October 2015 Scripting Game Submissions, Windos

Windos-ScriptingGames-2015-10

function Get-RSSFeed
{
    <#
        .SYNOPSIS
        Gets data from a RSS Feed.

        .DESCRIPTION
        The Get-RSSFeed function retrieves the title, link and excerpt from a specified rss feed.

        Multiple URIs can be provided as parameters or piped to the function.

        By default only post titles are displayed and optional switches can be provided to change this behaviour.
        
        .INPUTS
        System.String

        You can pipe input to this function

        .OUTPUTS
        PSCustomObject

        .PARAMETER Uri
        Specifies the Uniform Resource Identifier (URI) of the Internet resource to which the web request is sent.
        
        This parameter supports HTTP, HTTPS, FTP, and FILE values.
        
        This parameter is required. The parameter name (-Uri) is optional.
        
        .NOTES
        If you try this function on a RSS Feed and do not get back expected results, please submit a bug report
        via GitHub including the Uri used and the output you recieved.

        Run `Get-Help Get-RSSFeed -Online` to open a web browser to the relevant GitHub repo.

        .EXAMPLE
        Get-RSSFeed -Uri http://blog1.github.io/feed.xml

        Gets the titles of recent blog posts from Blog1
        
        .EXAMPLE
        http://blog1.github.io/feed.xml | Get-RSSFeed

        Gets the titles of recent blog posts from Blog1, via a piped Uri

        .EXAMPLE
        Get-RSSFeed -Uri http://blog1.github.io/feed.xml, http://feeds.feedburner.com/blog2

        Gets the titles of recent blog posts from Blog1 and Blog2

        .EXAMPLE
        Get-RSSFeed -Uri http://blog1.github.io/feed.xml -IncludeLink

        Gets the titles and links of recent blog posts from Blog1

        .EXAMPLE
        Get-RSSFeed -Uri http://blog1.github.io/feed.xml, http://feeds.feedburner.com/blog2 -IncludeLink -IncludeExcerpt

        Gets the titles, links and excerpts of recent blog posts from Blog1 and Blog2
        
        .LINK
        https://github.com/Windos/ScriptingGames
    #>

    [CmdletBinding()]
    [OutputType([PSCustomObject])]
    param
    (
        [Parameter(Mandatory = $true,
                   Position = 0,
                   ValueFromPipeline = $true,
                   ValueFromPipelineByPropertyName = $true)]
        [String[]] $Uri,

        [Switch] $IncludeLink,

        [Switch] $IncludeExcerpt
    )

    process
    {
        foreach ($Link in $Uri)
        {
            $Feed = Invoke-RestMethod -Uri $Link

            foreach ($Post in $Feed)
            {
                # Some Atom feeds weren't nice, the following if statements made my test cases work.
                $Title = $Post.Title
                if ($Title.ToString() -eq 'title')
                {
                    $Title = $Title.InnerText
                }
                
                $Link = $Post.Link
                if ($Link.ToString() -eq 'link')
                {
                    $Link = $Link.href
                }

                if ($Post.Description)
                {
                    $Excerpt = $Post.description.InnerText.Split('.')[0]
                }
                elseif ($Post.Content)
                {
                    $Excerpt = ($Post.Content.InnerText -replace '<[^>]*>', '').TrimStart().Split('.')[0]
                }
                else
                {
                    $Excerpt = ''
                }

                if ($Excerpt.Length -gt 75)
                {
                    $Excerpt = $Excerpt.Substring(0, 75) + '...'
                }

                $Result = New-Object -TypeName PSCustomObject -Property @{
                    'Title' = $Title
                    'Link' = $Link
                    'Excerpt' = $Excerpt
                }

                $defaultDisplaySet = @('Title')
                if ($IncludeLink) { $defaultDisplaySet += 'Link' }
                if ($IncludeExcerpt) { $defaultDisplaySet += 'Excerpt' }

                $defaultDisplayPropertySet = New-Object System.Management.Automation.PSPropertySet(‘DefaultDisplayPropertySet’,[string[]]$defaultDisplaySet)
                $PSStandardMembers = [System.Management.Automation.PSMemberInfo[]]@($defaultDisplayPropertySet)

                $Result | Add-Member MemberSet PSStandardMembers $PSStandardMembers
                $Result
            }
        }
    }
}