param(
    [string]$ApiBaseUrl = "http://192.168.200.61:18121/api/v1",
    [string]$ClusterID = "cfc0743d-d960-49fb-9de8-96e063d5e4aa",
    [string]$ActorUserID = "f67d943f-5397-4b3a-a229-695fe67ad700",
    [string]$EntryNodeName = "test-1",
    [string]$ExitNodeName = "test-3",
    [string]$DockerSSH = "test-docker",
    [string]$ExpectedBackendImage = "rap-backend:fabric-service-channel-0.2.281-c18z109",
    [string]$ExpectedNodeAgentImage = "rap-node-agent:0.2.270-c18z95",
    [string]$ResultPath = "artifacts\c18z92-node-agent-disabled-backend-fallback-smoke-result.json"
)

Set-StrictMode -Version Latest
$ErrorActionPreference = "Stop"
$scriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
$repoRoot = (Resolve-Path (Join-Path $scriptDir "..\..")).ProviderPath
$runId = "c18z92-" + (Get-Date -Format "yyyyMMdd-HHmmss")

function Invoke-Api {
    param([string]$Method, [string]$Path, [object]$Body = $null)
    $params = @{ Method = $Method; Uri = "$ApiBaseUrl$Path"; TimeoutSec = 30 }
    if ($null -ne $Body) {
        $params.ContentType = "application/json"
        $params.Body = ($Body | ConvertTo-Json -Depth 80)
    }
    return Invoke-RestMethod @params
}
function Get-PropertyValue {
    param([object]$Item, [string]$Name, [object]$Default = $null)
    if ($null -eq $Item) { return $Default }
    $property = $Item.PSObject.Properties[$Name]
    if ($null -eq $property) { return $Default }
    return $property.Value
}
function Get-NodeByName {
    param([string]$Name)
    $nodes = (Invoke-Api -Method GET -Path "/clusters/$ClusterID/nodes?actor_user_id=$ActorUserID").nodes
    $node = @($nodes | Where-Object { $_.name -eq $Name }) | Select-Object -First 1
    if ($null -eq $node) { throw "Node '$Name' was not found" }
    return $node
}
function ConvertTo-Base64UrlJson {
    param([object]$Value)
    $json = if ($Value -is [string]) { $Value } else { $Value | ConvertTo-Json -Depth 80 -Compress }
    $bytes = [System.Text.Encoding]::UTF8.GetBytes($json)
    return [Convert]::ToBase64String($bytes).TrimEnd("=").Replace("+", "-").Replace("/", "_")
}
function Disable-ExistingRoutePair {
    param([string]$SourceNodeID, [string]$DestinationNodeID)
    $items = (Invoke-Api -Method GET -Path "/clusters/$ClusterID/mesh/route-intents?actor_user_id=$ActorUserID").route_intents
    foreach ($item in @($items)) {
        if ([string](Get-PropertyValue -Item $item -Name "status" -Default "") -ne "active") { continue }
        if ([string](Get-PropertyValue -Item $item -Name "service_class" -Default "") -ne "vpn_packets") { continue }
        $sourceSelector = Get-PropertyValue -Item $item -Name "source_selector" -Default $null
        $destinationSelector = Get-PropertyValue -Item $item -Name "destination_selector" -Default $null
        if ([string](Get-PropertyValue -Item $sourceSelector -Name "node_id" -Default "") -ne $SourceNodeID) { continue }
        if ([string](Get-PropertyValue -Item $destinationSelector -Name "node_id" -Default "") -ne $DestinationNodeID) { continue }
        [void](Invoke-Api -Method POST -Path "/clusters/$ClusterID/mesh/route-intents/$($item.id)/disable" -Body @{
            actor_user_id = $ActorUserID
            reason = "c18z92 isolate disabled backend fallback route pair"
        })
    }
}
function Set-PoolPolicy {
    param([object]$Policy, [bool]$BackendFallbackAllowed)
    return Invoke-Api -Method PUT -Path "/clusters/$ClusterID/fabric/service-channels/pool-policy" -Body @{
        actor_user_id = $ActorUserID
        entry_pool_node_ids = @(Get-PropertyValue -Item $Policy -Name "entry_pool_node_ids" -Default @())
        exit_pool_node_ids = @(Get-PropertyValue -Item $Policy -Name "exit_pool_node_ids" -Default @())
        preferred_entry_node_id = [string](Get-PropertyValue -Item $Policy -Name "preferred_entry_node_id" -Default "")
        preferred_exit_node_id = [string](Get-PropertyValue -Item $Policy -Name "preferred_exit_node_id" -Default "")
        selection_strategy = [string](Get-PropertyValue -Item $Policy -Name "selection_strategy" -Default "fastest_healthy")
        route_rebuild = [string](Get-PropertyValue -Item $Policy -Name "route_rebuild" -Default "automatic")
        entry_failover = [string](Get-PropertyValue -Item $Policy -Name "entry_failover" -Default "automatic")
        exit_failover = [string](Get-PropertyValue -Item $Policy -Name "exit_failover" -Default "automatic")
        backend_fallback_allowed = $BackendFallbackAllowed
        sticky_session = [bool](Get-PropertyValue -Item $Policy -Name "sticky_session" -Default $true)
    }
}

$entryNode = Get-NodeByName -Name $EntryNodeName
$exitNode = Get-NodeByName -Name $ExitNodeName
$originalPolicy = (Invoke-Api -Method GET -Path "/clusters/$ClusterID/fabric/service-channels/pool-policy?actor_user_id=$ActorUserID").fabric_service_channel_pool_policy
$originalBackendFallback = [bool](Get-PropertyValue -Item $originalPolicy -Name "backend_fallback_allowed" -Default $true)
$lease = $null
$packetStatus = 0
$packetAcceptedBy = ""
try {
    Disable-ExistingRoutePair -SourceNodeID $entryNode.id -DestinationNodeID $exitNode.id
    [void](Set-PoolPolicy -Policy $originalPolicy -BackendFallbackAllowed $false)
    $lease = (Invoke-Api -Method POST -Path "/clusters/$ClusterID/fabric/service-channels/leases" -Body @{
        actor_user_id = $ActorUserID
        organization_id = "org-home"
        user_id = "user-m"
        resource_id = "$runId-vpn"
        service_class = "vpn_packets"
        entry_node_ids = @([string]$entryNode.id)
        exit_node_ids = @([string]$exitNode.id)
        preferred_entry_node_id = [string]$entryNode.id
        preferred_exit_node_id = [string]$exitNode.id
        allowed_channels = @("vpn_packet", "fabric_control")
        ttl_seconds = 120
        metadata = @{ smoke = "c18z92_node_agent_disabled_backend_fallback"; run_id = $runId }
    }).fabric_service_channel_lease
    $decodedAuthority = Get-PropertyValue -Item $lease -Name "authority_payload" -Default $null
    $authoritySignature = Get-PropertyValue -Item $lease -Name "authority_signature" -Default $null
    $packetUrl = "http://192.168.200.61:19131/api/v1/clusters/$ClusterID/fabric/service-channels/$($lease.channel_id)/vpn-connections/$($lease.resource_id)/packets"
    try {
        $packetResponse = Invoke-WebRequest -Method POST -Uri $packetUrl -Headers @{
            "X-RAP-Service-Channel-Token" = [string]$lease.token.token
            "X-RAP-Service-Channel-Authority-Payload" = ConvertTo-Base64UrlJson -Value $decodedAuthority
            "X-RAP-Service-Channel-Authority-Signature" = ConvertTo-Base64UrlJson -Value $authoritySignature
            "X-RAP-Service-Class" = "vpn_packets"
            "X-RAP-Channel-Class" = "vpn_packet"
        } -Body ([byte[]](0x45,0,0,40,0,0,0,0,64,6,0,0,10,77,0,2,192,168,200,95,0xD2,0x04,0x0D,0x3D,0,0,0,0,0,0,0,0,0x50,0,0,0,0,0,0,0)) -ContentType "application/octet-stream" -TimeoutSec 30
        $packetStatus = [int]$packetResponse.StatusCode
        $packetAcceptedBy = [string]$packetResponse.Headers["X-RAP-Service-Channel-Accepted-By"]
    } catch {
        $packetStatus = [int]$_.Exception.Response.StatusCode
        $packetAcceptedBy = [string]$_.Exception.Response.Headers["X-RAP-Service-Channel-Accepted-By"]
    }
} finally {
    try { [void](Set-PoolPolicy -Policy $originalPolicy -BackendFallbackAllowed $originalBackendFallback) } catch {}
}

$dataPlane = Get-PropertyValue -Item $lease -Name "data_plane" -Default $null
$backendLine = (& ssh $DockerSSH "docker ps --format '{{.Names}} {{.Image}} {{.Status}}' | grep '^rap_test_backend '") | Out-String
$nodeLines = (& ssh $DockerSSH "docker ps --format '{{.Names}} {{.Image}} {{.Status}}' | grep '^rap_test_node_test_'") | Out-String
$checks = [ordered]@{
    backend_expected_image_deployed = $backendLine.Contains($ExpectedBackendImage)
    node_agent_expected_image_deployed = $nodeLines.Contains($ExpectedNodeAgentImage)
    lease_blocks_without_fabric_route = ([string]$lease.status -eq "blocked_no_fabric_route")
    data_plane_disables_backend_relay = ($null -ne $dataPlane -and [string]$dataPlane.backend_relay_policy -eq "disabled")
    packet_rejected_without_backend_relay = ($packetStatus -eq 503)
    packet_contract_was_signed = ($packetAcceptedBy -eq "signed")
}
$failed = @($checks.GetEnumerator() | Where-Object { -not $_.Value } | ForEach-Object { $_.Key })
$result = [ordered]@{
    schema_version = "c18z92.node_agent_disabled_backend_fallback_smoke.v1"
    run_id = $runId
    cluster_id = $ClusterID
    channel_id = [string]$lease.channel_id
    passed = ($failed.Count -eq 0)
    checks = $checks
    failed_checks = $failed
    summary = [ordered]@{
        backend_container = $backendLine.Trim()
        node_containers = $nodeLines.Trim()
        lease = $lease
        packet_status_code = $packetStatus
        packet_accepted_by = $packetAcceptedBy
    }
}
$target = Join-Path $repoRoot $ResultPath
$result | ConvertTo-Json -Depth 80 | Set-Content -Path $target -Encoding UTF8
if (-not $result.passed) {
    throw "C18Z92 node-agent disabled backend fallback smoke failed: $($failed -join ', ')"
}
Write-Host "C18Z92 node-agent disabled backend fallback smoke passed. Result: $target"
$result