# ==============================================================================================
# 
# Microsoft PowerShell Source File -- Created with SAPIEN Technologies PrimalScript 2007
# 
# NAME: Get-Tweet.ps1
# VERSION: 0.6
# 
# AUTHOR: Jeffery Hicks , SAPIEN Technologies
# DATE  : 6/25/2008
# 
# COMMENT: This function will return all Twitter tweets from your friends
# timeline. At first run it will get all tweets from the past six hours.
# Everytime you run Get-Tweet a timestamp is written to another global 
# variable. The next time you run the function, only tweets since the last
# tweet check will be displayed

# The function will write an object to the pipeline with the tweet time stamp,
# the friend's name and the tweet. I like to use the function like this:
#
# get-tweet | format-table -autosize -wrap
#
# which presents it in a nicely formatted fashion. Perhaps you'd like to 
# filter out your own tweets:
#
#   get-tweet | where {$_.twitter -notmatch "JeffHicks"} | format-table -auto -wrap
# 
# Or maybe you only want to see tweets from a certain person:
# 
# get-tweet | where {$_.twitter match "halr9000"} | format-table Twitted,Tweet -autosize -wrap
#
# ==============================================================================================

Function Get-Tweet {

    #check for global Twitter credential
    if (!$global:Twitter_Credential) {
        $global:Twitter_Credential=Get-Credential
        }

    #check for last tweet check
    if ($global:Tweet_Check) {
        [datetime]$since=$global:Tweet_Check 
        }
    else {
        #if not found then calculate the date 6 hours ago
        [datetime]$since=(Get-Date).AddHours(-6)  
        }
	
	#convert to GMT and a string
	[string]$sinceGMT=$since.ToUniversalTime().ToString()
	
    #replace AM or PM with GMT
    if ($sinceGMT.EndsWith("AM")) {
        $sinceGMT=$sinceGMT.Replace("AM","GMT")
    }
    else {
        $sinceGMT=$sinceGMT.Replace("PM","GMT")
    }
    
    #construct URL
    [string]$urlbase="http://twitter.com/statuses/friends_timeline.rss?since={0}"
    [string]$url=$urlbase -f $sinceGMT
    
    #this line is optional, but informational
    Write-Host "Downloading $url [$since]" -foregroundcolor CYAN
    
    #create web client
    $webclient=New-Object "System.Net.WebClient"
    
    #create network credential
    $username=$global:Twitter_Credential.GetNetworkCredential().Username
    $password=$global:Twitter_Credential.GetNetworkCredential().Password
    $webclient.credentials = New-Object System.Net.NetworkCredential($username,$password)
     
     #retrieve RSS file and store as an XML object
     [xml]$tweets=$webclient.DownloadString($url)     
    
     #parse RSS/XML and write to the pipeline
     #only keep tweets that are newer than the last Tweet Check
    $tweets.rss.channel.item | 
    where {($_.pubDate -as [datetime]) -gt $global:Tweet_Check} | select `
        @{name="Twitted";Expression={
        #convert to a datetime object
        $_.pubDate -as [datetime]}},`
        @{name="Twitter";Expression={
        #parse out the friend name
          $t=$_.title
          $t.substring(0,$t.indexof(":"))}}, `
        @{name="Tweet";Expression={
        #parse out the message
          $t=$_.title    
          $t.substring($t.indexof(":")+1).Trim()}} 
     
    #store datetime for last tweet check  
    $global:Tweet_Check = Get-Date
    
}