import SwiftUI

#if canImport(UIKit)
    import UIKit

    private typealias PlatformColorType = UIColor
#elseif canImport(AppKit)
    import AppKit

    private typealias PlatformColorType = NSColor
#endif

/// Forest-Theme aus `mana/packages/themes/src/variants/forest.css`.
/// Lokal in cards-native nachgebaut, weil ManaTokens v1.0.0 nur den
/// Default-Theme (mana-Variant) liefert.
///
/// Migration auf einen Theme-Switch in ManaTokens ist Phase ε aus
/// `mana/docs/MANA_SWIFT.md` — bis dahin lebt forest hier.
enum CardsTheme {
    /// Page-Hintergrund
    static let background = dynamic(light: HSL(0, 0, 100), dark: HSL(142, 30, 8))

    /// Standard-Text
    static let foreground = dynamic(light: HSL(142, 30, 12), dark: HSL(142, 15, 95))

    /// Card, Panel, Modal
    static let surface = dynamic(light: HSL(142, 25, 98), dark: HSL(142, 25, 12))

    /// Hover-State auf Surface
    static let surfaceHover = dynamic(light: HSL(142, 20, 95), dark: HSL(142, 20, 16))

    /// Disabled-Felder, Skeleton
    static let muted = dynamic(light: HSL(142, 15, 93), dark: HSL(142, 18, 18))

    /// Sekundär-Text, Placeholder
    static let mutedForeground = dynamic(light: HSL(142, 10, 42), dark: HSL(142, 12, 65))

    /// Rahmen, Trennlinien
    static let border = dynamic(light: HSL(142, 15, 88), dark: HSL(142, 18, 22))

    /// Cards-Brand-Grün — Tiefgrün im Light, leuchtender im Dark
    static let primary = dynamic(light: HSL(142, 76, 28), dark: HSL(142, 71, 45))

    /// Text auf Primary
    static let primaryForeground = dynamic(light: HSL(0, 0, 100), dark: HSL(142, 30, 8))

    static let error = dynamic(light: HSL(0, 84, 60), dark: HSL(0, 63, 55))
    static let success = dynamic(light: HSL(142, 71, 45), dark: HSL(142, 71, 45))
    static let warning = dynamic(light: HSL(38, 92, 50), dark: HSL(48, 96, 53))

    // MARK: - HSL Helper

    /// Hue/Saturation/Lightness als Wert-Typ. HSL ist konkreter als ein
    /// 3-Tupel und macht die Call-Sites lesbar.
    struct HSL {
        let hue: Double
        let saturation: Double
        let lightness: Double

        init(_ hue: Double, _ saturation: Double, _ lightness: Double) {
            self.hue = hue
            self.saturation = saturation
            self.lightness = lightness
        }
    }

    private static func dynamic(light: HSL, dark: HSL) -> Color {
        let lightColor = fromHSL(light.hue, light.saturation, light.lightness)
        let darkColor = fromHSL(dark.hue, dark.saturation, dark.lightness)

        #if canImport(UIKit)
            return Color(uiColor: UIColor { trait in
                trait.userInterfaceStyle == .dark ? darkColor : lightColor
            })
        #elseif canImport(AppKit)
            return Color(nsColor: NSColor(name: nil) { appearance in
                let isDark = appearance.bestMatch(from: [.darkAqua, .vibrantDark]) != nil
                return isDark ? darkColor : lightColor
            })
        #else
            return Color(red: 0, green: 0, blue: 0)
        #endif
    }

    private static func fromHSL(_ hue: Double, _ saturation: Double, _ lightness: Double) -> PlatformColorType {
        let h = hue / 360
        let s = saturation / 100
        let l = lightness / 100

        if s == 0 {
            return PlatformColorType(red: l, green: l, blue: l, alpha: 1)
        }

        let q = l < 0.5 ? l * (1 + s) : l + s - l * s
        let p = 2 * l - q
        let r = hueToRGB(p, q, h + 1.0 / 3.0)
        let g = hueToRGB(p, q, h)
        let b = hueToRGB(p, q, h - 1.0 / 3.0)

        return PlatformColorType(red: r, green: g, blue: b, alpha: 1)
    }

    private static func hueToRGB(_ p: Double, _ q: Double, _ rawT: Double) -> Double {
        var t = rawT
        if t < 0 { t += 1 }
        if t > 1 { t -= 1 }
        if t < 1.0 / 6.0 { return p + (q - p) * 6 * t }
        if t < 1.0 / 2.0 { return q }
        if t < 2.0 / 3.0 { return p + (q - p) * (2.0 / 3.0 - t) * 6 }
        return p
    }
}