import AppKit

@MainActor
enum ThemePalette {
    private static let loaded: (scheme: ColorScheme, error: String?) = {
        do {
            return (try ColorScheme.load(from: ColorScheme.configurationDirectory), nil)
        } catch {
            return (.sunset, "Color configuration: \(error.localizedDescription)\nUsing the built-in sunset palette. Fix the file and restart Conjure.")
        }
    }()
    static let configurationError = loaded.error
    static let background = loaded.scheme.background.withAlphaComponent(0.55)
    static let text = loaded.scheme.text
    static let secondaryText = loaded.scheme.secondaryText
    static let accent = loaded.scheme.accent
    static let selectionFill = accent.withAlphaComponent(0.12)
    static let selectionBorder = accent.withAlphaComponent(0.30)
    static let glow = loaded.scheme.glow
    static let keyBackground = loaded.scheme.keyBackground.withAlphaComponent(0.5)
    static let error = loaded.scheme.error
}

@MainActor
final class LauncherBackground: NSView {
    weak var canvas: NSView?
    private let amber = NSGradient(colors: [
        ThemePalette.accent.withAlphaComponent(0.18),
        ThemePalette.accent.withAlphaComponent(0.065),
        ThemePalette.accent.withAlphaComponent(0),
    ])!
    private let ember = NSGradient(colors: [
        ThemePalette.glow.withAlphaComponent(0.26),
        ThemePalette.glow.withAlphaComponent(0.10),
        ThemePalette.glow.withAlphaComponent(0),
    ])!

    override func hitTest(_ point: NSPoint) -> NSView? { nil }

    override func draw(_ dirtyRect: NSRect) {
        ThemePalette.background.setFill()
        dirtyRect.fill()
        let canvasBounds = canvas.map { convert($0.bounds, from: $0) } ?? bounds
        let upperGlow = NSPoint(x: canvasBounds.minX + canvasBounds.width * 0.58,
                                y: canvasBounds.minY + canvasBounds.height * 0.94)
        ember.draw(fromCenter: upperGlow, radius: 0, toCenter: upperGlow,
                   radius: canvasBounds.width * 0.40, options: [])
        let lowerGlow = NSPoint(x: canvasBounds.minX + canvasBounds.width * 0.88,
                                y: canvasBounds.minY + canvasBounds.height * 0.10)
        amber.draw(fromCenter: lowerGlow, radius: 0, toCenter: lowerGlow,
                   radius: canvasBounds.width * 0.55, options: [])
        let leftGlow = NSPoint(x: canvasBounds.minX + canvasBounds.width * 0.08,
                               y: canvasBounds.minY + canvasBounds.height * 0.65)
        NSGraphicsContext.saveGraphicsState()
        NSGraphicsContext.current?.cgContext.setAlpha(0.45)
        amber.draw(fromCenter: leftGlow, radius: 0, toCenter: leftGlow,
                   radius: canvasBounds.width * 0.32, options: [])
        NSGraphicsContext.restoreGraphicsState()
    }
}