5dplomacy/MultiversalDiplomacy/Model/Season.cs

173 lines
6.3 KiB
C#

namespace MultiversalDiplomacy.Model;
/// <summary>
/// Represents a state of the map produced by a set of move orders on a previous season.
/// </summary>
public class Season
{
/// <summary>
/// The first turn number.
/// </summary>
public const int FIRST_TURN = 0;
/// <summary>
/// The season immediately preceding this season.
/// If this season is an alternate timeline root, the past is from the origin timeline.
/// The initial season does not have a past.
/// </summary>
public Season? Past { get; }
/// <summary>
/// The current turn, beginning at 0. Each season (spring and fall) is one turn.
/// Phases that only occur after the fall phase occur when Turn % 2 == 1.
/// The current year is (Turn / 2) + 1901.
/// </summary>
public int Turn { get; }
/// <summary>
/// The timeline to which this season belongs.
/// </summary>
public string Timeline { get; }
/// <summary>
/// The season's spatial location as a timeline-turn tuple.
/// </summary>
public (string Timeline, int Turn) Coord => (this.Timeline, this.Turn);
/// <summary>
/// The shared timeline number generator.
/// </summary>
private TimelineFactory Timelines { get; }
/// <summary>
/// Future seasons created directly from this season.
/// </summary>
public IEnumerable<Season> Futures => this.FutureList;
private List<Season> FutureList { get; }
private Season(Season? past, int turn, string timeline, TimelineFactory factory)
{
this.Past = past;
this.Turn = turn;
this.Timeline = timeline;
this.Timelines = factory;
this.FutureList = [];
past?.FutureList.Add(this);
}
public override string ToString()
{
return $"{this.Timeline}@{this.Turn}";
}
/// <summary>
/// Create a root season at the beginning of time.
/// </summary>
public static Season MakeRoot()
{
TimelineFactory factory = new TimelineFactory();
return new Season(
past: null,
turn: FIRST_TURN,
timeline: factory.NextTimeline(),
factory: factory);
}
/// <summary>
/// Create a season immediately after this one in the same timeline.
/// </summary>
public Season MakeNext()
=> new(this, Turn + 1, Timeline, Timelines);
/// <summary>
/// Create a season immediately after this one in a new timeline.
/// </summary>
public Season MakeFork()
=> new(this, Turn + 1, Timelines.NextTimeline(), Timelines);
/// <summary>
/// Returns the first season in this season's timeline. The first season is the
/// root of the first timeline. The earliest season in each alternate timeline is
/// the root of that timeline.
/// </summary>
public Season TimelineRoot()
=> this.Past != null && this.Timeline == this.Past.Timeline
? this.Past.TimelineRoot()
: this;
/// <summary>
/// Returns whether this season is in an adjacent timeline to another season.
/// Seasons are considered to be in adjacent timelines if they are in the same timeline,
/// one is in a timeline that branched from the other's timeline, or both are in timelines
/// that branched from the same point.
/// </summary>
public bool InAdjacentTimeline(Season other)
{
// Timelines are adjacent to themselves. Early out in that case.
if (this.Timeline == other.Timeline) return true;
// If the timelines aren't identical, one of them isn't the initial trunk.
// They can still be adjacent if one of them branched off of the other, or
// if they both branched off of the same point.
Season thisRoot = this.TimelineRoot();
Season otherRoot = other.TimelineRoot();
return // One branched off the other
thisRoot.Past?.Timeline == other.Timeline
|| otherRoot.Past?.Timeline == this.Timeline
// Both branched off of the same point
|| thisRoot.Past == otherRoot.Past;
}
/// <summary>
/// Returns all seasons that are adjacent to this season.
/// </summary>
public IEnumerable<Season> GetAdjacentSeasons()
{
List<Season> adjacents = [];
// The immediate past and all immediate futures are adjacent.
if (this.Past != null) adjacents.Add(this.Past);
adjacents.AddRange(this.FutureList);
// Find all adjacent timelines by finding all timelines that branched off of this season's
// timeline, i.e. all futures of this season's past that have different timelines. Also
// include any timelines that branched off of the timeline this timeline branched off from.
List<Season> adjacentTimelineRoots = new();
Season? current;
for (current = this;
current?.Past?.Timeline != null && current.Past.Timeline == current.Timeline;
current = current.Past)
{
adjacentTimelineRoots.AddRange(
current.FutureList.Where(s => s.Timeline != current.Timeline));
}
// At the end of the for loop, if this season is part of the first timeline, then current
// is the root season (current.past == null); if this season is in a branched timeline,
// then current is the branch timeline's root season (current.past.timeline !=
// current.timeline). There are co-branches if this season is in a branched timeline, since
// the first timeline by definition cannot have co-branches.
if (current?.Past != null)
{
IEnumerable<Season> cobranchRoots = current.Past.FutureList
.Where(s => s.Timeline != current.Timeline && s.Timeline != current.Past.Timeline);
adjacentTimelineRoots.AddRange(cobranchRoots);
}
// Walk up all alternate timelines to find seasons within one turn of this season.
foreach (Season timelineRoot in adjacentTimelineRoots)
{
for (Season? branchSeason = timelineRoot;
branchSeason != null && branchSeason.Turn <= this.Turn + 1;
branchSeason = branchSeason.FutureList
.FirstOrDefault(s => s!.Timeline == branchSeason.Timeline, null))
{
if (branchSeason.Turn >= this.Turn - 1) adjacents.Add(branchSeason);
}
}
return adjacents;
}
}