import Commanding
import SwiftUI
import WidgetKit

/// The style of the action buttons of the recording Live Activity: it renders a button's label as a fixed-size icon on a circle
/// colored by the ``ActionType`` given at initialization.
///
/// The style is a regular ``ButtonStyle`` — not a ``PrimitiveButtonStyle`` — so that SwiftUI and WidgetKit keep handling the
/// button's tap and fire its intent from the Live Activity; a primitive style would have to invoke the trigger itself, which arbitrary
/// gestures cannot do inside a widget.
struct ActionButtonStyle: ButtonStyle {

    // MARK: Properties

    /// The type of the action behind the styled button, deciding the color of the circular background.
    private let action: ActionType

    // MARK: Initializers

    /// Creates a style for a button behind the given type of action.
    ///
    /// - Parameter action: The type of the action behind the styled button.
    fileprivate init(
        _ action: ActionType
    ) {
        self.action = action
    }

    // MARK: Methods

    /// Builds the styled button: its label as a fixed-size, padded icon on a circle colored by the type of the action.
    ///
    /// - Parameter configuration: The properties of the button to style.
    /// - Returns: The styled button.
    func makeBody(
        configuration: Configuration
    ) -> some View {
        configuration.label
            .scaledToFit()
            .frame(
                width: Constant.Size.icon.width,
                height: Constant.Size.icon.height
            )
            .foregroundStyle(.primary)
            .padding(Constant.Padding.icon)
            .background {
                Circle()
                    .foregroundStyle(backgroundColor)
            }
    }

}

// MARK: - Helpers

private extension ActionButtonStyle {

    /// The color of the circular background, matching the type of the action behind the button.
    var backgroundColor: Color {
        switch action {
        case .confirmative: .green
        case .custom(let color): color
        case .default: .yellow
        case .destructive: .red
        }
    }

}

// MARK: - Enumerations

extension ActionButtonStyle {
    /// The types of action a styled button can stand behind, each coloring the button's background differently.
    enum ActionType {
        /// An action that confirms or submits, colored green.
        case confirmative
        /// An action colored by the given custom color.
        case custom(_ color: Color)
        /// A regular action, colored yellow.
        case `default`
        /// An action that throws something away, colored red.
        case destructive
    }
}

// MARK: - Constants

/// The constant values used across the action button style.
private enum Constant {
    /// The padding constants.
    enum Padding {
        /// The padding around the button's icon.
        static let icon: CGFloat = 16
    }
    /// The size constants.
    enum Size {
        /// The size of the button's icon.
        static let icon: CGSize = .init(
            width: 24,
            height: 24
        )
    }
}

// MARK: - Styles

extension ButtonStyle where Self == ActionButtonStyle {

    /// An action button style for a button behind the given type of action.
    ///
    /// - Parameter actionType: The type of the action behind the styled button.
    /// - Returns: The action button style colored for the given type.
    static func action(
        type actionType: ActionButtonStyle.ActionType
    ) -> ActionButtonStyle {
        .init(actionType)
    }

}