# 2b V6/V7 proof target: a dedicated WinForms window we own.
# ASCII-only source (PS 5.1 decodes BOM-less .ps1 as GBK; see personal lessons).
#
# Launched by text_injection_proof.ps1. Shows a topmost empty TextBox, writes
# its current text to ResultFile (UTF-8 with BOM) on every change, exits when
# StopFile appears. The proof injects through the remote-control pipeline and
# polls ResultFile - so "what arrived on the controlled desktop" is reported
# by the receiving application itself, not by a screenshot or OCR.

param(
    [Parameter(Mandatory = $true)][string]$PidFile,
    [Parameter(Mandatory = $true)][string]$ResultFile,
    [Parameter(Mandatory = $true)][string]$StopFile
)
$ErrorActionPreference = "Stop"
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing

# Event handler scriptblocks resolve script-scoped vars; make that explicit
# instead of relying on the param locals staying on a visible scope chain.
$script:PidFile = $PidFile
$script:ResultFile = $ResultFile
$script:StopFile = $StopFile
$script:lastWritten = $null

$form = New-Object System.Windows.Forms.Form
$form.Text = "RemoteTextTarget"
$form.ClientSize = New-Object System.Drawing.Size(420, 140)
$form.TopMost = $true
$form.StartPosition = "Manual"
$form.Location = New-Object System.Drawing.Point(80, 80)

$tb = New-Object System.Windows.Forms.TextBox
$tb.Multiline = $true
$tb.Font = New-Object System.Drawing.Font("Segoe UI", 16.0)
$tb.Dock = "Fill"
$form.Controls.Add($tb)

$timer = New-Object System.Windows.Forms.Timer
$timer.Interval = 150
$timer.Add_Tick({
    if (Test-Path $script:StopFile) {
        $form.Close()
        return
    }
    if ($tb.Text -ne $script:lastWritten) {
        $script:lastWritten = $tb.Text
        $enc = New-Object System.Text.UTF8Encoding($true)
        [System.IO.File]::WriteAllText($script:ResultFile, $tb.Text, $enc)
    }
    if (-not $tb.Focused) { [void]$tb.Focus() }
})

$form.Add_Shown({
    $form.Activate()
    [void]$tb.Focus()
    [System.IO.File]::WriteAllText($script:PidFile, "$PID")
})

$timer.Start()
[void]$form.ShowDialog()
$timer.Stop()