download-blobs.ps1

# Requires: Az.Accounts, Az.Storage

# --- Inputs ---
$SubscriptionId      = "<sub-id>"          # optional (if you want to force a sub)
$ResourceGroupName   = "<rg-name>"
$StorageAccountName  = "<storage-account-name>"   # single SA target

# Container filters (choose one style)
$ContainerNames      = @("container-a","container-b")   # exact list (optional)
$ContainerPatterns   = @("logs-*","exports-*")          # wildcard list (optional)

$DestinationRoot     = "C:\downloads\storage"           # local root folder
$Overwrite           = $true                            # overwrite local files if exists

# --- Login / context ---
Connect-AzAccount | Out-Null
if ($SubscriptionId -and $SubscriptionId -ne "<sub-id>") {
  Set-AzContext -SubscriptionId $SubscriptionId | Out-Null
}

# --- Filter to ONE storage account ---
$sa = Get-AzStorageAccount -ResourceGroupName $ResourceGroupName |
  Where-Object StorageAccountName -EQ $StorageAccountName |
  Select-Object -First 1

if (-not $sa) { throw "Storage account '$StorageAccountName' not found in RG '$ResourceGroupName'." }

$ctx = $sa.Context

# --- List containers and filter to the set you want ---
$containers = Get-AzStorageContainer -Context $ctx

if ($ContainerNames -and $ContainerNames.Count -gt 0) {
  $containers = $containers | Where-Object { $ContainerNames -contains $_.Name }
}

if ($ContainerPatterns -and $ContainerPatterns.Count -gt 0) {
  $containers = $containers | Where-Object {
    $name = $_.Name
    $ContainerPatterns | Where-Object { $name -like $_ } | Select-Object -First 1
  }
}

if (-not $containers) { throw "No containers matched the provided filters." }

# --- Download all blobs from each container ---
foreach ($c in $containers) {
  $containerName = $c.Name
  Write-Host "==> Container: $containerName"

  $containerDest = Join-Path $DestinationRoot $containerName
  New-Item -ItemType Directory -Path $containerDest -Force | Out-Null

  # Enumerate blobs (handles paging under the hood)
  $blobs = Get-AzStorageBlob -Container $containerName -Context $ctx

  foreach ($b in $blobs) {
    # Preserve "virtual folders" in blob names
    $relativePath = $b.Name -replace '/', '\'
    $localPath    = Join-Path $containerDest $relativePath
    $localDir     = Split-Path -Parent $localPath
    if ($localDir) { New-Item -ItemType Directory -Path $localDir -Force | Out-Null }

    if (-not $Overwrite -and (Test-Path $localPath)) {
      Write-Host "  Skipping existing: $($b.Name)"
      continue
    }

    Write-Host "  Downloading: $($b.Name)"
    Get-AzStorageBlobContent `
      -Container $containerName `
      -Blob $b.Name `
      -Destination $localPath `
      -Context $ctx `
      -Force | Out-Null
  }
}

Write-Host "Done. Downloaded to: $DestinationRoot"