@echo off
setlocal ENABLEDELAYEDEXPANSION

:: ------------------------------------------------------------
:: Select ico file via GUI
:: ------------------------------------------------------------
for /f "delims=" %%A in ('powershell -command ^
    "Add-Type -AssemblyName System.Windows.Forms | Out-Null; $f=New-Object Windows.Forms.OpenFileDialog; $f.Filter='Icon (*.ico)|*.ico'; if($f.ShowDialog() -eq 'OK'){Write-Output $f.FileName}"') do (
    set ICO=%%A
)

if "%ICO%"=="" (
    echo No file selected.
    pause
    exit /b
)

echo Checking icon: %ICO%
echo -----------------------------------------

:: ------------------------------------------------------------
:: Extract bytes via PowerShell (safe for PNG-ICON)
:: ------------------------------------------------------------
for /f "tokens=* delims=" %%B in ('powershell -command ^
    "[System.IO.File]::ReadAllBytes('%ICO%') -join ' '"') do (
    set RAW=%%B
)

:: Convert byte list into array
set i=0
for %%b in (%RAW%) do (
    set BYTE[!i!]=%%b
    set /a i+=1
)
set /a LEN=i

:: ICONDIR.Count = bytes 4-5
set /a COUNT=BYTE[4] + BYTE[5]*256
echo Total frames: %COUNT%
echo.

if %COUNT% LEQ 0 (
    echo ERROR: Invalid icon or no frames.
    pause
    exit /b
)

set HAS256=0
set FIRST256=0

echo Frame list:
echo -----------------------------------------

:: Each ICONDIRENTRY = 16 bytes starting at offset 6
for /l %%I in (0,1,%COUNT%-1) do (
    set /a OFFSET=6 + 16 * %%I

    set W=!BYTE[%OFFSET%]!
    set H=!BYTE[%OFFSET%+1]!

    if "!W!"=="0" set W=256
    if "!H!"=="0" set H=256

    echo Frame %%I = !W! x !H!

    if "!W!"=="256" if "!H!"=="256" (
        set HAS256=1
        if %%I==0 set FIRST256=1
    )
)

echo.
echo -----------------------------------------

if %HAS256%==0 (
    echo ERROR: No 256x256 frame found.
    echo This is why NSIS and Windows show a small icon.
    pause
    exit /b
)

if %FIRST256%==0 (
    echo WARNING: 256x256 exists but is NOT frame 0.
    echo This causes small icons in NSIS installers.
    echo You should reorder frames so 256x256 is the first frame.
    pause
    exit /b
)

echo SUCCESS: 256x256 frame exists AND is the first frame.
echo Icon is well-structured.
pause
exit /b