using Content.Shared.CCVar;
using Content.Shared.Construction.Components;
using Robust.Shared.Configuration;
using Robust.Shared.Map;

namespace Content.Shared.Mapping;

/// <summary>
/// This system can fix the rotation of structures like doors and firelocks, based on the surrounding walls/windows/doors.
/// See <see cref="StructureAlignerComponent"/> and <see cref="StructureAlignerPylonComponent"/>.
/// </summary>
/// <remarks>
/// This only works for sprites that are symmetrical, so only need to worry about 2 rotation states.
/// The correct rotation for sprites that (effectively) have 4 states is too fuzzy to be determined via scripted logic,
/// and they are probably always placed deliberately anyway. So they are exempt from this system.
/// This is primarily an assistive tool for fixing maps that were made before door sprites were directional.
/// </remarks>
/// TODO But it could also be upgraded to help auto-align construction ghosts for doors, as a potential QOL feature
public sealed partial class SharedStructureAlignerSystem : EntitySystem
{
    [Dependency] private IConfigurationManager _cfg = default!;
    [Dependency] private EntityLookupSystem _lookup = default!;
    [Dependency] private SharedTransformSystem _trans = default!;

    /// <summary>
    /// If enabled, every <see cref="StructureAlignerComponent"/> will be Aligned when it spawns.
    /// </summary>
    private static bool _mapInitAlign;

    private const float ProximityMin = 0.45f;
    private const float ProximityMax = 1.1f;
    private const float SearchBoxScale = 1.25f;

    /// <inheritdoc/>
    public override void Initialize()
    {
        Subs.CVar(_cfg, CCVars.MapInitAlign,  (b) => { _mapInitAlign = b; }, true);
    }

    [SubscribeLocalEvent]
    private void OnAnchored(Entity<StructureAlignerComponent> entity, ref UserAnchoredEvent args)
    {
        if (!entity.Comp.AnchorAlign)
            return;

        Align(entity);
    }

    /// <summary>
    /// If the cvar is enabled, every <see cref="StructureAlignerComponent"/> will be Aligned when the map initializes.
    /// </summary>
    /// <remarks>
    /// May be considered a stopgap measure when unupgraded maps are in rotation?
    /// </remarks>
    [SubscribeLocalEvent]
    private void OnMapInit(Entity<StructureAlignerComponent> entity, ref MapInitEvent args)
    {
        if (!_mapInitAlign)
            return;

        Align(entity);
    }

    /// <summary>
    /// Aligns every <see cref="StructureAlignerComponent"/> on the target map, or on every map if not specified.
    /// </summary>
    /// <returns>The feedback to be displayed to the user, if the command was triggered from the console</returns>
    /// <remarks>
    /// This can be expensive and lag the game for seconds. It should not be called after players are in the game.
    /// </remarks>
    /// <param name="map">The map that should be targetted; if left null, all maps are targetted.</param>
    /// <param name="dryRun">If true, the command only checks for misalignment, without doing any rotation.</param>
    /// <param name="verbose">If true, write a log message for each identified misalignment.</param>
    public string AlignAll(MapId? map = null, bool dryRun = false, bool verbose = false)
    {
        // It needs to be an All Entity Query so it works on pre-init maps during Mapping.
        var query = AllEntityQuery<StructureAlignerComponent, TransformComponent>();

        var countAll = 0;
        var countFixed = 0;

        //TODO: check if map exists so we can quit early
        //TODO: rewrite the flow to check which entities should be aligned in one method, and then align those entities in a separate method

        foreach (var (ent, comp, trans) in query)
        {
            if (map is not null && trans.MapID != map)
                continue;

            if (Align((ent, comp), dryRun, verbose))
                countFixed++;
            countAll++;
        }

        string message;
        if (countAll == 0)
            message = Loc.GetString("cmd-align-feedback-none", ("dry", dryRun));
        else if (countFixed == 0)
            message = Loc.GetString("cmd-align-feedback-good", ("dry", dryRun));
        else
            message = Loc.GetString("cmd-align-feedback", ("fixed", countFixed), ("dry", dryRun));

        // Logging both alignable and misaligned entities, console only gets the latter.
        Log.Info($"AlignAll found {countAll} entities. {countFixed} were misaligned { (dryRun ? ". Dry run, no rotations were performed." : " and have been fixed.") }");
        return message;
    }

    /// <summary>
    /// Aligns the target entity if there are any adjacent <see cref="StructureAlignerPylonComponent"/>s with matching types.
    /// </summary>
    private bool Align(Entity<StructureAlignerComponent> entity, bool dryRun = false, bool verbose = false)
    {
        var trans = Transform(entity);

        // Do not align loose entities.
        if (!trans.Anchored || trans.GridUid is null)
            return false;

        // Get nearby entities, so we don't need to check through all entities
        // Searchbox is scaled up because adjacent airlocks would otherwise not be caught, due to smaller hitboxes
        var searchBox = _lookup.GetWorldAABB(entity, trans).Scale(SearchBoxScale);
        HashSet<EntityUid> near = new();
        _lookup.GetEntitiesIntersecting(trans.GridUid.Value, searchBox, near);

        var northSouth = 0d;
        var eastWest = 0d;

        foreach (var neighborEnt in near)
        {
            if (entity.Owner == neighborEnt)
                continue;

            if (!TryComp<StructureAlignerPylonComponent>(neighborEnt, out var pylonComp))
                    continue;

            if (!pylonComp.AlignerPylonTypes.HasFlag(entity.Comp.AlignerType))
                continue;

            var neighborTrans = Transform(neighborEnt);

            // Ignore space debris or docked grids.
            if (neighborTrans.ParentUid != trans.ParentUid)
                continue;

            // The searchbox catches diagonally adjacent tiles, but we don't want those. So we filter them out with a maximum distance.
            // Minimum range is here to ignore overlapping entities.
            trans.Coordinates.TryDistance(EntityManager, _trans, neighborTrans.Coordinates, out var dist);
            if (dist > ProximityMax || dist < ProximityMin)
                continue;

            // Anchored objects have enough weight in the calculation to make unanchored ones irrelevant,
            // but if only unanchored ones are present, they will still matter.
            // For example, if a line of firelock frames are being anchored, with no adjacent walls.
            var weight = neighborTrans.Anchored ? 10 : 1;
            var neighborDir = (trans.Coordinates.Position - neighborTrans.Coordinates.Position).GetDir();
            switch (neighborDir)
            {
                case Direction.South or Direction.North:
                    northSouth += weight;
                    break;
                case Direction.East or Direction.West:
                    eastWest += weight;
                    break;
            }
        }

        // Determine correct orientation
        // A horizontal base sprite is assumed, with neighbors to the East or West being acceptable.
        // If the entity instead has N or S side neighbors, it will be rotated 90 degrees.
        // If ambiguous (neighbors on all sides, or in an L shape) then no rotation will occur.
        Direction targetDir;

        if (eastWest > northSouth)
        {
            targetDir = Direction.East;
        }
        else if (northSouth > eastWest)
        {
            targetDir = Direction.South;
        }
        else
            return false;

        // For our purposes the opposite of the target direction also works, as it's the same alignment axis.
        if (targetDir != trans.LocalRotation.GetDir() && targetDir != trans.LocalRotation.Opposite().GetDir())
            return false;

        var name = MetaData(entity.Owner).EntityName;
        var pos = _trans.GetWorldPosition(trans);

        if (!dryRun)
            _trans.SetLocalRotation(entity, trans.LocalRotation + Angle.FromDegrees(90));

        // Only generate individual logs if the user triggered alignment using the command.
        if (verbose)
            Log.Info($"Misaligned entity '{ entity.Owner }' on map { trans.MapID } at { pos } : { name }");

        return true;
    }
}

/// <summary>
/// Enum to use with <see cref="SharedStructureAlignerSystem"/> to determine how incorrectly rotated entities should be aligned.
/// </summary>
[Flags]
public enum StructureAlignerType : byte
{
    /// <summary>
    /// Airlocks, doors, shutters, blast doors and everything that would be functionally
    /// considered a room boundary (doors, walls, windows, full tile rocks etc.).
    /// No firelocks - they are their own category to avoid interference in atypical placement locations.
    /// No thin walls/doors, or docking airlocks - directionality is too important for these and must be decided manually.
    /// </summary>
    Door = 1,
    /// <summary>
    /// Firelocks and everything that would be functionally considered a room boundary
    /// (doors, walls, windows, full tile rocks etc.).
    /// </summary>
    Firelock = 2,
    /// Go go gadget OverrideInheritance
    DoNotAlign = 4,
}