[CmdletBinding()]
param(
    [Parameter(Mandatory = $true)]
    [string]$JobRoot,

    [Parameter(Mandatory = $true)]
    [string]$OutputPath,

    [ValidateRange(1, 1000)]
    [int]$FreeGiBFloor = 360
)

$ErrorActionPreference = "Stop"
$ProgressPreference = "SilentlyContinue"

function Assert-DDrivePath {
    param([string]$Path, [string]$Label)
    $fullPath = [IO.Path]::GetFullPath($Path)
    if ([IO.Path]::GetPathRoot($fullPath).TrimEnd("\") -ine "D:") {
        throw "$Label must be stored on D:"
    }
    return $fullPath
}

function Assert-FreeSpace {
    param([string]$Phase, [int64]$RequiredAdditionalBytes = 0)
    $freeBytes = [int64](Get-PSDrive -Name D).Free
    $floorBytes = [int64]$FreeGiBFloor * 1GB
    Write-Output (
        "DISK_GUARD PHASE={0} FREE_GIB={1} FLOOR_GIB={2}" -f
        $Phase,
        [math]::Round($freeBytes / 1GB, 3),
        $FreeGiBFloor
    )
    if ($freeBytes -lt ($floorBytes + $RequiredAdditionalBytes)) {
        throw "D: does not have the guarded replay reserve during $Phase"
    }
}

$jobDirectory = Assert-DDrivePath (
    (Resolve-Path -LiteralPath $JobRoot).Path
) "Job root"
$output = Assert-DDrivePath $OutputPath "Output path"
if (Test-Path -LiteralPath $output) {
    Write-Output "REPLAY_ALREADY_PRESENT=$output"
    exit 0
}

$jobPath = Join-Path $jobDirectory "job.json"
$job = Get-Content -LiteralPath $jobPath -Raw | ConvertFrom-Json
if (
    $job.schema_version -ne "missioncore.compute-job/v1" -or
    $job.job_id -ne "recorded-camera-602ac89026ed12978619801d" -or
    $job.input.session_id -ne "20260720T065719Z_viewer_live" -or
    $job.input.source_id -ne "sensor.camera.right" -or
    [int]$job.input.segment_count -ne 4489
) {
    throw "The requested job is not the immutable RAVNOVES00 right-camera source"
}

$epochRoot = Join-Path $jobDirectory "input\camera\sensor.camera.right\epoch-1"
$initPath = Join-Path $epochRoot "init.mp4"
$segmentsRoot = Join-Path $epochRoot "segments"
if (-not (Test-Path -LiteralPath $initPath -PathType Leaf)) {
    throw "Camera initialization segment is absent"
}
if (-not (Test-Path -LiteralPath $segmentsRoot -PathType Container)) {
    throw "Camera segment directory is absent"
}

$parent = Split-Path $output -Parent
$null = New-Item -ItemType Directory -Path $parent -Force
$temporary = Join-Path $parent (".{0}.{1}.partial" -f (Split-Path $output -Leaf), [Guid]::NewGuid().ToString("N"))
$requiredBytes = [int64]$job.input.byte_length + 1GB
Assert-FreeSpace "preflight" $requiredBytes

try {
    $destination = [IO.File]::Open(
        $temporary,
        [IO.FileMode]::CreateNew,
        [IO.FileAccess]::Write,
        [IO.FileShare]::None
    )
    try {
        $source = [IO.File]::OpenRead($initPath)
        try { $source.CopyTo($destination) } finally { $source.Dispose() }
        for ($sequence = 1; $sequence -le 4489; $sequence++) {
            $segment = Join-Path $segmentsRoot ("{0}.m4s" -f $sequence)
            if (-not (Test-Path -LiteralPath $segment -PathType Leaf)) {
                throw "Camera segment is absent: $sequence"
            }
            $source = [IO.File]::OpenRead($segment)
            try { $source.CopyTo($destination) } finally { $source.Dispose() }
        }
        $destination.Flush($true)
    }
    finally {
        $destination.Dispose()
    }

    $probe = & ffprobe -v error -select_streams v:0 -count_frames `
        -show_entries stream=width,height,nb_read_frames `
        -of json $temporary | ConvertFrom-Json
    if ($LASTEXITCODE -ne 0) {
        throw "ffprobe failed for the reconstructed camera source"
    }
    $stream = @($probe.streams)[0]
    if (
        [int]$stream.width -ne 800 -or
        [int]$stream.height -ne 600 -or
        [int]$stream.nb_read_frames -ne 4489
    ) {
        throw "Reconstructed camera stream violates the immutable frame contract"
    }
    Move-Item -LiteralPath $temporary -Destination $output
    Assert-FreeSpace "published"
    Write-Output "REPLAY_PATH=$output"
    Write-Output "FRAME_COUNT=4489"
}
finally {
    if (Test-Path -LiteralPath $temporary) {
        Remove-Item -LiteralPath $temporary -Force
    }
}