param(
    [Parameter(Mandatory = $true)][int]$CampaignId,
    [string]$ConfigPath = (Join-Path (Split-Path -Parent $PSScriptRoot) 'config.ini'),
    [switch]$Send,
    [string]$PickupDirectory
)
$ErrorActionPreference = 'Stop'
. (Join-Path $PSScriptRoot 'dispatch-common.ps1')
if ($CampaignId -lt 1) { throw 'CampaignId must be positive' }
if ([bool]$Send -eq [bool]$PickupDirectory) { throw 'Choose exactly one mode: -Send or -PickupDirectory' }
$context = Get-MailContext $ConfigPath
$settings = $context.Settings
if ($settings['SMTP_TLS'] -ne 'on' -or $settings['SMTP_STARTTLS'] -ne 'on') {
    throw 'SMTP_TLS and SMTP_STARTTLS must both be on'
}
$port = 0
if (-not [int]::TryParse($settings['SMTP_PORT'], [ref]$port) -or $port -lt 1 -or $port -gt 65535) {
    throw 'Invalid SMTP_PORT'
}
$testTo = [string]$settings['SMTP_TEST_TO']
$parsed = New-Object System.Net.Mail.MailAddress($testTo)
if ($parsed.Address -ne $testTo) { throw 'SMTP_TEST_TO must be a single bare email address' }
$db = Open-MailDatabase $context
$client = $null
$message = $null
$password = $null
try {
    $campaign = Get-ApprovedCampaignSnapshot $db $CampaignId
    $template = Get-TemplateSnapshot $db $campaign.TemplateId
    $html = Add-CampaignFooter $template.Document @{
        From = $campaign.From; ReplyTo = $campaign.ReplyTo; Postal = $campaign.Postal }
    $message = New-Object System.Net.Mail.MailMessage
    $message.From = New-Object System.Net.Mail.MailAddress($campaign.From)
    $null = $message.ReplyToList.Add($campaign.ReplyTo)
    $null = $message.To.Add($testTo)
    $message.Subject = '[TEST] ' + $campaign.Subject
    $message.SubjectEncoding = [System.Text.Encoding]::UTF8
    $view = [System.Net.Mail.AlternateView]::CreateAlternateViewFromString(
        $html, [System.Text.Encoding]::UTF8, 'text/html')
    foreach ($image in $template.Images) {
        $stream = New-Object System.IO.MemoryStream -ArgumentList (,([byte[]]$image.Bytes))
        $resource = New-Object System.Net.Mail.LinkedResource($stream, $image.Type)
        $resource.ContentId = $image.Cid
        $resource.TransferEncoding = [System.Net.Mime.TransferEncoding]::Base64
        $null = $view.LinkedResources.Add($resource)
    }
    $null = $message.AlternateViews.Add($view)
    $client = New-Object System.Net.Mail.SmtpClient($settings['SMTP_HOST'], $port)
    $client.Timeout = 20000
    if ($Send) {
        $password = Load-SmtpPassword $context
        $client.UseDefaultCredentials = $false
        $client.Credentials = New-Object System.Net.NetworkCredential -ArgumentList @($settings['SMTP_USER'], $password)
        $client.EnableSsl = $true
    }
    else {
        if (-not (Test-Path -LiteralPath $PickupDirectory -PathType Container)) {
            throw 'Pickup directory does not exist'
        }
        $client.DeliveryMethod = [System.Net.Mail.SmtpDeliveryMethod]::SpecifiedPickupDirectory
        $client.PickupDirectoryLocation = [System.IO.Path]::GetFullPath($PickupDirectory)
    }
    $client.Send($message)
    Write-CampaignAudit $db 'approved_campaign_test_accepted' ([string]$CampaignId) ("Internal test to $testTo")
    Write-Output "Approved campaign $CampaignId test accepted for $testTo. Live delivery counts did not advance."
}
finally {
    if ($client) { $client.Dispose() }
    if ($message) { $message.Dispose() }
    if ($password) { $password.Dispose() }
    $db.Dispose()
}