# Detect Windows Server Version
$OSVersion = (Get-CimInstance Win32_OperatingSystem).Version

if ($OSVersion -like "10.*") {
    $OSType = "WindowsServer2019or2022"
} else {
    Write-Host "Unsupported Windows Server version. This script is intended for Windows Server 2019 and 2022. Exiting."
    exit 1
}

# Retrieve Instance ID using IMDSv2 (with fallback to IMDSv1)
$Token = $null
try {
    $Token = Invoke-RestMethod -Uri "http://169.254.169.254/latest/api/token" -Method PUT -Headers @{"X-aws-ec2-metadata-token-ttl-seconds" = "21600"} -ErrorAction Stop
    Write-Host "Successfully retrieved IMDSv2 token."
} catch {
    Write-Warning "Failed to retrieve IMDSv2 token. Falling back to IMDSv1."
}

if ($Token) {
    try {
        $InstanceID = Invoke-RestMethod -Uri "http://169.254.169.254/latest/meta-data/instance-id" -Headers @{"X-aws-ec2-metadata-token" = $Token} -ErrorAction Stop
    } catch {
        Write-Error "Unable to retrieve instance ID using IMDSv2. Verify metadata service settings."
        exit 1
    }
} else {
    try {
        $InstanceID = Invoke-RestMethod -Uri "http://169.254.169.254/latest/meta-data/instance-id" -ErrorAction Stop
    } catch {
        Write-Error "Unable to retrieve instance ID using IMDSv1. Exiting."
        exit 1
    }
}

if (-not $InstanceID) {
    Write-Error "Failed to retrieve instance ID. Exiting."
    exit 1
}

Write-Host "Successfully retrieved instance ID: $InstanceID"

# Check if Fluentd service is already installed and running
$FluentdService = Get-Service -Name fluentdwinsvc -ErrorAction SilentlyContinue
if ($FluentdService) {
    if ($FluentdService.Status -eq "Running") {
        Write-Host "Fluentd service is already installed and running. Skipping installation."
        exit 0
    } else {
        Write-Host "Fluentd service is installed but not running. Starting the service..."
        Start-Service -Name fluentdwinsvc
        $ServiceStatus = Get-Service -Name fluentdwinsvc
        Write-Host "Fluentd service status: $($ServiceStatus.Status)"
        if ($ServiceStatus.Status -eq "Running") {
            Write-Host "Fluentd is now running successfully. Exiting script."
            exit 0
        } else {
            Write-Error "Failed to start Fluentd service. Exiting."
            exit 1
        }
    }
}

# Install Fluentd
$FluentdInstallerURL = "https://s3.amazonaws.com/packages.treasuredata.com/lts/5/windows/fluent-package-5.0.5-x64.msi"
$InstallerPath = "$env:TEMP\fluent-package-5.0.5-x64.msi"

Write-Host "Downloading Fluentd installer..."
Invoke-WebRequest -Uri $FluentdInstallerURL -OutFile $InstallerPath -ErrorAction Stop

Write-Host "Installing Fluentd..."
Start-Process -FilePath "msiexec.exe" -ArgumentList "/i", "`"$InstallerPath`"", "/quiet", "/norestart" -Wait

if (-not (Get-Service -Name fluentdwinsvc -ErrorAction SilentlyContinue)) {
    Write-Error "Fluentd installation failed. Exiting."
    exit 1
}

Write-Host "Fluentd installed successfully."

# Set Fluentd service to automatic start
Write-Host "Setting Fluentd service to start automatically on boot..."
Set-Service -Name fluentdwinsvc -StartupType Automatic

# Start Fluentd Service
Write-Host "Starting Fluentd service..."
Start-Service -Name fluentdwinsvc

# Check Fluentd Service Status
$ServiceStatus = Get-Service -Name fluentdwinsvc
Write-Host "Fluentd service status: $($ServiceStatus.Status)"

# Configure Fluentd
$FluentdConfigPath = "C:\opt\fluent\etc\fluent\fluentd.conf"  # Default Fluentd configuration path
$FluentdConfigContent = @"
<source>
  @type windows_eventlog
  channels ["System", "Application", "Security"]  # Collect System, Application, and Security logs
  read_interval 2  # Fetch logs every 2 seconds
  tag windows.eventlog  # Tag for filtering logs

  <storage>
    @type local
    persistent true
    path C:/fluentd/storage/system_winlog.json
    remove_on_idle true
    remove_interval 7200  # Remove logs older than 2 hours (7200 seconds)
  </storage>
</source>

<match windows.eventlog>
  @type s3
  s3_bucket abhi-1221               # Replace with your S3 bucket name
  s3_region ap-south-1              # Replace with your S3 region (e.g., us-east-1)
  path windows/$InstanceID/%Y/%m/%d/  # Use dynamic values from the record to organize logs by instance
  time_slice_format %Y%m%d%H                  # Log chunk format: year, month, day, hour
  time_slice_wait 2m                         # Wait before finalizing a log chunk
  localtime true 
  buffer_path C:/opt/fluent/buffer/s3         # Buffer directory for Fluentd
  <format>
    @type json                                # Store logs in JSON format
  </format>
  <buffer>
    @type file                                # File-based buffer
    path C:/opt/fluent/buffer/s3
    flush_mode interval                       # Flush logs at intervals
    flush_interval 1m                         # Flush every 1 minute
    retry_max_times 10                        # Retry up to 10 times on failure
    retry_wait 30                             # Wait 30 seconds between retries
    chunk_limit_records 1000                  # Adjust based on your needs (optional)
    flush_thread_count 2                      # Adjust for performance (optional)
    timekey 7200                              # Logs will expire after 2 hours (2 * 60 * 60)
  </buffer>
</match>
"@

Write-Host "Updating Fluentd configuration..."
Set-Content -Path $FluentdConfigPath -Value $FluentdConfigContent

# Create Necessary Directories and Set Permissions
$BufferPath = "C:\opt\fluent\buffer\s3"
if (-Not (Test-Path -Path $BufferPath)) {
    New-Item -ItemType Directory -Path $BufferPath
}
Write-Host "Setting permissions for Fluentd directories..."
icacls "C:\opt\fluent\" /grant "Everyone:(OI)(CI)F" /T

# Restart Fluentd Service
Write-Host "Restarting Fluentd service..."
Restart-Service -Name fluentdwinsvc

# Final Status Check
$ServiceStatus = Get-Service -Name fluentdwinsvc
if ($ServiceStatus.Status -eq "Running") {
    Write-Host "Fluentd is running successfully."
} else {
    Write-Error "Fluentd service failed to start. Check the logs for more information."
}