# atocore-backup-pull.ps1
#
# Pull the latest AtoCore backup snapshot from Dalidou to this Windows machine.
# Designed to be run by Windows Task Scheduler. Fail-open by design -- if
# Dalidou is unreachable (laptop on the road, etc.), exit cleanly without error.
#
# Usage (manual test):
#   powershell.exe -ExecutionPolicy Bypass -File atocore-backup-pull.ps1
#
# Scheduled task: see docs/windows-backup-setup.md for Task Scheduler config.

$ErrorActionPreference = "Continue"

# --- Configuration ---
$Remote           = "papa@dalidou"
$RemoteSnapshots  = "/srv/storage/atocore/backups/snapshots"
$LocalBackupDir   = "$env:USERPROFILE\Documents\ATOCore_Backups"
$LogDir           = "$LocalBackupDir\_logs"
$ReachabilityTest = 5   # seconds timeout for SSH probe

# --- Setup ---
if (-not (Test-Path $LocalBackupDir)) {
    New-Item -ItemType Directory -Path $LocalBackupDir -Force | Out-Null
}
if (-not (Test-Path $LogDir)) {
    New-Item -ItemType Directory -Path $LogDir -Force | Out-Null
}

$Timestamp = Get-Date -Format "yyyy-MM-dd_HHmmss"
$LogFile = "$LogDir\backup-$Timestamp.log"

function Log($msg) {
    $line = "[{0}] {1}" -f (Get-Date -Format "yyyy-MM-dd HH:mm:ss"), $msg
    Write-Host $line
    Add-Content -Path $LogFile -Value $line
}

Log "=== AtoCore backup pull starting ==="
Log "Remote: $Remote"
Log "Local target: $LocalBackupDir"

# --- Reachability check: fail open if Dalidou is offline ---
Log "Checking Dalidou reachability..."
$probe = & ssh -o ConnectTimeout=$ReachabilityTest -o BatchMode=yes `
              -o StrictHostKeyChecking=accept-new `
              $Remote "echo ok" 2>&1
if ($LASTEXITCODE -ne 0 -or $probe -ne "ok") {
    Log "Dalidou unreachable ($probe) -- fail-open exit"
    exit 0
}
Log "Dalidou reachable."

# --- Pull the entire snapshots directory ---
# Dalidou's retention policy (7 daily + 4 weekly + 6 monthly) already caps
# the snapshot count, so pulling the whole dir is bounded and simple. scp
# will overwrite local files -- we rely on this to pick up new snapshots.
Log "Pulling snapshots via scp..."
$LocalSnapshotsDir = Join-Path $LocalBackupDir "snapshots"
if (-not (Test-Path $LocalSnapshotsDir)) {
    New-Item -ItemType Directory -Path $LocalSnapshotsDir -Force | Out-Null
}

& scp -o BatchMode=yes -r "${Remote}:${RemoteSnapshots}/*" "$LocalSnapshotsDir\" 2>&1 |
    ForEach-Object { Add-Content -Path $LogFile -Value $_ }

if ($LASTEXITCODE -ne 0) {
    Log "scp failed with exit $LASTEXITCODE"
    exit 0  # fail-open
}

# --- Stats ---
$snapshots = Get-ChildItem -Path $LocalSnapshotsDir -Directory |
    Where-Object { $_.Name -match "^\d{8}T\d{6}Z$" } |
    Sort-Object Name -Descending

$totalSize = (Get-ChildItem $LocalSnapshotsDir -Recurse -File | Measure-Object -Property Length -Sum).Sum
$SizeMB = [math]::Round($totalSize / 1MB, 2)
$latest = if ($snapshots.Count -gt 0) { $snapshots[0].Name } else { "(none)" }

Log ("Pulled {0} snapshots successfully (total {1} MB, latest: {2})" -f $snapshots.Count, $SizeMB, $latest)
Log "=== backup complete ==="

# --- Log retention: keep last 30 log files ---
Get-ChildItem -Path $LogDir -Filter "backup-*.log" |
    Sort-Object Name -Descending |
    Select-Object -Skip 30 |
    ForEach-Object { Remove-Item $_.FullName -Force -ErrorAction SilentlyContinue }