ChatTTY - A wireframe of a chat app in PwshSpectreConsole

ChatTTY.ps1

#Requires -Modules @{ ModuleName = 'PwshSpectreConsole'; RequiredVersion = '2.1.1' }

Set-SpectreColors -AccentColor DeepPink1

# Build root layout scaffolding for:
# .--------------------------------.
# |             Title              | <- Update-TitleComponent will render the title
# |--------------------------------|
# |                                | <- Update-MessageListComponent will display the list of messages here
# |                                |
# |            Messages            |
# |                                |
# |                                |
# |--------------------------------|
# |        CustomTextEntry         | <- Update-CustomTextEntryComponent will create a text entry prompt here that is manually managed by pushing keys into a string
# |________________________________|

$layout = New-SpectreLayout -Name "root" -Rows @(
    # Row 1
    (New-SpectreLayout -Name "title" -MinimumSize 5 -Ratio 1 -Data ("empty")),
    # Row 2
    (New-SpectreLayout -Name "messages" -Ratio 10 -Data ("empty")),
    # Row 3
    (New-SpectreLayout -Name "customTextEntry" -MinimumSize 5 -Ratio 1 -Data ("empty"))
)

# Component functions for rendering the content of each panel
function Update-TitleComponent {
    param (
        [Spectre.Console.LiveDisplayContext] $Context,
        [Spectre.Console.Layout] $LayoutComponent
    )
    $component = "🧠 ChaTTY" | Format-SpectreAligned -HorizontalAlignment Center -VerticalAlignment Middle | Format-SpectrePanel -Expand
    $LayoutComponent.Update($component) | Out-Null
    $Context.Refresh()
}

function Update-MessageListComponent {
    param (
        [Spectre.Console.LiveDisplayContext] $Context,
        [Spectre.Console.Layout] $LayoutComponent,
        [System.Collections.Stack] $Messages
    )

    $rows = @()

    foreach ($message in $Messages) {
        if ($message.Actor -eq "System") {
            $rows += $message.Message.PadRight(6) `
                | Get-SpectreEscapedText `
                | Write-SpectreHost -Justify Left -PassThru `
                | Format-SpectrePanel -Color Grey -Header "System" `
                | Format-SpectreAligned -HorizontalAlignment Left `
                | Format-SpectrePadded -Top 0 -Left 10 -Bottom 0 -Right 0 `
                | New-SpectreGridRow
        } else {
            $rows += $message.Message.PadRight($message.Actor.Length) `
                | Get-SpectreEscapedText `
                | Write-SpectreHost -Justify Right -PassThru `
                | Format-SpectrePanel -Color Pink1 -Header $message.Actor `
                | Format-SpectreAligned -HorizontalAlignment Right `
                | Format-SpectrePadded -Top 0 -Left 0 -Bottom 0 -Right 10 `
                | New-SpectreGridRow
        }
    }

    # Stack is LIFO, so we need to reverse it to display the messages in the correct order
    [array]::Reverse($rows)

    # Just getting the last few for the demo, each single line message takes up about 3 lines of space
    $rowCount = [int] (($Host.UI.RawUI.WindowSize.Height - 10) / 3)

    $component = $rows | Select-Object -Last $rowCount | Format-SpectreGrid | Format-SpectrePanel -Border None
    $LayoutComponent.Update($component) | Out-Null
    $Context.Refresh()
}

function Update-CustomTextEntryComponent {
    param (
        [Spectre.Console.LiveDisplayContext] $Context,
        [Spectre.Console.Layout] $LayoutComponent,
        [string] $CurrentInput
    )
    $safeInput = [string]::IsNullOrEmpty($CurrentInput) ? "" : ($CurrentInput | Get-SpectreEscapedText)
    $component = "[gray]Prompt:[/] $safeInput" | Format-SpectrePanel -Expand | Format-SpectrePadded -Top 0 -Left 20 -Bottom 0 -Right 20 | Format-SpectreAligned -HorizontalAlignment Center
    $LayoutComponent.Update($component) | Out-Null
    $Context.Refresh()
}

# App logic functions
function Get-SomeChatResponse {
    param (
        [System.Collections.Stack] $Messages,
        [Spectre.Console.LiveDisplayContext] $Context,
        [Spectre.Console.Layout] $LayoutComponent
    )

    # Pretend to be thinking
    $ellipsisCount = 1
    for ($i = 0; $i -lt 3; $i++) {
        $Messages.Push(@{ Actor = "System"; Message = ("." * $ellipsisCount) })
        $ellipsisCount++

        Update-MessageListComponent -Context $Context -LayoutComponent $LayoutComponent -Messages $Messages
        Start-Sleep -Milliseconds 500

        # Remove the last thinking message
        $null = $Messages.Pop()
    }

    # Return the response
    return @{ Actor = "System"; Message = "I don't understand what you're saying." }
}

# Start live rendering the layout
Invoke-SpectreLive -Data $layout -ScriptBlock {
    param (
        [Spectre.Console.LiveDisplayContext] $Context
    )

    # State
    $messages = [System.Collections.Stack]::new(@(
        @{ Actor = "System"; Message = "👋 Hello, welcome to ChaTTY!" },
        @{ Actor = "System"; Message = "Type your message and press Enter to send it." },
        @{ Actor = "System"; Message = "Use the Up and Down arrow keys to scroll through previous messages." },
        @{ Actor = "System"; Message = "Press 'ctrl-c' to close the chat." }
    ))
    $currentInput = ""

    while ($true) {
        # Update components
        Update-TitleComponent -Context $Context -LayoutComponent $layout["title"]
        Update-MessageListComponent -Context $Context -LayoutComponent $layout["messages"] -Messages $messages
        Update-CustomTextEntryComponent -Context $Context -LayoutComponent $layout["customTextEntry"] -CurrentInput $currentInput

        # Real basic input handling, just add characters and remove if backspace is pressed, submit message if Enter is pressed
        [Console]::TreatControlCAsInput = $true
        $lastKeyPressed = [Console]::ReadKey($true)
        if ($lastKeyPressed.Key -eq [System.ConsoleKey]::C -and $lastKeyPressed.Modifiers -eq [System.ConsoleModifiers]::Control) {
            # Exit the loop. You have to treat ctrl-c as input to avoid the console readkey blocking the sigint
            return
        } elseif ($lastKeyPressed.Key -eq "Enter") {
            # Add the latest user message to the message stack
            $messages.Push(@{ Actor = ($env:USERNAME + $env:USER); Message = $currentInput })
            $currentInput = ""
            Update-CustomTextEntryComponent -Context $Context -LayoutComponent $layout["customTextEntry"] -CurrentInput $currentInput
            Update-MessageListComponent -Context $Context -LayoutComponent $layout["messages"] -Messages $messages
            $messages.Push((Get-SomeChatResponse -Messages $messages -Context $Context -LayoutComponent $layout["messages"]))
        } elseif ($lastKeyPressed.Key -eq [System.ConsoleKey]::Backspace) {
            # Remove the last character from the current input string
            $currentInput = $currentInput.Substring(0, [Math]::Max(0, $currentInput.Length - 1))
        } elseif ($lastKeyPressed.KeyChar) {
            # Add the character to the current input string
            $currentInput += $lastKeyPressed.KeyChar
        }
    }
}