//
//  ZyquoTheme.swift
//  Zyquo Local
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//

import AppKit
import SwiftUI

/// The single source of truth for colors, typography, spacing and radii.
/// Views never use raw hex values or magic numbers — only these tokens.
///
/// Light theme (flagship) per the Phase 4 spec: warm neutral off-white with
/// a faint green undertone and a refined emerald accent. Dark theme is
/// derived: deep graphite-green, never flat gray.
enum ZyquoTheme {
    // MARK: - Color tokens

    /// Main canvas.
    static let background = dynamic(light: 0xFAFBFA, dark: 0x121614)
    /// Cards, assistant bubbles, input bar.
    static let surface = dynamic(light: 0xFFFFFF, dark: 0x1A201C)
    /// Hover states, code blocks.
    static let surfaceSecondary = dynamic(light: 0xF2F5F3, dark: 0x232A26)
    /// Primary actions, selection, links, send.
    @MainActor static var accent: Color { ThemeStore.shared.accentChoice.color }
    /// Selected rows, user bubble tint.
    @MainActor static var accentSubtle: Color { ThemeStore.shared.accentChoice.subtleColor }
    /// Body text — never pure black on pure white.
    static let textPrimary = dynamic(light: 0x1A1E1C, dark: 0xE8ECEA)
    /// Metadata.
    static let textSecondary = dynamic(light: 0x6B7472, dark: 0x9BA6A2)
    /// Placeholders.
    static let textTertiary = dynamic(light: 0x9EA8A5, dark: 0x6A7572)
    /// 0.5 pt hairlines.
    static let border = dynamic(light: 0xE4E9E6, dark: 0x2A322D)
    static let success = dynamic(light: 0x2FA36B, dark: 0x37B57C)
    static let warning = dynamic(light: 0xD9822B, dark: 0xE09244)
    static let danger = dynamic(light: 0xD64545, dark: 0xE25D5D)

    // MARK: - Typography (identical scale to Zyquo Cloud)

    /// 20 pt semibold.
    static let title = Font.system(size: 20, weight: .semibold)
    /// 13.5 pt regular (body line height 1.45 → use `bodyLineSpacing`).
    static let body = Font.system(size: 13.5)
    /// 13.5 pt medium.
    static let bodyEmphasis = Font.system(size: 13.5, weight: .medium)
    /// 11 pt.
    static let caption = Font.system(size: 11)
    /// 12.5 pt SF Mono.
    static let code = Font.system(size: 12.5, design: .monospaced)

    /// Line spacing that yields a 1.45 line height at a given font size.
    static func lineSpacing(fontSize: CGFloat) -> CGFloat {
        fontSize * 0.45
    }

    /// User-adjustable chat body font (12–18 pt, from Settings).
    @MainActor static var chatBody: Font {
        Font.system(size: ThemeStore.shared.chatFontSize)
    }

    @MainActor static var chatFontSize: CGFloat { ThemeStore.shared.chatFontSize }

    /// Code font scaled proportionally to the chat size.
    @MainActor static var chatCode: Font {
        Font.system(size: max(11, ThemeStore.shared.chatFontSize - 1), design: .monospaced)
    }

    // MARK: - Spacing (4/8/12/16/20/24/32)

    enum Spacing {
        static let xxs: CGFloat = 4
        static let xs: CGFloat = 8
        static let s: CGFloat = 12
        static let m: CGFloat = 16
        static let l: CGFloat = 20
        static let xl: CGFloat = 24
        static let xxl: CGFloat = 32
    }

    // MARK: - Radii (6/10/14)

    enum Radius {
        static let s: CGFloat = 6
        static let m: CGFloat = 10
        static let l: CGFloat = 14
    }

    // MARK: - Metrics

    /// Message column max width, centered.
    static let messageColumnMaxWidth: CGFloat = 760
    static let sidebarWidth: CGFloat = 260
    static let chatHeaderHeight: CGFloat = 52
    /// Hairline width.
    static let hairline: CGFloat = 0.5

    // MARK: - Shadows (ultra-soft, floating panels only)

    static let shadowColor = Color.black.opacity(0.06)
    static let shadowRadius: CGFloat = 12
    static let shadowY: CGFloat = 2

    // MARK: - Syntax highlighting palette (code blocks)

    enum Syntax {
        static let comment = NSColor(hex: 0x8A948F)
        static let keyword = NSColor(hex: 0x0E86C4)
        static let number = NSColor(hex: 0xC47A0E)
        static let string = NSColor(hex: 0x2FA36B)
    }

    // MARK: - Helpers

    /// Appearance-adaptive color from light/dark hex values.
    private static func dynamic(light: UInt32, dark: UInt32) -> Color {
        Color(nsColor: NSColor(name: nil) { appearance in
            let isDark = appearance.bestMatch(from: [.aqua, .darkAqua]) == .darkAqua
            return NSColor(hex: isDark ? dark : light)
        })
    }
}

extension NSColor {
    /// Opaque sRGB color from a 0xRRGGBB literal.
    convenience init(hex: UInt32) {
        self.init(
            srgbRed: CGFloat((hex >> 16) & 0xFF) / 255,
            green: CGFloat((hex >> 8) & 0xFF) / 255,
            blue: CGFloat(hex & 0xFF) / 255,
            alpha: 1
        )
    }
}

/// User-selectable accent palettes (Settings ▸ Appearance).
enum AccentChoice: String, CaseIterable, Codable, Sendable {
    case emerald
    case graphite
    case sky
    case amber
    case rose

    var label: String {
        switch self {
        case .emerald: "Emerald"
        case .graphite: "Graphite"
        case .sky: "Sky"
        case .amber: "Amber"
        case .rose: "Rose"
        }
    }

    /// Primary accent (light, dark).
    private var hexes: (light: UInt32, dark: UInt32) {
        switch self {
        case .emerald: (0x0E9F6E, 0x17C787)
        case .graphite: (0x4A5450, 0x8B9995)
        case .sky: (0x0E86C4, 0x3FB2EC)
        case .amber: (0xC47A0E, 0xE8A33D)
        case .rose: (0xC44D68, 0xE87795)
        }
    }

    /// Subtle tint for selected rows / user bubbles (light, dark).
    private var subtleHexes: (light: UInt32, dark: UInt32) {
        switch self {
        case .emerald: (0xE7F6F0, 0x163026)
        case .graphite: (0xEDF0EF, 0x272D2A)
        case .sky: (0xE5F3FA, 0x142934)
        case .amber: (0xFAF1E2, 0x33270F)
        case .rose: (0xFAE9ED, 0x341A21)
        }
    }

    var color: Color {
        let h = hexes
        return Color(nsColor: NSColor(name: nil) { appearance in
            let isDark = appearance.bestMatch(from: [.aqua, .darkAqua]) == .darkAqua
            return NSColor(hex: isDark ? h.dark : h.light)
        })
    }

    var subtleColor: Color {
        let h = subtleHexes
        return Color(nsColor: NSColor(name: nil) { appearance in
            let isDark = appearance.bestMatch(from: [.aqua, .darkAqua]) == .darkAqua
            return NSColor(hex: isDark ? h.dark : h.light)
        })
    }
}

/// Observable appearance settings backing the theme tokens.
@MainActor
@Observable
final class ThemeStore {
    static let shared = ThemeStore()

    enum Mode: String, CaseIterable, Codable, Sendable {
        case system
        case light
        case dark

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

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

    var mode: Mode {
        didSet { persist() }
    }

    var accentChoice: AccentChoice {
        didSet { persist() }
    }

    /// Chat body size, 12–18 pt.
    var chatFontSize: CGFloat {
        didSet { persist() }
    }

    private struct Persisted: Codable {
        var mode: Mode
        var accent: AccentChoice
        var chatFontSize: CGFloat
    }

    private init() {
        let stored = PersistenceService.loadDocument(Persisted.self, named: "appearance")
        self.mode = stored?.mode ?? .system
        self.accentChoice = stored?.accent ?? .emerald
        self.chatFontSize = stored.map { min(18, max(12, $0.chatFontSize)) } ?? 13.5
    }

    private func persist() {
        PersistenceService.saveDocument(
            Persisted(mode: mode, accent: accentChoice, chatFontSize: chatFontSize),
            named: "appearance"
        )
    }
}