dotnetlogviewer_wf.ps1

<#
.SYNOPSIS
Reads a tab-separated .NET Core log file, displays it in a custom Windows Forms DataGridView,
and provides a refresh button. Rows are color-coded based on the LogLevel.
.NOTES
This script requires a Windows OS environment to load the System.Windows.Forms and System.Drawing assemblies.
#>

param(
    [Parameter(Mandatory=$true)]
    [string]$LogFilePath
)

# --- 1. Load Assemblies ---
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
Add-Type -AssemblyName System.Data # Needed for DataTable used for DataGridView source

# --- 2. Helper Function: Read and Structure the Tab-Separated Log ---
function Get-TabDelimitedLogs {
    param(
        [string]$Path
    )

    try {
        # Define the exact headers to match the log format
        $Headers = "Timestamp", "HostName", "AppName", "LogLevel", "UserName", "Category", "Message"
        
        # Read the content and convert it into structured objects
        $LogObjects = Get-Content -Path $Path | 
                      ConvertFrom-Csv -Delimiter "`t" -Header $Headers

        # Process the objects: Convert Timestamp to proper DateTime for sorting
        $ProcessedLogs = $LogObjects | Select-Object `
            @{Name='DateTime'; Expression={[datetime]::ParseExact($_.Timestamp, "yyyy-MM-dd h:mm:ss tt", [System.Globalization.CultureInfo]::InvariantCulture)}}, `
            "HostName", "AppName", "LogLevel", "UserName", "Category", "Message"

        # Sort the objects by the new DateTime column (most recent first)
        return $ProcessedLogs | Sort-Object -Property DateTime -Descending

    } catch {
        Write-Error "Error parsing log file: $($_.Exception.Message)"
        Write-Host "Please ensure the log format and path are correct." -ForegroundColor Red
        return @()
    }
}


# --- 3. Core Function: Refresh Data and Apply Coloring/Sorting ---
function Refresh-DataGridView {
    param(
        [Parameter(Mandatory=$true)]
        [System.Windows.Forms.DataGridView]$DataGridView,

        [Parameter(Mandatory=$true)]
        [string]$Path
    )

    Write-Host "Refreshing data from $Path..." -ForegroundColor Yellow

    # Load the structured log objects
    $Logs = Get-TabDelimitedLogs -Path $Path

    if (-not $Logs) {
        $DataGridView.DataSource = $null
        return
    }

    # Convert PowerShell objects to a DataTable for better performance and DataGridView binding
    # This step is critical for enabling native filtering and sorting within the DataGridView control.
    $DataTable = New-Object System.Data.DataTable
    
    # Define columns based on the processed object properties
    $Logs[0].psobject.Properties | ForEach-Object { 
        $DataTable.Columns.Add($_.Name, [System.Type]::GetType("System.String")) 
    }
    # Fix the DateTime column to be a DateTime type for native sorting
    $DataTable.Columns["DateTime"].DataType = [System.DateTime]

    # Populate the DataTable
    foreach ($Log in $Logs) {
        $row = $DataTable.NewRow()
        $Log.psobject.Properties | ForEach-Object {
            $row.$($_.Name) = $_.Value
        }
        $DataTable.Rows.Add($row)
    }

    # Bind the DataTable to the DataGridView
    $DataGridView.DataSource = $DataTable
    
    # Configure the DataGridView for user interaction
    $DataGridView.AllowUserToOrderColumns = $true
    $DataGridView.SelectionMode = [System.Windows.Forms.DataGridViewSelectionMode]::FullRowSelect
    $DataGridView.ReadOnly = $true
    $DataGridView.AutoSizeColumnsMode = [System.Windows.Forms.DataGridViewAutoSizeColumnsMode]::Fill
    $DataGridView.Columns["DateTime"].DefaultCellStyle.Format = "yyyy-MM-dd HH:mm:ss.fff"
    
    Write-Host "Refresh complete. $($Logs.Count) entries loaded." -ForegroundColor Green
}

# --- 4. Event Handler for Conditional Coloring ---
# This function is executed for every cell being drawn in the DataGridView
function LogLevel_CellFormatting {
    param(
        [Parameter(Mandatory=$true)]$sender,
        [Parameter(Mandatory=$true)]$e
    )

    # Check if we are formatting the LogLevel column
    if ($sender.Columns[$e.ColumnIndex].Name -eq "LogLevel") {
        # Get the value of the LogLevel cell
        $LogLevel = $e.Value.ToString().ToUpper()

        # Apply coloring based on the log level
        switch ($LogLevel) {
            "ERROR" { 
                $e.CellStyle.BackColor = [System.Drawing.Color]::FromArgb(255, 200, 200) # Light Red
                $e.CellStyle.ForeColor = [System.Drawing.Color]::Black
            }
            "CRITICAL" { 
                $e.CellStyle.BackColor = [System.Drawing.Color]::Red 
                $e.CellStyle.ForeColor = [System.Drawing.Color]::White
            }
            "WARNING" { 
                $e.CellStyle.BackColor = [System.Drawing.Color]::LightYellow 
                $e.CellStyle.ForeColor = [System.Drawing.Color]::DarkGoldenrod
            }
            "DEBUG" { 
                $e.CellStyle.BackColor = [System.Drawing.Color]::LightGray 
                $e.CellStyle.ForeColor = [System.Drawing.Color]::Black
            }
            "INFORMATION" { 
                # Keep default or set a light background
                $e.CellStyle.BackColor = [System.Drawing.Color]::White 
            }
        }
    }
}


# --- 5. Build and Show the Windows Form GUI ---

# Create the main form
$form = New-Object System.Windows.Forms.Form
$form.Text = "Custom .NET Core Log Viewer - $LogFilePath"
$form.Size = New-Object System.Drawing.Size(1200, 800)
$form.StartPosition = [System.Windows.Forms.FormStartPosition]::CenterScreen
$form.WindowState = [System.Windows.Forms.FormWindowState]::Maximized 

# Create the DataGridView
$dgv = New-Object System.Windows.Forms.DataGridView
$dgv.Location = New-Object System.Drawing.Point(10, 50)
$dgv.Size = New-Object System.Drawing.Size(1160, 680) # Initial size, will be anchored
$dgv.Anchor = [System.Windows.Forms.AnchorStyles]::Bottom -bor [System.Windows.Forms.AnchorStyles]::Right -bor [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left

# Hook up the cell formatting event handler
$dgv.Add_CellFormatting({ LogLevel_CellFormatting -sender $dgv -e $_ })

# Create the Refresh Button
$btnRefresh = New-Object System.Windows.Forms.Button
$btnRefresh.Text = "Refresh Logs"
$btnRefresh.Location = New-Object System.Drawing.Point(10, 10)
$btnRefresh.Size = New-Object System.Drawing.Size(150, 30)
$btnRefresh.Anchor = [System.Windows.Forms.AnchorStyles]::Top -bor [System.Windows.Forms.AnchorStyles]::Left

# Set the button click action to call the Refresh function
$btnRefresh.Add_Click({ Refresh-DataGridView -DataGridView $dgv -Path $LogFilePath })

# Add controls to the form
$form.Controls.Add($dgv)
$form.Controls.Add($btnRefresh)

# Load data on initial startup
Refresh-DataGridView -DataGridView $dgv -Path $LogFilePath

# Show the form and start the PowerShell application message pump
$form.ShowDialog() | Out-Null
```

### 💡 How to Use This Advanced Script

1.  **Save the Script:** Save the code block above as `CustomLogViewer.ps1`.
2.  **Ensure Log Format is Correct:** Your log file **must** be tab-separated and follow this header order:
    ```
    2025-10-31 3:00:00 PM<TAB>HostName<TAB>AppName<TAB>LogLevel<TAB>UserName<TAB>Category<TAB>Message
    ```
    *If your log file does not have this header line, the script assumes the first line is data.*
3.  **Run the Script:** Open a PowerShell console and run it, specifying the path:

    ```powershell
    .\CustomLogViewer.ps1 -LogFilePath "C:\path\to\your\log.txt"