import SwiftUI

public struct AIButtonStyle: ButtonStyle {
  public static let pressedScale: CGFloat = 0.97

  public enum Kind: Hashable {
    case primary
    case secondary
    case danger

    var foregroundColor: Color { foregroundColor(isEnabled: true) }

    var backgroundColor: Color { backgroundColor(isEnabled: true) }

    func foregroundColor(isEnabled: Bool) -> Color {
      switch self {
      case .primary: return isEnabled ? AITheme.onPrimary : AITheme.muted
      case .danger: return isEnabled ? AITheme.onDanger : AITheme.muted
      case .secondary: return isEnabled ? AITheme.ink : AITheme.muted
      }
    }

    func backgroundColor(isEnabled: Bool) -> Color {
      switch self {
      case .primary, .secondary, .danger:
        return isEnabled ? kindBackground : AITheme.control
      }
    }

    private var kindBackground: Color {
      switch self {
      case .primary: return AITheme.primary
      case .secondary: return AITheme.control
      case .danger: return AITheme.danger
      }
    }
  }

  public enum Size: Hashable {
    case compact
    case regular
    case large
    case toolbar
  }

  private let kind: Kind
  private let size: Size
  private let fixedWidthRequest: CGFloat?
  let fillsWidth: Bool
  @Environment(\.isEnabled) private var isEnabled

  public init(
    kind: Kind = .secondary,
    size: Size = .regular,
    fixedWidth: CGFloat? = nil,
    fillsWidth: Bool = false
  ) {
    self.kind = kind
    self.size = size
    self.fixedWidthRequest = fixedWidth
    self.fillsWidth = fillsWidth
  }

  public func makeBody(configuration: Configuration) -> some View {
    let height: CGFloat =
      switch size {
      case .compact: AITheme.compactButtonHeight
      case .large: AITheme.largeButtonHeight
      case .regular: AITheme.buttonHeight
      case .toolbar: AITheme.toolbarButtonHeight
      }

      configuration.label
      .labelStyle(.titleAndIcon)
      .font(.system(size: size == .toolbar ? 15 : 16, weight: .semibold))
      .lineLimit(1)
      .foregroundStyle(kind.foregroundColor(isEnabled: isEnabled))
      .padding(.horizontal, fixedWidth == nil ? (kind == .secondary ? 12 : 14) : 0)
      .frame(
        minWidth: (!fillsWidth && fixedWidth == nil) ? minimumWidth : 0,
        minHeight: height
      )
      .frame(maxWidth: fillsWidth ? .infinity : nil)
      .frame(width: fixedWidth)
      .background(
        RoundedRectangle(cornerRadius: AITheme.buttonRadius, style: .continuous)
          .fill(kind.backgroundColor(isEnabled: isEnabled))
          .shadow(
            color: (kind == .secondary || !isEnabled) ? .clear : .black.opacity(0.10),
            radius: 12,
            x: 0,
            y: 5
          )
      )
      .clipShape(RoundedRectangle(cornerRadius: AITheme.buttonRadius, style: .continuous))
      .overlay {
        RoundedRectangle(cornerRadius: AITheme.buttonRadius, style: .continuous)
          .strokeBorder(kind == .secondary || !isEnabled ? AITheme.line : .clear)
      }
      .scaleEffect(configuration.isPressed ? Self.pressedScale : 1)
      .opacity(configuration.isPressed ? 0.82 : 1)
  }

  private var minimumWidth: CGFloat {
    switch size {
    case .compact: return AITheme.compactButtonMinWidth
    case .regular: return AITheme.regularButtonMinWidth
    case .large: return 92
    case .toolbar: return AITheme.toolbarButtonMinWidth
    }
  }

  private var fixedWidth: CGFloat? {
    fixedWidthRequest ?? (size == .toolbar ? AITheme.toolbarButtonWidth : nil)
  }
}