import SwiftUI

struct LoadingView: View {
    var message: String = "Loading..."

    var body: some View {
        VStack(spacing: 16) {
            ProgressView()
                .scaleEffect(1.5)

            Text(message)
                .font(.subheadline)
                .foregroundColor(.secondary)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(Color(.systemBackground))
    }
}

struct AppLaunchLoadingView: View {
    var messageKey: LocalizedStringKey = "loading"

    var body: some View {
        VStack(spacing: 20) {
            Spacer()

            Image("BrandMark")
                .resizable()
                .scaledToFit()
                .frame(width: 140, height: 140)
                .padding(16)
                .background(Color.appPrimary.opacity(0.08))
                .cornerRadius(28)

            ProgressView()
                .scaleEffect(1.2)

            Text(messageKey)
                .font(.subheadline)
                .foregroundColor(.secondary)

            Spacer()
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(AppBackground())
    }
}

// MARK: - Skeleton Loading

struct SkeletonView: View {
    @State private var isAnimating = false

    var body: some View {
        Rectangle()
            .fill(
                LinearGradient(
                    colors: [
                        Color.gray.opacity(0.1),
                        Color.gray.opacity(0.2),
                        Color.gray.opacity(0.1)
                    ],
                    startPoint: .leading,
                    endPoint: .trailing
                )
            )
            .offset(x: isAnimating ? 200 : -200)
            .animation(
                Animation.linear(duration: 1.5)
                    .repeatForever(autoreverses: false),
                value: isAnimating
            )
            .mask(Rectangle())
            .onAppear {
                isAnimating = true
            }
    }
}

struct SkeletonCardView: View {
    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            SkeletonView()
                .frame(width: 100, height: 16)
                .cornerRadius(4)

            SkeletonView()
                .frame(height: 32)
                .cornerRadius(4)

            HStack {
                SkeletonView()
                    .frame(width: 80, height: 14)
                    .cornerRadius(4)

                Spacer()

                SkeletonView()
                    .frame(width: 60, height: 14)
                    .cornerRadius(4)
            }
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
    }
}

// MARK: - Empty State View

struct EmptyStateView: View {
    let icon: String
    let title: String
    let message: String
    var actionTitle: String?
    var action: (() -> Void)?

    var body: some View {
        VStack(spacing: 20) {
            Image(systemName: icon)
                .font(.system(size: 60))
                .foregroundColor(.secondary)

            Text(title)
                .font(.title2.weight(.semibold))

            Text(message)
                .font(.subheadline)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)
                .padding(.horizontal, 40)

            if let actionTitle = actionTitle, let action = action {
                Button(action: action) {
                    Text(actionTitle)
                        .font(.headline)
                        .foregroundColor(.white)
                        .padding()
                        .frame(maxWidth: 200)
                        .background(Color.appPrimary)
                        .cornerRadius(AppConstants.UI.cornerRadius)
                }
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }
}

// MARK: - Error View

struct ErrorView: View {
    let message: String
    var retryAction: (() -> Void)?

    var body: some View {
        VStack(spacing: 16) {
            Image(systemName: "exclamationmark.triangle.fill")
                .font(.system(size: 48))
                .foregroundColor(.appWarning)

            Text("Something went wrong")
                .font(.headline)

            Text(message)
                .font(.subheadline)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)
                .padding(.horizontal, 40)

            if let retryAction = retryAction {
                Button(action: retryAction) {
                    Label("Try Again", systemImage: "arrow.clockwise")
                        .font(.subheadline.weight(.semibold))
                        .padding(.horizontal, 20)
                        .padding(.vertical, 10)
                        .background(Color.appPrimary)
                        .foregroundColor(.white)
                        .cornerRadius(20)
                }
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }
}

// MARK: - Success View

struct SuccessView: View {
    let title: String
    let message: String
    var action: (() -> Void)?

    var body: some View {
        VStack(spacing: 20) {
            ZStack {
                Circle()
                    .fill(Color.positiveGreen.opacity(0.1))
                    .frame(width: 100, height: 100)

                Image(systemName: "checkmark.circle.fill")
                    .font(.system(size: 60))
                    .foregroundColor(.positiveGreen)
            }

            Text(title)
                .font(.title2.weight(.bold))

            Text(message)
                .font(.subheadline)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)
                .padding(.horizontal, 40)

            if let action = action {
                Button(action: action) {
                    Text("Continue")
                        .font(.headline)
                        .foregroundColor(.white)
                        .padding()
                        .frame(maxWidth: 200)
                        .background(Color.appPrimary)
                        .cornerRadius(AppConstants.UI.cornerRadius)
                }
            }
        }
    }
}

// MARK: - Toast View

struct ToastView: View {
    enum ToastType {
        case success, error, info

        var icon: String {
            switch self {
            case .success: return "checkmark.circle.fill"
            case .error: return "xmark.circle.fill"
            case .info: return "info.circle.fill"
            }
        }

        var color: Color {
            switch self {
            case .success: return .positiveGreen
            case .error: return .negativeRed
            case .info: return .appPrimary
            }
        }
    }

    let message: String
    let type: ToastType

    var body: some View {
        HStack(spacing: 12) {
            Image(systemName: type.icon)
                .foregroundColor(type.color)

            Text(message)
                .font(.subheadline)
        }
        .padding()
        .background(Color(.systemBackground))
        .cornerRadius(AppConstants.UI.cornerRadius)
        .shadow(color: .black.opacity(0.1), radius: 10, y: 5)
    }
}

#Preview {
    VStack(spacing: 20) {
        LoadingView()
            .frame(height: 100)

        SkeletonCardView()

        EmptyStateView(
            icon: "tray",
            title: "No Data",
            message: "Start adding your investments to see them here.",
            actionTitle: "Get Started",
            action: {}
        )
        .frame(height: 300)

        ToastView(message: "Successfully saved!", type: .success)
    }
    .padding()
}