using UnityEngine;

/// <summary>
/// regulare snap performed in free move
/// </summary>
public class DefaultSnapBehavior : ISnapBehavior
{
    public bool TrySnap(BlockEditContext ctx)
    {
        if (ctx.TargetSocket == null) return false;
        if (ctx.MySocket != null && !ctx.TargetSocket.CanAccept(ctx.MySocket)) return false;

        if (ctx.MySocket != null)
        {
            // 1. Primary Alignment: Align the exact socket normals
            Vector3 myNormal = ctx.MySocket.GetNormal().normalized;
            Vector3 targetNormal = -ctx.TargetSocket.GetNormal().normalized;
            
            Quaternion primaryRot = Quaternion.FromToRotation(myNormal, targetNormal);
            ctx.GhostTransform.rotation = primaryRot * ctx.GhostTransform.rotation;

            // 2. Secondary Alignment: Align the 'Up' (or Forward) vectors to prevent random twisting/rolling
            Vector3 mySecondary = Mathf.Abs(Vector3.Dot(ctx.MySocket.transform.up, targetNormal)) < 0.9f 
                ? ctx.MySocket.transform.up 
                : ctx.MySocket.transform.forward;
                
            Vector3 targetSecondary = Mathf.Abs(Vector3.Dot(ctx.TargetSocket.transform.up, -targetNormal)) < 0.9f 
                ? ctx.TargetSocket.transform.up 
                : ctx.TargetSocket.transform.forward;

            // Project secondary vectors onto the flat plane between the sockets
            Vector3 projectedMySecondary = Vector3.ProjectOnPlane(mySecondary, targetNormal).normalized;
            Vector3 projectedTargetSecondary = Vector3.ProjectOnPlane(targetSecondary, targetNormal).normalized;

            if (projectedMySecondary != Vector3.zero && projectedTargetSecondary != Vector3.zero)
            {
                // Find the twist angle needed to align the secondary axes
                float angle = Vector3.SignedAngle(projectedMySecondary, projectedTargetSecondary, targetNormal);
                // Snap to the nearest 45 degrees to allow manual 'R' rotations to persist!
                float correction = angle - Mathf.Round(angle / 45f) * 45f;
                // Rotate the ghost around its own pivot (since we haven't translated yet)
                ctx.GhostTransform.rotation = Quaternion.AngleAxis(correction, targetNormal) * ctx.GhostTransform.rotation;
            }

            // 3. Translate the ghost so the sockets physically touch
            ctx.GhostTransform.position += 
                ctx.TargetSocket.transform.position - ctx.MySocket.transform.position;
        }
        else
        {
            Transform pivot = ctx.AttachPoint != null ? ctx.AttachPoint : ctx.GhostTransform;
            Vector3 pivotOffset = pivot.position - ctx.GhostTransform.position;
            ctx.GhostTransform.position = ctx.TargetSocket.transform.position - pivotOffset;
        }

        return true;
    }
}