# WebView2 CDP (Chrome DevTools Protocol) E2E helper.
# Usage: . .\scripts\cdp.ps1; Invoke-Cdp "document.title"
#        . .\scripts\cdp.ps1; Save-CdpScreenshot shot.png
# Prereq: app launched with WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS=--remote-debugging-port=9223
# NOTE: ASCII only in this file (PS 5.1 reads BOM-less files as ANSI).

function Invoke-Cdp {
    param(
        [Parameter(Mandatory)] [string]$Expression,
        [int]$Port = 9223,
        [int]$TimeoutSec = 20
    )
    $targets = Invoke-RestMethod "http://127.0.0.1:$Port/json"
    $page = $targets | Where-Object { $_.type -eq 'page' -and $_.url -notlike 'devtools*' } | Select-Object -First 1
    if (-not $page) { throw "no CDP page target" }

    $ws = New-Object System.Net.WebSockets.ClientWebSocket
    $ct = [System.Threading.CancellationToken]::None
    $uri = [Uri]$page.webSocketDebuggerUrl
    $ws.ConnectAsync($uri, $ct).GetAwaiter().GetResult() | Out-Null

    $msg = @{
        id     = 1
        method = "Runtime.evaluate"
        params = @{
            expression    = $Expression
            returnByValue = $true
            awaitPromise  = $true
        }
    } | ConvertTo-Json -Depth 6 -Compress
    $bytes = [System.Text.Encoding]::UTF8.GetBytes($msg)
    $seg = New-Object System.ArraySegment[byte] -ArgumentList @(,$bytes)
    $ws.SendAsync($seg, [System.Net.WebSockets.WebSocketMessageType]::Text, $true, $ct).GetAwaiter().GetResult() | Out-Null

    $buffer = New-Object byte[] 1048576
    $deadline = (Get-Date).AddSeconds($TimeoutSec)
    $response = $null
    while ((Get-Date) -lt $deadline) {
        $sb = New-Object System.Text.StringBuilder
        do {
            $rseg = New-Object System.ArraySegment[byte] -ArgumentList @(,$buffer)
            $result = $ws.ReceiveAsync($rseg, $ct).GetAwaiter().GetResult()
            $sb.Append([System.Text.Encoding]::UTF8.GetString($buffer, 0, $result.Count)) | Out-Null
        } while (-not $result.EndOfMessage)
        $obj = $sb.ToString() | ConvertFrom-Json
        if ($obj.id -eq 1) { $response = $obj; break }
    }
    $ws.Abort()
    if (-not $response) { throw "CDP response timeout" }
    if ($response.result.exceptionDetails) {
        throw "JS exception: $($response.result.exceptionDetails.text) $($response.result.exceptionDetails.exception.description)"
    }
    return $response.result.result.value
}

# Call any CDP method and return the raw result object.
# Invoke-Cdp is hardcoded to Runtime.evaluate; use this for Page.*, Emulation.*, etc.
function Invoke-CdpMethod {
    param(
        [Parameter(Mandatory)] [string]$Method,
        [hashtable]$Params = @{},
        [int]$Port = 9223,
        [int]$TimeoutSec = 30
    )
    $targets = Invoke-RestMethod "http://127.0.0.1:$Port/json"
    $page = $targets | Where-Object { $_.type -eq 'page' -and $_.url -notlike 'devtools*' } | Select-Object -First 1
    if (-not $page) { throw "no CDP page target" }

    $ws = New-Object System.Net.WebSockets.ClientWebSocket
    $ct = [System.Threading.CancellationToken]::None
    $ws.ConnectAsync([Uri]$page.webSocketDebuggerUrl, $ct).GetAwaiter().GetResult() | Out-Null

    $msg = @{ id = 1; method = $Method; params = $Params } | ConvertTo-Json -Depth 6 -Compress
    $bytes = [System.Text.Encoding]::UTF8.GetBytes($msg)
    $seg = New-Object System.ArraySegment[byte] -ArgumentList @(, $bytes)
    $ws.SendAsync($seg, [System.Net.WebSockets.WebSocketMessageType]::Text, $true, $ct).GetAwaiter().GetResult() | Out-Null

    # Screenshots are large: keep reading frames until EndOfMessage, then match the id.
    $buffer = New-Object byte[] 1048576
    $deadline = (Get-Date).AddSeconds($TimeoutSec)
    $response = $null
    while ((Get-Date) -lt $deadline) {
        $sb = New-Object System.Text.StringBuilder
        do {
            $rseg = New-Object System.ArraySegment[byte] -ArgumentList @(, $buffer)
            $result = $ws.ReceiveAsync($rseg, $ct).GetAwaiter().GetResult()
            $sb.Append([System.Text.Encoding]::UTF8.GetString($buffer, 0, $result.Count)) | Out-Null
        } while (-not $result.EndOfMessage)
        $obj = $sb.ToString() | ConvertFrom-Json
        if ($obj.id -eq 1) { $response = $obj; break }
    }
    $ws.Abort()
    if (-not $response) { throw "CDP response timeout" }
    if ($response.error) { throw "CDP error: $($response.error.message)" }
    return $response.result
}

# Save the page as a PNG (what the WebView actually renders, not the OS window).
function Save-CdpScreenshot {
    param(
        [Parameter(Mandatory)] [string]$Path,
        [int]$Port = 9223,
        [int]$TimeoutSec = 30
    )
    $r = Invoke-CdpMethod -Method "Page.captureScreenshot" -Params @{ format = "png" } -Port $Port -TimeoutSec $TimeoutSec
    if (-not $r.data) { throw "no screenshot data" }
    [System.IO.File]::WriteAllBytes($Path, [System.Convert]::FromBase64String($r.data))
    return (Get-Item $Path).Length
}