<#
.SYNOPSIS
    This script automates the process of creating snapshots for a virtual machine (VM) in Azure across multiple subscriptions.
    The script will locate the VM by its name, determine the resource group where it exists, and create snapshots for both the
    OS disk and any attached data disks. It ensures that the snapshot names follow a specific naming convention while removing
    any random characters appended to the disk names.

.DESCRIPTION
    - Loops through all Azure subscriptions attached to the account.
    - Searches for a specified VM by name across all subscriptions.
    - Identifies the resource group of the VM.
    - Creates snapshots for the OS disk and all data disks in the same resource group as the VM.
    - Follows the snapshot naming convention: computername_diskname_dd-mm-yyyy_hh_mm.
    - Removes random characters (e.g., GUIDs) after the disk name in snapshot naming.

.HOW TO RUN
    1. Make sure you have the Azure PowerShell module installed (`Az.Accounts` and `Az.Compute`).
       If not, install them by running the following commands in PowerShell:

        Install-Module -Name Az -Repository PSGallery -Force
        Update-Module -Name Az -Force


    2. Run the script in PowerShell. If not logged in already, it will prompt you to sign in to your Azure account.


       .\Create-AzVMSnapshot.ps1


    3. After logging in, the script will prompt you to enter the name of the VM you want to snapshot.
       Enter the exact name of the VM. The script will search for this VM across all subscriptions linked to your account.

    4. The script will create snapshots for the OS disk and all attached data disks, following a naming convention
       and removing any random characters from disk names.

    5. When finished, the script will output a message indicating that the snapshot creation process is complete.

.AUTHOR
    Vivek Chandran, Senior Systems Engineer

.DEPARTMENT
    Technology Services - Processing

.DATE CREATED
    02-08-2023
#>

# Check if the user is already logged in to Azure
$context = Get-AzContext

if (-not $context) {
    # If not logged in, prompt the user to log in to Azure
    Write-Host "You are not logged in to Azure. Please log in..."
    Connect-AzAccount
} else {
    Write-Host "You are already logged in to Azure."
}

# Prompt the user to enter the VM name
$computerName = Read-Host -Prompt "Please enter the name of the VM you want to snapshot"

# Get all subscriptions available to the account
$subscriptions = Get-AzSubscription

# Loop through each subscription to find the specified VM
foreach ($subscription in $subscriptions) {
    # Set the subscription context so that all subsequent commands target this subscription
    Set-AzContext -SubscriptionId $subscription.Id

    # Retrieve all VMs in the current subscription
    $vms = Get-AzVM

    # Check if a VM with the specified name exists in this subscription
    $vm = $vms | Where-Object { $_.Name -eq $computerName }

    if ($vm) {
        # Output message indicating the VM was found
        Write-Host "VM '$computerName' found in subscription '$($subscription.Name)'"

        # Retrieve the resource group where the VM resides
        $resourceGroup = $vm.ResourceGroupName

        # Loop through each data disk attached to the VM and create a snapshot
        foreach ($disk in $vm.StorageProfile.DataDisks) {
            # Get the name of the data disk
            $diskName = $disk.Name

            # Remove any random characters from the disk name after the first underscore (if present)
            $cleanedDiskName = ($diskName -split '_')[0..1] -join '_'

            # Get the current date and time in the format 'dd-MM-yyyy_HH_mm' for use in the snapshot name
            $currentDateTime = Get-Date -Format 'dd-MM-yyyy_HH_mm'

            # Construct the snapshot name using the cleaned disk name and the date/time
            $snapshotNameWithDataDisk = "$computerName-$cleanedDiskName-$currentDateTime"

            # Define the snapshot configuration using the disk's managed disk ID
            $snapshotConfig = New-AzSnapshotConfig -SourceUri $disk.ManagedDisk.Id -Location $vm.Location -CreateOption Copy -AccountType Standard_LRS

            # Create the snapshot in the same resource group as the VM
            New-AzSnapshot -Snapshot $snapshotConfig -ResourceGroupName $resourceGroup -SnapshotName $snapshotNameWithDataDisk

            # Output message indicating that the snapshot was successfully created for the data disk
            Write-Host "Snapshot created for data disk: $snapshotNameWithDataDisk"
        }

        # Create a snapshot for the OS disk of the VM
        $osDisk = $vm.StorageProfile.OsDisk

        # Get the name of the OS disk
        $osDiskName = $osDisk.Name

        # Remove any random characters from the OS disk name after the first underscore (if present)
        $cleanedOsDiskName = ($osDiskName -split '_')[0..1] -join '_'

        # Get the current date and time in the format 'dd-MM-yyyy_HH_mm' for use in the snapshot name
        $currentDateTime = Get-Date -Format 'dd-MM-yyyy_HH_mm'

        # Construct the snapshot name using the cleaned OS disk name and the date/time
        $snapshotNameWithOSDisk = "$computerName-$cleanedOsDiskName-$currentDateTime"

        # Define the snapshot configuration using the OS disk's managed disk ID
        $snapshotConfig = New-AzSnapshotConfig -SourceUri $osDisk.ManagedDisk.Id -Location $vm.Location -CreateOption Copy -AccountType Standard_LRS

        # Create the snapshot in the same resource group as the VM
        New-AzSnapshot -Snapshot $snapshotConfig -ResourceGroupName $resourceGroup -SnapshotName $snapshotNameWithOSDisk

        # Output message indicating that the snapshot was successfully created for the OS disk
        Write-Host "Snapshot created for OS disk: $snapshotNameWithOSDisk"

        # Exit the loop since the VM has been found and processed
        break
    } else {
        # Output message indicating that the VM was not found in this subscription
        Write-Host "VM '$computerName' not found in subscription '$($subscription.Name)'"
    }
}

# Output a final message indicating that the snapshot process has completed
Write-Host "Snapshots process completed!"