function Start-Demo

{

  param($file=".\demo.txt", [int]$command=0)

  $CommentColor = "Yellow"

  $MetaCommandColor = "Red"

  Clear-Host

#Typo fun
  $bs = [char]8


 

  $_Random = New-Object System.Random

  $_lines = @(Get-Content $file)

  $_starttime = [DateTime]::now

  Write-Host -for $CommentColor "<Demo [$file] Started>"

 

 

  # We use a FOR and an INDEX ($_i) instead of a FOREACH because

  # it is possible to start at a different location and/or jump 

  # around in the order.

  for ($_i = $Command; $_i -lt $_lines.count; $_i++)

  {  

    if ($_lines[$_i].StartsWith("#"))

    {

        Write-Host -NoNewLine $("`n[$_i]PS> ")

        Write-Host -NoNewLine -Foreground $CommentColor $($($_Lines[$_i]) + "  ")

        continue

    }else

    {

        Write-Host -NoNewLine $("`n[$_i]PS> ")

        $_SimulatedLine = $($_Lines[$_i]) + "  "

        for ($_j = 0; $_j -lt $_SimulatedLine.Length; $_j++)

        {

           Write-Host -NoNewLine $_SimulatedLine[$_j]

           if ($_Backup -eq $false)

           {

#typo fun
 
               if ($_Random.Next(50) -le 1) {

                    $rchar = [char]($_Random.Next(90) + 32)
 
                    Start-Sleep -milliseconds $(10 + $_Random.Next(100)) 

                    Write-Host -NoNewLine $rchar

                    Start-Sleep -milliseconds $(10 + $_Random.Next(100)) 

                    Write-Host -NoNewLine $bs

                }


               Start-Sleep -milliseconds $(10 + $_Random.Next(30))

           }

        }     

        $_Backup = $false    

    }

    # Put the current command in the Window Title along with the demo duration

    $_Duration = [DateTime]::Now - $_StartTime

    $Host.UI.RawUI.WindowTitle = "[{0}m, {1}s]    {2}" -f [int]$_Duration.TotalMinutes, [int]$_Duration.Seconds, $($_Lines[$_i])

    $_OldColor = $host.UI.RawUI.ForeGroundColor

    $host.UI.RawUI.ForeGroundColor = $MetaCommandColor

    $_input=[System.Console]::ReadLine()

    $host.UI.RawUI.ForeGroundColor = $_OldColor

    switch ($_input)

    {

      "?"  

          {

            Write-Host -ForeGroundColor $CommentColor "Running demo: $file`n(q) Quit (!) Suspend (#x) Goto Command #x (fx) Find cmds using X`n(B) backup (t) Timecheck (s) Skip (d) Dump demo"

            $_i -= 1

          }

      "b" { 

                if($_i -gt 0)

                {

                    $_i --

 

                    while (($_i -gt 0) -and ($_lines[$($_i)].StartsWith("#")))

                    {   $_i -= 1

                    }

                }

 

                $_i --

                $_Backup = $true

          }

      "q"  

          {

            Write-Host -ForeGroundColor $CommentColor "<Quit demo>"

            return          

          }

      "s"

          {

            Write-Host -ForeGroundColor $CommentColor "<Skipping Cmd>"

          }

      "d"

          {

            for ($_ni = 0; $_ni -lt $_lines.Count; $_ni++)

            {

               if ($_i -eq $_ni)

               {   Write-Host -ForeGroundColor $MetaCommandColor ("*" * 80)

               } 

               Write-Host -ForeGroundColor $CommentColor ("[{0,2}] {1}" -f $_ni, $_lines[$_ni])

            }

            $_i -= 1

          }

      "t"  

          {

             $_Duration = [DateTime]::Now - $_StartTime

             Write-Host -ForeGroundColor $CommentColor $("Demo has run {0} Minutes and {1} Seconds" -f [int]$_Duration.TotalMinutes, [int]$_Duration.Seconds)

             $_i -= 1

          }

      {$_.StartsWith("f")}

          {

            for ($_ni = 0; $_ni -lt $_lines.Count; $_ni++)

            {

               if ($_lines[$_ni] -match $_.SubString(1))

               {

                  Write-Host -ForeGroundColor $CommentColor ("[{0,2}] {1}" -f $_ni, $_lines[$_ni])

               }

            }

            $_i -= 1

          }

      {$_.StartsWith("!")}

          {

             if ($_.Length -eq 1)

             {

                 Write-Host -ForeGroundColor $CommentColor "<Suspended demo - type 'Exit' to resume>"

                 function Prompt {"[Demo Suspended]`nPS>"}

                 $host.EnterNestedPrompt()

             }else

             {

                 trap [System.Exception] {Write-Error $_;continue;}

                 Invoke-Expression $(".{" + $_.SubString(1) + "}| out-host")

             }

             $_i -= 1

          }

      {$_.StartsWith("#")}  

          {

             $_i = [int]($_.SubString(1)) - 1

             continue

          }

      default

          {

             trap [System.Exception] {Write-Error $_;continue;}

             Invoke-Expression $(".{" + $_lines[$_i] + "}| out-host")

             $_Duration = [DateTime]::Now - $_StartTime

             $Host.UI.RawUI.WindowTitle = "[{0}m, {1}s]    {2}" -f [int]$_Duration.TotalMinutes, [int]$_Duration.Seconds, $($_Lines[$_i])

             [System.Console]::ReadLine()

          }

    }

  }

  $_Duration = [DateTime]::Now - $_StartTime

  Write-Host -ForeGroundColor $CommentColor $("<Demo Complete {0} Minutes and {1} Seconds>" -f [int]$_Duration.TotalMinutes, [int]$_Duration.Seconds)

  Write-Host -ForeGroundColor $CommentColor $([DateTime]::now)

}