using Robust.Client.GameObjects;
using Robust.Client.Graphics;
using static Robust.Client.GameObjects.SpriteComponent;
using Robust.Client.Utility;
using Robust.Shared.Graphics;
using Direction = Robust.Shared.Maths.Direction;
using System.Numerics;

namespace Content.Client.Clickable;

public sealed partial class ClickableSystem : EntitySystem
{
    [Dependency] private readonly IClickMapManager _clickMapManager = default!;
    [Dependency] private readonly SharedTransformSystem _transformSystem = default!;

    /// <summary>
    /// Used to check whether a click worked. Will first check if the click falls inside of some explicit bounding
    /// boxes (see <see cref="Bounds"/>). If that fails, attempts to use automatically generated click maps.
    /// </summary>
    /// <param name="entity">The entity that we are trying to click.</param>
    /// <param name="worldPos">The world position that was clicked.</param>
    /// <param name="eye">The PoV the click is originating from.</param>
    /// <param name="drawDepth">The draw depth for the sprite that captured the click.</param>
    /// <param name="renderOrder">The render order for the sprite that captured the click.</param>
    /// <param name="bottom">The bottom of the sprite AABB from the perspective of the eye doing the click.</param>
    /// <returns>True if the click worked, false otherwise.</returns>
    public bool CheckClick(Entity<ClickableComponent, SpriteComponent, TransformComponent> entity, Vector2 worldPos, IEye eye, out int drawDepth, out uint renderOrder, out float bottom)
    {
        var (uid, clickable, sprite, xform) = entity;

        if (!sprite.Visible)
        {
            drawDepth = default;
            renderOrder = default;
            bottom = default;
            return false;
        }

        drawDepth = sprite.DrawDepth;
        renderOrder = sprite.RenderOrder;
        var (spritePos, spriteRot) = _transformSystem.GetWorldPositionRotation(xform);
        var spriteBB = sprite.CalculateRotatedBoundingBox(spritePos, spriteRot, eye.Rotation);
        bottom = Matrix3.CreateRotation(eye.Rotation).TransformBox(spriteBB).Bottom;

        var invSpriteMatrix = Matrix3.Invert(sprite.GetLocalMatrix());

        // This should have been the rotation of the sprite relative to the screen, but this is not the case with no-rot or directional sprites.
        var relativeRotation = (spriteRot + eye.Rotation).Reduced().FlipPositive();

        Angle cardinalSnapping = sprite.SnapCardinals ? relativeRotation.GetCardinalDir().ToAngle() : Angle.Zero;

        // First we get `localPos`, the clicked location in the sprite-coordinate frame.
        var entityXform = Matrix3.CreateInverseTransform(_transformSystem.GetWorldPosition(xform), sprite.NoRotation ? -eye.Rotation : spriteRot - cardinalSnapping);
        var localPos = invSpriteMatrix.Transform(entityXform.Transform(worldPos));

        // Check explicitly defined click-able bounds
        if (CheckDirBound((uid, clickable, sprite), relativeRotation, localPos))
            return true;

        // Next check each individual sprite layer using automatically computed click maps.
        foreach (var spriteLayer in sprite.AllLayers)
        {
            if (!spriteLayer.Visible || spriteLayer is not Layer layer)
                continue;

            // Check the layer's texture, if it has one
            if (layer.Texture != null)
            {
                // Convert to image coordinates
                var imagePos = (Vector2i) (localPos * EyeManager.PixelsPerMeter * new Vector2(1, -1) + layer.Texture.Size / 2f);

                if (_clickMapManager.IsOccluding(layer.Texture, imagePos))
                    return true;
            }

            // Either we weren't clicking on the texture, or there wasn't one. In which case: check the RSI next
            if (layer.ActualRsi is not { } rsi || !rsi.TryGetState(layer.State, out var rsiState))
                continue;

            var dir = Layer.GetDirection(rsiState.RsiDirections, relativeRotation);

            // convert to layer-local coordinates
            layer.GetLayerDrawMatrix(dir, out var matrix);
            var inverseMatrix = Matrix3.Invert(matrix);
            var layerLocal = inverseMatrix.Transform(localPos);

            // Convert to image coordinates
            var layerImagePos = (Vector2i) (layerLocal * EyeManager.PixelsPerMeter * new Vector2(1, -1) + rsiState.Size / 2f);

            // Next, to get the right click map we need the "direction" of this layer that is actually being used to draw the sprite on the screen.
            // This **can** differ from the dir defined before, but can also just be the same.
            if (sprite.EnableDirectionOverride)
                dir = sprite.DirectionOverride.Convert(rsiState.RsiDirections);
            dir = dir.OffsetRsiDir(layer.DirOffset);

            if (_clickMapManager.IsOccluding(layer.ActualRsi!, layer.State, dir, layer.AnimationFrame, layerImagePos))
                return true;
        }

        drawDepth = default;
        renderOrder = default;
        bottom = default;
        return false;
    }

    /// <summary>
    /// Used to check whether a click worked lands inside of the AABB for the current sprite for a clickable entity.
    /// </summary>
    /// <param name="localPos">The world position that was clicked.</param>
    /// <param name="relativeRotation">The angle of the entity to check relative to the PoV that the click is coming from.</param>
    /// <returns>True if the click lands inside the relevant AABB.</returns>
    public bool CheckDirBound(Entity<ClickableComponent, SpriteComponent> entity, Angle relativeRotation, Vector2 localPos)
    {
        var (uid, clickable, sprite) = entity;

        if (clickable.Bounds == null)
            return false;

        // These explicit bounds only work for either 1 or 4 directional sprites.

        // This would be the orientation of a 4-directional sprite.
        var direction = relativeRotation.GetCardinalDir();

        var modLocalPos = sprite.NoRotation
            ? localPos
            : direction.ToAngle().RotateVec(localPos);

        // First, check the bounding box that is valid for all orientations
        if (clickable.Bounds.All.Contains(modLocalPos))
            return true;

        // Next, get and check the appropriate bounding box for the current sprite orientation
        var boundsForDir = (sprite.EnableDirectionOverride ? sprite.DirectionOverride : direction) switch
        {
            Direction.East => clickable.Bounds.East,
            Direction.North => clickable.Bounds.North,
            Direction.South => clickable.Bounds.South,
            Direction.West => clickable.Bounds.West,
            _ => throw new InvalidOperationException()
        };

        return boundsForDir.Contains(modLocalPos);
    }
}