param(
    [string]$ConfigPath = (Join-Path (Split-Path -Parent $PSScriptRoot) 'config.ini'),
    [switch]$Send,
    [string]$PickupDirectory,
    [int]$SessionPid,
    [string]$SessionToken,
    [string]$TestNowUtc,
    [switch]$TestSimulateUnknownAfterSend
)
$ErrorActionPreference = 'Stop'
. (Join-Path $PSScriptRoot 'dispatch-common.ps1')
if ([bool]$Send -eq [bool]$PickupDirectory) { throw 'Choose exactly one mode: -Send or -PickupDirectory' }
if ($Send -and $TestNowUtc) { throw 'TestNowUtc is only available in pickup mode' }
if ($Send -and $TestSimulateUnknownAfterSend) { throw 'Failure injection is only available in pickup mode' }
if ($Send) { Assert-OpenHtaSession $SessionPid $SessionToken }
elseif (-not (Test-Path -LiteralPath $PickupDirectory -PathType Container)) {
    throw 'Pickup directory does not exist'
}
$now = if ($TestNowUtc) {
    [DateTime]::Parse($TestNowUtc, [cultureinfo]::InvariantCulture,
        [System.Globalization.DateTimeStyles]::AdjustToUniversal)
} else { [DateTime]::UtcNow }
$context = Get-MailContext $ConfigPath
$settings = $context.Settings
$interval = Get-QueueInterval $context
if ($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'
}
$sender = $settings['SMTP_USER'].ToLowerInvariant()
$lock = Enter-DispatchLock
$db = $null
$password = $null
$client = $null
$message = $null
$reservedDelivery = 0
$reservedAttempt = 0
$sendStarted = $false
try {
    $db = Open-MailDatabase $context
    $state = Get-OperationalState $db
    if ($state.Paused) { Write-Output 'Dispatch paused'; return }
    Assert-OptOutReviewCurrent $context $state
    $clock = Get-DispatchClock $db $sender $interval
    if ($null -ne $clock.Next -and $now -lt $clock.Next) {
        Write-Output ('Next attempt allowed at ' + $clock.Next.ToString('o'))
        return
    }
    if ($Send) { $password = Load-SmtpPassword $context }
    $transaction = $db.BeginTransaction()
    try {
        while ($true) {
            $sql = "SELECT TOP 1 d.[Id],d.[EmailKey] FROM [Delivery] AS d INNER JOIN [Campaign] AS m ON d.[CampaignId]=m.[Id] WHERE d.[Status]='pending' AND m.[Status]='running' AND m.[StartAtUtc]<=? ORDER BY d.[Id]"
            $pick = New-DbCommand $db $sql $transaction
            $null = $pick.Parameters.Add('now', [System.Data.OleDb.OleDbType]::Date)
            $pick.Parameters[0].Value = $now
            $reader = $pick.ExecuteReader()
            try {
                if (-not $reader.Read()) { $candidate = $null }
                else { $candidate = @{ Id = [int]$reader.GetValue(0); Key = [string]$reader.GetValue(1) } }
            }
            finally { $reader.Dispose() }
            if ($null -eq $candidate) { break }
            if (-not (Test-Suppressed $db $candidate.Key $transaction)) { break }
            $skip = New-DbCommand $db "UPDATE [Delivery] SET [Status]='suppressed' WHERE [Id]=? AND [Status]='pending'" $transaction
            $null = $skip.Parameters.Add('id', [System.Data.OleDb.OleDbType]::Integer)
            $skip.Parameters[0].Value = $candidate.Id
            $null = $skip.ExecuteNonQuery()
        }
        if ($null -eq $candidate) {
            $transaction.Commit()
            Complete-FinishedCampaigns $db
            Write-Output 'No pending delivery is due'
            return
        }
        $delivery = New-DbCommand $db "UPDATE [Delivery] SET [Status]='in_flight',[AttemptCount]=[AttemptCount]+1,[LastAttemptAtUtc]=? WHERE [Id]=? AND [Status]='pending'" $transaction
        $null = $delivery.Parameters.Add('now', [System.Data.OleDb.OleDbType]::Date)
        $delivery.Parameters[0].Value = $now
        $null = $delivery.Parameters.Add('id', [System.Data.OleDb.OleDbType]::Integer)
        $delivery.Parameters[1].Value = $candidate.Id
        if ($delivery.ExecuteNonQuery() -ne 1) { throw 'Delivery was already reserved' }
        $attempt = New-DbCommand $db 'INSERT INTO [Attempt] ([DeliveryId],[StartedAtUtc],[Outcome]) VALUES (?,?,?)' $transaction
        $null = $attempt.Parameters.Add('delivery', [System.Data.OleDb.OleDbType]::Integer)
        $attempt.Parameters[0].Value = $candidate.Id
        $null = $attempt.Parameters.Add('now', [System.Data.OleDb.OleDbType]::Date)
        $attempt.Parameters[1].Value = $now
        Add-TextParameter $attempt 'outcome' 30 'started'
        $null = $attempt.ExecuteNonQuery()
        $identity = New-DbCommand $db 'SELECT @@IDENTITY' $transaction
        $reservedAttempt = [int]$identity.ExecuteScalar()
        $next = $now.AddSeconds($interval)
        if ($clock.Exists) {
            $pace = New-DbCommand $db 'UPDATE [DispatchState] SET [LastAttemptAtUtc]=?,[NextAllowedAttemptUtc]=? WHERE [SenderKey]=?' $transaction
            $null = $pace.Parameters.Add('last', [System.Data.OleDb.OleDbType]::Date)
            $pace.Parameters[0].Value = $now
            $null = $pace.Parameters.Add('next', [System.Data.OleDb.OleDbType]::Date)
            $pace.Parameters[1].Value = $next
            Add-TextParameter $pace 'sender' 254 $sender
        }
        else {
            $pace = New-DbCommand $db 'INSERT INTO [DispatchState] ([SenderKey],[LastAttemptAtUtc],[NextAllowedAttemptUtc]) VALUES (?,?,?)' $transaction
            Add-TextParameter $pace 'sender' 254 $sender
            $null = $pace.Parameters.Add('last', [System.Data.OleDb.OleDbType]::Date)
            $pace.Parameters[1].Value = $now
            $null = $pace.Parameters.Add('next', [System.Data.OleDb.OleDbType]::Date)
            $pace.Parameters[2].Value = $next
        }
        $null = $pace.ExecuteNonQuery()
        $reservedDelivery = $candidate.Id
        $transaction.Commit()
    }
    catch { $transaction.Rollback(); throw }

    try {
        if ($Send) { Assert-OpenHtaSession $SessionPid $SessionToken }
        $snapshot = Get-DeliverySnapshot $db $reservedDelivery
        if ($snapshot.CampaignStatus -ne 'running') { throw 'Campaign was paused or canceled before send' }
        if (Test-Suppressed $db $snapshot.EmailKey) {
            Complete-DeliveryAttempt $db $reservedDelivery $reservedAttempt 'skipped' 'suppressed' 'suppressed_before_send'
            Write-Output "Delivery $reservedDelivery skipped because it is suppressed"
            return
        }
        $template = Get-TemplateSnapshot $db $snapshot.TemplateId
        $html = Add-CampaignFooter $template.Document @{
            From = $snapshot.From; ReplyTo = $snapshot.ReplyTo; Postal = $snapshot.Postal }
        $message = New-Object System.Net.Mail.MailMessage
        $message.From = New-Object System.Net.Mail.MailAddress($snapshot.From)
        $null = $message.ReplyToList.Add($snapshot.ReplyTo)
        $null = $message.To.Add($snapshot.Email)
        $message.Subject = $snapshot.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) {
            $client.UseDefaultCredentials = $false
            $client.Credentials = New-Object System.Net.NetworkCredential -ArgumentList @($settings['SMTP_USER'], $password)
            $client.EnableSsl = $true
            Assert-OpenHtaSession $SessionPid $SessionToken
            if ((Get-OperationalState $db).Paused -or (Test-Suppressed $db $snapshot.EmailKey)) {
                throw 'Campaign paused or recipient suppressed before SMTP call'
            }
        }
        else {
            $client.DeliveryMethod = [System.Net.Mail.SmtpDeliveryMethod]::SpecifiedPickupDirectory
            $client.PickupDirectoryLocation = [System.IO.Path]::GetFullPath($PickupDirectory)
        }
        $sendStarted = $true
        $client.Send($message)
        if ($TestSimulateUnknownAfterSend) { throw 'Injected loss of provider acknowledgement' }
        Complete-DeliveryAttempt $db $reservedDelivery $reservedAttempt 'accepted' 'accepted'
        Complete-FinishedCampaigns $db
        Write-Output "SMTP accepted delivery $reservedDelivery. Next slot at $($next.ToString('o'))."
        if ($Send) { $sentNote = Save-SentCopySafely $settings $password $message; if ($sentNote) { Write-Output $sentNote } }
    }
    catch {
        $code = if ($_.Exception -is [System.Net.Mail.SmtpException]) {
            'smtp_' + $_.Exception.StatusCode.ToString()
        } elseif ($sendStarted) { 'provider_outcome_unknown' } else { 'before_send_error' }
        if ($sendStarted) {
            Complete-DeliveryAttempt $db $reservedDelivery $reservedAttempt 'uncertain' 'uncertain' $code
            Pause-DispatchForReview $db $reservedDelivery
            Write-Output "Delivery $reservedDelivery has uncertain provider outcome ($code). All campaigns paused for manual review."
        }
        elseif ($_.Exception.Message -match 'HTA session|Campaign was paused') {
            Complete-DeliveryAttempt $db $reservedDelivery $reservedAttempt 'aborted' 'pending' 'session_closed_before_send'
            Write-Output "Delivery $reservedDelivery was not sent because the HTA session closed or paused. It remains pending."
        }
        else {
            Complete-DeliveryAttempt $db $reservedDelivery $reservedAttempt 'failed' 'failed' $code
            Write-Output "Delivery $reservedDelivery failed before SMTP ($code)."
        }
    }
}
finally {
    if ($client) { $client.Dispose() }
    if ($message) { $message.Dispose() }
    if ($password) { $password.Dispose() }
    if ($db) { $db.Dispose() }
    $lock.Dispose()
}