using System;
using System.Drawing;

public static class DisplayFusionFunction
{
    public static void Run(IntPtr windowHandle)
    {
        if (windowHandle == IntPtr.Zero)
            return;

        // Get current window bounds and its centre point
        Rectangle win = BFS.Window.GetBounds(windowHandle);
        int centerX = win.X + (win.Width / 2);
        int centerY = win.Y + (win.Height / 2);

        // Get the bounds of all *physical* monitors (ignores splits)
        Rectangle[] physicalMons = BFS.Monitor.GetMonitorBoundsNoSplits();

        Rectangle monitorRect = Rectangle.Empty;

        // Find which physical monitor the window centre is on
        foreach (Rectangle m in physicalMons)
        {
            if (centerX >= m.X && centerX < m.Right &&
                centerY >= m.Y && centerY < m.Bottom)
            {
                monitorRect = m;
                break;
            }
        }

        if (monitorRect == Rectangle.Empty)
            return;

        // Divide that physical monitor into 3 equal vertical thirds
        int thirdWidth = monitorRect.Width / 3;
        if (thirdWidth <= 0)
            return;

        // Position of window centre relative to that monitor
        int relX = centerX - monitorRect.X;

        Rectangle targetRect;

        if (relX < thirdWidth)
        {
            // Window is in LEFT third -> span LEFT + MIDDLE (splits 1 + 2)
            targetRect = new Rectangle(
                monitorRect.X,
                monitorRect.Y,
                thirdWidth * 2,
                monitorRect.Height
            );
        }
        else
        {
            // Window is in MIDDLE or RIGHT third -> span MIDDLE + RIGHT (splits 2 + 3)
            targetRect = new Rectangle(
                monitorRect.X + thirdWidth,
                monitorRect.Y,
                thirdWidth * 2,
                monitorRect.Height
            );
        }

        // Resize/move the window to fill exactly 2/3 of the physical monitor
        BFS.Window.SetSizeAndLocation(
            windowHandle,
            targetRect.X,
            targetRect.Y,
            targetRect.Width,
            targetRect.Height
        );
    }
}