using System;
using System.Collections.Generic;
using System.Text;
using System.Workflow.Runtime.Hosting;
using System.Workflow.Runtime;
using System.Diagnostics;
using System.Collections.Specialized;

namespace WFServices
{
    // Define the delegate that will be used when writing output
    internal delegate void WriterDelegate ( string output );

    /// <summary>
    /// This service is designed to output all events raised by the workflow runtime to the Debug log
    /// </summary>
    public class RuntimeEventWriter : WorkflowRuntimeService
    {
        /// <summary>
        /// Construct the object and decide which writer(s) we're going to use
        /// </summary>
        /// <param name="args"></param>
        public RuntimeEventWriter(NameValueCollection args)
        {
            // Create an empty delegate just in case the user has not supplied any parameters
            _writers = new WriterDelegate(WriteNowhere);

            if (args["Console"] == "true")
                _writers = (WriterDelegate)Delegate.Combine(_writers, new WriterDelegate(WriteToConsole));
            if ( args["Trace"] == "true")
                _writers = (WriterDelegate)Delegate.Combine(_writers, new WriterDelegate(WriteToTrace));
            if (args["Debug"] == "true")
                _writers = (WriterDelegate)Delegate.Combine(_writers, new WriterDelegate(WriteToDebug));
        }

        /// <summary>
        /// Hook all runtime events
        /// </summary>
        protected override void OnStarted()
        {
            Runtime.WorkflowAborted += new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowAborted);
            Runtime.WorkflowCompleted += new EventHandler<System.Workflow.Runtime.WorkflowCompletedEventArgs>(OnWorkflowCompleted);
            Runtime.WorkflowCreated += new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowCreated);
            Runtime.WorkflowIdled += new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowIdled);
            Runtime.WorkflowLoaded += new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowLoaded);
            Runtime.WorkflowPersisted += new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowPersisted);
            Runtime.WorkflowResumed += new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowResumed);
            Runtime.WorkflowStarted += new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowStarted);
            Runtime.WorkflowSuspended += new EventHandler<System.Workflow.Runtime.WorkflowSuspendedEventArgs>(OnWorkflowSuspended);
            Runtime.WorkflowTerminated += new EventHandler<System.Workflow.Runtime.WorkflowTerminatedEventArgs>(OnWorkflowTerminated);
            Runtime.WorkflowUnloaded += new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowUnloaded);
        }

        /// <summary>
        /// Unhook all runtime events
        /// </summary>
        protected override void OnStopped()
        {
            Runtime.WorkflowAborted -= new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowAborted);
            Runtime.WorkflowCompleted -= new EventHandler<System.Workflow.Runtime.WorkflowCompletedEventArgs>(OnWorkflowCompleted);
            Runtime.WorkflowCreated -= new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowCreated);
            Runtime.WorkflowIdled -= new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowIdled);
            Runtime.WorkflowLoaded -= new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowLoaded);
            Runtime.WorkflowPersisted += new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowPersisted);
            Runtime.WorkflowResumed -= new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowResumed);
            Runtime.WorkflowStarted -= new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowStarted);
            Runtime.WorkflowSuspended -= new EventHandler<System.Workflow.Runtime.WorkflowSuspendedEventArgs>(OnWorkflowSuspended);
            Runtime.WorkflowTerminated -= new EventHandler<System.Workflow.Runtime.WorkflowTerminatedEventArgs>(OnWorkflowTerminated);
            Runtime.WorkflowUnloaded -= new EventHandler<System.Workflow.Runtime.WorkflowEventArgs>(OnWorkflowUnloaded);
        }

        void OnWorkflowUnloaded(object sender, WorkflowEventArgs e)
        {
            _writers.Invoke (string.Format("Workflow {0} Unloaded at {1}.", e.WorkflowInstance.InstanceId, DateTime.Now));
        }

        void OnWorkflowTerminated(object sender, WorkflowTerminatedEventArgs e)
        {
            _writers.Invoke (string.Format("Workflow {0} Terminated at {1}.\r\n  Exception was '{2}'.\r\n{3}", e.WorkflowInstance.InstanceId, DateTime.Now, e.Exception.Message, e.Exception.StackTrace));
        }

        void OnWorkflowSuspended(object sender, WorkflowSuspendedEventArgs e)
        {
            if ( string.IsNullOrEmpty ( e.Error) )
                _writers.Invoke(string.Format("Workflow {0} Suspended at {1}.", e.WorkflowInstance.InstanceId, DateTime.Now));
            else
                _writers.Invoke(string.Format("Workflow {0} Suspended with error at {1}.\r\n  Error was '{2}'.", e.WorkflowInstance.InstanceId, DateTime.Now, e.Error));
        }

        void OnWorkflowStarted(object sender, WorkflowEventArgs e)
        {
            _writers.Invoke(string.Format("Workflow {0} Started at {1}.", e.WorkflowInstance.InstanceId, DateTime.Now));
        }

        void OnWorkflowResumed(object sender, WorkflowEventArgs e)
        {
            _writers.Invoke(string.Format("Workflow {0} Resumed at {1}.", e.WorkflowInstance.InstanceId, DateTime.Now));
        }

        void OnWorkflowPersisted(object sender, WorkflowEventArgs e)
        {
            _writers.Invoke(string.Format("Workflow {0} Persisted at {1}.", e.WorkflowInstance.InstanceId, DateTime.Now));
        }

        void OnWorkflowLoaded(object sender, WorkflowEventArgs e)
        {
            _writers.Invoke(string.Format("Workflow {0} Loaded at {1}.", e.WorkflowInstance.InstanceId, DateTime.Now));
        }

        void OnWorkflowIdled(object sender, WorkflowEventArgs e)
        {
            _writers.Invoke(string.Format("Workflow {0} Idled at {1}.", e.WorkflowInstance.InstanceId, DateTime.Now));
        }

        void OnWorkflowCreated(object sender, WorkflowEventArgs e)
        {
            _writers.Invoke(string.Format("Workflow {0} Created at {1}.", e.WorkflowInstance.InstanceId, DateTime.Now));
        }

        void OnWorkflowCompleted(object sender, WorkflowCompletedEventArgs e)
        {
            StringBuilder sb = new StringBuilder();

            foreach (KeyValuePair<string, object> kvp in e.OutputParameters)
            {
                sb.AppendFormat("    {0} = {1}\r\n", kvp.Key, (kvp.Value == null) ? "null" : kvp.Value );
            }

            _writers.Invoke(string.Format("Workflow {0} Completed at {1}.\r\n  Output Parameters were...\r\n{2}", e.WorkflowInstance.InstanceId, DateTime.Now, sb.ToString()));
        }

        void OnWorkflowAborted(object sender, WorkflowEventArgs e)
        {
            Debug.WriteLine(string.Format("Workflow {0} Aborted at {1}.", e.WorkflowInstance.InstanceId, DateTime.Now));
        }

        /// <summary>
        /// Write the text to the console
        /// </summary>
        /// <param name="text"></param>
        void WriteToConsole(string text)
        {
            Console.WriteLine(text);
        }

        /// <summary>
        /// Write the text to the debug stream
        /// </summary>
        /// <param name="text"></param>
        void WriteToDebug(string text)
        {
            Debug.WriteLine(text);
        }

        /// <summary>
        /// Write the text to the trace stream
        /// </summary>
        /// <param name="text"></param>
        void WriteToTrace(string text)
        {
            Trace.WriteLine(text);
        }

        /// <summary>
        /// Don't write the text anywhere
        /// </summary>
        /// <param name="text"></param>
        void WriteNowhere(string text)
        {
        }

        /// <summary>
        /// Delegate used to output data to the console/debug/trace
        /// </summary>
        private WriterDelegate _writers;

    }
}