swift-buttons/Sources/LilithButtons/FloatingActionButton.swift

// FloatingActionButton.swift
// iOS UI Components - Button Components
//
// Floating action button (FAB) for primary screen actions

import SwiftUI
import LilithDesignTokens

/// Floating Action Button (FAB)
///
/// Use for the primary action on a screen. Floats above content.
/// Typically positioned in bottom-right corner.
///
/// Example:
/// ```swift
/// FloatingActionButton(icon: Image(systemName: "plus")) {
///     showCreateSheet()
/// }
/// .fabPosition(.bottomTrailing)
/// ```
public struct FloatingActionButton: View {
    // MARK: - Size

    public enum Size {
        case regular  // 56pt
        case large    // 72pt

        var dimension: CGFloat {
            switch self {
            case .regular: return 56
            case .large: return 72
            }
        }

        var iconSize: CGFloat {
            switch self {
            case .regular: return AppTypography.FontSize.xl
            case .large: return AppTypography.FontSize.xl2
            }
        }
    }

    // MARK: - Properties

    private let icon: Image
    private let label: String
    private let size: Size
    private let action: () -> Void

    // MARK: - State

    @State private var isPressed = false

    // MARK: - Initialization

    /// Create a floating action button
    /// - Parameters:
    ///   - icon: SF Symbol or custom image
    ///   - label: Accessibility label
    ///   - size: FAB size (regular or large)
    ///   - action: Action to perform on tap
    public init(
        icon: Image,
        label: String = "Primary action",
        size: Size = .regular,
        action: @escaping () -> Void
    ) {
        self.icon = icon
        self.label = label
        self.size = size
        self.action = action
    }

    // MARK: - Body

    public var body: some View {
        Button(action: handleTap) {
            ZStack {
                // Background circle
                Circle()
                    .fill(AppColors.primary)
                    .frame(width: size.dimension, height: size.dimension)
                    .shadow(AppShadows.floating)

                // Icon
                icon
                    .font(.system(size: size.iconSize, weight: .semibold))
                    .foregroundColor(.white)
            }
            .scaleEffect(isPressed ? 0.9 : 1.0)
            .animation(AppAnimations.spring, value: isPressed)
        }
        .buttonStyle(PlainButtonStyle())
        .accessibilityLabel(label)
        .accessibilityHint("Double tap to activate")
        .accessibilityAddTraits(.isButton)
        .onLongPressGesture(minimumDuration: .infinity, maximumDistance: .infinity, pressing: { pressing in
            isPressed = pressing
        }, perform: {})
    }

    // MARK: - Methods

    private func handleTap() {
        // Strong haptic feedback for primary action
        #if canImport(UIKit)
        let generator = UIImpactFeedbackGenerator(style: .heavy)
        generator.impactOccurred()
        #endif

        action()
    }
}

// MARK: - View Extension (FAB Positioning)

extension View {
    /// Position a FAB on the screen
    /// - Parameters:
    ///   - alignment: Screen alignment (default: .bottomTrailing)
    ///   - padding: Distance from edges (default: 16pt)
    public func fabPosition(
        _ alignment: Alignment = .bottomTrailing,
        padding: CGFloat = AppSpacing.base
    ) -> some View {
        ZStack(alignment: alignment) {
            self

            // FAB placeholder (will be replaced with actual FAB)
            Color.clear
                .frame(width: 0, height: 0)
        }
        .padding(padding)
    }
}

// MARK: - Extended FAB (with label)

/// Extended Floating Action Button with text label
///
/// Use when you need to provide more context for the primary action.
///
/// Example:
/// ```swift
/// ExtendedFAB(icon: Image(systemName: "plus"), text: "New Post") {
///     showCreatePost()
/// }
/// ```
public struct ExtendedFAB: View {
    // MARK: - Properties

    private let icon: Image
    private let text: String
    private let action: () -> Void

    // MARK: - State

    @State private var isPressed = false

    // MARK: - Initialization

    public init(
        icon: Image,
        text: String,
        action: @escaping () -> Void
    ) {
        self.icon = icon
        self.text = text
        self.action = action
    }

    // MARK: - Body

    public var body: some View {
        Button(action: handleTap) {
            HStack(spacing: AppSpacing.md) {
                icon
                    .font(.system(size: AppTypography.FontSize.lg, weight: .semibold))

                Text(text)
                    .font(AppTypography.body(weight: .bold))
            }
            .foregroundColor(.white)
            .padding(.horizontal, AppSpacing.xl)
            .padding(.vertical, AppSpacing.base)
            .background(AppColors.primary)
            .clipShape(RoundedRectangle(cornerRadius: AppRadius.full))
            .shadow(AppShadows.floating)
            .scaleEffect(isPressed ? 0.95 : 1.0)
            .animation(AppAnimations.spring, value: isPressed)
        }
        .buttonStyle(PlainButtonStyle())
        .accessibilityLabel(text)
        .accessibilityHint("Double tap to activate")
        .accessibilityAddTraits(.isButton)
        .onLongPressGesture(minimumDuration: .infinity, maximumDistance: .infinity, pressing: { pressing in
            isPressed = pressing
        }, perform: {})
    }

    // MARK: - Methods

    private func handleTap() {
        #if canImport(UIKit)
        let generator = UIImpactFeedbackGenerator(style: .heavy)
        generator.impactOccurred()
        #endif

        action()
    }
}

// MARK: - Preview Provider

#if DEBUG
struct FloatingActionButton_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            // Regular FAB
            ZStack {
                Color.gray.opacity(0.1)
                    .ignoresSafeArea()

                VStack {
                    Spacer()

                    HStack {
                        Spacer()

                        FloatingActionButton(
                            icon: Image(systemName: "plus"),
                            label: "Create new"
                        ) {
                            print("FAB tapped")
                        }
                        .padding()
                    }
                }
            }
            .previewDisplayName("Regular FAB")

            // Large FAB
            ZStack {
                Color.gray.opacity(0.1)
                    .ignoresSafeArea()

                VStack {
                    Spacer()

                    HStack {
                        Spacer()

                        FloatingActionButton(
                            icon: Image(systemName: "camera.fill"),
                            label: "Take photo",
                            size: .large
                        ) {
                            print("Large FAB tapped")
                        }
                        .padding()
                    }
                }
            }
            .previewDisplayName("Large FAB")

            // Extended FAB
            ZStack {
                Color.gray.opacity(0.1)
                    .ignoresSafeArea()

                VStack {
                    Spacer()

                    HStack {
                        Spacer()

                        ExtendedFAB(
                            icon: Image(systemName: "plus"),
                            text: "New Post"
                        ) {
                            print("Extended FAB tapped")
                        }
                        .padding()
                    }
                }
            }
            .previewDisplayName("Extended FAB")

            // Multiple FAB states
            VStack(spacing: AppSpacing.xl2) {
                FloatingActionButton(icon: Image(systemName: "plus")) {}
                FloatingActionButton(icon: Image(systemName: "camera.fill")) {}
                FloatingActionButton(icon: Image(systemName: "mic.fill")) {}
                FloatingActionButton(icon: Image(systemName: "pencil")) {}
            }
            .padding()
            .previewLayout(.sizeThatFits)
            .background(AppColors.background)
            .previewDisplayName("FAB Icons")
        }
    }
}
#endif