import AppKit

@MainActor
final class ActionPill: NSView {
    private var themeObservation: ThemeObservation?
    init(primaryButton: NSButton, actionsButton: NSButton, primaryCommand: String? = nil) {
        super.init(frame: .zero)
        wantsLayer = true
        layer?.cornerRadius = 18
        layer?.borderWidth = 0.5
        layer?.borderColor = ThemePalette.accent.withAlphaComponent(0.35).cgColor
        layer?.backgroundColor = ThemePalette.background.withAlphaComponent(0.25).cgColor
        for button in [primaryButton, actionsButton] {
            button.isBordered = false
            button.font = .systemFont(ofSize: 12, weight: .medium)
            button.contentTintColor = ThemePalette.text
        }
        primaryButton.keyEquivalent = primaryCommand ?? "\r"
        primaryButton.keyEquivalentModifierMask = primaryCommand == nil ? [] : .command
        actionsButton.title = "Actions"
        actionsButton.keyEquivalent = "k"
        actionsButton.keyEquivalentModifierMask = .command
        let returnKey = primaryCommand.map { ShortcutIndicator("⌘", $0.uppercased()) } ?? ShortcutIndicator("↵")
        let actionKeys = ShortcutIndicator("⌘", "K")
        for control in [primaryButton, returnKey, actionsButton, actionKeys] {
            control.translatesAutoresizingMaskIntoConstraints = false
            addSubview(control)
        }
        NSLayoutConstraint.activate([
            heightAnchor.constraint(equalToConstant: 36),
            primaryButton.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 14),
            primaryButton.centerYAnchor.constraint(equalTo: centerYAnchor),
            returnKey.leadingAnchor.constraint(equalTo: primaryButton.trailingAnchor, constant: 8),
            returnKey.centerYAnchor.constraint(equalTo: centerYAnchor),
            actionsButton.leadingAnchor.constraint(equalTo: returnKey.trailingAnchor, constant: 14),
            actionsButton.centerYAnchor.constraint(equalTo: centerYAnchor),
            actionKeys.leadingAnchor.constraint(equalTo: actionsButton.trailingAnchor, constant: 8),
            actionKeys.centerYAnchor.constraint(equalTo: centerYAnchor),
            actionKeys.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -12),
        ])
        themeObservation = ThemeObservation { [weak self, weak primaryButton, weak actionsButton] in
            self?.layer?.borderColor = ThemePalette.accent.withAlphaComponent(0.35).cgColor
            self?.layer?.backgroundColor = ThemePalette.background.withAlphaComponent(0.25).cgColor
            primaryButton?.contentTintColor = ThemePalette.text
            actionsButton?.contentTintColor = ThemePalette.text
        }
    }

    required init?(coder: NSCoder) { fatalError("Conjure creates action pills programmatically") }
}

/// Keeps palette subscriptions scoped to the existing control's lifetime.
@MainActor
final class ThemeObservation {
    nonisolated(unsafe) private let token: NSObjectProtocol

    init(_ apply: @escaping @MainActor () -> Void) {
        ThemePalette.appearance.performAsCurrentDrawingAppearance(apply)
        token = NotificationCenter.default.addObserver(
            forName: ThemePalette.didChangeNotification, object: nil, queue: .main
        ) { _ in
            MainActor.assumeIsolated { ThemePalette.appearance.performAsCurrentDrawingAppearance(apply) }
        }
    }

    deinit { NotificationCenter.default.removeObserver(token) }
}

extension NSSearchField {
    /// Recolors the current presentation without changing the query or field-editor selection.
    func applyTheme() {
        textColor = ThemePalette.text
        if let placeholderAttributedString {
            let placeholder = NSMutableAttributedString(attributedString: placeholderAttributedString)
            placeholder.addAttribute(.foregroundColor, value: ThemePalette.secondaryText,
                                     range: NSRange(location: 0, length: placeholder.length))
            self.placeholderAttributedString = placeholder
        }
        if let editor = currentEditor() as? NSTextView {
            editor.textColor = ThemePalette.text
        }
    }
}