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# inspired by:
#   https://stackoverflow.com/questions/53653473/generating-an-sas-token-in-java-to-download-a-file-in-an-azure-data-storage-cont?rq=1
#   https://purple.telstra.com.au/blog/loading-and-querying-data-in-azure-table-storage-using-powershell
#   https://docs.microsoft.com/en-us/rest/api/storageservices/authorize-with-shared-key

function Create-Signature( [string] $Operation, [string] $Container, [string] $Blob, [string] $Account, [string] $AccessKey, [string] $Version, [DateTime] $Now, [int] $ContentLength=-1 )
{
    [Reflection.Assembly]::LoadWithPartialName("System.Web") | Out-Null

    if ( $ContentLength -gt -1 )
    {
        $contentLengthValue = $ContentLength
    } else {
        $contentLengthValue = ''
    }

    $partToSign =      "`n" `
                     + "`n" `
                     + "`n" `
                     + $contentLengthValue + "`n" `
                     + "`n" `
                     + "`n" `
                     + "`n" `
                     + "`n" `
                     + "`n" `
                     + "`n" `
                     + "`n" `
                     + "`n" `
                     + "x-ms-blob-type:BlockBlob" + "`n" `
                     + "x-ms-date:$(Get-Date (Get-Date $Now).ToUniversalTime() -Format 'R')" + "`n" `
                     + "x-ms-version:$Version" + "`n"

    switch ( $Operation )                 
    {                 
        'GET'       {
                        $stringToSign  = 'GET' `
                                       + $partToSign `
                                       + "/$Account/$Container/$Blob"
                        break
                    }
                    
        'PUT'       {
                        $stringToSign  = 'PUT' `
                                       + $partToSign `
                                       + "/$Account/$Container/$Blob"
                        break
                    }
                    
        'LIST'      { 
                        $stringToSign  = "GET" `
                                       + $partToSign `
                                       + "/$Account/$Container" + "`n" `
                                       + "comp:list" + "`n" `
                                       + "restype:container"
                        break
                    }
                    
        default     {
                        throw "invalid operation: $Operation"
                    }
    }

    $hmac = New-Object System.Security.Cryptography.HMACSHA256
    $hmac.key = [Convert]::FromBase64String( $AccessKey )
    
    $signature = $hmac.ComputeHash( [Text.Encoding]::UTF8.GetBytes( $stringToSign ) )
    $signature = [Convert]::ToBase64String( $signature )

    Write-Debug "container: $Container"
    Write-Debug "Accoount: $Account"
    Write-Debug "AccessKey: $AccessKey"
    Write-Debug "stringToSign: $stringToSign"

    $signature
}

function Invoke-BlobRequest( [Uri] $Uri, [string] $Account, [string] $Signature, [DateTime] $Now, [string] $Version, [string] $Method='GET', [string] $FilePath='' )
{
    $requestParams = @{}
    $requestParams.Add( 'Uri', $Uri )
    $requestParams.Add( 'Method', $Method )
    
    if ( $FilePath )
    {
        $requestParams.Add( 'Infile', $FilePath )
    }
    
    $requestParams.Add( 'Headers', @{ `
                                      'x-ms-blob-type' = 'BlockBlob'; `
                                      'x-ms-date' = "$(Get-Date (Get-Date $Now).ToUniversalTime() -Format 'R')"; `
                                      'x-ms-version' = $Version; `
                                      'Authorization' = "SharedKey $($Account):$($Signature)" `
                                    } `
                      )

    Write-Debug ".... Invoke-WebRequest: $Uri"
    
    $requestParams.Keys | % {
        if ( $_ -eq 'Headers' )
        {
            $item = $_
            $requestParams.Item($_).Keys | % {
                Write-Debug "...... Headers $_ : $($requestParams.Item($item).Item($_))"
            }
        } else {
            Write-Debug "...... $_  $($requestParams.Item($_))"
        }
    }

    # run the web service request
    $response = Invoke-WebRequest @requestParams
    $response
}


# ---------- ---------- ----------
# Main
# ---------- ---------- ----------

$ownerAccount     = '<storage account>'
$ownerAccessKey   = '<storage account access key>'
$requesterAccount = '<requester account>'
$version          = '2019-10-10'

# consider badly synchronized server time and start 3 minutes in the past
$now = (Get-Date).ToUniversalTime().AddMinutes(-3)


Write-Host "`n"
Write-Host "# ++++++++++++++++++++++++++++++"
Write-Host "# List Blobs in Container"
Write-Host "# ++++++++++++++++++++++++++++++"

# step 1: create signature
$container = 'yade'
$signature = Create-Signature -Operation 'LIST' -Container $container -Account $ownerAccount -AccessKey $ownerAccessKey -Version $version -Now $now

    Write-Debug "Signature: $signature"

# step 2: send web service request
$uri      = "https://$($ownerAccount).blob.core.windows.net/$($container)?restype=container&comp=list"
$response = Invoke-BlobRequest -Uri $uri -Account $requesterAccount -Signature $signature -Now $now -Version $version -Method 'GET'

    Write-Host "Status Code: $($response.StatusCode)"
    Write-Host $response.Content


Write-Host "`n"
Write-Host "# ++++++++++++++++++++++++++++++"
Write-Host "# Get Blob from Container"
Write-Host "# ++++++++++++++++++++++++++++++"

# step 1: create signature
$container = 'yade'
$blob      = 'test.txt'
$signature = Create-Signature -Operation 'GET' -Container $container -Blob $blob -Account $ownerAccount -AccessKey $ownerAccessKey -Version $version -Now $now

    Write-Debug "Signature: $signature"

# step 2: send web service request
$uri      = "https://$($ownerAccount).blob.core.windows.net/$($container)/$($blob)"
$response = Invoke-BlobRequest -Uri $uri -Account $requesterAccount -Signature $signature -Now $now -Version $version -Method 'GET'

    Write-Host "Status Code: $($response.StatusCode)"
    Write-Host $response.Content

Write-Host "`n"
Write-Host "# ++++++++++++++++++++++++++++++"
Write-Host "# Write Blob to Container"
Write-Host "# ++++++++++++++++++++++++++++++"

# step 1: create signature
$container = 'yade'
$filePath  = "c:/tmp/some_blob.txt"
$blob      = (Get-Item $filePath).Name
$signature = Create-Signature -Operation 'PUT' -Container $container -Blob $blob -Account $ownerAccount -AccessKey $ownerAccessKey -Version $version -Now $now -ContentLength (Get-Content $filePath -Raw).length

    Write-Debug "Signature: $signature"

# step 2: send web service request
$uri      = "https://$($ownerAccount).blob.core.windows.net/$($container)/$($blob)"
$response = Invoke-BlobRequest -Uri $uri -Account $requesterAccount -Signature $signature -Now $now -Version $version -Method 'PUT' -FilePath $filePath

    Write-Host "Status Code: $($response.StatusCode)"
    Write-Host $response.Content