//
//  AtlasTheme.swift
//  Zyquo Atlas
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//
//  The user-overridable theme value type (Phase 4.2). A theme is a named color
//  palette + background + appearance, Codable so it imports/exports as a small
//  JSON file. The base tokens in ZyquoTheme seed the flagship "Atlas Light"
//  theme (Phase 4.1); the ThemeEngine swaps the active AtlasTheme live. Layout
//  and typography preferences live in LayoutSettings (separate from color
//  themes) so changing colors never disturbs the user's layout.
//

import SwiftUI

extension Color {
    /// 0xRRGGBB → Color (sRGB).
    init(hex: UInt32) {
        self.init(.sRGB,
                  red: Double((hex >> 16) & 0xFF) / 255,
                  green: Double((hex >> 8) & 0xFF) / 255,
                  blue: Double(hex & 0xFF) / 255,
                  opacity: 1)
    }
}

enum ThemeAppearance: String, Codable, Hashable {
    case light, dark
}

/// The 13 semantic color slots (the flagship "Atlas Light" values are the
/// Phase 4.1 base spec).
struct AtlasPalette: Codable, Hashable {
    var background: UInt32
    var surface: UInt32
    var surfaceSecondary: UInt32
    var accent: UInt32
    var accentIndigo: UInt32
    var accentSubtle: UInt32
    var textPrimary: UInt32
    var textSecondary: UInt32
    var textTertiary: UInt32
    var border: UInt32
    var success: UInt32
    var warning: UInt32
    var danger: UInt32
}

/// Background behind the chrome / new-tab page.
struct BackgroundStyle: Codable, Hashable {
    enum Kind: String, Codable { case solid, gradient, image }
    var kind: Kind = .solid
    var colorA: UInt32 = 0xFAFBFC
    var colorB: UInt32 = 0xE6F5F3
    /// Absolute path to a wallpaper image (image kind only).
    var imagePath: String?
}

struct AtlasTheme: Codable, Hashable, Identifiable {
    var id: String
    var name: String
    var appearance: ThemeAppearance
    var palette: AtlasPalette
    var background: BackgroundStyle

    // MARK: - Resolved SwiftUI colors (views read these)

    var backgroundColor: Color { Color(hex: palette.background) }
    var surface: Color { Color(hex: palette.surface) }
    var surfaceSecondary: Color { Color(hex: palette.surfaceSecondary) }
    var accent: Color { Color(hex: palette.accent) }
    var accentIndigo: Color { Color(hex: palette.accentIndigo) }
    var accentSubtle: Color { Color(hex: palette.accentSubtle) }
    var textPrimary: Color { Color(hex: palette.textPrimary) }
    var textSecondary: Color { Color(hex: palette.textSecondary) }
    var textTertiary: Color { Color(hex: palette.textTertiary) }
    var border: Color { Color(hex: palette.border) }
    var success: Color { Color(hex: palette.success) }
    var warning: Color { Color(hex: palette.warning) }
    var danger: Color { Color(hex: palette.danger) }

    var colorScheme: ColorScheme { appearance == .dark ? .dark : .light }

    /// The chrome/new-tab background as a SwiftUI view.
    @ViewBuilder
    var backgroundView: some View {
        switch background.kind {
        case .solid:
            backgroundColor
        case .gradient:
            LinearGradient(colors: [Color(hex: background.colorA), Color(hex: background.colorB)],
                           startPoint: .top, endPoint: .bottom)
        case .image:
            if let path = background.imagePath, let img = NSImage(contentsOfFile: path) {
                Image(nsImage: img).resizable().aspectRatio(contentMode: .fill)
            } else {
                backgroundColor
            }
        }
    }
}

// MARK: - Layout & typography (separate from color themes)

enum TabPosition: String, Codable, Hashable, CaseIterable {
    case top, left
}

enum Density: String, Codable, Hashable, CaseIterable {
    case compact, comfortable
}

/// User layout/typography preferences, persisted per profile and applied live.
struct LayoutSettings: Codable, Hashable {
    var tabPosition: TabPosition = .top
    var density: Density = .comfortable
    var uiScale: Double = 1.0          // 0.85 … 1.30
    var defaultPageZoom: Double = 1.0
    var showBookmarksBar: Bool = false
    var translucency: Bool = false

    // Density-derived metrics.
    var toolbarHeight: CGFloat { density == .compact ? 38 : 44 }
    var tabBarHeight: CGFloat { density == .compact ? 30 : 36 }
    var verticalTabWidth: CGFloat { 220 }
    var rowSpacing: CGFloat { density == .compact ? ZyquoSpacing.xxs : ZyquoSpacing.xs }

    /// UI font at a base size, scaled by the user's uiScale.
    func font(_ base: Double, weight: Font.Weight = .regular) -> Font {
        .system(size: base * uiScale, weight: weight)
    }
}