using System;
using System.Collections.Generic;
using System.Linq;
using System.Management.Automation;
using System.Management.Automation.Runspaces;
using System.Text;

namespace OpenIdProvider.Shared
{
    public class PowerShellInvoker : IDisposable
    {
        private readonly Runspace _runspace;
        private readonly RunspaceInvoke _invoker;

        public PowerShellInvoker(params string[] modules)
        {
            var iss = InitialSessionState.CreateDefault();
            iss.ImportPSModule(modules);
            iss.ThrowOnRunspaceOpenError = true;

            _runspace = RunspaceFactory.CreateRunspace(iss);
            _runspace.Open();
            _invoker = new RunspaceInvoke(_runspace);
        }

        public ICollection<PSObject> ExecuteScript(string scriptText)
        {
            return _invoker.Invoke(scriptText).ToList();
        }

        public ICollection<PSObject> ExecuteCommand(string cmdlet, object parameters = null)
        {
            using (var pipeline = _runspace.CreatePipeline())
            {
                var cmd = new Command(cmdlet);

                if (parameters != null)
                {
                    foreach (var property in parameters.GetType().GetProperties())
                    {
                        cmd.Parameters.Add(property.Name, property.GetValue(parameters, null));
                    }
                }

                pipeline.Commands.Add(cmd);
                
                var result = pipeline.Invoke();

                if (pipeline.Error.Count > 0)
                {
                    var psError = (PSObject) pipeline.Error.Read();
                    var error = (ErrorRecord) psError.BaseObject;
                    throw error.Exception;
                }

                return result.ToList();
            }
        }

        public void SetVariable(string name, object value)
        {
            _runspace.SessionStateProxy.SetVariable(name, value);
        }

        #region Implementation of IDisposable

        public void Dispose()
        {
            if (_invoker != null)
            {
                _invoker.Dispose();
            }

            if (_runspace != null)
            {
                _runspace.Close();
                _runspace.Dispose();
            }
        }

        #endregion
    }
}