using System.Collections.Generic;
using System.Linq;
using Editor;
using Sandbox;

namespace RedSnail.WaterTool2.Editor;

/// <summary>
/// Root tool of Water Tool 2. Resolves the network being edited and draws the water graph over the scene; the actual
/// interaction lives in the sub tools: drawing rivers, editing them, laying out lakes, and building the sea's coast.
/// </summary>
[EditorTool]
[Title("Water Tool")]
[Icon("water")]
[Alias("watertool2")]
[Group("Tools")]
public class WaterNetworkTool : EditorTool
{
	/// <summary>
	/// The network edits go to. Null until the first river or lake is drawn in a scene without one.
	/// </summary>
	public WaterNetwork Network { get; private set; }



	public override IEnumerable<EditorTool> GetSubtools()
	{
		yield return new WaterRiverTool();
		yield return new WaterEditTool();
		yield return new WaterLakeTool();
		yield return new WaterSeaTool();
	}



	public override void OnEnabled()
	{
		AllowGameObjectSelection = false;
		ResolveNetwork();
	}



	public override void OnSelectionChanged()
	{
		ResolveNetwork();
	}



	public override void OnUpdate()
	{
		if (!Network.IsValid())
			ResolveNetwork();

		DrawGraph();
	}



	/// <summary>
	/// Prefers a selected network, else the scene's own.
	/// </summary>
	public void ResolveNetwork()
	{
		var selected = Selection.OfType<GameObject>()
			.Select(gameObject => gameObject.Components.Get<WaterNetwork>())
			.FirstOrDefault(network => network.IsValid());

		Network = selected ?? Scene.Get<WaterNetwork>();
	}



	/// <summary>
	/// Creates a fresh network at the scene root. Call it inside an undo scope that records GameObject creations.
	/// </summary>
	public WaterNetwork CreateNetwork()
	{
		var gameObject = Scene.CreateObject();
		gameObject.Name = "Water Network";

		Network = gameObject.AddComponent<WaterNetwork>();

		return Network;
	}



	/// <summary>
	/// The rivers, which way they flow, their nodes, the lakes and the coast, faintly, so the graph can be read at a
	/// glance.
	/// </summary>
	private void DrawGraph()
	{
		if (!Network.IsValid())
			return;

		var transform = Network.WorldTransform;

		using (Gizmo.Scope("watertool2_graph"))
		{
			Gizmo.Draw.IgnoreDepth = true;
			Gizmo.Draw.LineThickness = 1.0f;

			foreach (var river in Network.Rivers)
			{
				if (!Network.TryGetCurve(river, out var curve))
					continue;

				Gizmo.Draw.Color = Color.Cyan.WithAlpha(0.35f);
				WaterGizmos.DrawCurve(curve, transform);

				float size = float.Max(40.0f, Network.WidthOf(river).MaxHalf * 0.6f);

				Gizmo.Draw.Color = Color.Cyan.WithAlpha(0.6f);
				WaterGizmos.DrawFlowArrows(curve, transform, size * 6.0f, size);
			}

			foreach (var lake in Network.Lakes)
			{
				Gizmo.Draw.Color = (lake.IsCoast ? Color.Blue : Color.Cyan).WithAlpha(lake.IsCoast ? 0.5f : 0.3f);
				WaterGizmos.DrawLake(Network, lake, transform);
			}

			Gizmo.Draw.Color = Color.White.WithAlpha(0.6f);

			foreach (var node in Network.Nodes)
				WaterGizmos.DrawNode(transform.PointToWorld(node.Position), false);
		}
	}
}