import SwiftUI
import UIKit

// MARK: — Appearance preference

enum AppearanceMode: String, CaseIterable {
    case system, light, dark

    var resolvedScheme: ColorScheme? {
        switch self {
        case .system: return nil
        case .light:  return .light
        case .dark:   return .dark
        }
    }

    var label: String {
        switch self {
        case .system: return "System"
        case .light:  return "Light"
        case .dark:   return "Dark"
        }
    }

    var icon: String {
        switch self {
        case .system: return "circle.lefthalf.filled"
        case .light:  return "sun.max"
        case .dark:   return "moon"
        }
    }
}

enum AppTheme {
    // MARK: — Surfaces
    static let background    = Color(UIColor.systemBackground)
    static let surfaceRaised = Color(UIColor.systemBackground)
    static let surfaceSunken = Color(UIColor { t in
        t.userInterfaceStyle == .dark
            ? UIColor(white: 0.11, alpha: 1)
            : UIColor(white: 0.961, alpha: 1)
    })

    // MARK: — Ink
    static let ink = Color(UIColor { t in
        t.userInterfaceStyle == .dark
            ? UIColor(white: 0.93, alpha: 1)
            : UIColor(red: 0.059, green: 0.059, blue: 0.059, alpha: 1)
    })
    static let inkSecondary = Color(UIColor { t in
        t.userInterfaceStyle == .dark
            ? UIColor(white: 0.58, alpha: 1)
            : UIColor(white: 0.42, alpha: 1)
    })
    static let inkTertiary = Color(UIColor { t in
        t.userInterfaceStyle == .dark
            ? UIColor(white: 0.40, alpha: 1)
            : UIColor(white: 0.67, alpha: 1)
    })
    static let inkQuaternary = Color(UIColor { t in
        t.userInterfaceStyle == .dark
            ? UIColor(white: 0.22, alpha: 1)
            : UIColor(white: 0.83, alpha: 1)
    })

    // Readable on AppTheme.ink background in both color schemes
    static let inkInverse = Color(UIColor { t in
        t.userInterfaceStyle == .dark
            ? UIColor(red: 0.059, green: 0.059, blue: 0.059, alpha: 1)
            : UIColor(white: 1.0, alpha: 1)
    })

    // MARK: — Semantic
    static let positive    = Color(hex: "#16A34A")
    static let destructive = Color(hex: "#DC2626")
    static let interactive = Color(hex: "#2563EB")

    // MARK: — Chrome
    static let separator = Color(UIColor.separator)
    static let cardShadow = Color(UIColor { t in
        t.userInterfaceStyle == .dark
            ? UIColor.clear
            : UIColor.black.withAlphaComponent(0.048)
    })
    static let cardBorderColor = Color(UIColor.separator)

    // MARK: — Metrics
    static let radius: CGFloat      = 14
    static let radiusLarge: CGFloat = 18
    static let hPad: CGFloat        = 20
    static let cardPad: CGFloat     = 16
    static let sectionGap: CGFloat  = 28

    // MARK: — Typography
    static func display(_ size: CGFloat = 32) -> Font {
        .system(size: size, weight: .semibold, design: .default)
    }
    static func title(_ size: CGFloat = 20) -> Font { .system(size: size, weight: .semibold) }
    static func headline(_ size: CGFloat = 15) -> Font { .system(size: size, weight: .medium) }
    static func body(_ size: CGFloat = 15) -> Font { .system(size: size, weight: .regular) }
    static func caption(_ size: CGFloat = 13) -> Font { .system(size: size, weight: .regular) }
    static func micro(_ size: CGFloat = 11) -> Font { .system(size: size, weight: .medium) }

    // MARK: — Back-compat aliases
    static let blue             = interactive
    static let green            = positive
    static let red              = destructive
    static let textPrimary      = ink
    static let textSecondary    = inkSecondary
    static let textTertiary     = inkTertiary
    static let cardBorder       = cardBorderColor
    static let connectedBorder  = positive
    static let lanBorder        = interactive
    static let cardCornerRadius = radius
    static let cardBackground   = surfaceRaised
    static let titleFont        = Font.system(size: 28, weight: .bold)
    static let headlineFont     = Font.system(size: 17, weight: .semibold)
    static let bodyFont         = Font.system(size: 15, weight: .regular)
    static let captionFont      = Font.system(size: 13, weight: .regular)
    static let smallFont        = Font.system(size: 11, weight: .medium)
    static let sectionSpacing: CGFloat = 28
}

// MARK: — Card modifier
struct CardStyle: ViewModifier {
    var padded: Bool = true
    func body(content: Content) -> some View {
        content
            .if(padded) { $0.padding(AppTheme.cardPad) }
            .background(AppTheme.surfaceRaised)
            .clipShape(RoundedRectangle(cornerRadius: AppTheme.radius, style: .continuous))
            .shadow(color: AppTheme.cardShadow, radius: 12, x: 0, y: 2)
    }
}

extension View {
    func card(padded: Bool = true) -> some View { modifier(CardStyle(padded: padded)) }

    @ViewBuilder func `if`<T: View>(_ condition: Bool, transform: (Self) -> T) -> some View {
        if condition { transform(self) } else { self }
    }
}

extension Color {
    init(hex: String) {
        var h = hex.trimmingCharacters(in: .init(charactersIn: "#"))
        if h.count == 3 { h = h.map { "\($0)\($0)" }.joined() }
        let n = UInt64(h, radix: 16) ?? 0
        self.init(
            red:   Double((n >> 16) & 0xFF) / 255,
            green: Double((n >>  8) & 0xFF) / 255,
            blue:  Double( n        & 0xFF) / 255
        )
    }
}