[CmdletBinding()]
param(
    [Parameter(Mandatory = $true)]
    [string]$SiteUrl,

    [string]$PollListTitle = 'Polls',

    [string]$AnswerListTitle = 'Poll Answers'
)

$ErrorActionPreference = 'Stop'

function Ensure-Field {
    param(
        [Microsoft.SharePoint.SPList]$List,
        [string]$InternalName,
        [string]$SchemaXml
    )

    if (-not $List.Fields.ContainsField($InternalName)) {
        [void]$List.Fields.AddFieldAsXml($SchemaXml, $true, [Microsoft.SharePoint.SPAddFieldOptions]::AddFieldInternalNameHint)
        $List.Update()
    }
}

$web = Get-SPWeb -Identity $SiteUrl
try {
    $polls = $web.Lists.TryGetList($PollListTitle)
    if (-not $polls) {
        $listId = $web.Lists.Add($PollListTitle, 'Questions and options for the Dynamic Poll web part.', [Microsoft.SharePoint.SPListTemplateType]::GenericList)
        $polls = $web.Lists[$listId]
        $polls.OnQuickLaunch = $true
        $polls.Update()
    }

    Ensure-Field -List $polls -InternalName 'Question' -SchemaXml '<Field Type="Text" DisplayName="Question" Name="Question" StaticName="Question" Required="TRUE" />'
    Ensure-Field -List $polls -InternalName 'Options' -SchemaXml '<Field Type="MultiChoice" DisplayName="Options" Name="Options" StaticName="Options" Required="TRUE" FillInChoice="TRUE"><CHOICES><CHOICE>Option 1</CHOICE><CHOICE>Option 2</CHOICE></CHOICES></Field>'
    Ensure-Field -List $polls -InternalName 'StartDate' -SchemaXml '<Field Type="DateTime" DisplayName="Start date" Name="StartDate" StaticName="StartDate" Format="DateTime" />'
    Ensure-Field -List $polls -InternalName 'EndDate' -SchemaXml '<Field Type="DateTime" DisplayName="End date" Name="EndDate" StaticName="EndDate" Format="DateTime" />'
    Ensure-Field -List $polls -InternalName 'IsActive' -SchemaXml '<Field Type="Boolean" DisplayName="Active" Name="IsActive" StaticName="IsActive"><Default>0</Default></Field>'

    $answers = $web.Lists.TryGetList($AnswerListTitle)
    if (-not $answers) {
        $listId = $web.Lists.Add($AnswerListTitle, 'Votes submitted through the Dynamic Poll web part.', [Microsoft.SharePoint.SPListTemplateType]::GenericList)
        $answers = $web.Lists[$listId]
        $answers.OnQuickLaunch = $false
        $answers.Update()
    }

    $pollListId = $polls.ID.ToString('B')
    Ensure-Field -List $answers -InternalName 'Poll' -SchemaXml (('<Field Type="Lookup" DisplayName="Poll" Name="Poll" StaticName="Poll" List="{0}" ShowField="Title" Required="TRUE" />' -f $pollListId))
    Ensure-Field -List $answers -InternalName 'Answer' -SchemaXml '<Field Type="Text" DisplayName="Answer" Name="Answer" StaticName="Answer" Required="TRUE" MaxLength="255" />'

    Write-Host ('Dynamic Poll lists are ready at {0}' -f $web.Url) -ForegroundColor Green
    Write-Host ('Poll list: {0} ({1})' -f $polls.Title, $polls.ID)
    Write-Host ('Answer list: {0} ({1})' -f $answers.Title, $answers.ID)
}
finally {
    if ($web) { $web.Dispose() }
}