import AppKit
import SwiftUI

struct MenuEntry: Identifiable {
    let id: String
    let label: String
    let badge: TabBadge
    let action: () -> Void
}

struct OverlayMenu {
    let anchor: CGRect
    let accent: Color
    let entries: [MenuEntry]
}

struct ModalButton {
    let label: String
    let value: String
    var primary = false
    var danger = false
    var help = ""
}

struct OverlayModal {
    let content: AnyView
    let buttons: [ModalButton]
    let anchor: CGRect?
    let inPane: Bool
    let canSubmit: @MainActor () -> Bool
    let done: (String) -> Void
}

struct OverlayAlert: Identifiable {
    let id = UUID()
    let content: AnyView
}

enum LeftTab {
    case lead, status, server, settings
}

@MainActor
@Observable
final class Overlays {
    var alerts: [OverlayAlert] = []
    var image: NSImage?
    var menu: OverlayMenu? {
        didSet {
            menuHover = false
        }
    }
    var modal: OverlayModal?
    var switcher: SwitcherModel?
    var leftTab = LeftTab.lead
    var leadFocus = 0
    @ObservationIgnored var pickerFrame: CGRect = .zero
    @ObservationIgnored var menuHover = false
    var paneFrame: CGRect = .zero
    @ObservationIgnored weak var window: NSWindow?
    @ObservationIgnored private var monitor: Any?
    @ObservationIgnored private var mouseMonitor: Any?

    var isOpen: Bool {
        !alerts.isEmpty || image != nil || menu != nil || modal != nil || switcher != nil
    }

    var dialogOpen: Bool {
        !alerts.isEmpty || modal != nil
    }

    func showAlert(_ text: String) {
        menu = nil
        alerts.append(OverlayAlert(content: AnyView(ModalText(text: text))))
    }

    func showAlert(_ content: some View) {
        menu = nil
        alerts.append(OverlayAlert(content: AnyView(content)))
    }

    func showModal(_ content: some View, _ buttons: [ModalButton], anchor: CGRect? = nil, inPane: Bool = false, canSubmit: @escaping @MainActor () -> Bool = { true }) async -> String {
        modal?.done("cancel")
        menu = nil
        return await withCheckedContinuation { cont in
            modal = OverlayModal(content: AnyView(content), buttons: buttons, anchor: anchor, inPane: inPane, canSubmit: canSubmit) { value in
                cont.resume(returning: value)
            }
        }
    }

    func showConfirm(_ paragraphs: [String], action: String, danger: Bool = false, anchor: CGRect? = nil) async -> Bool {
        let content = VStack(alignment: .leading, spacing: 12) {
            ForEach(Array(paragraphs.enumerated()), id: \.offset) { _, p in
                ModalText(text: p)
            }
        }
        return await showModal(content, [ModalButton(label: "Cancel", value: "cancel"), ModalButton(label: action, value: "ok", primary: true, danger: danger)], anchor: anchor) == "ok"
    }

    func showChoice(_ content: some View, _ choices: [ModalButton], anchor: CGRect? = nil) async -> String {
        await showModal(content, [ModalButton(label: "Cancel", value: "cancel")] + choices, anchor: anchor)
    }

    func answerModal(_ value: String) {
        let m = modal
        modal = nil
        m?.done(value)
    }

    func openSwitcher(_ store: Store) {
        if switcher != nil {
            return
        }
        logFocus("open switcher")
        switcher = SwitcherModel(store: store, overlays: self, anchor: pickerFrame)
    }

    func closeTop() {
        if !alerts.isEmpty {
            alerts.removeLast()
        } else if modal != nil {
            answerModal("cancel")
        } else if image != nil {
            image = nil
        } else if let switcher {
            switcher.escape()
        } else if menu != nil {
            menu = nil
        }
    }

    func install(_ ctrl: @escaping @MainActor (String) -> Bool) {
        if monitor != nil {
            return
        }
        monitor = NSEvent.addLocalMonitorForEvents(matching: .keyDown) { [weak self] event in
            let win = event.window.map(ObjectIdentifier.init)
            let code = event.keyCode
            let flags = event.modifierFlags.intersection(.deviceIndependentFlagsMask)
            let chars = event.charactersIgnoringModifiers ?? ""
            let taken = MainActor.assumeIsolated {
                guard let self, let window = self.window, win == ObjectIdentifier(window) else {
                    return false
                }
                return self.key(code, flags, chars, ctrl)
            }
            return taken ? nil : event
        }
        mouseMonitor = NSEvent.addLocalMonitorForEvents(matching: [.leftMouseDown, .rightMouseDown, .otherMouseDown]) { [weak self] event in
            let win = event.window.map(ObjectIdentifier.init)
            MainActor.assumeIsolated {
                if let self, let window = self.window, win == ObjectIdentifier(window), self.menu != nil, !self.menuHover {
                    self.menu = nil
                }
            }
            return event
        }
    }

    private func key(_ code: UInt16, _ flags: NSEvent.ModifierFlags, _ chars: String, _ ctrl: @MainActor (String) -> Bool) -> Bool {
        if !dialogOpen && flags.contains(.control) && !flags.contains(.command) && goKeys.contains(chars) {
            return ctrl(chars)
        }
        if !isOpen {
            return false
        }
        if code == 53 {
            closeTop()
            return true
        }
        let enter = code == 36 || code == 76
        let marked = (NSApp.keyWindow?.firstResponder as? NSTextView)?.hasMarkedText() ?? false
        if !alerts.isEmpty {
            if enter {
                alerts.removeLast()
                return true
            }
            return false
        }
        if let modal {
            if enter && !marked {
                if modal.canSubmit(), let last = modal.buttons.last {
                    answerModal(last.value)
                }
                return true
            }
            return false
        }
        if image == nil, !marked, let switcher {
            if code == 125 {
                switcher.move(1)
                return true
            }
            if code == 126 {
                switcher.move(-1)
                return true
            }
            if enter {
                switcher.pick()
                return true
            }
        }
        return false
    }

    func uninstall() {
        if let monitor {
            NSEvent.removeMonitor(monitor)
        }
        if let mouseMonitor {
            NSEvent.removeMonitor(mouseMonitor)
        }
        monitor = nil
        mouseMonitor = nil
    }
}

@MainActor
func logFocus(_ what: String) {
    let key = NSApp.keyWindow
    let main = NSApp.mainWindow
    let responder = key?.firstResponder.map { String(describing: type(of: $0)) } ?? "nil"
    log.notice("focus debug: \(what, privacy: .public) active=\(NSApp.isActive) key=\(key?.title ?? "nil", privacy: .public) main=\(main?.title ?? "nil", privacy: .public) mainIsKey=\(main?.isKeyWindow ?? false) responder=\(responder, privacy: .public)")
}

struct ModalText: View {
    let text: String

    var body: some View {
        Text(text)
            .textSelection(.enabled)
            .fixedSize(horizontal: false, vertical: true)
            .frame(maxWidth: .infinity, alignment: .leading)
    }
}

struct OverlayHost: View {
    @Environment(Overlays.self) private var overlays

    var body: some View {
        ZStack(alignment: .topLeading) {
            if let switcher = overlays.switcher {
                Color.black.opacity(0.35)
                    .contentShape(Rectangle())
                    .onTapGesture {
                        switcher.close()
                    }
                SwitcherPlacement(model: switcher)
            }
            if let image = overlays.image {
                Color.black.opacity(0.6)
                    .onTapGesture {
                        overlays.image = nil
                    }
                Image(nsImage: image)
                    .resizable()
                    .scaledToFit()
                    .frame(maxWidth: image.size.width, maxHeight: image.size.height)
                    .padding(24)
                    .frame(maxWidth: .infinity, maxHeight: .infinity)
                    .onTapGesture {
                        overlays.image = nil
                    }
            }
            if let menu = overlays.menu {
                VStack(alignment: .leading, spacing: 0) {
                    ForEach(menu.entries) { entry in
                        MenuRow(entry: entry) {
                            overlays.menu = nil
                            entry.action()
                        }
                    }
                }
                .padding(4)
                .background(Palette.raised, in: RoundedRectangle(cornerRadius: 6))
                .overlay(RoundedRectangle(cornerRadius: 6).stroke(Palette.border))
                .shadow(color: overlayShadow, radius: 14, y: 8)
                .environment(\.paneAccent, menu.accent)
                .onHover { inside in
                    overlays.menuHover = inside
                }
                .fixedSize()
                .offset(x: menu.anchor.minX, y: menu.anchor.maxY + 4)
            }
            if let m = overlays.modal {
                Color.black.opacity(0.35)
                    .contentShape(Rectangle())
                ModalPlacement(modal: m, pane: overlays.paneFrame) { value in
                    overlays.answerModal(value)
                }
            }
            if let alert = overlays.alerts.last {
                Color.black.opacity(0.35)
                    .contentShape(Rectangle())
                GeometryReader { g in
                    AlertBox(alert: alert, maxText: max(60, g.size.height - 48 - 90)) {
                        overlays.alerts.removeLast()
                    }
                    .frame(maxWidth: .infinity, maxHeight: .infinity)
                }
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
    }
}

private struct MenuRow: View {
    let entry: MenuEntry
    let action: () -> Void
    @ViewState private var hover = false

    var body: some View {
        Button(action: action) {
            HStack(spacing: 6) {
                Text(entry.label)
                TabBadgeView(badge: entry.badge)
            }
            .padding(.horizontal, 12)
            .padding(.vertical, 4)
            .frame(maxWidth: .infinity, alignment: .leading)
            .background(hover ? Palette.surface : .clear, in: RoundedRectangle(cornerRadius: 4))
            .contentShape(Rectangle())
        }
        .buttonStyle(.plain)
        .onHover { hover = $0 }
    }
}

let overlayMargin: CGFloat = 8

private struct AnchoredBox: Layout {
    let anchor: CGRect

    func sizeThatFits(proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) -> CGSize {
        proposal.replacingUnspecifiedDimensions()
    }

    func placeSubviews(in bounds: CGRect, proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) {
        let width = min(520, bounds.width - overlayMargin * 2)
        let size = subviews[0].sizeThatFits(ProposedViewSize(width: width, height: nil))
        let below = anchor.maxY + 4
        let above = anchor.minY - 4 - size.height
        let y: CGFloat
        if below + size.height <= bounds.height - overlayMargin {
            y = below
        } else if above >= overlayMargin {
            y = above
        } else {
            y = max(overlayMargin, bounds.height - overlayMargin - size.height)
        }
        let x = min(max(overlayMargin, anchor.maxX - size.width), bounds.width - overlayMargin - size.width)
        subviews[0].place(at: CGPoint(x: bounds.minX + x, y: bounds.minY + y), proposal: ProposedViewSize(width: width, height: size.height))
    }
}

private struct PaneCenteredBox: Layout {
    let pane: CGRect

    func sizeThatFits(proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) -> CGSize {
        proposal.replacingUnspecifiedDimensions()
    }

    func placeSubviews(in bounds: CGRect, proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) {
        let width = min(520, pane.width - 48)
        let size = subviews[0].sizeThatFits(ProposedViewSize(width: width, height: nil))
        let x = pane.midX - size.width / 2
        let y = min(max(overlayMargin, pane.midY - size.height / 2), bounds.height - overlayMargin - size.height)
        subviews[0].place(at: CGPoint(x: bounds.minX + x, y: bounds.minY + y), proposal: ProposedViewSize(width: width, height: size.height))
    }
}

private struct ModalPlacement: View {
    let modal: OverlayModal
    let pane: CGRect
    let answer: (String) -> Void

    var body: some View {
        GeometryReader { g in
            let box = ModalBox(modal: modal, maxText: max(60, g.size.height - overlayMargin * 2 - 90), answer: answer)
            if let anchor = modal.anchor {
                AnchoredBox(anchor: anchor) {
                    box
                }
            } else if modal.inPane {
                PaneCenteredBox(pane: pane) {
                    box
                }
            } else {
                box
                    .padding(24)
                    .frame(maxWidth: .infinity, maxHeight: .infinity)
            }
        }
    }
}

private struct ModalBox: View {
    let modal: OverlayModal
    let maxText: CGFloat
    let answer: (String) -> Void

    var body: some View {
        let ok = modal.canSubmit()
        VStack(alignment: .leading, spacing: 12) {
            ScrollView {
                modal.content
                    .frame(maxWidth: .infinity, alignment: .leading)
            }
            .scrollBounceBehavior(.basedOnSize)
            .frame(maxHeight: maxText)
            .fixedSize(horizontal: false, vertical: true)
            HStack(spacing: 8) {
                Spacer()
                ForEach(Array(modal.buttons.enumerated()), id: \.offset) { _, b in
                    Button(b.label) {
                        answer(b.value)
                    }
                    .buttonStyle(WebButtonStyle(primary: b.primary, danger: b.danger))
                    .disabled(b.value != "cancel" && !ok)
                    .help(b.help)
                }
            }
            .padding(.top, 4)
        }
        .padding(16)
        .frame(maxWidth: 520)
        .background(Palette.raised, in: RoundedRectangle(cornerRadius: 10))
        .overlay(RoundedRectangle(cornerRadius: 10).stroke(Palette.border))
        .shadow(color: overlayShadow, radius: 14, y: 8)
    }
}

private struct AlertBox: View {
    let alert: OverlayAlert
    let maxText: CGFloat
    let ok: () -> Void

    var body: some View {
        VStack(alignment: .leading, spacing: 16) {
            ScrollView {
                alert.content
                    .frame(maxWidth: .infinity, alignment: .leading)
            }
            .scrollBounceBehavior(.basedOnSize)
            .frame(maxHeight: maxText)
            .fixedSize(horizontal: false, vertical: true)
            HStack {
                Spacer()
                Button("OK", action: ok)
                    .buttonStyle(WebButtonStyle(primary: true))
            }
        }
        .padding(16)
        .frame(maxWidth: 520)
        .background(Palette.raised, in: RoundedRectangle(cornerRadius: 10))
        .overlay(RoundedRectangle(cornerRadius: 10).stroke(Palette.border))
        .shadow(color: overlayShadow, radius: 14, y: 8)
        .padding(24)
    }
}