import AppKit
import Foundation
import SwiftUI

/// Small, non-modal confirmations ("Path copied", "3 files converted").
/// Nothing here blocks the user's flow, which is the whole point of the app.
enum Notifier {
    private static var toastWindow: NSWindow?
    private static var dismissWorkItem: DispatchWorkItem?

    @MainActor
    static func flash(title: String, body: String? = nil, symbol: String = "checkmark.circle.fill") {
        guard Settings.shared.showProgressWindow else { return }
        show(title: title, body: body, symbol: symbol, tone: .success, duration: 2.0)
    }

    @MainActor
    static func error(_ title: String, _ message: String) {
        show(title: title, body: message, symbol: "exclamationmark.triangle.fill", tone: .failure, duration: 6.0)
    }

    private enum Tone { case success, failure }

    @MainActor
    private static func show(title: String, body: String?, symbol: String, tone: Tone, duration: TimeInterval) {
        dismissWorkItem?.cancel()
        toastWindow?.close()

        let accent: Color = tone == .success ? .green : .orange
        let view = HStack(spacing: 10) {
            Image(systemName: symbol)
                .font(.system(size: 16, weight: .semibold))
                .foregroundStyle(accent)
            VStack(alignment: .leading, spacing: 2) {
                Text(title)
                    .font(.system(size: 12, weight: .semibold))
                    .lineLimit(1)
                if let body, !body.isEmpty {
                    Text(body)
                        .font(.system(size: 11))
                        .foregroundStyle(.secondary)
                        .lineLimit(2)
                        .truncationMode(.middle)
                }
            }
        }
        .padding(.horizontal, 14)
        .padding(.vertical, 10)
        .frame(minWidth: 220, maxWidth: 420, alignment: .leading)
        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 12, style: .continuous))
        .overlay(
            RoundedRectangle(cornerRadius: 12, style: .continuous)
                .strokeBorder(Color.primary.opacity(0.08))
        )

        let controller = NSHostingController(rootView: view)
        let window = NSWindow(contentViewController: controller)
        window.styleMask = [.borderless]
        window.isOpaque = false
        window.backgroundColor = .clear
        window.hasShadow = true
        window.level = .statusBar
        window.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary, .stationary]
        window.ignoresMouseEvents = true
        window.appearance = NSApp.effectiveAppearance

        let size = controller.view.fittingSize
        let screen = NSScreen.main ?? NSScreen.screens.first
        if let frame = screen?.visibleFrame {
            let origin = CGPoint(x: frame.midX - size.width / 2, y: frame.minY + 96)
            window.setFrame(CGRect(origin: origin, size: size), display: true)
        }
        window.orderFrontRegardless()
        toastWindow = window

        let work = DispatchWorkItem { [weak window] in
            NSAnimationContext.runAnimationGroup { context in
                context.duration = 0.25
                window?.animator().alphaValue = 0
            } completionHandler: {
                window?.close()
            }
            if toastWindow === window { toastWindow = nil }
        }
        dismissWorkItem = work
        DispatchQueue.main.asyncAfter(deadline: .now() + duration, execute: work)
    }
}