import AppKit

/// Renders the capture overlay. All interaction state lives in
/// CaptureController (driven by the CGEventTap); this view only draws.
final class OverlayWindow: NSPanel {
    init(screen: NSScreen, controller: CaptureController) {
        let content = OverlayView()
        super.init(
            contentRect: screen.frame,
            styleMask: [.borderless],
            backing: .buffered,
            defer: false
        )
        contentView = content
        content.controller = controller
        level = .screenSaver
        collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary, .stationary]
        backgroundColor = .clear
        isOpaque = false
        hasShadow = false
        isReleasedWhenClosed = false
        acceptsMouseMovedEvents = true
    }

    override var canBecomeKey: Bool { true }
}

final class OverlayView: NSView {
    weak var controller: CaptureController?

    override var acceptsFirstResponder: Bool { true }

    override func acceptsFirstMouse(for event: NSEvent?) -> Bool { true }

    override func resetCursorRects() {
        addCursorRect(bounds, cursor: .crosshair)
    }

    /// The screen frame this overlay covers, in AppKit global space.
    private var screenFrame: NSRect {
        guard let window else { return .zero }
        return window.convertToScreen(NSRect(origin: .zero, size: bounds.size))
    }

    /// Convert an AppKit-global rect into this view's coordinates.
    private func viewRect(_ global: NSRect) -> NSRect {
        let sf = screenFrame
        return NSRect(
            x: global.origin.x - sf.origin.x,
            y: global.origin.y - sf.origin.y,
            width: global.width,
            height: global.height
        )
    }

    override func draw(_ dirtyRect: NSRect) {
        NSColor.black.withAlphaComponent(0.35).setFill()
        NSBezierPath(rect: bounds).fill()

        guard let controller else { return }

        // Highlight the hovered window (rounded, like real window corners)
        if let frame = controller.hoverFrame {
            let vf = viewRect(frame)
            NSGraphicsContext.current?.saveGraphicsState()
            NSGraphicsContext.current?.compositingOperation = .clear
            NSColor.black.setFill()
            NSBezierPath(roundedRect: vf, xRadius: 10, yRadius: 10).fill()
            NSGraphicsContext.current?.restoreGraphicsState()

            let border = NSBezierPath(roundedRect: vf, xRadius: 10, yRadius: 10)
            border.lineWidth = 2
            NSColor.controlAccentColor.setStroke()
            border.stroke()
            return
        }

        // Marquee selection
        guard let sel = controller.marqueeRect, sel.width > 0, sel.height > 0 else { return }
        let vf = viewRect(sel)

        NSGraphicsContext.current?.saveGraphicsState()
        NSGraphicsContext.current?.compositingOperation = .clear
        NSColor.black.setFill()
        NSBezierPath(rect: vf).fill()
        NSGraphicsContext.current?.restoreGraphicsState()

        let border = NSBezierPath(rect: vf)
        border.lineWidth = 1.5
        NSColor.controlAccentColor.setStroke()
        border.stroke()

        let label = "\(Int(sel.width)) × \(Int(sel.height))"
        let attrs: [NSAttributedString.Key: Any] = [
            .font: NSFont.monospacedDigitSystemFont(ofSize: 12, weight: .medium),
            .foregroundColor: NSColor.white,
        ]
        let labelSize = label.size(withAttributes: attrs)
        let labelRect = NSRect(
            x: vf.maxX - labelSize.width - 8,
            y: vf.minY - labelSize.height - 10,
            width: labelSize.width + 8,
            height: labelSize.height + 6
        )
        NSColor.black.withAlphaComponent(0.6).setFill()
        NSBezierPath(roundedRect: labelRect, xRadius: 4, yRadius: 4).fill()
        label.draw(
            at: NSPoint(x: labelRect.minX + 4, y: labelRect.minY + 3),
            withAttributes: attrs
        )
    }
}