$taskDefinitionCutoverContract = Join-Path $PSScriptRoot "public-runtime-task-definition-cutover.ps1"
if (-not (Test-Path -LiteralPath $taskDefinitionCutoverContract -PathType Leaf)) {
  throw "Public runtime task definition cutover contract is unavailable"
}
. $taskDefinitionCutoverContract

function Assert-PublicRuntimeTasksDisabledAndIdle {
  param(
    [Parameter(Mandatory = $true)][object[]]$Snapshot,
    [int]$TimeoutSec = 30
  )

  $deadline = (Get-Date).AddSeconds($TimeoutSec)
  do {
    $allDisabledAndIdle = $true
    foreach ($entry in @($Snapshot)) {
      if (-not [bool]$entry.exists) {
        $unexpectedTask = Get-ScheduledTask `
          -TaskName ([string]$entry.task_name) `
          -TaskPath "\" `
          -ErrorAction SilentlyContinue
        if ($null -ne $unexpectedTask) {
          throw "A coordinated public runtime task appeared during maintenance: $($entry.task_name)"
        }
        continue
      }
      $task = Get-ScheduledTask `
        -TaskName ([string]$entry.task_name) `
        -TaskPath "\" `
        -ErrorAction Stop
      if ([bool]$task.Settings.Enabled -or [string]$task.State -eq "Running") {
        $allDisabledAndIdle = $false
        break
      }
    }
    if ($allDisabledAndIdle) {
      return
    }
    Start-Sleep -Milliseconds 250
  } while ((Get-Date) -lt $deadline)

  throw "Public runtime scheduled tasks did not become disabled and idle"
}

function Get-PublicRuntimeTaskMaintenanceState {
  param([Parameter(Mandatory = $true)][object[]]$Snapshot)

  $allDisabledAndIdle = $true
  $restoredToSnapshot = $true
  $verified = $true
  foreach ($entry in @($Snapshot)) {
    if (-not [bool]$entry.exists) {
      try {
        $unexpectedTask = Get-ScheduledTask `
          -TaskName ([string]$entry.task_name) `
          -TaskPath "\" `
          -ErrorAction SilentlyContinue
        if ($null -ne $unexpectedTask) {
          $allDisabledAndIdle = $false
          $restoredToSnapshot = $false
        }
      } catch {
        $verified = $false
        $allDisabledAndIdle = $false
        $restoredToSnapshot = $false
      }
      continue
    }
    try {
      $task = Get-ScheduledTask `
        -TaskName ([string]$entry.task_name) `
        -TaskPath "\" `
        -ErrorAction Stop
      $isEnabled = [bool]$task.Settings.Enabled
      $isRunning = [string]$task.State -eq "Running"
      if ($isEnabled -or $isRunning) {
        $allDisabledAndIdle = $false
      }
      if ($isEnabled -ne [bool]$entry.was_enabled) {
        $restoredToSnapshot = $false
      }
    } catch {
      $verified = $false
      $allDisabledAndIdle = $false
      $restoredToSnapshot = $false
    }
  }

  return [pscustomobject][ordered]@{
    verified = $verified
    all_disabled_and_idle = $allDisabledAndIdle
    restored_to_snapshot = $restoredToSnapshot
  }
}

function Suspend-PublicRuntimeTasks {
  param(
    [Parameter(Mandatory = $true)][object[]]$Snapshot,
    [int]$TimeoutSec = 30
  )

  foreach ($entry in @($Snapshot)) {
    if (-not [bool]$entry.exists) {
      continue
    }
    Disable-ScheduledTask `
      -TaskName ([string]$entry.task_name) `
      -TaskPath "\" `
      -ErrorAction Stop `
      | Out-Null
  }
  Assert-PublicRuntimeTasksDisabledAndIdle `
    -Snapshot $Snapshot `
    -TimeoutSec $TimeoutSec
}

function Enter-PublicRuntimeTaskMaintenance {
  param(
    [Parameter(Mandatory = $true)][string[]]$TaskNames,
    [int]$TimeoutSec = 30
  )

  $snapshot = @()
  try {
    # 모든 원상복구 정보를 먼저 캡처한다. disable 도중 두 번째 task에서 오류가 나도
    # 첫 번째 task를 포함한 완전한 snapshot으로 되돌릴 수 있어야 한다.
    foreach ($taskName in @($TaskNames | Sort-Object -Unique)) {
      if ([string]::IsNullOrWhiteSpace($taskName)) {
        throw "Public runtime scheduled task name is empty"
      }
      $task = Get-ScheduledTask `
        -TaskName $taskName `
        -TaskPath "\" `
        -ErrorAction SilentlyContinue
      if ($null -eq $task) {
        $snapshot += [pscustomobject][ordered]@{
          task_name = $taskName
          exists = $false
          was_enabled = $false
        }
        continue
      }
      $wasEnabled = [bool]$task.Settings.Enabled
      $snapshot += [pscustomobject][ordered]@{
        task_name = $taskName
        exists = $true
        was_enabled = $wasEnabled
      }
    }

    $result = @($snapshot)
    Suspend-PublicRuntimeTasks `
      -Snapshot $result `
      -TimeoutSec $TimeoutSec
    return $result
  } catch {
    foreach ($entry in @($snapshot)) {
      if ([bool]$entry.exists -and [bool]$entry.was_enabled) {
        Enable-ScheduledTask `
          -TaskName ([string]$entry.task_name) `
          -TaskPath "\" `
          -ErrorAction SilentlyContinue `
          | Out-Null
      }
    }
    foreach ($entry in @($snapshot)) {
      if (-not [bool]$entry.exists) {
        continue
      }
      $task = Get-ScheduledTask `
        -TaskName ([string]$entry.task_name) `
        -TaskPath "\" `
        -ErrorAction Stop
      if ([bool]$task.Settings.Enabled -ne [bool]$entry.was_enabled) {
        throw "Public runtime task maintenance entry rollback failed: $($entry.task_name)"
      }
    }
    throw
  }
}

function Exit-PublicRuntimeTaskMaintenance {
  param([Parameter(Mandatory = $true)][object[]]$Snapshot)

  try {
    foreach ($entry in @($Snapshot)) {
      if (-not [bool]$entry.exists -or -not [bool]$entry.was_enabled) {
        continue
      }
      Enable-ScheduledTask `
        -TaskName ([string]$entry.task_name) `
        -TaskPath "\" `
        -ErrorAction Stop `
        | Out-Null
    }

    foreach ($entry in @($Snapshot)) {
      if (-not [bool]$entry.exists -or -not [bool]$entry.was_enabled) {
        continue
      }
      $task = Get-ScheduledTask `
        -TaskName ([string]$entry.task_name) `
        -TaskPath "\" `
        -ErrorAction Stop
      if (-not [bool]$task.Settings.Enabled) {
        throw "Public runtime scheduled task was not re-enabled: $($entry.task_name)"
      }
    }
    $restoredTruth = Get-PublicRuntimeTaskMaintenanceState -Snapshot $Snapshot
    if (
      -not [bool]$restoredTruth.verified -or
      -not [bool]$restoredTruth.restored_to_snapshot
    ) {
      throw "Public runtime scheduled task set drifted during maintenance"
    }
  } catch {
    Suspend-PublicRuntimeTasks -Snapshot $Snapshot -TimeoutSec 30
    throw
  }
}