import Foundation

public struct LauncherAlignment: Sendable {
    public let targetFrame: CGRect
    public let snappedOrigin: CGPoint

    public init(windowFrame: CGRect, visibleFrame: CGRect) {
        // Whole-point origins keep the guides aligned with AppKit's window positioning.
        targetFrame = CGRect(
            x: (visibleFrame.midX - windowFrame.width / 2).rounded(.down),
            y: (visibleFrame.maxY - visibleFrame.height / 5 - windowFrame.height).rounded(.down),
            width: windowFrame.width,
            height: windowFrame.height
        )
        snappedOrigin = CGPoint(
            x: abs(windowFrame.minX - targetFrame.minX) <= 12 ? targetFrame.minX : windowFrame.minX,
            y: abs(windowFrame.maxY - targetFrame.maxY) <= 12 ? targetFrame.minY : windowFrame.minY
        )
    }

    public static func restoredFrame(savedCenter: CGPoint?, windowSize: CGSize, visibleFrame: CGRect) -> CGRect {
        if let savedCenter, savedCenter.x.isFinite, savedCenter.y.isFinite {
            let saved = CGRect(x: savedCenter.x - windowSize.width / 2,
                               y: savedCenter.y - windowSize.height / 2,
                               width: windowSize.width, height: windowSize.height)
            if visibleFrame.contains(saved) { return saved }
        }
        var frame = LauncherAlignment(
            windowFrame: CGRect(origin: .zero, size: windowSize), visibleFrame: visibleFrame
        ).targetFrame
        frame.origin.x = max(visibleFrame.minX, min(frame.minX, visibleFrame.maxX - frame.width))
        frame.origin.y = max(visibleFrame.minY, min(frame.minY, visibleFrame.maxY - frame.height))
        return frame
    }
}