using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using CefSharp;
using CefSharp.Event;
using CefSharp.Wpf;

namespace CEFHelpers {
	public class Helper {
		private ChromiumWebBrowser browser;
		public Helper(ChromiumWebBrowser browser) {
			this.browser = browser;
			browser.JavascriptObjectRepository.ObjectBoundInJavascript += ObjectBound;
		}
		public async Task EnsureRegistered(params String[] names) {//not sure if we need to consider context
			while (!browser.CanExecuteJavascriptInMainFrame) {
				await Task.Delay(100);
			}
			var js_cmd = $@"CefSharp.BindObjectAsync('{String.Join("','", names)}');";
			var tasks = new List<Task>();
			lock (obj_bound_tasks) {
				foreach (var name in names) {
					if (obj_bound_tasks.TryGetValue(name, out var tsk_src)) {
						if (tsk_src.Task.IsCompleted)
							tsk_src = null;
					}
					if (tsk_src == null) {
						tsk_src = new TaskCompletionSource<bool>();
						obj_bound_tasks[name] = tsk_src;
					}
					tasks.Add(tsk_src.Task);
				}
			}
			browser.ExecuteScriptAsync(js_cmd);
			await Task.WhenAll(tasks);
		}
		private Dictionary<string, TaskCompletionSource<bool>> obj_bound_tasks = new Dictionary<string, System.Threading.Tasks.TaskCompletionSource<bool>>();

		private void ObjectBound(object sender, JavascriptBindingEventArgs e) {
			var name = e.ObjectName;
			lock (obj_bound_tasks) {
				if (obj_bound_tasks.TryGetValue(name, out var tsk_src)) {
					tsk_src.SetResult(true);
					obj_bound_tasks.Remove(name);
				}
			}
		}
	}
}