriter != null && tracing)
                        StartTracing();
                }
            }
        }

        /// <summary>
        /// Controls where Console.Out is directed
        /// </summary>
        public TextWriter Out
        {
            get { return outWriter; }
            set
            {
                if (outWriter != value)
                {
                    outWriter = value;
                    Console.Out.Flush();
                    Console.SetOut(outWriter);
                }
            }
        }

        /// <summary>
        /// Controls where Console.Error is directed
        /// </summary>
        public TextWriter Error
        {
            get { return errorWriter; }
            set
            {
                if (errorWriter != value)
                {
                    errorWriter = value;
                    Console.Error.Flush();
                    Console.SetError(errorWriter);
                }
            }
        }

        /// <summary>
        /// Controls where Trace output is directed
        /// </summary>
        public TextWriter TraceWriter
        {
            get { return traceWriter; }
            set
            {
                if (traceWriter != value)
                {
                    if (traceWriter != null && tracing)
                        StopTracing();

                    traceWriter = value;

                    if (traceWriter != null && tracing)
                        StartTracing();
                }
            }
        }

        /// <summary>
        ///  Gets or sets the Log writer, which is actually held by a log4net 
        ///  TextWriterAppender. When first set, the appender will be created
        ///  and will thereafter send any log events to the writer.
        ///  
        ///  In normal operation, LogWriter is set to an EventListenerTextWriter
        ///  connected to the EventQueue in the test domain. The events are
        ///  subsequently captured in the Gui an the output displayed in
        ///  the Log tab. The application under test does not need to define
        ///  any additional appenders.
        /// </summary>
        public TextWriter LogWriter
        {
            get { return logCapture.Writer; }
            set { logCapture.Writer = value; }
        }

        public LoggingThreshold LogLevel
        {
            get { return logCapture.Threshold; }
            set { logCapture.Threshold = value; }
        }

        private void StopTracing()
        {
            traceWriter.Close();
            System.Diagnostics.Trace.Listeners.Remove("NUnit");
        }

        private void StartTracing()
        {
            System.Diagnostics.Trace.Listeners.Add(new TextWriterTraceListener(traceWriter, "NUnit"));
        }

        /// <summary>
        /// Saves and restores the CurrentDirectory
        /// </summary>
        public string CurrentDirectory
        {
            get { return currentDirectory; }
            set
            {
                currentDirectory = value;
                Environment.CurrentDirectory = currentDirectory;
            }
        }

        /// <summary>
        /// Saves or restores the CurrentCulture
        /// </summary>
        public CultureInfo CurrentCulture
        {
            get { return currentCulture; }
            set
            {
                currentCulture = value;
                Thread.CurrentThread.CurrentCulture = currentCulture;
            }
        }

        /// <summary>
        /// Saves or restores the CurrentUICulture
        /// </summary>
        public CultureInfo CurrentUICulture
        {
            get { return currentUICulture; }
            set
            {
                currentUICulture = value;
                Thread.CurrentThread.CurrentUICulture = currentUICulture;
            }
        }

        /// <summary>
        /// Gets or sets the current <see cref="IPrincipal"/> for the Thread.
        /// </summary>
        public IPrincipal CurrentPrincipal
        {
            get { return this.currentPrincipal; }
            set
            {
                this.currentPrincipal = value;
                Thread.CurrentPrincipal = this.currentPrincipal;
            }
        }

        /// <summary>
        /// Gets or sets the test case timeout value
        /// </summary>
        public int TestCaseTimeout
        {
            get { return testCaseTimeout; }
            set { testCaseTimeout = value; }
        }

        /// <summary>
        /// Gets or sets the current test
        /// </summary>
        public Test CurrentTest
        {
            get { return currentTest; }
            set { currentTest = value; }
        }

        /// <summary>
        /// Gets or sets the current test result
        /// </summary>
        public TestResult CurrentResult
        {
            get { return currentResult; }
            set { currentResult = value; }
        }

        /// <summary>
        /// Gets the test package currently being run
        /// </summary>
        public TestPackage TestPackage
        {
            get { return testPackage; }
            set { testPackage = value; }
        }

        #endregion

        #region Static Methods

        /// <summary>
        /// Saves the old context and makes a fresh one 
        /// current without changing any settings.
        /// </summary>
        public static void Save()
        {
            TestExecutionContext.current = new TestExecutionContext(current);
        }

        /// <summary>
        /// Restores the last saved context and puts
        /// any saved settings back into effect.
        /// </summary>
        public static void Restore()
        {
            current.ReverseChanges();
            current = current.prior;
        }
        #endregion

        #region Instance Methods

        /// <summary>
        /// Used to restore settings to their prior
        /// values before reverting to a prior context.
        /// </summary>
        public void ReverseChanges()
        {
            if (prior == null)
                throw new InvalidOperationException("TestContext: too many Restores");

            this.Tracing = prior.Tracing;
            this.Out = prior.Out;
            this.Error = prior.Error;
            this.CurrentDirectory = prior.CurrentDirectory;
            this.CurrentCulture = prior.CurrentCulture;
            this.CurrentUICulture = prior.CurrentUICulture;
            this.TestCaseTimeout = prior.TestCaseTimeout;
            this.CurrentPrincipal = prior.CurrentPrincipal;
        }

        /// <summary>
        /// Record any changed values in the current context
        /// </summary>
        public void Update()
        {
            this.currentDirectory = Environment.CurrentDirectory;
            this.currentCulture = CultureInfo.CurrentCulture;
            this.currentUICulture = CultureInfo.CurrentUICulture;
            this.currentPrincipal = System.Threading.Thread.CurrentPrincipal;
        }

        #endregion
	}
}
