import SwiftUI
#if canImport(UIKit)
import UIKit
#elseif canImport(AppKit)
import AppKit
#endif

// MARK: - Colors

enum AppColors {
    // Brandbook 2026 (Pedi Foods)
    // Primary now follows the "FOODS" dark green tone from the logo.
    static let primary = Color(hex: "#345D54")
    // Secondary keeps the vivid lime from the symbol/logo body.
    static let secondary = Color(hex: "#D5D841")
    static let tertiary = Color(hex: "#A7BF42")

    static let brandDark = Color(hex: "#1F2D40")
    static let brandSoft = Color(hex: "#F2F5E3")

    static let backgroundLight = Color(hex: "#F3F5F7")
    static let backgroundDark = Color(hex: "#1F2D40")
    static let surface = Color(hex: "#FFFFFF")
    static let textPrimary = Color(hex: "#000000")
    static let textInverse = Color(hex: "#FFFFFF")
    static let textMuted = Color(hex: "#667085")
}

enum AppDarkColors {
    static let background = Color(hex: "#1F2D40")
    static let surface = Color(hex: "#FFFFFF", alpha: 0.08)
    static let textPrimary = Color(hex: "#FFFFFF")
    static let textSecondary = Color(hex: "#D0D5DD")
    static let primary = AppColors.primary
    static let secondary = AppColors.secondary
    static let tertiary = AppColors.tertiary
}

// MARK: - Typography

enum AppTypography {
    // Brandbook typography: Nexa (fallback: system font)
    static let fontFamily = "Nexa-Regular"

    static let heading1 = resolvedFont(size: 28, fallbackWeight: .bold)
    static let heading25 = resolvedFont(size: 25, fallbackWeight: .bold)
    static let heading2 = resolvedFont(size: 20, fallbackWeight: .semibold)
    static let heading3 = resolvedFont(size: 16, fallbackWeight: .semibold)
    static let body = resolvedFont(size: 16, fallbackWeight: .regular)
    static let button = resolvedFont(size: 14, fallbackWeight: .semibold)
    static let caption = resolvedFont(size: 10, fallbackWeight: .regular)
    static let overline = resolvedFont(size: 11, fallbackWeight: .regular)

    static let bodyLineHeight: CGFloat = 1.6
    static let buttonLetterSpacing: CGFloat = 0.08
    static let captionLetterSpacing: CGFloat = 0.12

    private static func resolvedFont(size: CGFloat, fallbackWeight: Font.Weight) -> Font {
        if isBrandFontAvailable {
            return Font.custom(fontFamily, size: size)
        }
        return .system(size: size, weight: fallbackWeight, design: .default)
    }

    private static var isBrandFontAvailable: Bool {
        #if canImport(UIKit)
        return UIFont(name: fontFamily, size: 16) != nil
        #elseif canImport(AppKit)
        return NSFont(name: fontFamily, size: 16) != nil
        #else
        return false
        #endif
    }
}

// MARK: - Layout

enum AppLayout {
    static let radiusMD: CGFloat = 12
    static let radiusLG: CGFloat = 16
    static let radiusXL: CGFloat = 24
    static let radiusFull: CGFloat = 9999

    static let spacing: [CGFloat] = [4, 8, 12, 16, 24, 32]
}

// MARK: - Shadow

struct ShadowSpec {
    let color: Color
    let radius: CGFloat
    let y: CGFloat
}

enum AppShadow {
    static let soft = ShadowSpec(color: Color.black.opacity(0.08), radius: 20, y: 6)
    static let glow = ShadowSpec(color: AppColors.tertiary.opacity(0.2), radius: 24, y: 8)
}

// MARK: - Helpers

extension Color {
    init(hex: String, alpha: Double = 1.0) {
        let cleaned = hex.trimmingCharacters(in: CharacterSet.alphanumerics.inverted)
        var int: UInt64 = 0
        Scanner(string: cleaned).scanHexInt64(&int)

        let r, g, b: UInt64
        switch cleaned.count {
        case 6: // RRGGBB
            r = (int >> 16) & 0xFF
            g = (int >> 8) & 0xFF
            b = int & 0xFF
        case 3: // RGB
            r = ((int >> 8) & 0xF) * 17
            g = ((int >> 4) & 0xF) * 17
            b = (int & 0xF) * 17
        default:
            r = 0; g = 0; b = 0
        }

        self.init(.sRGB,
                  red: Double(r) / 255,
                  green: Double(g) / 255,
                  blue: Double(b) / 255,
                  opacity: alpha)
    }
}