#Requires -Version 5.1
<#
.SYNOPSIS
    SSH/SCP transport helpers for Linux build VMs.

.DESCRIPTION
    SSH-only transport layer for the Linux branch of the CI/CD system.
    The existing WinRM transport (used by Windows VMs) is NOT modified.

    Exported functions:
      Invoke-SshCommand  — run a command in a Linux guest via ssh.exe
      Copy-SshItem       — copy files to/from a Linux guest via scp.exe
      Test-SshReady      — poll until SSH is ready (port 22 open + login succeeds)

    Requirements:
      - ssh.exe and scp.exe in PATH (default on Windows 11 / Server 2022)
      - SSH private key at the path provided
      - Guest user must be set up for key-based auth (no passphrase)
#>
Set-StrictMode -Version Latest
$ErrorActionPreference = 'Stop'

function Invoke-SshCommand {
    <#
    .SYNOPSIS
        Run a command in a Linux guest via ssh.exe
    #>
    [CmdletBinding()]
    param(
        [Parameter(Mandatory)]
        [string] $IP,

        [string] $User = 'ci_build',

        [string] $KeyPath = 'F:\CI\keys\ci_linux',

        [Parameter(Mandatory)]
        [string] $Command,

        [int] $ConnectTimeout = 10,

        # Capture + return stdout/stderr instead of printing to console.
        [switch] $PassThru,

        # Don't throw on non-zero exit — just return the output.
        [switch] $AllowFail
    )

    $sshArgs = @(
        '-i', $KeyPath,
        '-o', 'StrictHostKeyChecking=no',
        '-o', 'UserKnownHostsFile=NUL',
        '-o', "ConnectTimeout=$ConnectTimeout",
        '-o', 'BatchMode=yes',
        "$User@$IP",
        $Command
    )

    if ($PassThru) {
        $output = & ssh @sshArgs 2>&1
        $exit   = $LASTEXITCODE
    }
    else {
        & ssh @sshArgs
        $exit   = $LASTEXITCODE
        $output = @()
    }

    if ($exit -ne 0 -and -not $AllowFail) {
        throw "[SSH] Command failed (exit $exit): $Command"
    }

    return [pscustomobject]@{
        ExitCode = [int]$exit
        Output   = [string[]]$output
    }
}

function Copy-SshItem {
    <#
    .SYNOPSIS
        Copy files to/from Linux guest via scp.exe
    #>
    [CmdletBinding()]
    param(
        [Parameter(Mandatory)]
        [string] $Source,

        [Parameter(Mandatory)]
        [string] $Destination,

        # Guest IP — used to build user@host prefix when Direction is set.
        [string] $IP = '',

        [string] $User = 'ci_build',

        [Parameter(Mandatory)]
        [string] $KeyPath,

        [ValidateSet('ToGuest', 'FromGuest', 'Direct')]
        [string] $Direction = 'Direct',

        # Pass -r to scp (recursive copy).
        [switch] $Recurse,

        [int] $ConnectTimeout = 10
    )

    if ($Direction -eq 'ToGuest') {
        $Destination = "$User@${IP}:$Destination"
    }
    elseif ($Direction -eq 'FromGuest') {
        $Source = "$User@${IP}:$Source"
    }
    # Direction = 'Direct': use Source + Destination as-is

    $scpArgs = @(
        '-i', $KeyPath,
        '-o', 'StrictHostKeyChecking=no',
        '-o', 'UserKnownHostsFile=NUL',
        '-o', "ConnectTimeout=$ConnectTimeout"
    )
    if ($Recurse) { $scpArgs += '-r' }
    $scpArgs += @($Source, $Destination)

    & scp @scpArgs
    if ($LASTEXITCODE -ne 0) {
        throw "[SCP] Copy failed (exit $LASTEXITCODE): $Source -> $Destination"
    }
}

function Test-SshReady {
    <#
    .SYNOPSIS
        Poll until SSH port 22 is open and a login command succeeds.
    #>
    [CmdletBinding()]
    param(
        [Parameter(Mandatory)]
        [string] $IP,

        [string] $User = 'ci_build',

        [string] $KeyPath = 'F:\CI\keys\ci_linux',

        [int] $TimeoutSec = 300,

        [int] $PollSec = 10
    )

    $deadline = (Get-Date).AddSeconds($TimeoutSec)

    # Phase 1: wait for port 22 to be open
    $portOpen = $false
    while (-not $portOpen -and (Get-Date) -lt $deadline) {
        $portOpen = (Test-NetConnection -ComputerName $IP -Port 22 `
            -InformationLevel Quiet -WarningAction SilentlyContinue `
            -ErrorAction SilentlyContinue)
        if (-not $portOpen) {
            Start-Sleep -Seconds $PollSec
        }
    }

    if (-not $portOpen) {
        throw "[Test-SshReady] Timed out after ${TimeoutSec}s waiting for SSH at $IP"
    }

    # Phase 2: try ssh echo — success when output contains 'ready'
    while ((Get-Date) -lt $deadline) {
        $result = Invoke-SshCommand -IP $IP -User $User -KeyPath $KeyPath `
            -Command 'echo ready' -AllowFail -PassThru
        if ($result.ExitCode -eq 0 -and ($result.Output -join '') -like '*ready*') {
            return $true
        }
        Start-Sleep -Seconds $PollSec
    }

    throw "[Test-SshReady] Timed out after ${TimeoutSec}s waiting for SSH at $IP"
}

Export-ModuleMember -Function Invoke-SshCommand, Copy-SshItem, Test-SshReady