import SwiftUI

/// A name space for info button styles.
public enum InfoButtonType { }

/// A name space for info button styles.
public enum NextButtonType { }

/// A name space for info button styles.
public enum ResetButtonType { }

/// A type erased button style, used to style buttons in a namespace.
public struct AnyButtonStyle<ButtonType>: ButtonStyle {
  private let _makeBody: (Configuration) -> AnyView

  public init<S: ButtonStyle>(_ style: S) {
    self._makeBody = { configuration in
      AnyView(style.makeBody(configuration: configuration))
    }
  }

  public func makeBody(configuration: Configuration) -> some View {
    self._makeBody(configuration)
  }
}

/// A type erased primitive button style, used to style buttons in a namespace.
public struct AnyPrimitiveButtonStyle<ButtonType>: PrimitiveButtonStyle {
  private let _makeBody: (Configuration) -> AnyView

  public init<S: PrimitiveButtonStyle>(_ style: S) {
    self._makeBody = { configuration in
      AnyView(style.makeBody(configuration: configuration))
    }
  }

  public func makeBody(configuration: Configuration) -> some View {
    self._makeBody(configuration)
  }
}

/// The default info button style.
public struct DefaultInfoButtonStyle<Style: LabelStyle>: ButtonStyle {
  let color: Color
  let font: Font
  let labelStyle: Style
  
  init(
    color: Color = .accentColor,
    font: Font = .title2,
    labelStyle: Style
  ) {
    self.color = color
    self.font = font
    self.labelStyle = labelStyle
  }
  
  public func makeBody(configuration: Configuration) -> some View {
    configuration.label
      .font(font)
      .foregroundStyle(color.opacity(configuration.isPressed ? 0.5 : 1))
      .labelStyle(labelStyle)
      .scaleEffect(configuration.isPressed ? 0.8 : 1)
  }
}

public struct DefaultNextButtonStyle<ButtonStyle: PrimitiveButtonStyle, Label: LabelStyle>: PrimitiveButtonStyle {
  let buttonStyle: ButtonStyle
  let labelStyle: Label
  
  public init(buttonStyle: ButtonStyle, labelStyle: Label) {
    self.buttonStyle = buttonStyle
    self.labelStyle = labelStyle
  }
  
  public func makeBody(configuration: Configuration) -> some View {
    Button(role: configuration.role, action: configuration.trigger) {
      configuration.label
    }
    .labelStyle(labelStyle)
    .buttonStyle(buttonStyle)
  }
}

extension DefaultNextButtonStyle where ButtonStyle == BorderedProminentButtonStyle, Label == ReverseLabelStyle {
  init() {
    self.init(buttonStyle: .borderedProminent, labelStyle: .reverse())
  }
}

extension AnyButtonStyle where ButtonType == InfoButtonType {
  public static var `default`: Self {
    .init(DefaultInfoButtonStyle<IconOnlyLabelStyle>(labelStyle: .iconOnly))
  }
  
  public static func `default`<S: LabelStyle>(color: Color, font: Font, labelStyle: S) -> Self {
    .init(DefaultInfoButtonStyle<S>(color: color, font: font, labelStyle: labelStyle))
  }
}

private struct InfoButtonStyleKey: EnvironmentKey {
  static var defaultValue = AnyButtonStyle<InfoButtonType>.default
}

private struct NextButtonStyleKey: EnvironmentKey {
  static var defaultValue = AnyPrimitiveButtonStyle<NextButtonType>(
    DefaultNextButtonStyle<BorderedProminentButtonStyle, ReverseLabelStyle>()
  )
}

private struct ResetButtonStyleKey: EnvironmentKey {
  static var defaultValue = AnyPrimitiveButtonStyle<ResetButtonType>(.borderedProminent)
}

extension EnvironmentValues {
  var infoButtonStyle: AnyButtonStyle<InfoButtonType> {
    get { self[InfoButtonStyleKey.self] }
    set { self[InfoButtonStyleKey.self] = newValue }
  }
  
  var nextButtonStyle: AnyPrimitiveButtonStyle<NextButtonType> {
    get { self[NextButtonStyleKey.self] }
    set { self[NextButtonStyleKey.self] = newValue }
  }
  
  var resetButtonStyle: AnyPrimitiveButtonStyle<ResetButtonType> {
    get { self[ResetButtonStyleKey.self] }
    set { self[ResetButtonStyleKey.self] = newValue }
  }
}

extension View {

  /// Sets the button style for the ``InfoButton`` type.
  public func infoButtonStyle(_ style: AnyButtonStyle<InfoButtonType>) -> some View {
    environment(\.infoButtonStyle, style)
  }

  /// Sets the button style for the ``InfoButton`` type.
  public func infoButtonStyle<S: ButtonStyle>(_ style: S) -> some View {
    infoButtonStyle(AnyButtonStyle(style))
  }
  
  /// Sets the button style for the ``NextButton`` type.
  public func nextButtonStyle(_ style: AnyPrimitiveButtonStyle<NextButtonType>) -> some View {
    environment(\.nextButtonStyle, style)
  }
  
  /// Sets the button style for the ``NextButton`` type.
  public func nextButtonStyle<S: PrimitiveButtonStyle>(_ style: S) -> some View {
    nextButtonStyle(AnyPrimitiveButtonStyle(style))
  }
  
  /// Sets the button style for the ``ResetButton`` type.
  public func resetButtonStyle(_ style: AnyPrimitiveButtonStyle<ResetButtonType>) -> some View {
    environment(\.resetButtonStyle, style)
  }
  
  /// Sets the button style for the ``ResetButton`` type.
  public func resetButtonStyle<S: PrimitiveButtonStyle>(_ style: S) -> some View {
    resetButtonStyle(AnyPrimitiveButtonStyle(style))
  }
}