using Microsoft.Web.WebView2.Core;
using Microsoft.Web.WebView2.WinForms;
using System.Text.Json;

namespace anjianjingling.Browser
{
    /// <summary>
    /// 内嵌 WebView2 命令桥：把脚本命令同步封送到 UI 线程执行。
    /// 脚本引擎在后台线程，WebView2 必须在 UI 线程访问。
    /// </summary>
    public sealed class WebViewBridge
    {
        private readonly WebView2 _web;
        private const int DefaultTimeoutMs = 30000;

        public WebViewBridge(WebView2 web) { _web = web; }

        private T Invoke<T>(Func<Task<T>> func, int timeoutMs = DefaultTimeoutMs)
        {
            var tcs = new TaskCompletionSource<T>();
            _web.BeginInvoke(async () =>
            {
                try { tcs.TrySetResult(await func()); }
                catch (Exception ex) { tcs.TrySetException(ex); }
            });
            if (!tcs.Task.Wait(timeoutMs))
                throw new TimeoutException("浏览器操作超时");
            return tcs.Task.Result;
        }

        private void InvokeAction(Func<Task> func, int timeoutMs = DefaultTimeoutMs)
        {
            Invoke(async () => { await func(); return true; }, timeoutMs);
        }

        /// <summary>ExecuteScriptAsync 返回的是 JSON 字符串，解码为可读文本。</summary>
        private static string DecodeJsResult(string json)
        {
            if (json == "null" || string.IsNullOrEmpty(json)) return "";
            try
            {
                var el = JsonSerializer.Deserialize<JsonElement>(json);
                return el.ValueKind == JsonValueKind.String
                    ? el.GetString() ?? ""
                    : el.GetRawText();
            }
            catch { return json; }
        }

        private static string Js(string code) => JsonSerializer.Serialize(code);

        // ===================== 命令 =====================

        public void Open(string url)
        {
            Invoke(async () =>
            {
                var nav = new TaskCompletionSource<bool>();
                void Handler(object? s, CoreWebView2NavigationCompletedEventArgs e)
                {
                    _web.NavigationCompleted -= Handler;
                    nav.TrySetResult(e.IsSuccess);
                }
                _web.NavigationCompleted += Handler;
                _web.CoreWebView2.Navigate(url);
                bool ok = await nav.Task;
                return ok;
            });
        }

        public string ExecJs(string js)
            => DecodeJsResult(Invoke(() => _web.CoreWebView2.ExecuteScriptAsync(js)));

        public bool Click(string selector)
        {
            string js = $$"""
(()=>{
  const el=document.querySelector({{Js(selector)}});
  if(!el) return false;
  el.scrollIntoView({block:'center'});
  el.dispatchEvent(new MouseEvent('mousedown',{bubbles:true}));
  el.dispatchEvent(new MouseEvent('mouseup',{bubbles:true}));
  el.click();
  return true;
})()
""";
            return ExecJs(js) == "True";
        }

        public bool Type(string selector, string text)
        {
            string js = $$"""
(()=>{
  const el=document.querySelector({{Js(selector)}});
  if(!el) return false;
  const proto = el.tagName==='TEXTAREA' ? HTMLTextAreaElement.prototype : HTMLInputElement.prototype;
  const setter = Object.getOwnPropertyDescriptor(proto,'value').set;
  setter.call(el, {{Js(text)}});
  el.dispatchEvent(new Event('input',{bubbles:true}));
  el.dispatchEvent(new Event('change',{bubbles:true}));
  return true;
})()
""";
            return ExecJs(js) == "True";
        }

        private bool Exists(string selector)
            => ExecJs($"!!document.querySelector({Js(selector)})") == "True";

        public bool WaitFor(string selector, int timeoutMs)
        {
            var tcs = new TaskCompletionSource<bool>();
            Task.Run(async () =>
            {
                var sw = System.Diagnostics.Stopwatch.StartNew();
                while (sw.ElapsedMilliseconds < timeoutMs)
                {
                    try { if (Exists(selector)) { tcs.TrySetResult(true); return; } }
                    catch { }
                    await Task.Delay(200);
                }
                tcs.TrySetResult(false);
            });
            return tcs.Task.Wait(timeoutMs + 5000) && tcs.Task.Result;
        }

        public string GetText(string selector)
        {
            string js = $$"""
(()=>{
  const el=document.querySelector({{Js(selector)}});
  if(!el) return null;
  return el.value!==undefined ? el.value : (el.innerText||el.textContent);
})()
""";
            return ExecJs(js);
        }

        public void Shot(string path)
        {
            InvokeAction(async () =>
            {
                Directory.CreateDirectory(Path.GetDirectoryName(Path.GetFullPath(path))!);
                await using var fs = new FileStream(path, FileMode.Create);
                await _web.CoreWebView2.CapturePreviewAsync(
                    CoreWebView2CapturePreviewImageFormat.Png, fs);
            });
        }
    }
}