* AntennaRelay.cs:
[AntennaRange.git] / AntennaRelay.cs
blob:a/AntennaRelay.cs -> blob:b/AntennaRelay.cs
--- a/AntennaRelay.cs
+++ b/AntennaRelay.cs
@@ -1,46 +1,103 @@
-// AntennaRange © 2014 toadicus
+// AntennaRange
 //
-// AntennaRange provides incentive and requirements for the use of the various antenna parts.
-// Nominally, the breakdown is as follows:
+// AntennaRelay.cs
 //
-//     Communotron 16 - Suitable up to Kerbalsynchronous Orbit
-//     Comms DTS-M1 - Suitable throughout the Kerbin subsystem
-//     Communotron 88-88 - Suitable throughout the Kerbol system.
+// Copyright © 2014, toadicus
+// All rights reserved.
 //
-// This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a
-// copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/
+// Redistribution and use in source and binary forms, with or without modification,
+// are permitted provided that the following conditions are met:
 //
-// This software uses the ModuleManager library © 2013 ialdabaoth, used under a Creative Commons Attribution-ShareAlike
-// 3.0 Uported License.
+// 1. Redistributions of source code must retain the above copyright notice,
+//    this list of conditions and the following disclaimer.
 //
-// This software uses code from the MuMechLib library, © 2013 r4m0n, used under the GNU GPL version 3.
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be used
+//    to endorse or promote products derived from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 using System;
 using System.Collections.Generic;
-using System.Linq;
+using ToadicusTools;
 
 namespace AntennaRange
 {
-	public class AntennaRelay : IAntennaRelay
+	/// <summary>
+	/// Relay code at the heart of AntennaRange
+	/// </summary>
+	public class AntennaRelay
 	{
+		private static readonly System.Diagnostics.Stopwatch searchTimer = new System.Diagnostics.Stopwatch();
+		private const long millisecondsBetweenSearches = 125L;
+
 		// We don't have a Bard, so we'll hide Kerbin here.
-		protected CelestialBody Kerbin;
+		private static CelestialBody _Kerbin;
+
+		/// <summary>
+		/// Fetches, caches, and returns a <see cref="CelestialBody"/> reference to Kerbin
+		/// </summary>
+		public static CelestialBody Kerbin
+		{
+			get
+			{
+				if (_Kerbin == null && FlightGlobals.ready)
+				{
+					_Kerbin = FlightGlobals.GetHomeBody();
+				}
+
+				return _Kerbin;
+			}
+		}
+
+		private long lastSearch;
+
+		private bool canTransmit;
+		private bool isChecked;
+
+		private IAntennaRelay nearestRelay;
+		private IAntennaRelay bestOccludedRelay;
+
+		/// <summary>
+		/// The <see cref="AntennaRange.ModuleLimitedDataTransmitter"/> reference underlying this AntennaRelay, as an
+		/// <see cref="AntennaRange.IAntennaRelay"/>
+		/// </summary>
+		protected IAntennaRelay moduleRef;
 
 		/// <summary>
 		/// Gets the parent Vessel.
 		/// </summary>
 		/// <value>The parent Vessel.</value>
-		public Vessel vessel
+		public virtual Vessel vessel
+		{
+			get
+			{
+				return this.moduleRef.vessel;
+			}
+		}
+
+		/// <summary>
+		/// Gets the target <see cref="AntennaRange.IAntennaRelay"/>relay.
+		/// </summary>
+		public IAntennaRelay targetRelay
 		{
 			get;
 			protected set;
 		}
 
 		/// <summary>
-		/// Gets or sets the nearest relay.
-		/// </summary>
-		/// <value>The nearest relay</value>
-		public IAntennaRelay nearestRelay
+		/// Gets the first <see cref="CelestialBody"/> found to be blocking line of sight.
+		/// </summary>
+		public virtual CelestialBody firstOccludingBody
 		{
 			get;
 			protected set;
@@ -54,38 +111,41 @@
 		{
 			get
 			{
-				this.nearestRelay = this.FindNearestRelay();
-
-				// If there is no available relay nearby...
-				if (nearestRelay == null)
-				{
-					// .. return the distance to Kerbin
-					return this.DistanceTo(this.Kerbin);
+				if (this.KerbinDirect || this.targetRelay == null)
+				{
+					return this.DistanceTo(Kerbin);
 				}
 				else
 				{
-					/// ...otherwise, return the distance to the nearest available relay.
-					return this.DistanceTo(nearestRelay);
-				}
-			}
-		}
-
-		/// <summary>
-		/// The maximum distance at which this relay can operate.
-		/// </summary>
-		/// <value>The max transmit distance.</value>
-		public virtual float maxTransmitDistance
+					return this.DistanceTo(this.targetRelay);
+				}
+			}
+		}
+
+		/// <summary>
+		/// Gets the nominal transmit distance at which the Antenna behaves just as prescribed by Squad's config.
+		/// </summary>
+		public virtual double nominalTransmitDistance
 		{
 			get;
 			set;
 		}
 
 		/// <summary>
-		/// Gets a value indicating whether this <see cref="AntennaRange.ProtoDataTransmitter"/> has been checked during
-		/// the current relay attempt.
-		/// </summary>
-		/// <value><c>true</c> if relay checked; otherwise, <c>false</c>.</value>
-		public virtual bool relayChecked
+		/// The maximum distance at which this relay can operate.
+		/// </summary>
+		/// <value>The max transmit distance.</value>
+		public virtual double maxTransmitDistance
+		{
+			get;
+			set;
+		}
+
+		/// <summary>
+		/// Gets a value indicating whether this <see cref="AntennaRange.IAntennaRelay"/> Relay is communicating
+		/// directly with Kerbin.
+		/// </summary>
+		public virtual bool KerbinDirect
 		{
 			get;
 			protected set;
@@ -95,162 +155,518 @@
 		/// Determines whether this instance can transmit.
 		/// </summary>
 		/// <returns><c>true</c> if this instance can transmit; otherwise, <c>false</c>.</returns>
-		public bool CanTransmit()
-		{
-			if (this.transmitDistance > this.maxTransmitDistance)
-			{
-				return false;
-			}
+		public virtual bool CanTransmit()
+		{
+			return this.canTransmit;
+		}
+
+		/// <summary>
+		/// Finds the nearest relay.
+		/// </summary>
+		/// <returns>The nearest relay or null, if no relays in range.</returns>
+		public void FindNearestRelay()
+		{
+			if (!FlightGlobals.ready)
+			{
+				return;
+			}
+
+			if (!searchTimer.IsRunning)
+			{
+				searchTimer.Start();
+			}
+
+			Tools.DebugLogger log;
+			#if DEBUG
+			log = Tools.DebugLogger.New(this);
+			#endif
+
+			long searchTime = searchTimer.ElapsedMilliseconds;
+			long timeSinceLast = searchTime - this.lastSearch;
+
+			if (timeSinceLast < millisecondsBetweenSearches)
+			{
+				log.AppendFormat(
+					"{0}: Target search skipped because it's not time to search again yet ({1} - {2}) < {3})",
+					this, searchTime, this.lastSearch, millisecondsBetweenSearches
+				);
+				log.Print();
+				return;
+			}
+
+			// Skip vessels that have already been checked for a nearest relay this pass.
+			if (this.isChecked)
+			{
+				log.AppendFormat("{0}: Target search skipped because our vessel has been checked already this search.",
+					this);
+				log.Print();
+				return;
+			}
+
+			log.AppendFormat("{0}: Target search started at {1} ms ({2} ms since last search).",
+				this.ToString(), searchTime, timeSinceLast);
+
+			#if DEBUG
+			try {
+			#endif
+			// Set this vessel as checked, so that we don't check it again.
+			this.isChecked = true;
+
+			this.lastSearch = searchTime;
+
+			// Blank everything we're trying to find before the search.
+			this.firstOccludingBody = null;
+			this.bestOccludedRelay = null;
+			this.targetRelay = null;
+			this.nearestRelay = null;
+
+			// Default to KerbinDirect = true in case something in here doesn't work right.
+			this.KerbinDirect = true;
+
+			CelestialBody bodyOccludingBestOccludedRelay = null;
+
+			double nearestRelaySqrDistance = double.PositiveInfinity;
+			double bestOccludedSqrDistance = double.PositiveInfinity;
+			double maxTransmitSqrDistance = this.maxTransmitDistance * this.maxTransmitDistance;
+
+			/*
+			 * Loop through all the vessels and exclude this vessel, vessels of the wrong type, and vessels that are too
+			 * far away.  When we find a candidate, get through its antennae for relays which have not been checked yet
+			 * and that can transmit.  Once we find a suitable candidate, assign it to nearestRelay for comparison
+			 * against future finds.
+			 * */
+			Vessel potentialVessel;
+			IList<IAntennaRelay> vesselRelays;
+			for (int vIdx = 0; vIdx < FlightGlobals.Vessels.Count; vIdx++)
+			{
+				log.AppendFormat("\nFetching vessel at index {0}", vIdx);
+				potentialVessel = FlightGlobals.Vessels[vIdx];
+				
+				if (potentialVessel == null)
+				{
+					log.AppendFormat("\n\tSkipping vessel at index {0} because it is null.", vIdx);
+					log.Print();
+					return;
+				}
+				#if DEBUG
+				else
+				{
+					log.AppendFormat("\n\tGot vessel {0}", potentialVessel);
+				}
+				#endif
+
+				// Skip vessels of the wrong type.
+				log.Append("\n\tchecking vessel type");
+				switch (potentialVessel.vesselType)
+				{
+					case VesselType.Debris:
+					case VesselType.Flag:
+					case VesselType.EVA:
+					case VesselType.SpaceObject:
+					case VesselType.Unknown:
+							log.Append("\n\tSkipping because vessel is the wrong type.");
+						continue;
+					default:
+						break;
+				}
+				
+				log.Append("\n\tchecking if vessel is this vessel");
+				// Skip vessels with the wrong ID
+				if (potentialVessel.id == vessel.id)
+				{
+					log.Append("\n\tSkipping because vessel is this vessel.");
+					continue;
+				}
+
+				// Find the distance from here to the vessel...
+				log.Append("\n\tgetting distance to potential vessel");
+				double potentialSqrDistance = this.sqrDistanceTo(potentialVessel);
+				log.Append("\n\tgetting vessel relays");
+				vesselRelays = potentialVessel.GetAntennaRelays();
+					log.AppendFormat("\n\t\tvesselRelays: {0}",
+						vesselRelays == null ? "null" : vesselRelays.Count.ToString());
+
+				CelestialBody fob = null;
+				
+				log.Append("\n\tdoing LOS check");
+				// Skip vessels to which we do not have line of sight.
+				if (
+					ARConfiguration.RequireLineOfSight &&
+					!this.vessel.hasLineOfSightTo(potentialVessel, out fob, ARConfiguration.RadiusRatio)
+				)
+				{
+					log.Append("\n\tfailed LOS check");
+					this.firstOccludingBody = fob;
+					
+					log.AppendFormat("\n\t{0}: Vessel {1} not in line of sight.",
+						this.ToString(), potentialVessel.vesselName);
+					
+					log.AppendFormat("\n\t\tpotentialSqrDistance: {0}", potentialSqrDistance);
+					log.AppendFormat("\n\t\tbestOccludedSqrDistance: {0}", bestOccludedSqrDistance);
+					log.AppendFormat("\n\t\tmaxTransmitSqrDistance: {0}", maxTransmitSqrDistance);
+
+					if (
+						(potentialSqrDistance < bestOccludedSqrDistance) &&
+						(potentialSqrDistance < maxTransmitSqrDistance)
+					)
+					{
+						log.Append("\n\t\t...vessel is close enough to check for occluded relays");
+						log.AppendFormat("\n\t\tthis: {0}", this);
+						log.AppendFormat("\n\t\tpotentialVessel: {0}",
+							potentialVessel == null ? "null" : potentialVessel.ToString());
+						log.AppendFormat("\n\t\tvesselRelays: {0}",
+							vesselRelays == null ? "null" : vesselRelays.ToString());
+
+						log.AppendFormat("\n\t\t{0}: Checking {1} relays on occluded vessel {2}.",
+							this.ToString(),
+							vesselRelays.Count,
+							potentialVessel
+						);
+
+						IAntennaRelay occludedRelay;
+						for (int rIdx = 0; rIdx < vesselRelays.Count; rIdx++)
+						{
+							occludedRelay = vesselRelays[rIdx];
+
+							log.AppendFormat(
+								"\n\t\t{0}: Checking candidate for bestOccludedRelay: {1}" +
+								"\n\t\tCanTransmit: {2}",
+								this.ToString(), occludedRelay, occludedRelay.CanTransmit()
+							);
+							
+							if (occludedRelay.CanTransmit())
+							{
+								this.bestOccludedRelay = occludedRelay;
+								bodyOccludingBestOccludedRelay = fob;
+								bestOccludedSqrDistance = potentialSqrDistance;
+
+								log.AppendFormat("\n\t{0}: Found new bestOccludedRelay: {1}" +
+									" (blocked by {2}; distance: {3} m)",
+									this.ToString(),
+									occludedRelay.ToString(),
+									fob,
+									potentialSqrDistance
+								);
+								break;
+							}
+						}
+					}
+					
+					log.Append("\n\t\t...vessel is not close enough to check for occluded relays, carrying on");
+					continue;
+				}
+
+				log.Append("\n\tpassed LOS check");
+
+				/*
+				 * ...so that we can skip the vessel if it is further away than a vessel we've already checked.
+				 * */
+				if (potentialSqrDistance > nearestRelaySqrDistance)
+				{
+					
+					log.AppendFormat("\n\t{0}: Vessel {1} discarded because it is farther than another the nearest relay.",
+						this.ToString(),
+						potentialVessel.vesselName
+					);
+					continue;
+				}
+
+				log.Append("\n\tpassed distance check");
+
+				IAntennaRelay potentialRelay;
+				for (int rIdx = 0; rIdx < vesselRelays.Count; rIdx++)
+				{
+					log.AppendFormat("\n\t\tfetching vessel relay at index {0}", rIdx);
+					potentialRelay = vesselRelays[rIdx];
+					log.AppendFormat("\n\t\tgot relay {0}", potentialRelay == null ? "null" : potentialRelay.ToString());
+
+					if (potentialRelay == null)
+					{
+						log.Append("\n\t\t...skipping null relay");
+						continue;
+					}
+
+					if (
+						potentialRelay.CanTransmit() &&
+						(potentialRelay.targetRelay == null || potentialRelay.targetRelay.vessel != this.vessel))
+					{
+						// @TODO: Moved this here from outside the loop; why was it there?
+						nearestRelaySqrDistance = potentialSqrDistance;
+						this.nearestRelay = potentialRelay;
+
+						log.AppendFormat("\n\t{0}: found new nearest relay {1} ({2}m)",
+							this.ToString(),
+							this.nearestRelay.ToString(),
+							Math.Sqrt(nearestRelaySqrDistance)
+						);
+						
+						break;
+					}
+				}
+			}
+
+			CelestialBody bodyOccludingKerbin = null;
+
+			double kerbinSqrDistance = this.vessel.DistanceTo(Kerbin) - Kerbin.Radius;
+			kerbinSqrDistance *= kerbinSqrDistance;
+
+			log.AppendFormat("\n{0} ({1}): Search done, figuring status.", this.ToString(), this.GetType().Name);
+
+			// If we don't have LOS to Kerbin, focus on relays
+			if (!this.vessel.hasLineOfSightTo(Kerbin, out bodyOccludingKerbin, ARConfiguration.RadiusRatio))
+			{
+				log.AppendFormat("\n\tKerbin LOS is blocked by {0}.", bodyOccludingKerbin.bodyName);
+
+				// nearestRelaySqrDistance will be infinity if all relays are occluded or none exist.
+				// Therefore, this will only be true if a valid relay is in range.
+				if (nearestRelaySqrDistance <= maxTransmitSqrDistance)
+				{
+					log.AppendFormat("\n\t\tCan transmit to nearby relay {0} ({1} <= {2}).",
+						this.nearestRelay == null ? "null" : this.nearestRelay.ToString(),
+							nearestRelaySqrDistance, maxTransmitSqrDistance);
+
+					this.KerbinDirect = false;
+					this.canTransmit = true;
+					this.targetRelay = this.nearestRelay;
+				}
+				// If this isn't true, we can't transmit, but pick a second best of bestOccludedRelay and Kerbin anyway
+				else
+				{
+					log.AppendFormat("\n\t\tCan't transmit to nearby relay {0} ({1} > {2}).",
+						this.nearestRelay == null ? "null" : this.nearestRelay.ToString(),
+							nearestRelaySqrDistance, maxTransmitSqrDistance);
+
+					this.canTransmit = false;
+
+					// If the best occluded relay is closer than Kerbin, check it against the nearest relay.
+					// Since bestOccludedSqrDistance is infinity if there are no occluded relays, this is safe
+					if (bestOccludedSqrDistance < kerbinSqrDistance)
+					{
+						log.AppendFormat("\n\t\t\tBest occluded relay is closer than Kerbin ({0} < {1})",
+							bestOccludedRelay, kerbinSqrDistance);
+						
+						this.KerbinDirect = false;
+
+						// If the nearest relay is closer than the best occluded relay, pick it.
+						// Since nearestRelaySqrDistane is infinity if there are no nearby relays, this is safe.
+						if (nearestRelaySqrDistance < bestOccludedSqrDistance)
+						{
+							log.AppendFormat("\n\t\t\t\t...but the nearest relay is closer ({0} < {1}), so picking it.",
+								nearestRelaySqrDistance, bestOccludedSqrDistance);
+							
+							this.targetRelay = nearestRelay;
+							this.firstOccludingBody = null;
+						}
+						// Otherwise, target the best occluded relay.
+						else
+						{
+							log.AppendFormat("\n\t\t\t\t...and closer than the nearest relay ({0} >= {1}), so picking it.",
+								nearestRelaySqrDistance, bestOccludedSqrDistance);
+							
+							this.targetRelay = bestOccludedRelay;
+							this.firstOccludingBody = bodyOccludingBestOccludedRelay;
+						}
+					}
+					// Otherwise, check Kerbin against the nearest relay.
+					// Since we have LOS, blank the first occluding body.
+					else
+					{
+						log.AppendFormat("\n\t\t\tKerbin is closer than the best occluded relay ({0} >= {1})",
+							bestOccludedRelay, kerbinSqrDistance);
+						
+						this.firstOccludingBody = null;
+
+						// If the nearest relay is closer than Kerbin, pick it.
+						// Since nearestRelaySqrDistane is infinity if there are no nearby relays, this is safe.
+						if (nearestRelaySqrDistance < kerbinSqrDistance)
+						{
+							log.AppendFormat("\n\t\t\t\t...but the nearest relay is closer ({0} < {1}), so picking it.",
+								nearestRelaySqrDistance, kerbinSqrDistance);
+							
+							this.KerbinDirect = false;
+							this.targetRelay = nearestRelay;
+						}
+						// Otherwise, pick Kerbin.
+						else
+						{
+							log.AppendFormat("\n\t\t\t\t...and closer than the nearest relay ({0} >= {1}), so picking it.",
+								nearestRelaySqrDistance, kerbinSqrDistance);
+							
+							this.KerbinDirect = true;
+							this.targetRelay = null;
+						}
+					}
+				}
+			}
+			// If we do have LOS to Kerbin, try to prefer the closest of nearestRelay and Kerbin
 			else
 			{
-				return true;
-			}
-		}
-
-		/// <summary>
-		/// Finds the nearest relay.
-		/// </summary>
-		/// <returns>The nearest relay or null, if no relays in range.</returns>
-		public IAntennaRelay FindNearestRelay()
-		{
-			// Set this relay as checked, so that we don't check it again.
-			this.relayChecked = true;
-
-			// Get a list of vessels within transmission range.
-			List<Vessel> nearbyVessels = FlightGlobals.Vessels
-				.Where(v => (v.GetWorldPos3D() - vessel.GetWorldPos3D()).magnitude < this.maxTransmitDistance)
-					.ToList();
-
-			nearbyVessels.RemoveAll(v => v.vesselType == VesselType.Debris);
-
-			Tools.PostDebugMessage(string.Format(
-				"{0}: Non-debris vessels in range: {1}",
-				this.GetType().Name,
-				nearbyVessels.Count
-				));
-
-			// Remove this vessel.
-			nearbyVessels.RemoveAll(v => v.id == vessel.id);
-
-			Tools.PostDebugMessage(string.Format(
-				"{0}: Vessels in range excluding self: {1}",
-				this.GetType().Name,
-				nearbyVessels.Count
-				));
-
-			// Get a flattened list of all IAntennaRelay modules and protomodules in transmission range.
-			List<IAntennaRelay> nearbyRelays = nearbyVessels.SelectMany(v => v.GetAntennaRelays()).ToList();
-
-			Tools.PostDebugMessage(string.Format(
-				"{0}: Found {1} nearby relays.",
-				this.GetType().Name,
-				nearbyRelays.Count
-				));
-
-			// Remove all relays already checked this time.
-			nearbyRelays.RemoveAll(r => r.relayChecked);
-
-			Tools.PostDebugMessage(string.Format(
-				"{0}: Found {1} nearby relays not already checked.",
-				this.GetType().Name,
-				nearbyRelays.Count
-				));
-
-			// Remove all relays that cannot transmit.
-			// This call to r.CanTransmit() starts a depth-first recursive search for relays with a path back to Kerbin.
-			nearbyRelays.RemoveAll(r => !r.CanTransmit());
-
-			Tools.PostDebugMessage(string.Format(
-				"{0}: Found {1} nearby relays not already checked that can transmit.",
-				this.GetType().Name,
-				nearbyRelays.Count
-				));
-
-			// Sort the available relays by distance.
-			nearbyRelays.Sort(new RelayComparer(this.vessel));
-
-			// Get the nearest available relay, or null if there are no available relays nearby.
-			IAntennaRelay _nearestRelay = nearbyRelays.FirstOrDefault();
-
-			// If we have a nearby relay...
-			if (_nearestRelay != null)
-			{
-				// ...but that relay is farther than Kerbin...
-				if (this.DistanceTo(_nearestRelay) > this.DistanceTo(Kerbin))
-				{
-					// ...just use Kerbin.
-					_nearestRelay = null;
-				}
-			}
-
+				log.AppendFormat("\n\tKerbin is in LOS.");
+
+				// If the nearest relay is closer than Kerbin and in range, transmit to it.
+				if (nearestRelaySqrDistance <= maxTransmitSqrDistance)
+				{
+					log.AppendFormat("\n\t\tCan transmit to nearby relay {0} ({1} <= {2}).",
+						this.nearestRelay == null ? "null" : this.nearestRelay.ToString(),
+							nearestRelaySqrDistance, maxTransmitSqrDistance);
+
+					this.canTransmit = true;
+
+					// If the nearestRelay is closer than Kerbin, use it.
+					if (nearestRelaySqrDistance < kerbinSqrDistance)
+					{
+						log.AppendFormat("\n\t\t\tPicking relay {0} over Kerbin ({1} < {2}).",
+							this.nearestRelay == null ? "null" : this.nearestRelay.ToString(),
+							nearestRelaySqrDistance, kerbinSqrDistance);
+
+						this.KerbinDirect = false;
+						this.targetRelay = this.nearestRelay;
+					}
+					// Otherwise, Kerbin is closer, so use it.
+					else
+					{
+						log.AppendFormat("\n\t\t\tBut picking Kerbin over nearby relay {0} ({1} >= {2}).",
+							this.nearestRelay == null ? "null" : this.nearestRelay.ToString(),
+								nearestRelaySqrDistance, kerbinSqrDistance);
+
+						this.KerbinDirect = true;
+						this.targetRelay = null;
+					}
+				}
+				// If the nearest relay is out of range, we still need to check on Kerbin.
+				else
+				{
+					log.AppendFormat("\n\t\tCan't transmit to nearby relay {0} ({1} > {2}).",
+						this.nearestRelay == null ? "null" : this.nearestRelay.ToString(),
+							nearestRelaySqrDistance, maxTransmitSqrDistance);
+
+					// If Kerbin is in range, use it.
+					if (kerbinSqrDistance <= maxTransmitSqrDistance)
+					{
+						log.AppendFormat("\n\t\t\tCan transmit to Kerbin ({0} <= {1}).",
+							kerbinSqrDistance, maxTransmitSqrDistance);
+
+						this.canTransmit = true;
+						this.KerbinDirect = true;
+						this.targetRelay = null;
+					}
+					// If Kerbin is out of range and the nearest relay is out of range, pick a second best between
+					// Kerbin and bestOccludedRelay
+					else
+					{
+						log.AppendFormat("\n\t\t\tCan't transmit to Kerbin ({0} > {1}).",
+							kerbinSqrDistance, maxTransmitSqrDistance);
+
+						this.canTransmit = false;
+
+						// If the best occluded relay is closer than Kerbin, check it against the nearest relay.
+						// Since bestOccludedSqrDistance is infinity if there are no occluded relays, this is safe
+						if (bestOccludedSqrDistance < kerbinSqrDistance)
+						{
+							log.AppendFormat("\n\t\t\tBest occluded relay is closer than Kerbin ({0} < {1})",
+								bestOccludedRelay, kerbinSqrDistance);
+							
+							this.KerbinDirect = false;
+
+							// If the nearest relay is closer than the best occluded relay, pick it.
+							// Since nearestRelaySqrDistane is infinity if there are no nearby relays, this is safe.
+							if (nearestRelaySqrDistance < bestOccludedSqrDistance)
+							{
+								log.AppendFormat("\n\t\t\t\t...but the nearest relay is closer ({0} < {1}), so picking it.",
+									nearestRelaySqrDistance, bestOccludedSqrDistance);
+								
+								this.targetRelay = nearestRelay;
+								this.firstOccludingBody = null;
+							}
+							// Otherwise, target the best occluded relay.
+							else
+							{
+								log.AppendFormat("\n\t\t\t\t...and closer than the nearest relay ({0} >= {1}), so picking it.",
+									nearestRelaySqrDistance, bestOccludedSqrDistance);
+								
+								this.targetRelay = bestOccludedRelay;
+								this.firstOccludingBody = bodyOccludingBestOccludedRelay;
+							}
+						}
+						// Otherwise, check Kerbin against the nearest relay.
+						// Since we have LOS, blank the first occluding body.
+						else
+						{
+							log.AppendFormat("\n\t\t\tKerbin is closer than the best occluded relay ({0} >= {1})",
+								bestOccludedRelay, kerbinSqrDistance);
+							
+							this.firstOccludingBody = null;
+
+							// If the nearest relay is closer than Kerbin, pick it.
+							// Since nearestRelaySqrDistane is infinity if there are no nearby relays, this is safe.
+							if (nearestRelaySqrDistance < kerbinSqrDistance)
+							{
+								log.AppendFormat("\n\t\t\t\t...but the nearest relay is closer ({0} < {1}), so picking it.",
+									nearestRelaySqrDistance, kerbinSqrDistance);
+								
+								this.KerbinDirect = false;
+								this.targetRelay = nearestRelay;
+							}
+							// Otherwise, pick Kerbin.
+							else
+							{
+								log.AppendFormat("\n\t\t\t\t...and closer than the nearest relay ({0} >= {1}), so picking it.",
+									nearestRelaySqrDistance, kerbinSqrDistance);
+								
+								this.KerbinDirect = true;
+								this.targetRelay = null;
+							}
+						}
+					}
+				}
+			}
+
+			log.AppendFormat("{0}: Target search completed at {1} ms ({2} ms elapsed).",
+				this.ToString(), searchTimer.ElapsedMilliseconds, searchTimer.ElapsedMilliseconds - searchTime);;
+
+			log.AppendFormat("\n{0}: Status determination complete.", this.ToString());
+			
+			#if DEBUG
+			} catch (Exception ex) {
+				log.AppendFormat("\nCaught {0}: {1}\n{2}", ex.GetType().FullName, ex.ToString(), ex.StackTrace);
+			#if QUIT_ON_EXCEPTION
+				UnityEngine.Application.Quit();
+			#endif
+			} finally {
+			#endif
+			log.Print(false);
+			#if DEBUG
+			}
+			#endif
 			// Now that we're done with our recursive CanTransmit checks, flag this relay as not checked so it can be
 			// used next time.
-			this.relayChecked = false;
-
-			// Return the nearest available relay, or null if there are no available relays nearby.
-			return _nearestRelay;
-		}
-
+			this.isChecked = false;
+		}
+
+		/// <summary>
+		/// Returns a <see cref="System.String"/> that represents the current <see cref="AntennaRange.AntennaRelay"/>.
+		/// </summary>
+		/// <returns>A <see cref="System.String"/> that represents the current <see cref="AntennaRange.AntennaRelay"/>.</returns>
 		public override string ToString()
 		{
-			return string.Format(
-				"Antenna relay on vessel {0} (range to relay: {1}m)",
-				vessel,
-				Tools.MuMech_ToSI(transmitDistance)
-			);
-		}
-
-		/// <summary>
-		/// Initializes a new instance of the <see cref="AntennaRange.ProtoDataTransmitter"/> class.
-		/// </summary>
-		/// <param name="ms"><see cref="ProtoPartModuleSnapshot"/></param>
-		public AntennaRelay(Vessel v)
-		{
-			this.vessel = v;
-
-			// HACK: This might not be safe in all circumstances, but since AntennaRelays are not built until Start,
-			// we hope it is safe enough.
-			this.Kerbin = FlightGlobals.Bodies.FirstOrDefault(b => b.name == "Kerbin");
-		}
-
-		/*
-		 * Class implementing IComparer<IAntennaRelay> for use in sorting relays by distance.
-		 * */
-		internal class RelayComparer : IComparer<IAntennaRelay>
-		{
-			/// <summary>
-			/// The reference Vessel (usually the active vessel).
-			/// </summary>
-			protected Vessel referenceVessel;
-
-			// We don't want no stinking public parameterless constructors.
-			private RelayComparer() {}
-
-			/// <summary>
-			/// Initializes a new instance of the <see cref="AntennaRange.AntennaRelay+RelayComparer"/> class for use
-			/// in sorting relays by distance.
-			/// </summary>
-			/// <param name="reference">The reference Vessel</param>
-			public RelayComparer(Vessel reference)
-			{
-				this.referenceVessel = reference;
-			}
-
-			/// <summary>
-			/// Compare the <see cref="IAntennaRelay"/>s "one" and "two".
-			/// </summary>
-			/// <param name="one">The first IAntennaRelay in the comparison</param>
-			/// <param name="two">The second IAntennaRelay in the comparison</param>
-			public int Compare(IAntennaRelay one, IAntennaRelay two)
-			{
-				double distanceOne;
-				double distanceTwo;
-
-				distanceOne = one.vessel.DistanceTo(referenceVessel);
-				distanceTwo = two.vessel.DistanceTo(referenceVessel);
-
-				return distanceOne.CompareTo(distanceTwo);
-			}
+			if (this is ProtoAntennaRelay)
+			{
+				return (this as ProtoAntennaRelay).ToString();
+			}
+			return this.moduleRef.ToString();
+		}
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="AntennaRange.AntennaRelay"/> class.
+		/// </summary>
+		/// <param name="module">The module reference underlying this AntennaRelay,
+		/// as an <see cref="AntennaRange.IAntennaRelay"/></param>
+		public AntennaRelay(IAntennaRelay module)
+		{
+			this.moduleRef = module;
+			this.isChecked = false;
+
+			Tools.PostLogMessage("{0}: constructed {1}", this.GetType().Name, this.ToString());
 		}
 	}
 }