import AppKit
import ObjectiveC
#if DEBUG
import Bonsplit
#endif

private var cmuxWindowTerminalPortalKey: UInt8 = 0
private var cmuxWindowTerminalPortalCloseObserverKey: UInt8 = 0

#if DEBUG
private func portalDebugToken(_ view: NSView?) -> String {
    guard let view else { return "nil" }
    let ptr = Unmanaged.passUnretained(view).toOpaque()
    return String(describing: ptr)
}

private func portalDebugFrame(_ rect: NSRect) -> String {
    String(format: "%.1f,%.1f %.1fx%.1f", rect.origin.x, rect.origin.y, rect.size.width, rect.size.height)
}
#endif

final class WindowTerminalHostView: NSView {
    private struct DividerRegion {
        let rectInWindow: NSRect
        let isVertical: Bool
    }

    private enum DividerCursorKind: Equatable {
        case vertical
        case horizontal

        var cursor: NSCursor {
            switch self {
            case .vertical: return .resizeLeftRight
            case .horizontal: return .resizeUpDown
            }
        }
    }

    override var isOpaque: Bool { false }
    private static let sidebarLeadingEdgeEpsilon: CGFloat = 1
    private static let minimumVisibleLeadingContentWidth: CGFloat = 24
    private var cachedSidebarDividerX: CGFloat?
    private var sidebarDividerMissCount = 0
    private var trackingArea: NSTrackingArea?
    private var activeDividerCursorKind: DividerCursorKind?
#if DEBUG
    private var lastDragRouteSignature: String?
#endif

    override func viewDidMoveToWindow() {
        super.viewDidMoveToWindow()
        if window == nil {
            clearActiveDividerCursor(restoreArrow: false)
        }
        window?.invalidateCursorRects(for: self)
    }

    override func setFrameSize(_ newSize: NSSize) {
        super.setFrameSize(newSize)
        window?.invalidateCursorRects(for: self)
    }

    override func setFrameOrigin(_ newOrigin: NSPoint) {
        super.setFrameOrigin(newOrigin)
        window?.invalidateCursorRects(for: self)
    }

    override func resetCursorRects() {
        super.resetCursorRects()
        guard let window, let rootView = window.contentView else { return }
        var regions: [DividerRegion] = []
        Self.collectSplitDividerRegions(in: rootView, into: &regions)
        let expansion: CGFloat = 4
        for region in regions {
            var rectInHost = convert(region.rectInWindow, from: nil)
            rectInHost = rectInHost.insetBy(
                dx: region.isVertical ? -expansion : 0,
                dy: region.isVertical ? 0 : -expansion
            )
            let clipped = rectInHost.intersection(bounds)
            guard !clipped.isNull, clipped.width > 0, clipped.height > 0 else { continue }
            addCursorRect(clipped, cursor: region.isVertical ? .resizeLeftRight : .resizeUpDown)
        }
    }

    override func updateTrackingAreas() {
        if let trackingArea {
            removeTrackingArea(trackingArea)
        }
        let options: NSTrackingArea.Options = [
            .inVisibleRect,
            .activeAlways,
            .cursorUpdate,
            .mouseMoved,
            .mouseEnteredAndExited,
            .enabledDuringMouseDrag,
        ]
        let next = NSTrackingArea(rect: .zero, options: options, owner: self, userInfo: nil)
        addTrackingArea(next)
        trackingArea = next
        super.updateTrackingAreas()
    }

    override func cursorUpdate(with event: NSEvent) {
        let point = convert(event.locationInWindow, from: nil)
        updateDividerCursor(at: point)
    }

    override func mouseMoved(with event: NSEvent) {
        let point = convert(event.locationInWindow, from: nil)
        updateDividerCursor(at: point)
    }

    override func mouseExited(with event: NSEvent) {
        clearActiveDividerCursor(restoreArrow: true)
    }

    override func hitTest(_ point: NSPoint) -> NSView? {
        updateDividerCursor(at: point)

        if shouldPassThroughToSidebarResizer(at: point) {
            return nil
        }

        if shouldPassThroughToSplitDivider(at: point) {
            return nil
        }

        let dragPasteboardTypes = NSPasteboard(name: .drag).types
        let eventType = NSApp.currentEvent?.type
        let shouldPassThrough = DragOverlayRoutingPolicy.shouldPassThroughPortalHitTesting(
            pasteboardTypes: dragPasteboardTypes,
            eventType: eventType
        )
        if shouldPassThrough {
#if DEBUG
            logDragRouteDecision(
                passThrough: true,
                eventType: eventType,
                pasteboardTypes: dragPasteboardTypes,
                hitView: nil
            )
#endif
            return nil
        }

        let hitView = super.hitTest(point)
#if DEBUG
        logDragRouteDecision(
            passThrough: false,
            eventType: eventType,
            pasteboardTypes: dragPasteboardTypes,
            hitView: hitView
        )
#endif
        return hitView === self ? nil : hitView
    }

    private func shouldPassThroughToSidebarResizer(at point: NSPoint) -> Bool {
        // The sidebar resizer handle is implemented in SwiftUI. When terminals
        // are portal-hosted, this AppKit host can otherwise sit above the handle
        // and steal hover/mouse events.
        let visibleHostedViews = subviews.compactMap { $0 as? GhosttySurfaceScrollView }
            .filter { !$0.isHidden && $0.window != nil && $0.frame.width > 1 && $0.frame.height > 1 }

        // If content is flush to the leading edge, sidebar is effectively hidden.
        // In that state, treating any internal split edge as a sidebar divider
        // steals split-divider cursor/drag behavior.
        let hasLeadingContent = visibleHostedViews.contains {
            $0.frame.minX <= Self.sidebarLeadingEdgeEpsilon
                && $0.frame.maxX > Self.minimumVisibleLeadingContentWidth
        }
        if hasLeadingContent {
            if cachedSidebarDividerX != nil {
                sidebarDividerMissCount += 1
                if sidebarDividerMissCount >= 2 {
                    cachedSidebarDividerX = nil
                    sidebarDividerMissCount = 0
                }
            }
            return false
        }

        // Ignore transient 0-origin hosts while layouts churn (e.g. workspace
        // creation/switching). They can temporarily report minX=0 and would
        // otherwise clear divider pass-through, causing hover flicker.
        let dividerCandidates = visibleHostedViews
            .map(\.frame.minX)
            .filter { $0 > Self.sidebarLeadingEdgeEpsilon }
        if let leftMostEdge = dividerCandidates.min() {
            cachedSidebarDividerX = leftMostEdge
            sidebarDividerMissCount = 0
        } else if cachedSidebarDividerX != nil {
            // Keep cache briefly for layout churn, but clear if we miss repeatedly
            // so stale divider positions don't steal pointer routing.
            sidebarDividerMissCount += 1
            if sidebarDividerMissCount >= 4 {
                cachedSidebarDividerX = nil
                sidebarDividerMissCount = 0
            }
        }

        guard let dividerX = cachedSidebarDividerX else {
            return false
        }

        let regionMinX = dividerX - SidebarResizeInteraction.hitWidthPerSide
        let regionMaxX = dividerX + SidebarResizeInteraction.hitWidthPerSide
        return point.x >= regionMinX && point.x <= regionMaxX
    }

    private func updateDividerCursor(at point: NSPoint) {
        if shouldPassThroughToSidebarResizer(at: point) {
            clearActiveDividerCursor(restoreArrow: false)
            return
        }

        guard let nextKind = splitDividerCursorKind(at: point) else {
            clearActiveDividerCursor(restoreArrow: true)
            return
        }
        activeDividerCursorKind = nextKind
        nextKind.cursor.set()
    }

    private func clearActiveDividerCursor(restoreArrow: Bool) {
        guard activeDividerCursorKind != nil else { return }
        window?.invalidateCursorRects(for: self)
        activeDividerCursorKind = nil
        if restoreArrow {
            NSCursor.arrow.set()
        }
    }

    private func splitDividerCursorKind(at point: NSPoint) -> DividerCursorKind? {
        guard let window else { return nil }
        let windowPoint = convert(point, to: nil)
        guard let rootView = window.contentView else { return nil }
        return Self.dividerCursorKind(at: windowPoint, in: rootView)
    }

    private func shouldPassThroughToSplitDivider(at point: NSPoint) -> Bool {
        splitDividerCursorKind(at: point) != nil
    }

    private static func dividerCursorKind(at windowPoint: NSPoint, in view: NSView) -> DividerCursorKind? {
        guard !view.isHidden else { return nil }

        if let splitView = view as? NSSplitView {
            let pointInSplit = splitView.convert(windowPoint, from: nil)
            if splitView.bounds.contains(pointInSplit) {
                // Keep divider interactions reliable even when portal-hosted terminal frames
                // temporarily overlap divider edges during rapid layout churn.
                let expansion: CGFloat = 5
                let dividerCount = max(0, splitView.arrangedSubviews.count - 1)
                for dividerIndex in 0..<dividerCount {
                    let first = splitView.arrangedSubviews[dividerIndex].frame
                    let second = splitView.arrangedSubviews[dividerIndex + 1].frame
                    let thickness = splitView.dividerThickness
                    let dividerRect: NSRect
                    if splitView.isVertical {
                        // Keep divider hit-testing active even when one side is nearly collapsed,
                        // so users can drag the divider back out from the border.
                        // But ignore transient states where both panes are effectively 0-width.
                        guard first.width > 1 || second.width > 1 else { continue }
                        let x = max(0, first.maxX)
                        dividerRect = NSRect(
                            x: x,
                            y: 0,
                            width: thickness,
                            height: splitView.bounds.height
                        )
                    } else {
                        // Same behavior for horizontal splits with a near-zero-height pane.
                        guard first.height > 1 || second.height > 1 else { continue }
                        let y = max(0, first.maxY)
                        dividerRect = NSRect(
                            x: 0,
                            y: y,
                            width: splitView.bounds.width,
                            height: thickness
                        )
                    }
                    let expandedDividerRect = dividerRect.insetBy(dx: -expansion, dy: -expansion)
                    if expandedDividerRect.contains(pointInSplit) {
                        return splitView.isVertical ? .vertical : .horizontal
                    }
                }
            }
        }

        for subview in view.subviews.reversed() {
            if let kind = dividerCursorKind(at: windowPoint, in: subview) {
                return kind
            }
        }

        return nil
    }

    private static func collectSplitDividerRegions(in view: NSView, into result: inout [DividerRegion]) {
        guard !view.isHidden else { return }

        if let splitView = view as? NSSplitView {
            let dividerCount = max(0, splitView.arrangedSubviews.count - 1)
            for dividerIndex in 0..<dividerCount {
                let first = splitView.arrangedSubviews[dividerIndex].frame
                let second = splitView.arrangedSubviews[dividerIndex + 1].frame
                let thickness = splitView.dividerThickness
                let dividerRect: NSRect
                if splitView.isVertical {
                    guard first.width > 1 || second.width > 1 else { continue }
                    let x = max(0, first.maxX)
                    dividerRect = NSRect(x: x, y: 0, width: thickness, height: splitView.bounds.height)
                } else {
                    guard first.height > 1 || second.height > 1 else { continue }
                    let y = max(0, first.maxY)
                    dividerRect = NSRect(x: 0, y: y, width: splitView.bounds.width, height: thickness)
                }
                let dividerRectInWindow = splitView.convert(dividerRect, to: nil)
                guard dividerRectInWindow.width > 0, dividerRectInWindow.height > 0 else { continue }
                result.append(
                    DividerRegion(
                        rectInWindow: dividerRectInWindow,
                        isVertical: splitView.isVertical
                    )
                )
            }
        }

        for subview in view.subviews {
            collectSplitDividerRegions(in: subview, into: &result)
        }
    }

#if DEBUG
    private func logDragRouteDecision(
        passThrough: Bool,
        eventType: NSEvent.EventType?,
        pasteboardTypes: [NSPasteboard.PasteboardType]?,
        hitView: NSView?
    ) {
        let hasRelevantTypes = DragOverlayRoutingPolicy.hasBonsplitTabTransfer(pasteboardTypes)
            || DragOverlayRoutingPolicy.hasSidebarTabReorder(pasteboardTypes)
        guard passThrough || hasRelevantTypes else { return }

        let targetClass = hitView.map { NSStringFromClass(type(of: $0)) } ?? "nil"
        let signature = [
            passThrough ? "1" : "0",
            debugEventName(eventType),
            debugPasteboardTypes(pasteboardTypes),
            targetClass,
        ].joined(separator: "|")
        guard lastDragRouteSignature != signature else { return }
        lastDragRouteSignature = signature

        dlog(
            "portal.dragRoute passThrough=\(passThrough ? 1 : 0) " +
            "event=\(debugEventName(eventType)) target=\(targetClass) " +
            "types=\(debugPasteboardTypes(pasteboardTypes))"
        )
    }

    private func debugPasteboardTypes(_ types: [NSPasteboard.PasteboardType]?) -> String {
        guard let types, !types.isEmpty else { return "-" }
        return types.map(\.rawValue).joined(separator: ",")
    }

    private func debugEventName(_ eventType: NSEvent.EventType?) -> String {
        guard let eventType else { return "none" }
        switch eventType {
        case .cursorUpdate: return "cursorUpdate"
        case .appKitDefined: return "appKitDefined"
        case .systemDefined: return "systemDefined"
        case .applicationDefined: return "applicationDefined"
        case .periodic: return "periodic"
        case .mouseMoved: return "mouseMoved"
        case .mouseEntered: return "mouseEntered"
        case .mouseExited: return "mouseExited"
        case .flagsChanged: return "flagsChanged"
        case .leftMouseDragged: return "leftMouseDragged"
        case .rightMouseDragged: return "rightMouseDragged"
        case .otherMouseDragged: return "otherMouseDragged"
        case .leftMouseDown: return "leftMouseDown"
        case .leftMouseUp: return "leftMouseUp"
        case .rightMouseDown: return "rightMouseDown"
        case .rightMouseUp: return "rightMouseUp"
        case .otherMouseDown: return "otherMouseDown"
        case .otherMouseUp: return "otherMouseUp"
        default: return "other(\(eventType.rawValue))"
        }
    }
#endif
}

private final class SplitDividerOverlayView: NSView {
    private struct DividerSegment {
        let rect: NSRect
        let color: NSColor
        let isVertical: Bool
    }

    override var isOpaque: Bool { false }
    override var acceptsFirstResponder: Bool { false }

    override func hitTest(_ point: NSPoint) -> NSView? { nil }

    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)
        guard let window, let rootView = window.contentView else { return }

        var dividerSegments: [DividerSegment] = []
        collectDividerSegments(in: rootView, into: &dividerSegments)
        guard !dividerSegments.isEmpty else { return }
        let hostedFrames = hostedFramesLikelyToOccludeDividers()
        let visibleSegments = dividerSegments.filter { shouldRenderOverlay(for: $0, hostedFrames: hostedFrames) }
        guard !visibleSegments.isEmpty else { return }

        NSGraphicsContext.saveGraphicsState()
        defer { NSGraphicsContext.restoreGraphicsState() }

        // Keep separators visible above portal-hosted surfaces while matching each split view's
        // native divider color (avoids visible color shifts at tiny pane sizes).
        for segment in visibleSegments where segment.rect.intersects(dirtyRect) {
            segment.color.setFill()
            let rect = segment.rect
            let pixelAligned = NSRect(
                x: floor(rect.origin.x),
                y: floor(rect.origin.y),
                width: max(1, round(rect.size.width)),
                height: max(1, round(rect.size.height))
            )
            NSBezierPath(rect: pixelAligned).fill()
        }
    }

    private func collectDividerSegments(in view: NSView, into result: inout [DividerSegment]) {
        guard !view.isHidden else { return }

        if let splitView = view as? NSSplitView {
            let dividerCount = max(0, splitView.arrangedSubviews.count - 1)
            let dividerColor = overlayDividerColor(for: splitView)
            for dividerIndex in 0..<dividerCount {
                let first = splitView.arrangedSubviews[dividerIndex].frame
                let thickness = max(splitView.dividerThickness, 1)
                let dividerRectInSplit: NSRect
                if splitView.isVertical {
                    dividerRectInSplit = NSRect(
                        x: first.maxX,
                        y: 0,
                        width: thickness,
                        height: splitView.bounds.height
                    )
                } else {
                    dividerRectInSplit = NSRect(
                        x: 0,
                        y: first.maxY,
                        width: splitView.bounds.width,
                        height: thickness
                    )
                }

                let dividerRectInWindow = splitView.convert(dividerRectInSplit, to: nil)
                let dividerRectInOverlay = convert(dividerRectInWindow, from: nil)
                if dividerRectInOverlay.intersects(bounds) {
                    result.append(
                        DividerSegment(
                            rect: dividerRectInOverlay,
                            color: dividerColor,
                            isVertical: splitView.isVertical
                        )
                    )
                }
            }
        }

        for subview in view.subviews {
            collectDividerSegments(in: subview, into: &result)
        }
    }

    private func hostedFramesLikelyToOccludeDividers() -> [NSRect] {
        guard let hostView = superview else { return [] }
        return hostView.subviews.compactMap { subview -> NSRect? in
            guard let hosted = subview as? GhosttySurfaceScrollView else { return nil }
            guard !hosted.isHidden, hosted.window != nil else { return nil }
            return hosted.frame
        }
    }

    private func shouldRenderOverlay(for segment: DividerSegment, hostedFrames: [NSRect]) -> Bool {
        // Draw only when a hosted surface actually intrudes across the divider centerline.
        // This preserves tiny-pane visibility fixes without darkening regular dividers.
        let axisEpsilon: CGFloat = 0.01
        let axis = segment.isVertical ? segment.rect.midX : segment.rect.midY
        let extentRect = segment.rect.insetBy(
            dx: segment.isVertical ? 0 : -1,
            dy: segment.isVertical ? -1 : 0
        )

        for frame in hostedFrames where frame.intersects(extentRect) {
            if segment.isVertical {
                if frame.minX < axis - axisEpsilon && frame.maxX > axis + axisEpsilon {
                    return true
                }
            } else if frame.minY < axis - axisEpsilon && frame.maxY > axis + axisEpsilon {
                return true
            }
        }
        return false
    }

    private func overlayDividerColor(for splitView: NSSplitView) -> NSColor {
        let divider = splitView.dividerColor.usingColorSpace(.deviceRGB) ?? splitView.dividerColor
        let alpha = divider.alphaComponent
        guard alpha < 0.999 else { return divider }

        guard let bgColor = splitView.layer?.backgroundColor.flatMap(NSColor.init(cgColor:)),
              let bgRGB = bgColor.usingColorSpace(.deviceRGB) else {
            return divider
        }

        let opaqueBG = bgRGB.withAlphaComponent(1)
        let opaqueDivider = divider.withAlphaComponent(1)
        return opaqueBG.blended(withFraction: alpha, of: opaqueDivider) ?? divider
    }
}

@MainActor
final class WindowTerminalPortal: NSObject {
    private weak var window: NSWindow?
    private let hostView = WindowTerminalHostView(frame: .zero)
    private let dividerOverlayView = SplitDividerOverlayView(frame: .zero)
    private weak var installedContainerView: NSView?
    private weak var installedReferenceView: NSView?
    private var installConstraints: [NSLayoutConstraint] = []
    private var hasDeferredFullSyncScheduled = false

    private struct Entry {
        weak var hostedView: GhosttySurfaceScrollView?
        weak var anchorView: NSView?
        var visibleInUI: Bool
        var zPriority: Int
    }

    private var entriesByHostedId: [ObjectIdentifier: Entry] = [:]
    private var hostedByAnchorId: [ObjectIdentifier: ObjectIdentifier] = [:]

    init(window: NSWindow) {
        self.window = window
        super.init()
        hostView.wantsLayer = false
        hostView.translatesAutoresizingMaskIntoConstraints = false
        dividerOverlayView.translatesAutoresizingMaskIntoConstraints = true
        dividerOverlayView.autoresizingMask = [.width, .height]
        _ = ensureInstalled()
    }

    private func ensureDividerOverlayOnTop() {
        if dividerOverlayView.superview !== hostView {
            dividerOverlayView.frame = hostView.bounds
            hostView.addSubview(dividerOverlayView, positioned: .above, relativeTo: nil)
        } else if hostView.subviews.last !== dividerOverlayView {
            hostView.addSubview(dividerOverlayView, positioned: .above, relativeTo: nil)
        }

        if !Self.rectApproximatelyEqual(dividerOverlayView.frame, hostView.bounds) {
            dividerOverlayView.frame = hostView.bounds
        }
        dividerOverlayView.needsDisplay = true
    }

    @discardableResult
    private func ensureInstalled() -> Bool {
        guard let window else { return false }
        guard let (container, reference) = installationTarget(for: window) else { return false }

        if hostView.superview !== container ||
            installedContainerView !== container ||
            installedReferenceView !== reference {
            NSLayoutConstraint.deactivate(installConstraints)
            installConstraints.removeAll()

            hostView.removeFromSuperview()
            container.addSubview(hostView, positioned: .above, relativeTo: reference)

            installConstraints = [
                hostView.leadingAnchor.constraint(equalTo: reference.leadingAnchor),
                hostView.trailingAnchor.constraint(equalTo: reference.trailingAnchor),
                hostView.topAnchor.constraint(equalTo: reference.topAnchor),
                hostView.bottomAnchor.constraint(equalTo: reference.bottomAnchor),
            ]
            NSLayoutConstraint.activate(installConstraints)
            installedContainerView = container
            installedReferenceView = reference
        } else if !Self.isView(hostView, above: reference, in: container) {
            container.addSubview(hostView, positioned: .above, relativeTo: reference)
        }

        // Keep the drag/mouse forwarding overlay above portal-hosted terminal views.
        if let overlay = objc_getAssociatedObject(window, &fileDropOverlayKey) as? NSView,
           overlay.superview === container,
           !Self.isView(overlay, above: hostView, in: container) {
            container.addSubview(overlay, positioned: .above, relativeTo: hostView)
        }

        ensureDividerOverlayOnTop()

        return true
    }

    private func installationTarget(for window: NSWindow) -> (container: NSView, reference: NSView)? {
        guard let contentView = window.contentView else { return nil }

        // If NSGlassEffectView wraps the original content view, install inside the glass view
        // so terminals are above the glass background but below SwiftUI content.
        if contentView.className == "NSGlassEffectView",
           let foreground = contentView.subviews.first(where: { $0 !== hostView }) {
            return (contentView, foreground)
        }

        guard let themeFrame = contentView.superview else { return nil }
        return (themeFrame, contentView)
    }

    private static func isHiddenOrAncestorHidden(_ view: NSView) -> Bool {
        if view.isHidden { return true }
        var current = view.superview
        while let v = current {
            if v.isHidden { return true }
            current = v.superview
        }
        return false
    }

    private static func rectApproximatelyEqual(_ lhs: NSRect, _ rhs: NSRect, epsilon: CGFloat = 0.5) -> Bool {
        abs(lhs.origin.x - rhs.origin.x) <= epsilon &&
            abs(lhs.origin.y - rhs.origin.y) <= epsilon &&
            abs(lhs.size.width - rhs.size.width) <= epsilon &&
            abs(lhs.size.height - rhs.size.height) <= epsilon
    }

    private static func isView(_ view: NSView, above reference: NSView, in container: NSView) -> Bool {
        guard let viewIndex = container.subviews.firstIndex(of: view),
              let referenceIndex = container.subviews.firstIndex(of: reference) else {
            return false
        }
        return viewIndex > referenceIndex
    }

    func detachHostedView(withId hostedId: ObjectIdentifier) {
        guard let entry = entriesByHostedId.removeValue(forKey: hostedId) else { return }
        if let anchor = entry.anchorView {
            hostedByAnchorId.removeValue(forKey: ObjectIdentifier(anchor))
        }
#if DEBUG
        let hadSuperview = (entry.hostedView?.superview === hostView) ? 1 : 0
        dlog(
            "portal.detach hosted=\(portalDebugToken(entry.hostedView)) " +
            "anchor=\(portalDebugToken(entry.anchorView)) hadSuperview=\(hadSuperview)"
        )
#endif
        if let hostedView = entry.hostedView, hostedView.superview === hostView {
            hostedView.removeFromSuperview()
        }
    }

    /// Hide a portal entry without detaching it. Updates visibleInUI to false and
    /// sets isHidden = true so subsequent synchronizeHostedView calls keep it hidden.
    /// Used when a workspace is permanently unmounted (vs. transient bonsplit dismantles).
    func hideEntry(forHostedId hostedId: ObjectIdentifier) {
        guard var entry = entriesByHostedId[hostedId] else { return }
        guard entry.visibleInUI else { return }
        entry.visibleInUI = false
        entriesByHostedId[hostedId] = entry
        entry.hostedView?.isHidden = true
#if DEBUG
        dlog("portal.hideEntry hosted=\(portalDebugToken(entry.hostedView)) reason=workspaceUnmount")
#endif
    }

    /// Update the visibleInUI flag on an existing entry without rebinding.
    /// Used when a deferred bind is pending — this ensures synchronizeHostedView
    /// won't hide a view that updateNSView has already marked as visible.
    func updateEntryVisibility(forHostedId hostedId: ObjectIdentifier, visibleInUI: Bool) {
        guard var entry = entriesByHostedId[hostedId] else { return }
        entry.visibleInUI = visibleInUI
        entriesByHostedId[hostedId] = entry
    }

    func bind(hostedView: GhosttySurfaceScrollView, to anchorView: NSView, visibleInUI: Bool, zPriority: Int = 0) {
        guard ensureInstalled() else { return }

        let hostedId = ObjectIdentifier(hostedView)
        let anchorId = ObjectIdentifier(anchorView)
        let previousEntry = entriesByHostedId[hostedId]

        if let previousHostedId = hostedByAnchorId[anchorId], previousHostedId != hostedId {
#if DEBUG
            let previousToken = entriesByHostedId[previousHostedId]
                .map { portalDebugToken($0.hostedView) }
                ?? String(describing: previousHostedId)
            dlog(
                "portal.bind.replace anchor=\(portalDebugToken(anchorView)) " +
                "oldHosted=\(previousToken) newHosted=\(portalDebugToken(hostedView))"
            )
#endif
            detachHostedView(withId: previousHostedId)
        }

        if let oldEntry = entriesByHostedId[hostedId],
           let oldAnchor = oldEntry.anchorView,
           oldAnchor !== anchorView {
            hostedByAnchorId.removeValue(forKey: ObjectIdentifier(oldAnchor))
        }

        hostedByAnchorId[anchorId] = hostedId
        entriesByHostedId[hostedId] = Entry(
            hostedView: hostedView,
            anchorView: anchorView,
            visibleInUI: visibleInUI,
            zPriority: zPriority
        )

        let didChangeAnchor: Bool = {
            guard let previousAnchor = previousEntry?.anchorView else { return true }
            return previousAnchor !== anchorView
        }()
        let becameVisible = (previousEntry?.visibleInUI ?? false) == false && visibleInUI
        let priorityIncreased = zPriority > (previousEntry?.zPriority ?? Int.min)
#if DEBUG
        if previousEntry == nil || didChangeAnchor || becameVisible || priorityIncreased || hostedView.superview !== hostView {
            dlog(
                "portal.bind hosted=\(portalDebugToken(hostedView)) " +
                "anchor=\(portalDebugToken(anchorView)) prevAnchor=\(portalDebugToken(previousEntry?.anchorView)) " +
                "visible=\(visibleInUI ? 1 : 0) prevVisible=\((previousEntry?.visibleInUI ?? false) ? 1 : 0) " +
                "z=\(zPriority) prevZ=\(previousEntry?.zPriority ?? Int.min)"
            )
        }
#endif

        if hostedView.superview !== hostView {
#if DEBUG
            dlog(
                "portal.reparent hosted=\(portalDebugToken(hostedView)) " +
                "reason=attach super=\(portalDebugToken(hostedView.superview))"
            )
#endif
            hostView.addSubview(hostedView, positioned: .above, relativeTo: nil)
        } else if (becameVisible || priorityIncreased), hostView.subviews.last !== hostedView {
            // Refresh z-order only when a view becomes visible or gets a higher priority.
            // Anchor-only churn is common during split tree updates; forcing remove/add there
            // causes transient inWindow=0 -> 1 bounces that can flash black.
#if DEBUG
            dlog(
                "portal.reparent hosted=\(portalDebugToken(hostedView)) reason=raise " +
                "didChangeAnchor=\(didChangeAnchor ? 1 : 0) becameVisible=\(becameVisible ? 1 : 0) " +
                "priorityIncreased=\(priorityIncreased ? 1 : 0)"
            )
#endif
            hostView.addSubview(hostedView, positioned: .above, relativeTo: nil)
        }

        ensureDividerOverlayOnTop()

        synchronizeHostedView(withId: hostedId)
        pruneDeadEntries()
    }

    func synchronizeHostedViewForAnchor(_ anchorView: NSView) {
        pruneDeadEntries()
        let anchorId = ObjectIdentifier(anchorView)
        let primaryHostedId = hostedByAnchorId[anchorId]
        if let primaryHostedId {
            synchronizeHostedView(withId: primaryHostedId)
        }

        // Failsafe: during aggressive divider drags/structural churn, one anchor can miss a
        // geometry callback while another fires. Reconcile all mapped hosted views so no stale
        // frame remains "stuck" onscreen until the next interaction.
        synchronizeAllHostedViews(excluding: primaryHostedId)
        scheduleDeferredFullSynchronizeAll()
    }

    private func scheduleDeferredFullSynchronizeAll() {
        guard !hasDeferredFullSyncScheduled else { return }
        hasDeferredFullSyncScheduled = true
        DispatchQueue.main.async { [weak self] in
            guard let self else { return }
            self.hasDeferredFullSyncScheduled = false
            self.synchronizeAllHostedViews(excluding: nil)
        }
    }

    private func synchronizeAllHostedViews(excluding hostedIdToSkip: ObjectIdentifier?) {
        guard ensureInstalled() else { return }
        pruneDeadEntries()
        let hostedIds = Array(entriesByHostedId.keys)
        for hostedId in hostedIds {
            if hostedId == hostedIdToSkip { continue }
            synchronizeHostedView(withId: hostedId)
        }
    }

    private func synchronizeHostedView(withId hostedId: ObjectIdentifier) {
        guard ensureInstalled() else { return }
        guard let entry = entriesByHostedId[hostedId] else { return }
        guard let hostedView = entry.hostedView else {
            entriesByHostedId.removeValue(forKey: hostedId)
            return
        }
        guard let anchorView = entry.anchorView, let window else {
            // Only hide if the entry is not marked visibleInUI. When a workspace is
            // remounting, updateNSView sets visibleInUI=true before the deferred bind
            // provides an anchor — hiding here would race with that and cause a flash.
            if !entry.visibleInUI {
#if DEBUG
                if !hostedView.isHidden {
                    dlog("portal.hidden hosted=\(portalDebugToken(hostedView)) value=1 reason=missingAnchorOrWindow")
                }
#endif
                hostedView.isHidden = true
            }
            return
        }
        guard anchorView.window === window else {
#if DEBUG
            if !hostedView.isHidden {
                dlog(
                    "portal.hidden hosted=\(portalDebugToken(hostedView)) value=1 " +
                    "reason=anchorWindowMismatch anchorWindow=\(portalDebugToken(anchorView.window?.contentView))"
                )
            }
#endif
            hostedView.isHidden = true
            return
        }

        let frameInWindow = anchorView.convert(anchorView.bounds, to: nil)
        let frameInHost = hostView.convert(frameInWindow, from: nil)
        let hasFiniteFrame =
            frameInHost.origin.x.isFinite &&
            frameInHost.origin.y.isFinite &&
            frameInHost.size.width.isFinite &&
            frameInHost.size.height.isFinite
        let anchorHidden = Self.isHiddenOrAncestorHidden(anchorView)
        let tinyFrame = frameInHost.width <= 1 || frameInHost.height <= 1
        let outsideHostBounds = !frameInHost.intersects(hostView.bounds)
        let shouldHide =
            !entry.visibleInUI ||
            anchorHidden ||
            tinyFrame ||
            !hasFiniteFrame ||
            outsideHostBounds

        let oldFrame = hostedView.frame
#if DEBUG
        let collapsedToTiny = oldFrame.width > 1 && oldFrame.height > 1 && tinyFrame
        let restoredFromTiny = (oldFrame.width <= 1 || oldFrame.height <= 1) && !tinyFrame
        if collapsedToTiny {
            dlog(
                "portal.frame.collapse hosted=\(portalDebugToken(hostedView)) anchor=\(portalDebugToken(anchorView)) " +
                "old=\(portalDebugFrame(oldFrame)) new=\(portalDebugFrame(frameInHost))"
            )
        } else if restoredFromTiny {
            dlog(
                "portal.frame.restore hosted=\(portalDebugToken(hostedView)) anchor=\(portalDebugToken(anchorView)) " +
                "old=\(portalDebugFrame(oldFrame)) new=\(portalDebugFrame(frameInHost))"
            )
        }
#endif

        // Hide before updating the frame when this entry should not be visible.
        // This avoids a one-frame flash of unrendered terminal background when a portal
        // briefly transitions through offscreen/tiny geometry during rapid split churn.
        if shouldHide, !hostedView.isHidden {
#if DEBUG
            dlog(
                "portal.hidden hosted=\(portalDebugToken(hostedView)) value=1 " +
                "visibleInUI=\(entry.visibleInUI ? 1 : 0) anchorHidden=\(anchorHidden ? 1 : 0) " +
                "tiny=\(tinyFrame ? 1 : 0) finite=\(hasFiniteFrame ? 1 : 0) " +
                "outside=\(outsideHostBounds ? 1 : 0) frame=\(portalDebugFrame(frameInHost))"
            )
#endif
            hostedView.isHidden = true
        }

        if !Self.rectApproximatelyEqual(oldFrame, frameInHost) {
            CATransaction.begin()
            CATransaction.setDisableActions(true)
            hostedView.frame = frameInHost
            CATransaction.commit()

            if abs(oldFrame.size.width - frameInHost.size.width) > 0.5 ||
                abs(oldFrame.size.height - frameInHost.size.height) > 0.5,
                !shouldHide {
                hostedView.reconcileGeometryNow()
            }
        }

        if !shouldHide, hostedView.isHidden {
#if DEBUG
            dlog(
                "portal.hidden hosted=\(portalDebugToken(hostedView)) value=0 " +
                "visibleInUI=\(entry.visibleInUI ? 1 : 0) anchorHidden=\(anchorHidden ? 1 : 0) " +
                "tiny=\(tinyFrame ? 1 : 0) finite=\(hasFiniteFrame ? 1 : 0) " +
                "outside=\(outsideHostBounds ? 1 : 0) frame=\(portalDebugFrame(frameInHost))"
            )
#endif
            hostedView.isHidden = false
        }

        ensureDividerOverlayOnTop()
    }

    private func pruneDeadEntries() {
        let currentWindow = window
        let deadHostedIds = entriesByHostedId.compactMap { hostedId, entry -> ObjectIdentifier? in
            guard entry.hostedView != nil else { return hostedId }
            guard let anchor = entry.anchorView else { return hostedId }
            if anchor.window !== currentWindow || anchor.superview == nil {
                return hostedId
            }
            if let reference = installedReferenceView,
               !anchor.isDescendant(of: reference) {
                return hostedId
            }
            return nil
        }

        for hostedId in deadHostedIds {
            detachHostedView(withId: hostedId)
        }

        let validAnchorIds = Set(entriesByHostedId.compactMap { _, entry in
            entry.anchorView.map { ObjectIdentifier($0) }
        })
        hostedByAnchorId = hostedByAnchorId.filter { validAnchorIds.contains($0.key) }
    }

    func hostedIds() -> Set<ObjectIdentifier> {
        Set(entriesByHostedId.keys)
    }

    func tearDown() {
        for hostedId in Array(entriesByHostedId.keys) {
            detachHostedView(withId: hostedId)
        }
        NSLayoutConstraint.deactivate(installConstraints)
        installConstraints.removeAll()
        hostView.removeFromSuperview()
        installedContainerView = nil
        installedReferenceView = nil
    }

#if DEBUG
    func debugEntryCount() -> Int {
        entriesByHostedId.count
    }

    func debugHostedSubviewCount() -> Int {
        hostView.subviews.count
    }
#endif

    func viewAtWindowPoint(_ windowPoint: NSPoint) -> NSView? {
        guard ensureInstalled() else { return nil }
        let point = hostView.convert(windowPoint, from: nil)

        // Restrict hit-testing to currently mapped entries so stale detached views
        // can't steal file-drop/mouse routing.
        for subview in hostView.subviews.reversed() {
            guard let hostedView = subview as? GhosttySurfaceScrollView else { continue }
            let hostedId = ObjectIdentifier(hostedView)
            guard entriesByHostedId[hostedId] != nil else { continue }
            guard !hostedView.isHidden else { continue }
            guard hostedView.frame.contains(point) else { continue }
            let localPoint = hostedView.convert(point, from: hostView)
            return hostedView.hitTest(localPoint) ?? hostedView
        }

        return nil
    }

    func terminalViewAtWindowPoint(_ windowPoint: NSPoint) -> GhosttyNSView? {
        guard ensureInstalled() else { return nil }
        let point = hostView.convert(windowPoint, from: nil)

        for subview in hostView.subviews.reversed() {
            guard let hostedView = subview as? GhosttySurfaceScrollView else { continue }
            let hostedId = ObjectIdentifier(hostedView)
            guard entriesByHostedId[hostedId] != nil else { continue }
            guard !hostedView.isHidden else { continue }
            guard hostedView.frame.contains(point) else { continue }
            let localPoint = hostedView.convert(point, from: hostView)
            if let terminal = hostedView.terminalViewForDrop(at: localPoint) {
                return terminal
            }
        }

        return nil
    }
}

@MainActor
enum TerminalWindowPortalRegistry {
    private static var portalsByWindowId: [ObjectIdentifier: WindowTerminalPortal] = [:]
    private static var hostedToWindowId: [ObjectIdentifier: ObjectIdentifier] = [:]

    private static func installWindowCloseObserverIfNeeded(for window: NSWindow) {
        guard objc_getAssociatedObject(window, &cmuxWindowTerminalPortalCloseObserverKey) == nil else { return }
        let windowId = ObjectIdentifier(window)
        let observer = NotificationCenter.default.addObserver(
            forName: NSWindow.willCloseNotification,
            object: window,
            queue: .main
        ) { [weak window] _ in
            MainActor.assumeIsolated {
                if let window {
                    removePortal(for: window)
                } else {
                    removePortal(windowId: windowId, window: nil)
                }
            }
        }
        objc_setAssociatedObject(
            window,
            &cmuxWindowTerminalPortalCloseObserverKey,
            observer,
            .OBJC_ASSOCIATION_RETAIN_NONATOMIC
        )
    }

    private static func removePortal(for window: NSWindow) {
        removePortal(windowId: ObjectIdentifier(window), window: window)
    }

    private static func removePortal(windowId: ObjectIdentifier, window: NSWindow?) {
        if let portal = portalsByWindowId.removeValue(forKey: windowId) {
            portal.tearDown()
        }
        hostedToWindowId = hostedToWindowId.filter { $0.value != windowId }

        guard let window else { return }
        if let observer = objc_getAssociatedObject(window, &cmuxWindowTerminalPortalCloseObserverKey) {
            NotificationCenter.default.removeObserver(observer)
        }
        objc_setAssociatedObject(window, &cmuxWindowTerminalPortalCloseObserverKey, nil, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        objc_setAssociatedObject(window, &cmuxWindowTerminalPortalKey, nil, .OBJC_ASSOCIATION_RETAIN)
    }

    private static func pruneHostedMappings(for windowId: ObjectIdentifier, validHostedIds: Set<ObjectIdentifier>) {
        hostedToWindowId = hostedToWindowId.filter { hostedId, mappedWindowId in
            mappedWindowId != windowId || validHostedIds.contains(hostedId)
        }
    }

    private static func portal(for window: NSWindow) -> WindowTerminalPortal {
        if let existing = objc_getAssociatedObject(window, &cmuxWindowTerminalPortalKey) as? WindowTerminalPortal {
            portalsByWindowId[ObjectIdentifier(window)] = existing
            installWindowCloseObserverIfNeeded(for: window)
            return existing
        }

        let portal = WindowTerminalPortal(window: window)
        objc_setAssociatedObject(window, &cmuxWindowTerminalPortalKey, portal, .OBJC_ASSOCIATION_RETAIN)
        portalsByWindowId[ObjectIdentifier(window)] = portal
        installWindowCloseObserverIfNeeded(for: window)
        return portal
    }

    static func bind(hostedView: GhosttySurfaceScrollView, to anchorView: NSView, visibleInUI: Bool, zPriority: Int = 0) {
        guard let window = anchorView.window else { return }

        let windowId = ObjectIdentifier(window)
        let hostedId = ObjectIdentifier(hostedView)
        let nextPortal = portal(for: window)

        if let oldWindowId = hostedToWindowId[hostedId],
           oldWindowId != windowId {
            portalsByWindowId[oldWindowId]?.detachHostedView(withId: hostedId)
        }

        nextPortal.bind(hostedView: hostedView, to: anchorView, visibleInUI: visibleInUI, zPriority: zPriority)
        hostedToWindowId[hostedId] = windowId
        pruneHostedMappings(for: windowId, validHostedIds: nextPortal.hostedIds())
    }

    static func synchronizeForAnchor(_ anchorView: NSView) {
        guard let window = anchorView.window else { return }
        let portal = portal(for: window)
        portal.synchronizeHostedViewForAnchor(anchorView)
    }

    static func hideHostedView(_ hostedView: GhosttySurfaceScrollView) {
        let hostedId = ObjectIdentifier(hostedView)
        guard let windowId = hostedToWindowId[hostedId],
              let portal = portalsByWindowId[windowId] else { return }
        portal.hideEntry(forHostedId: hostedId)
    }

    /// Update the visibleInUI flag on an existing portal entry without rebinding.
    /// Called when a bind is deferred (host not yet in window) to prevent stale
    /// portal syncs from hiding a view that is about to become visible.
    static func updateEntryVisibility(for hostedView: GhosttySurfaceScrollView, visibleInUI: Bool) {
        let hostedId = ObjectIdentifier(hostedView)
        guard let windowId = hostedToWindowId[hostedId],
              let portal = portalsByWindowId[windowId] else { return }
        portal.updateEntryVisibility(forHostedId: hostedId, visibleInUI: visibleInUI)
    }

    static func viewAtWindowPoint(_ windowPoint: NSPoint, in window: NSWindow) -> NSView? {
        let portal = portal(for: window)
        return portal.viewAtWindowPoint(windowPoint)
    }

    static func terminalViewAtWindowPoint(_ windowPoint: NSPoint, in window: NSWindow) -> GhosttyNSView? {
        let portal = portal(for: window)
        return portal.terminalViewAtWindowPoint(windowPoint)
    }

#if DEBUG
    static func debugPortalCount() -> Int {
        portalsByWindowId.count
    }
#endif
}