// Copyright © 2015 Abhishek Banthia

import Cocoa

func isDarkModeOn() -> Bool {
    if #available(macOS 10.14, *) {
        return NSAppearance.current.name == NSAppearance.Name.darkAqua
    }

    return false
}

extension Notification.Name {
    static let themeDidChangeNotification = Notification.Name(rawValue: "ThemeDidChangeNotification")
}

enum Theme: Int {
    case light = 0
    case dark
    case system
}

class Themer: NSObject {
    private static var sharedInstance = Themer()

    private var themeIndex: Theme {
        didSet {
            NotificationCenter.default.post(name: .themeDidChangeNotification, object: nil)
        }
    }

    override init() {
        let defaultTheme = UserDefaults.standard.integer(forKey: CLThemeKey)

        switch defaultTheme {
        case 0:
            themeIndex = Theme.light
        case 1:
            themeIndex = Theme.dark
        case 2:
            themeIndex = Theme.system
        default:
            themeIndex = Theme.light
        }

        super.init()

        setAppAppearance()

        DistributedNotificationCenter.default.addObserver(self,
                                                          selector: #selector(respondToInterfaceStyle),
                                                          name: .interfaceStyleDidChange,
                                                          object: nil)
    }
}

extension Themer {
    class func shared() -> Themer {
        return sharedInstance
    }

    func set(theme: Int) {
        if themeIndex.rawValue == theme {
            return
        }

        switch theme {
        case 0:
            themeIndex = Theme.light
        case 1:
            themeIndex = Theme.dark
        case 2:
            themeIndex = Theme.system
        default:
            themeIndex = Theme.light
        }

        setAppAppearance()
    }

    @objc func respondToInterfaceStyle() {
        OperationQueue.main.addOperation {
            self.setAppAppearance()
        }
    }

    private func setAppAppearance() {
        if #available(OSX 10.14, *) {
            var appAppearance = NSAppearance(named: .aqua)

            if themeIndex == .dark {
                appAppearance = NSAppearance(named: .darkAqua)
            } else if themeIndex == .system {
                appAppearance = NSAppearance.current
            }
            NSApp.appearance = appAppearance
        }
    }

    func sliderKnobColor() -> NSColor {
        return themeIndex == .light ? NSColor(deviceRed: 255.0, green: 255.0, blue: 255, alpha: 0.9) : NSColor(deviceRed: 0.0, green: 0.0, blue: 0, alpha: 0.9)
    }

    func sliderRightColor() -> NSColor {
        return themeIndex == .dark ? NSColor.white : NSColor.gray
    }

    func mainControlColor() -> NSColor {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSColor.white
            case .dark:
                return NSColor(deviceRed: 42.0 / 255.0, green: 42.0 / 255.0, blue: 42.0 / 255.0, alpha: 1.0)
            case .system:
                return NSColor.controlBackgroundColor
            }
        }

        return themeIndex == .light ? NSColor.white : NSColor(deviceRed: 42.0 / 255.0, green: 42.0 / 255.0, blue: 42.0 / 255.0, alpha: 1.0)
    }

    func mainBackgroundColor() -> NSColor {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSColor.white
            case .dark:
                return NSColor(deviceRed: 42.0 / 255.0, green: 42.0 / 255.0, blue: 42.0 / 255.0, alpha: 1.0)
            case .system:
                return NSColor.windowBackgroundColor
            }
        }

        return themeIndex == .light ? NSColor.white : NSColor(deviceRed: 55.0 / 255.0, green: 71.0 / 255.0, blue: 79.0 / 255.0, alpha: 1.0)
    }

    func mainTextColor() -> NSColor {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSColor.black
            case .dark:
                return NSColor.white
            case .system:
                return NSColor.textColor
            }
        }

        return themeIndex == .light ? NSColor.black : NSColor.white
    }

    func shutdownImage() -> NSImage {
        if let symbolImageForShutdown = symbolImage(for: "ellipsis.circle") {
            return symbolImageForShutdown
        }

        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("PowerIcon"))!
            case .dark:
                return NSImage(named: NSImage.Name("PowerIcon-White"))!
            case .system:
                return NSImage(named: NSImage.Name("Power"))!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("PowerIcon"))! : NSImage(named: NSImage.Name("PowerIcon-White"))!
    }

    func preferenceImage() -> NSImage {
        if let symbolImageForPreference = symbolImage(for: "gear") {
            return symbolImageForPreference
        }

        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Settings"))!
            case .dark:
                return NSImage(named: NSImage.Name("Settings-White"))!
            case .system:
                return NSImage(named: NSImage.actionTemplateName)!
            }
        }

        return
            themeIndex == .light
            ? NSImage(named: NSImage.Name("Settings"))!
            : NSImage(named: NSImage.Name("Settings-White"))!
    }

    func pinImage() -> NSImage {
        if let pinImage = symbolImage(for: "macwindow.on.rectangle") {
            return pinImage
        }

        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Float"))!
            case .dark:
                return NSImage(named: NSImage.Name("Float-White"))!
            case .system:
                return NSImage(named: NSImage.Name("Pin"))!
            }
        }

        return themeIndex == .light
            ? NSImage(named: NSImage.Name("Float"))!
            : NSImage(named: NSImage.Name("Float-White"))!
    }

    func sunriseImage() -> NSImage {
        if let symbolImage = symbolImage(for: "sunrise.fill") {
            return symbolImage
        }

        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Sunrise"))!
            case .dark:
                return NSImage(named: NSImage.Name("WhiteSunrise"))!
            case .system:
                return NSImage(named: NSImage.Name("Sunrise Dynamic"))!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("Sunrise"))! : NSImage(named: NSImage.Name("WhiteSunrise"))!
    }

    func sunsetImage() -> NSImage {
        if let symbolImage = symbolImage(for: "sunset.fill") {
            return symbolImage
        }

        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Sunset"))!
            case .dark:
                return NSImage(named: NSImage.Name("WhiteSunset"))!
            case .system:
                return NSImage(named: NSImage.Name("Sunset Dynamic"))!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("Sunset"))! : NSImage(named: NSImage.Name("WhiteSunset"))!
    }

    func removeImage() -> NSImage {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Remove"))!
            case .dark:
                return NSImage(named: NSImage.Name("WhiteRemove"))!
            case .system:
                return NSImage(named: NSImage.Name("Remove Dynamic"))!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("Remove"))! : NSImage(named: NSImage.Name("WhiteRemove"))!
    }

    func extraOptionsImage() -> NSImage {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Extra"))!
            case .dark:
                return NSImage(named: NSImage.Name("ExtraWhite"))!
            case .system:
                return NSImage(named: NSImage.Name("Extra Dynamic"))!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("Extra"))! : NSImage(named: NSImage.Name("ExtraWhite"))!
    }

    func menubarOnboardingImage() -> NSImage {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .system:
                return NSImage(named: NSImage.Name("Dynamic Menubar"))!
            default:
                return UserDefaults.standard.string(forKey: "AppleInterfaceStyle") == "Dark" ? NSImage(named: NSImage.Name("Dark Menubar"))! : NSImage(named: NSImage.Name("Light Menubar"))!
            }
        }

        return UserDefaults.standard.string(forKey: "AppleInterfaceStyle") == "Dark" ? NSImage(named: NSImage.Name("Dark Menubar"))! : NSImage(named: NSImage.Name("Light Menubar"))!
    }

    func extraOptionsHighlightedImage() -> NSImage {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("ExtraHighlighted"))!
            case .dark:
                return NSImage(named: NSImage.Name("ExtraWhiteHighlighted"))!
            case .system:
                return NSImage(named: NSImage.Name("ExtraHighlighted Dynamic"))!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("ExtraHighlighted"))! : NSImage(named: NSImage.Name("ExtraWhiteHighlighted"))!
    }

    func sharingImage() -> NSImage {
        if let sharingImage = symbolImage(for: "square.and.arrow.up.on.square.fill") {
            return sharingImage
        }

        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Sharing"))!
            case .dark:
                return NSImage(named: NSImage.Name("SharingDarkIcon"))!
            case .system:
                return NSImage(named: NSImage.Name("Sharing Dynamic"))!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.shareTemplateName)! : NSImage(named: NSImage.Name("SharingDarkIcon"))!
    }

    func currentLocationImage() -> NSImage {
        if let symbolImage = symbolImage(for: "location.fill") {
            return symbolImage
        }

        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("CurrentLocation"))!
            case .dark:
                return NSImage(named: NSImage.Name("CurrentLocationWhite"))!
            case .system:
                return NSImage(named: NSImage.Name("CurrentLocationDynamic"))!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("CurrentLocation"))! : NSImage(named: NSImage.Name("CurrentLocationWhite"))!
    }

    func popoverAppearance() -> NSAppearance {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSAppearance(named: NSAppearance.Name.vibrantLight)!
            case .dark:
                return NSAppearance(named: NSAppearance.Name.vibrantDark)!
            case .system:
                return NSAppearance.current
            }
        }

        return themeIndex == .light ? NSAppearance(named: NSAppearance.Name.vibrantLight)! : NSAppearance(named: NSAppearance.Name.vibrantDark)!
    }

    func addImage() -> NSImage {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Add Icon"))!
            case .dark:
                return NSImage(named: NSImage.Name("Add White"))!
            case .system:
                return NSImage(named: .addDynamicIcon)!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("Add Icon"))! : NSImage(named: NSImage.Name("Add White"))!
    }

    func addImageHighlighted() -> NSImage {
        return themeIndex == .light ? NSImage(named: NSImage.Name("Add Highlighted"))! : NSImage(named: NSImage.Name("Add White"))!
    }

    func privacyTabImage() -> NSImage {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Privacy"))!
            case .dark:
                return NSImage(named: NSImage.Name("Privacy Dark"))!
            case .system:
                return NSImage(named: .permissionTabIcon)!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("Privacy"))! : NSImage(named: NSImage.Name("Privacy Dark"))!
    }

    func appearanceTabImage() -> NSImage {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Appearance"))!
            case .dark:
                return NSImage(named: NSImage.Name("Appearance Dark"))!
            case .system:
                return NSImage(named: .appearanceTabIcon)!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("Appearance"))! : NSImage(named: NSImage.Name("Appearance Dark"))!
    }

    func calendarTabImage() -> NSImage {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSImage(named: NSImage.Name("Calendar Tab Icon"))!
            case .dark:
                return NSImage(named: NSImage.Name("Calendar Tab Dark"))!
            case .system:
                return NSImage(named: .calendarTabIcon)!
            }
        }

        return themeIndex == .light ? NSImage(named: NSImage.Name("Calendar Tab Icon"))! : NSImage(named: NSImage.Name("Calendar Tab Dark"))!
    }

    func textBackgroundColor() -> NSColor {
        if #available(macOS 10.14, *) {
            switch themeIndex {
            case .light:
                return NSColor(deviceRed: 241.0 / 255.0, green: 241.0 / 255.0, blue: 241.0 / 255.0, alpha: 1.0)
            case .dark:
                return NSColor(deviceRed: 42.0 / 255.0, green: 55.0 / 255.0, blue: 62.0 / 255.0, alpha: 1.0)
            case .system:
                return NSColor.controlBackgroundColor
            }
        }

        return themeIndex == .light ?
            NSColor(deviceRed: 241.0 / 255.0, green: 241.0 / 255.0, blue: 241.0 / 255.0, alpha: 1.0) :
            NSColor(deviceRed: 42.0 / 255.0, green: 55.0 / 255.0, blue: 62.0 / 255.0, alpha: 1.0)
    }

    func symbolImage(for name: String) -> NSImage? {
        assert(name.isEmpty == false)

        if #available(OSX 11.0, *) {
            return NSImage(systemSymbolName: name,
                           accessibilityDescription: name)
        }

        return nil
    }
}