#Requires -RunAsAdministrator
$ErrorActionPreference = "Stop"

$Target = "C:\MinerOpsAgent"
$BackupRoot = Join-Path $Target "backups"
$BackupTimestamp = Get-Date -Format "yyyyMMdd-HHmmss"
$BackupSuffix = [guid]::NewGuid().ToString("N").Substring(0, 8)
$Backup = Join-Path $BackupRoot "$BackupTimestamp-$BackupSuffix"
$RuntimeFiles = @(
    "MinerOpsAgentService.ps1", "MinerOpsAgentTray.ps1", "MinerOpsAgentGUI.ps1",
    "MinerOpsApi3EnrichmentPoller.ps1", "MinerOpsPoolPoller.ps1",
    "MinerOpsPoolPollerTask.ps1", "EnrichOneMiner.ps1", "MinerOpsControl.ps1",
    "VERSION"
)

function Get-MinerOpsScheduledTask {
    param([Parameter(Mandatory)][string]$Name)

    return Get-ScheduledTask -TaskName $Name -ErrorAction SilentlyContinue
}

function Stop-MinerOpsScheduledTaskForUpgrade {
    param(
        [Parameter(Mandatory)][string]$Name,
        [TimeSpan]$Timeout = [TimeSpan]::FromSeconds(30)
    )

    Stop-ScheduledTask -TaskName $Name -ErrorAction Stop
    $deadline = [DateTime]::UtcNow.Add($Timeout)
    do {
        Start-Sleep -Milliseconds 500
        $task = Get-MinerOpsScheduledTask -Name $Name
        if ($null -eq $task) {
            throw "Scheduled Task $Name disappeared while stopping it."
        }
        if ([string]$task.State -ne "Running") {
            return
        }
    } while ([DateTime]::UtcNow -lt $deadline)

    throw "Scheduled Task $Name did not stop within $($Timeout.TotalSeconds) seconds."
}

function Start-MinerOpsScheduledTask {
    param([Parameter(Mandatory)][string]$Name)

    Start-ScheduledTask -TaskName $Name -ErrorAction Stop
}

# Validate the complete source before creating directories, stopping tasks, or
# replacing any target file.
foreach ($name in $RuntimeFiles) {
    $source = Join-Path $PSScriptRoot $name
    if (!(Test-Path -LiteralPath $source -PathType Leaf)) {
        throw "Deployment source is missing $name"
    }
}

$mainTask = Get-MinerOpsScheduledTask -Name "MinerOpsAgent"
$mainTaskExisted = $null -ne $mainTask
$mainTaskWasRunning = $mainTaskExisted -and [string]$mainTask.State -eq "Running"
$mainTaskStoppedForUpgrade = $false
$deploymentStarted = $false
$existing = @()
$createdTaskNames = [System.Collections.Generic.List[string]]::new()

try {
    New-Item -ItemType Directory -Force -Path $Target, $BackupRoot | Out-Null
    $existing = @($RuntimeFiles | Where-Object {
        Test-Path -LiteralPath (Join-Path $Target $_) -PathType Leaf
    })
    if ($existing.Count -gt 0) {
        New-Item -ItemType Directory -Force -Path $Backup | Out-Null
        foreach ($name in $existing) {
            Copy-Item -LiteralPath (Join-Path $Target $name) `
                -Destination (Join-Path $Backup $name) -Force
        }
    }

    if ($mainTaskWasRunning) {
        $mainTaskStoppedForUpgrade = $true
        Stop-MinerOpsScheduledTaskForUpgrade -Name "MinerOpsAgent"
    }

    $deploymentStarted = $true
    foreach ($name in $RuntimeFiles) {
        Copy-Item -LiteralPath (Join-Path $PSScriptRoot $name) `
            -Destination (Join-Path $Target $name) -Force
    }

    $powerShell = "$env:SystemRoot\System32\WindowsPowerShell\v1.0\powershell.exe"
    $system = New-ScheduledTaskPrincipal -UserId "SYSTEM" `
        -LogonType ServiceAccount -RunLevel Highest
    $startup = New-ScheduledTaskTrigger -AtStartup
    $fiveMinutes = New-ScheduledTaskTrigger -Once -At (Get-Date).AddMinutes(1) `
        -RepetitionInterval (New-TimeSpan -Minutes 5)
    $commonSettings = New-ScheduledTaskSettingsSet -MultipleInstances IgnoreNew `
        -StartWhenAvailable -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries `
        -ExecutionTimeLimit (New-TimeSpan -Hours 72)
    $agentSettings = New-ScheduledTaskSettingsSet -MultipleInstances IgnoreNew `
        -StartWhenAvailable -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries `
        -ExecutionTimeLimit (New-TimeSpan -Hours 72) -RestartCount 3 `
        -RestartInterval (New-TimeSpan -Minutes 1)

    $definitions = @(
        @{
            Name = "MinerOpsAgent"; Script = "MinerOpsAgentService.ps1"
            Trigger = $startup; Principal = $system; Settings = $agentSettings
            ExtraArguments = ""
        },
        @{
            Name = "MinerOpsAgentTray"; Script = "MinerOpsAgentTray.ps1"
            Trigger = (New-ScheduledTaskTrigger -AtLogOn); Principal = $null
            Settings = $commonSettings; ExtraArguments = "-WindowStyle Hidden"
        },
        @{
            Name = "MinerOpsApi3Enrichment"
            Script = "MinerOpsApi3EnrichmentPoller.ps1"
            Trigger = $fiveMinutes; Principal = $system; Settings = $commonSettings
            ExtraArguments = "-Limit 0 -TimeoutMs 8000"
        },
        @{
            Name = "MinerOpsPoolPoller"; Script = "MinerOpsPoolPollerTask.ps1"
            Trigger = $fiveMinutes; Principal = $system; Settings = $commonSettings
            ExtraArguments = ""
        }
    )
    foreach ($definition in $definitions) {
        if ($null -ne (Get-MinerOpsScheduledTask -Name $definition.Name)) {
            Write-Host "Preserving existing Scheduled Task $($definition.Name)."
            continue
        }

        $arguments = '-NoProfile -ExecutionPolicy Bypass -File "{0}"' -f `
            (Join-Path $Target $definition.Script)
        if ($definition.ExtraArguments) {
            $arguments = "$arguments $($definition.ExtraArguments)"
        }
        $action = New-ScheduledTaskAction -Execute $powerShell -Argument $arguments
        $registration = @{
            TaskName = $definition.Name
            Action = $action
            Trigger = $definition.Trigger
            Settings = $definition.Settings
        }
        if ($definition.Principal) {
            $registration.Principal = $definition.Principal
        }
        Register-ScheduledTask @registration | Out-Null
        $createdTaskNames.Add($definition.Name)
    }

    if ($mainTaskWasRunning) {
        Start-MinerOpsScheduledTask -Name "MinerOpsAgent"
        $mainTaskStoppedForUpgrade = $false
    }

    Write-Host "MinerOps Windows Agent installed. Existing task definitions, config, state, logs, and backups were preserved."
} catch {
    $deploymentError = $_
    $rollbackErrors = [System.Collections.Generic.List[string]]::new()

    foreach ($taskName in $createdTaskNames) {
        try {
            Unregister-ScheduledTask -TaskName $taskName -Confirm:$false `
                -ErrorAction Stop
        } catch {
            $rollbackErrors.Add("could not remove new task ${taskName}: $($_.Exception.Message)")
        }
    }

    if ($deploymentStarted) {
        foreach ($name in $RuntimeFiles) {
            try {
                $targetPath = Join-Path $Target $name
                if ($existing -contains $name) {
                    Copy-Item -LiteralPath (Join-Path $Backup $name) `
                        -Destination $targetPath -Force
                } elseif (Test-Path -LiteralPath $targetPath) {
                    Remove-Item -LiteralPath $targetPath -Force
                }
            } catch {
                $rollbackErrors.Add("could not restore ${name}: $($_.Exception.Message)")
            }
        }
    }

    if ($mainTaskWasRunning -and $mainTaskStoppedForUpgrade) {
        try {
            Start-MinerOpsScheduledTask -Name "MinerOpsAgent"
            $mainTaskStoppedForUpgrade = $false
        } catch {
            $rollbackErrors.Add("could not restart restored MinerOpsAgent: $($_.Exception.Message)")
        }
    }

    if ($rollbackErrors.Count -gt 0) {
        $rollbackSummary = $rollbackErrors -join "; "
        throw "Deployment failed: $($deploymentError.Exception.Message). Rollback errors: $rollbackSummary"
    }
    throw $deploymentError
}