using System.Linq;
using Content.Shared.Interfaces;
using Content.Shared.Interfaces.GameObjects.Components;
using Content.Shared.Physics;
using JetBrains.Annotations;
using Robust.Shared.GameObjects.Systems;
using Robust.Shared.Interfaces.GameObjects;
using Robust.Shared.Interfaces.Physics;
using Robust.Shared.IoC;
using Robust.Shared.Localization;
using Robust.Shared.Map;
using Robust.Shared.Maths;

namespace Content.Shared.GameObjects.EntitySystems
{
    /// <summary>
    /// Governs interactions during clicking on entities
    /// </summary>
    [UsedImplicitly]
    public class SharedInteractionSystem : EntitySystem
    {
        [Dependency] private readonly IPhysicsManager _physicsManager = default!;

        public const float InteractionRange = 2;
        public const float InteractionRangeSquared = InteractionRange * InteractionRange;

        public delegate bool Ignored(IEntity entity);

        /// <summary>
        ///     Traces a ray from coords to otherCoords and returns the length
        ///     of the vector between coords and the ray's first hit.
        /// </summary>
        /// <param name="origin">Set of coordinates to use.</param>
        /// <param name="other">Other set of coordinates to use.</param>
        /// <param name="collisionMask">the mask to check for collisions</param>
        /// <param name="predicate">
        ///     A predicate to check whether to ignore an entity or not.
        ///     If it returns true, it will be ignored.
        /// </param>
        /// <returns>Length of resulting ray.</returns>
        public float UnobstructedDistance(
            MapCoordinates origin,
            MapCoordinates other,
            int collisionMask = (int) CollisionGroup.Impassable,
            Ignored predicate = null)
        {
            var dir = other.Position - origin.Position;

            if (dir.LengthSquared.Equals(0f)) return 0f;

            predicate ??= _ => false;
            var ray = new CollisionRay(origin.Position, dir.Normalized, collisionMask);
            var rayResults = _physicsManager.IntersectRayWithPredicate(origin.MapId, ray, dir.Length, predicate.Invoke, false).ToList();

            if (rayResults.Count == 0) return dir.Length;
            return (rayResults[0].HitPos - origin.Position).Length;
        }

        /// <summary>
        ///     Traces a ray from coords to otherCoords and returns the length
        ///     of the vector between coords and the ray's first hit.
        /// </summary>
        /// <param name="origin">Set of coordinates to use.</param>
        /// <param name="other">Other set of coordinates to use.</param>
        /// <param name="collisionMask">The mask to check for collisions</param>
        /// <param name="ignoredEnt">
        ///     The entity to be ignored when checking for collisions.
        /// </param>
        /// <returns>Length of resulting ray.</returns>
        public float UnobstructedDistance(
            MapCoordinates origin,
            MapCoordinates other,
            int collisionMask = (int) CollisionGroup.Impassable,
            IEntity ignoredEnt = null)
        {
            var predicate = ignoredEnt == null
                ? null
                : (Ignored) (e => e == ignoredEnt);

            return UnobstructedDistance(origin, other, collisionMask, predicate);
        }

        /// <summary>
        ///     Checks that these coordinates are within a certain distance without any
        ///     entity that matches the collision mask obstructing them.
        ///     If the <paramref name="range"/> is zero or negative,
        ///     this method will only check if nothing obstructs the two sets
        ///     of coordinates.
        /// </summary>
        /// <param name="origin">Set of coordinates to use.</param>
        /// <param name="other">Other set of coordinates to use.</param>
        /// <param name="range">
        ///     Maximum distance between the two sets of coordinates.
        /// </param>
        /// <param name="collisionMask">The mask to check for collisions.</param>
        /// <param name="predicate">
        ///     A predicate to check whether to ignore an entity or not.
        ///     If it returns true, it will be ignored.
        /// </param>
        /// <param name="ignoreInsideBlocker">
        ///     If true and <see cref="origin"/> or <see cref="other"/> are inside
        ///     the obstruction, ignores the obstruction and considers the interaction
        ///     unobstructed.
        ///     Therefore, setting this to true makes this check more permissive,
        ///     such as allowing an interaction to occur inside something impassable
        ///     (like a wall). The default, false, makes the check more restrictive.
        /// </param>
        /// <returns>
        ///     True if the two points are within a given range without being obstructed.
        /// </returns>
        public bool InRangeUnobstructed(
            MapCoordinates origin,
            MapCoordinates other,
            float range = InteractionRange,
            CollisionGroup collisionMask = CollisionGroup.Impassable,
            Ignored predicate = null,
            bool ignoreInsideBlocker = false)
        {
            if (!origin.InRange(other, range)) return false;

            var dir = other.Position - origin.Position;

            if (dir.LengthSquared.Equals(0f)) return true;
            if (range > 0f && !(dir.LengthSquared <= range * range)) return false;

            predicate ??= _ => false;

            var ray = new CollisionRay(origin.Position, dir.Normalized, (int) collisionMask);
            var rayResults = _physicsManager.IntersectRayWithPredicate(origin.MapId, ray, dir.Length, predicate.Invoke, false).ToList();

            if (rayResults.Count == 0) return true;

            if (!ignoreInsideBlocker) return false;

            if (rayResults.Count <= 0) return false;

            return (rayResults[0].HitPos - other.Position).Length < 1f;
        }

        /// <summary>
        ///     Checks that two entities are within a certain distance without any
        ///     entity that matches the collision mask obstructing them.
        ///     If the <paramref name="range"/> is zero or negative,
        ///     this method will only check if nothing obstructs the two entities.
        /// </summary>
        /// <param name="origin">The first entity to use.</param>
        /// <param name="other">Other entity to use.</param>
        /// <param name="range">
        ///     Maximum distance between the two entities.
        /// </param>
        /// <param name="collisionMask">The mask to check for collisions.</param>
        /// <param name="predicate">
        ///     A predicate to check whether to ignore an entity or not.
        ///     If it returns true, it will be ignored.
        /// </param>
        /// <param name="ignoreInsideBlocker">
        ///     If true and <see cref="origin"/> or <see cref="other"/> are inside
        ///     the obstruction, ignores the obstruction and considers the interaction
        ///     unobstructed.
        ///     Therefore, setting this to true makes this check more permissive,
        ///     such as allowing an interaction to occur inside something impassable
        ///     (like a wall). The default, false, makes the check more restrictive.
        /// </param>
        /// <param name="popup">
        ///     Whether or not to popup a feedback message on the origin entity for
        ///     it to see.
        /// </param>
        /// <returns>
        ///     True if the two points are within a given range without being obstructed.
        /// </returns>
        public bool InRangeUnobstructed(
            IEntity origin,
            IEntity other,
            float range = InteractionRange,
            CollisionGroup collisionMask = CollisionGroup.Impassable,
            Ignored predicate = null,
            bool ignoreInsideBlocker = false,
            bool popup = false)
        {
            var originPosition = origin.Transform.MapPosition;
            var otherPosition = other.Transform.MapPosition;
            predicate ??= e => e == origin || e == other;

            var inRange = InRangeUnobstructed(originPosition, otherPosition, range, collisionMask, predicate, ignoreInsideBlocker);

            if (!inRange && popup)
            {
                var message = Loc.GetString("You can't reach there!");
                origin.PopupMessage(message);
            }

            return inRange;
        }

        /// <summary>
        ///     Checks that an entity and a component are within a certain
        ///     distance without any entity that matches the collision mask
        ///     obstructing them.
        ///     If the <paramref name="range"/> is zero or negative,
        ///     this method will only check if nothing obstructs the entity and component.
        /// </summary>
        /// <param name="origin">The entity to use.</param>
        /// <param name="other">The component to use.</param>
        /// <param name="range">
        ///     Maximum distance between the entity and component.
        /// </param>
        /// <param name="collisionMask">The mask to check for collisions.</param>
        /// <param name="predicate">
        ///     A predicate to check whether to ignore an entity or not.
        ///     If it returns true, it will be ignored.
        /// </param>
        /// <param name="ignoreInsideBlocker">
        ///     If true and <see cref="origin"/> or <see cref="other"/> are inside
        ///     the obstruction, ignores the obstruction and considers the interaction
        ///     unobstructed.
        ///     Therefore, setting this to true makes this check more permissive,
        ///     such as allowing an interaction to occur inside something impassable
        ///     (like a wall). The default, false, makes the check more restrictive.
        /// </param>
        /// <param name="popup">
        ///     Whether or not to popup a feedback message on the origin entity for
        ///     it to see.
        /// </param>
        /// <returns>
        ///     True if the two points are within a given range without being obstructed.
        /// </returns>
        public bool InRangeUnobstructed(
            IEntity origin,
            IComponent other,
            float range = InteractionRange,
            CollisionGroup collisionMask = CollisionGroup.Impassable,
            Ignored predicate = null,
            bool ignoreInsideBlocker = false,
            bool popup = false)
        {
            var originPosition = origin.Transform.MapPosition;
            var otherPosition = other.Owner.Transform.MapPosition;
            predicate ??= e => e == origin || e == other.Owner;

            var inRange = InRangeUnobstructed(originPosition, otherPosition, range, collisionMask, predicate, ignoreInsideBlocker);

            if (!inRange && popup)
            {
                var message = Loc.GetString("You can't reach there!");
                origin.PopupMessage(message);
            }

            return inRange;
        }

        /// <summary>
        ///     Checks that an entity and a set of grid coordinates are within a certain
        ///     distance without any entity that matches the collision mask
        ///     obstructing them.
        ///     If the <paramref name="range"/> is zero or negative,
        ///     this method will only check if nothing obstructs the entity and component.
        /// </summary>
        /// <param name="origin">The entity to use.</param>
        /// <param name="other">The grid coordinates to use.</param>
        /// <param name="range">
        ///     Maximum distance between the two entity and set of grid coordinates.
        /// </param>
        /// <param name="collisionMask">The mask to check for collisions.</param>
        /// <param name="predicate">
        ///     A predicate to check whether to ignore an entity or not.
        ///     If it returns true, it will be ignored.
        /// </param>
        /// <param name="ignoreInsideBlocker">
        ///     If true and <see cref="origin"/> or <see cref="other"/> are inside
        ///     the obstruction, ignores the obstruction and considers the interaction
        ///     unobstructed.
        ///     Therefore, setting this to true makes this check more permissive,
        ///     such as allowing an interaction to occur inside something impassable
        ///     (like a wall). The default, false, makes the check more restrictive.
        /// </param>
        /// <param name="popup">
        ///     Whether or not to popup a feedback message on the origin entity for
        ///     it to see.
        /// </param>
        /// <returns>
        ///     True if the two points are within a given range without being obstructed.
        /// </returns>
        public bool InRangeUnobstructed(
            IEntity origin,
            EntityCoordinates other,
            float range = InteractionRange,
            CollisionGroup collisionMask = CollisionGroup.Impassable,
            Ignored predicate = null,
            bool ignoreInsideBlocker = false,
            bool popup = false)
        {
            var originPosition = origin.Transform.MapPosition;
            var otherPosition = other.ToMap(EntityManager);
            predicate ??= e => e == origin;

            var inRange = InRangeUnobstructed(originPosition, otherPosition, range, collisionMask, predicate, ignoreInsideBlocker);

            if (!inRange && popup)
            {
                var message = Loc.GetString("You can't reach there!");
                origin.PopupMessage(message);
            }

            return inRange;
        }

        /// <summary>
        ///     Checks that an entity and a set of map coordinates are within a certain
        ///     distance without any entity that matches the collision mask
        ///     obstructing them.
        ///     If the <paramref name="range"/> is zero or negative,
        ///     this method will only check if nothing obstructs the entity and component.
        /// </summary>
        /// <param name="origin">The entity to use.</param>
        /// <param name="other">The map coordinates to use.</param>
        /// <param name="range">
        ///     Maximum distance between the two entity and set of map coordinates.
        /// </param>
        /// <param name="collisionMask">The mask to check for collisions.</param>
        /// <param name="predicate">
        ///     A predicate to check whether to ignore an entity or not.
        ///     If it returns true, it will be ignored.
        /// </param>
        /// <param name="ignoreInsideBlocker">
        ///     If true and <see cref="origin"/> or <see cref="other"/> are inside
        ///     the obstruction, ignores the obstruction and considers the interaction
        ///     unobstructed.
        ///     Therefore, setting this to true makes this check more permissive,
        ///     such as allowing an interaction to occur inside something impassable
        ///     (like a wall). The default, false, makes the check more restrictive.
        /// </param>
        /// <param name="popup">
        ///     Whether or not to popup a feedback message on the origin entity for
        ///     it to see.
        /// </param>
        /// <returns>
        ///     True if the two points are within a given range without being obstructed.
        /// </returns>
        public bool InRangeUnobstructed(
            IEntity origin,
            MapCoordinates other,
            float range = InteractionRange,
            CollisionGroup collisionMask = CollisionGroup.Impassable,
            Ignored predicate = null,
            bool ignoreInsideBlocker = false,
            bool popup = false)
        {
            var originPosition = origin.Transform.MapPosition;
            predicate ??= e => e == origin;

            var inRange = InRangeUnobstructed(originPosition, other, range, collisionMask, predicate, ignoreInsideBlocker);

            if (!inRange && popup)
            {
                var message = Loc.GetString("You can't reach there!");
                origin.PopupMessage(message);
            }

            return inRange;
        }

        /// <summary>
        ///     Checks that the user and target of a
        ///     <see cref="ITargetedInteractEventArgs"/> are within a certain
        ///     distance without any entity that matches the collision mask
        ///     obstructing them.
        ///     If the <paramref name="range"/> is zero or negative,
        ///     this method will only check if nothing obstructs the entity and component.
        /// </summary>
        /// <param name="args">The event args to use.</param>
        /// <param name="range">
        ///     Maximum distance between the two entity and set of map coordinates.
        /// </param>
        /// <param name="collisionMask">The mask to check for collisions.</param>
        /// <param name="predicate">
        ///     A predicate to check whether to ignore an entity or not.
        ///     If it returns true, it will be ignored.
        /// </param>
        /// <param name="ignoreInsideBlocker">
        ///     If true and both the user and target are inside
        ///     the obstruction, ignores the obstruction and considers the interaction
        ///     unobstructed.
        ///     Therefore, setting this to true makes this check more permissive,
        ///     such as allowing an interaction to occur inside something impassable
        ///     (like a wall). The default, false, makes the check more restrictive.
        /// </param>
        /// <param name="popup">
        ///     Whether or not to popup a feedback message on the user entity for
        ///     it to see.
        /// </param>
        /// <returns>
        ///     True if the two points are within a given range without being obstructed.
        /// </returns>
        public bool InRangeUnobstructed(
            ITargetedInteractEventArgs args,
            float range = InteractionRange,
            CollisionGroup collisionMask = CollisionGroup.Impassable,
            Ignored predicate = null,
            bool ignoreInsideBlocker = false,
            bool popup = false)
        {
            var origin = args.User;
            var other = args.Target;

            return InRangeUnobstructed(origin, other, range, collisionMask, predicate, ignoreInsideBlocker, popup);
        }

        /// <summary>
        ///     Checks that the user of a <see cref="DragDropEventArgs"/> is within a
        ///     certain distance of the target and dropped entities without any entity
        ///     that matches the collision mask obstructing them.
        ///     If the <paramref name="range"/> is zero or negative,
        ///     this method will only check if nothing obstructs the entity and component.
        /// </summary>
        /// <param name="args">The event args to use.</param>
        /// <param name="range">
        ///     Maximum distance between the two entity and set of map coordinates.
        /// </param>
        /// <param name="collisionMask">The mask to check for collisions.</param>
        /// <param name="predicate">
        ///     A predicate to check whether to ignore an entity or not.
        ///     If it returns true, it will be ignored.
        /// </param>
        /// <param name="ignoreInsideBlocker">
        ///     If true and both the user and target are inside
        ///     the obstruction, ignores the obstruction and considers the interaction
        ///     unobstructed.
        ///     Therefore, setting this to true makes this check more permissive,
        ///     such as allowing an interaction to occur inside something impassable
        ///     (like a wall). The default, false, makes the check more restrictive.
        /// </param>
        /// <param name="popup">
        ///     Whether or not to popup a feedback message on the user entity for
        ///     it to see.
        /// </param>
        /// <returns>
        ///     True if the two points are within a given range without being obstructed.
        /// </returns>
        public bool InRangeUnobstructed(
            DragDropEventArgs args,
            float range = InteractionRange,
            CollisionGroup collisionMask = CollisionGroup.Impassable,
            Ignored predicate = null,
            bool ignoreInsideBlocker = false,
            bool popup = false)
        {
            var user = args.User;
            var dropped = args.Dropped;
            var target = args.Target;

            if (!InRangeUnobstructed(user, target, range, collisionMask, predicate, ignoreInsideBlocker))
            {
                if (popup)
                {
                    var message = Loc.GetString("You can't reach there!");
                    target.PopupMessage(user, message);
                }

                return false;
            }

            if (!InRangeUnobstructed(user, dropped, range, collisionMask, predicate, ignoreInsideBlocker))
            {
                if (popup)
                {
                    var message = Loc.GetString("You can't reach there!");
                    dropped.PopupMessage(user, message);
                }

                return false;
            }

            return true;
        }

        /// <summary>
        ///     Checks that the user and target of a
        ///     <see cref="AfterInteractEventArgs"/> are within a  certain distance
        ///     without any entity that matches the collision mask obstructing them.
        ///     If the <paramref name="range"/> is zero or negative,
        ///     this method will only check if nothing obstructs the entity and component.
        /// </summary>
        /// <param name="args">The event args to use.</param>
        /// <param name="range">
        ///     Maximum distance between the two entity and set of map coordinates.
        /// </param>
        /// <param name="collisionMask">The mask to check for collisions.</param>
        /// <param name="predicate">
        ///     A predicate to check whether to ignore an entity or not.
        ///     If it returns true, it will be ignored.
        /// </param>
        /// <param name="ignoreInsideBlocker">
        ///     If true and both the user and target are inside
        ///     the obstruction, ignores the obstruction and considers the interaction
        ///     unobstructed.
        ///     Therefore, setting this to true makes this check more permissive,
        ///     such as allowing an interaction to occur inside something impassable
        ///     (like a wall). The default, false, makes the check more restrictive.
        /// </param>
        /// <param name="popup">
        ///     Whether or not to popup a feedback message on the user entity for
        ///     it to see.
        /// </param>
        /// <returns>
        ///     True if the two points are within a given range without being obstructed.
        /// </returns>
        public bool InRangeUnobstructed(
            AfterInteractEventArgs args,
            float range = InteractionRange,
            CollisionGroup collisionMask = CollisionGroup.Impassable,
            Ignored predicate = null,
            bool ignoreInsideBlocker = false,
            bool popup = false)
        {
            var user = args.User;
            var target = args.Target;
            predicate ??= e => e == user;

            MapCoordinates otherPosition;

            if (target == null)
            {
                otherPosition = args.ClickLocation.ToMap(EntityManager);
            }
            else
            {
                otherPosition = target.Transform.MapPosition;
                predicate += e => e == target;
            }

            return InRangeUnobstructed(user, otherPosition, range, collisionMask, predicate, ignoreInsideBlocker, popup);
        }
    }
}