using System.Text.Json;
using FlaUI.Core.AutomationElements;
using FlaUI.UIA3;
using WxAgent.Core;

namespace WxAgent.Windows;

public static class WechatUiInspector
{
    public static async Task<UiNodeSnapshot> CaptureAsync(string outputPath, CancellationToken cancellationToken, string? windowTitle = null)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(outputPath);
        cancellationToken.ThrowIfCancellationRequested();

        using var automation = new UIA3Automation();
        var window = (windowTitle is null ? WechatDoctor.FindWechatWindow(automation)
            : WechatDoctor.FindNamedWechatWindow(automation, windowTitle, cancellationToken))
            ?? throw new WxAgentException(WxAgentErrorCode.WindowNotFound, "WeChat window was not found in the current interactive session.");

        var guard = new UiTraversalGuard();
        var snapshot = Capture(window, cancellationToken, guard, 0);
        var fullPath = Path.GetFullPath(outputPath);
        Directory.CreateDirectory(Path.GetDirectoryName(fullPath)!);
        await using var stream = new FileStream(fullPath, FileMode.Create, FileAccess.Write, FileShare.None, 81920, FileOptions.Asynchronous);
        await JsonSerializer.SerializeAsync(stream, snapshot, new JsonSerializerOptions { WriteIndented = true, MaxDepth = 128 }, cancellationToken);
        if (guard.Truncated || guard.CycleDetected)
            throw new WxAgentException(WxAgentErrorCode.UiStructureChanged, "UI snapshot was saved partially: traversal limit or repeated runtime ID detected.");
        return snapshot;
    }

    private static UiNodeSnapshot Capture(
        AutomationElement element,
        CancellationToken cancellationToken,
        UiTraversalGuard guard,
        int depth)
    {
        cancellationToken.ThrowIfCancellationRequested();
        var identity = SafeRead(() => string.Join(',', element.Properties.RuntimeId.ValueOrDefault ?? []));
        var canDescend = guard.TryVisit(identity, depth);
        var children = new List<UiNodeSnapshot>();
        if (canDescend)
        {
            AutomationElement[] rawChildren;
            try { rawChildren = element.FindAllChildren(); }
            catch { rawChildren = []; }

            foreach (var child in rawChildren)
            {
                if (guard.Truncated) break;
                children.Add(Capture(child, cancellationToken, guard, depth + 1));
            }
        }

        string bounds;
        try
        {
            var rectangle = element.BoundingRectangle;
            bounds = $"{rectangle.Left:0},{rectangle.Top:0},{rectangle.Width:0},{rectangle.Height:0}";
        }
        catch
        {
            bounds = string.Empty;
        }

        return new UiNodeSnapshot(
            SafeRead(() => element.ControlType.ToString()),
            UiSnapshotSanitizer.SanitizeName(SafeRead(() => element.Name)),
            UiSnapshotSanitizer.SanitizeAutomationId(SafeRead(() => element.AutomationId)),
            SafeRead(() => element.IsEnabled, false),
            bounds,
            children);
    }

    private static string SafeRead(Func<string> read)
    {
        try { return read() ?? string.Empty; } catch { return string.Empty; }
    }

    private static T SafeRead<T>(Func<T> read, T fallback)
    {
        try { return read(); } catch { return fallback; }
    }
}