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

namespace Sunless.Architecture;

[Title( "Road" ), Icon( "add_road" ), Group( "02" )]
public sealed class ArchRoadSubtool( ArchTool owner ) : ArchSubtool( owner )
{
	protected override ArchKind? DraftKind => ArchKind.Road;

	public override ArchSurface[] Surfaces => new[]
	{
		ArchSurface.Road, ArchSurface.Pavement, ArchSurface.Kerb, ArchSurface.RoadLine, ArchSurface.Deck, ArchSurface.Railing
	};

	readonly List<ArchCurveNode> nodes = new();
	readonly ArchRoadPart draft = new();

	bool straight;
	// Nothing else could put a centreline in the air - a deck is the road's own surface.
	float lift;

	protected override bool UsesDrag => false;

	protected override string Title() => "Road";

	protected override string Advice() => "Click to lay the centreline. Click the first node again to close a loop.";

	protected override ArchRunState Run() => new( nodes.Count > 0, $"{nodes.Count} node{(nodes.Count == 1 ? "" : "s")}" );

	protected override void FinishRun() => Finish( false );

	protected override void CancelRun() => nodes.Clear();

	protected override void OnClick( Vector2 point )
	{
		if ( nodes.Count >= 3 && (Flat( nodes[0] ) - point).Length < Owner.Kit.GridSize )
		{
			Finish( true );
			return;
		}

		nodes.Add( Node( Grounded( point ) ) );
	}

	// Tangent mode is per node, so a road can turn a corner and then curve.
	ArchCurveNode Node( Vector3 position )
	{
		return new ArchCurveNode
		{
			Position = position,
			Mode = straight ? ArchTangentMode.Linear : ArchTangentMode.Auto
		};
	}

	// Draped on terrain or laid on the level, standing its own section clear of whichever. Neither height lands on
	// the ladder: a rung is coarser than the whole ride and rounds it away, which is a road laid in the ground.
	Vector3 Grounded( Vector2 point )
	{
		var lifted = MathF.Max( 0f, lift );

		if ( draft.Conform && ArchTerrain.Sample( Owner.Scene, point, out var sampled ) )
		{
			return Owner.Grid.Draped( new Vector3( point.x, point.y, sampled + draft.Seat( Owner.Kit ) + lifted ) );
		}

		// A level's height already carries the ground clearance, so only the camber is still owed.
		return Owner.Grid.Draped( new Vector3( point.x, point.y, Owner.LevelHeight + MathF.Max( 0f, draft.Camber ) + lifted ) );
	}

	protected override void DrawHover( Vector2 point )
	{
		base.DrawHover( point );

		if ( nodes.Count == 0 )
		{
			ArchGhost.Note( new Vector3( point.x, point.y, Owner.LevelHeight ), "click to start the centreline" );

			return;
		}

		var line = new List<ArchCurveNode>( nodes ) { Node( Grounded( point ) ) };
		var curve = ArchCurve.Of( line );

		if ( !curve.IsUsable )
		{
			return;
		}

		var frames = ArchRoadGen.Frames( Sketch( line, false ), curve );

		ArchGhost.Curve( curve );
		ArchGhost.Verges( curve, frames, draft.HalfWidth );

		if ( draft.Pavements != RoadSide.None )
		{
			ArchGhost.Verges( curve, frames, draft.HalfWidth + draft.PavementWidth );
		}

		Gizmo.Draw.Color = ArchGhost.Accent;
		Gizmo.Draw.LineSphere( nodes[0].Position, Owner.Kit.GridSize * 0.5f );
		ArchGhost.Note( frames[^1].Position, $"{curve.Length / 12f:0.#} ft" );
	}

	ArchRoadPart Sketch( IReadOnlyList<ArchCurveNode> line, bool closed )
	{
		var road = draft.Copy();

		road.Nodes = line.Select( node => node.Copy() ).ToList();
		road.Closed = closed;

		return road;
	}

	void Finish( bool closed )
	{
		if ( nodes.Count >= 2 )
		{
			var road = Sketch( nodes, closed );

			road.Id = Owner.Plan.AllocateId();
			road.Name = $"Road{Owner.Plan.Roads().Count + 1}";

			Owner.Plan.Units.Add( road );
			FinishDraft( road.Id );
			Owner.Commit( "Create Road" );
		}

		nodes.Clear();
	}

	static Vector2 Flat( ArchCurveNode node ) => new( node.Position.x, node.Position.y );

	protected override void BuildOptions( ToolSidebarWidget panel )
	{
		ArchSidebarSection.Show( panel, Scope( "centreline" ), "Centreline", centreline =>
		{
			using ( var shape = ArchIconGrid.In( centreline ) )
			{
				shape.Pick( "Spline: eased through every node", "road_spline", "gesture", !straight, () => { straight = false; Refresh(); } );
				shape.Pick( "Straight: a corner at every node", "road_straight", "timeline", straight, () => { straight = true; Refresh(); } );
			}

			var deck = ArchPartUi.Number( "Deck height", lift, 0f, value => lift = value );

			deck.ToolTip = "Raise it before the middle nodes to carry a run over something, then span it with the Bridge tool.";
			centreline.Add( deck );
		} );

		ArchRoadUi.Build( panel, draft, Owner.Kit, Refresh, null );
	}
}