## The bug
Any property getter reached from `GetProperties` that calls `InvalidateProperties` takes the tooltip build down with it:
```
System.ArgumentNullException: Value cannot be null. (Parameter 'array')
at Server.ObjectPropertyList.AppendStringDirect(String value)
at Server.Mobiles.PlayerMobile.GetProperties(IPropertyList list)
```
`InvalidateProperties` rebuilds **in place** — `Reset()`, then `GetProperties()` again on the same instance — and `Reset()` does two destructive things to a build already in flight:
1. **It returns the pooled interpolation buffer.** The compiler rents it in the handler ctor and returns it in the closing `Add`, so *every hole is evaluated while it is live*:
```csharp
var handler = new InterpolatedStringHandler(1, 2, list); // InitializeInterpolation() RENTS
handler.AppendFormatted(pl.Rank.Title); // <-- getter runs HERE
handler.AppendLiteral("\t");
handler.AppendFormatted(faction.Definition.PropName);
list.Add(1060776, ref handler); // consumes span, RETURNS
```
```
GetProperties(list)
├─ InitializeInterpolation() -> _arrayToReturnToPool = Rent(256) buffer LIVE
├─ « hole 1: pl.Rank.Title »
│ └─ PlayerState.Rank.get (lazy recompute)
│ └─ Invalidate() -> InvalidateProperties() -> m_PropertyList.Reset()
│ └─ Dispose(): Return(buf); _arrayToReturnToPool = null buffer GONE
└─ handler.AppendFormatted("Knight")
└─ _arrayToReturnToPool.AsSpan(_pos..)
└─ ArgumentNullException (Parameter 'array')
```
It surfaces as `ArgumentNullException` rather than `NullReferenceException` because the `Range` overload of `AsSpan` must read `array.Length`, so the BCL null-checks and names the parameter `array`.
2. **It rewinds the packet cursor**, so properties already written are overwritten by the nested pass — a silently corrupted tooltip even where the buffer survives.
## The fix: refuse, don't recover
There is no correct recovery, and retrying the build would only hide the defect. A nested invalidation now logs an error with a stack trace, **throws in `DEBUG`** so it gets found and fixed, and in `RELEASE` returns without touching the list — a possibly stale tooltip, but no crash, no corrupted packet, and nothing leaked back to the pool. Getters that genuinely must invalidate should defer:
```csharp
Timer.DelayCall(InvalidateProperties);
```
The guard flag lives on the `ObjectPropertyList`, not the entity: it is that list's own lifecycle, it costs nothing (both `Item` and `ObjectPropertyList` absorb it in existing padding, and the list is allocated lazily), and it stays correct when builds for different entities nest.
Base instance sizes are unchanged from `main`: Item 128 B, Mobile 792 B, ObjectPropertyList 72 B, PlayerMobile 1216 B.
`PropertyList` also publishes the list into `m_PropertyList` **before** building it rather than assigning through `??=` afterwards, so a nested `InvalidateProperties` sees the build in progress instead of recursing into a second throwaway list whose work is discarded.
`ObjectPropertyList` re-rents its scratch buffer instead of spanning a null array, so a stray `Reset()` from any other caller degrades rather than aborting `GetProperties`.
## Factions `PlayerState`: maintained, not lazily computed
The getter that surfaced this is now a plain field read — the whole `if (m_InvalidateRank)` block and the flag itself are gone:
```csharp
public RankDefinition Rank => m_Rank;
```
`UpdateRank()` recomputes at each point an input actually changes:
| Site | Why |
|---|---|
| `RankIndex` setter | this player's index changed |
| end of `KillPoints` setter | two paths write `m_RankIndex` directly, bypassing the setter; runs once the swap bookkeeping and `ZeroRankOffset` have settled |
| `Faction.AddMember` | *after* the insert — the member count is not settled during the ctor |
| `FactionState` load | once ordering and `ZeroRankOffset` are final |
Supporting fixes this forced out:
- **Both ctors seed the lowest rank.** Nothing recomputes on read any more, so `Rank` has to be usable immediately — including for members that never get a `RankIndex` assigned, which is *every member with no kill points*. Without this, `Rank.Title` NREs.
- **`Rank` always resolves.** Ranks are ordered by `Required` descending ending at `0`, so a *negative* percent (`RankIndex` out of sync with `ZeroRankOffset`) matched nothing and left `m_Rank` null. It no longer divides by a zero `ZeroRankOffset` either.
- **A pre-existing staleness bug.** The `KillPoints` setter writes `m_RankIndex` directly in two places, so the cached rank was never refreshed when a player crossed zero kill points.
All six readers of `Rank` were checked; none relied on the old side effect.
One behaviour change worth flagging: rank refreshes are now **eager** where they used to be lazy, so a `KillPoints` change invalidates each swapped player as it happens. The swap loops break as soon as ordering is satisfied — typically 0–2 swaps — but it is on the path that runs on every faction kill.
## Documentation
The rule is written down so it is enforceable rather than folklore:
- **CLAUDE.md** audit rule 19
- **`dev-docs/property-lists.md`** — new "Never Invalidate From Inside `GetProperties`" section with the failing/passing pattern
- **`dev-docs/claude-skills/modernuo-property-lists.md`** — key rule + anti-pattern
- **`dev-docs/claude-skills/modernuo-code-audit.md`** — rule 19, ERROR severity
## Tests
- `ObjectPropertyListReentrancyTests` — `Reset()` and `Dispose()` re-entered mid-hole (both red against `main` with the exact exception above), nesting behaviour, and the new contract: `DEBUG` throws, `RELEASE` survives, and the build is never retried into a loop.
- `FactionRankTests` — `Rank` is populated before anything reads it, tracks `RankIndex` without a read, is stable across reads, and still resolves when `RankIndex` is out of sync with `ZeroRankOffset`. Red-verified: removing the ctor seed fails the first one.
793/793 `Server.Tests` and 608/608 `UOContent.Tests` pass.
## Noted, not addressed here
`~ObjectPropertyList()` returns the rented array to `STArrayPool<char>.Shared` from the **finalizer thread**, and that pool is single-threaded by design. Left alone as a separate concern.
315 lines
8.1 KiB
C#
315 lines
8.1 KiB
C#
using System;
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using System.Collections.Generic;
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namespace Server.Factions;
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public class FactionState
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{
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private const int BroadcastsPerPeriod = 2;
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private static readonly TimeSpan BroadcastPeriod = TimeSpan.FromHours(1.0);
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private readonly Faction m_Faction;
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private readonly DateTime[] m_LastBroadcasts = new DateTime[BroadcastsPerPeriod];
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private Mobile m_Commander;
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public FactionState(Faction faction)
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{
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m_Faction = faction;
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Tithe = 50;
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Members = [];
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Election = new Election(faction);
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FactionItems = [];
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Traps = [];
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}
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public FactionState(IGenericReader reader)
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{
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var version = reader.ReadEncodedInt();
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switch (version)
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{
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case 5:
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{
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LastAtrophy = reader.ReadDateTime();
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goto case 4;
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}
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case 4:
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{
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var count = reader.ReadEncodedInt();
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for (var i = 0; i < count; ++i)
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{
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var time = reader.ReadDateTime();
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if (i < m_LastBroadcasts.Length)
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{
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m_LastBroadcasts[i] = time;
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}
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}
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goto case 3;
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}
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case 3:
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case 2:
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case 1:
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{
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Election = new Election(reader);
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goto case 0;
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}
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case 0:
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{
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m_Faction = Faction.ReadReference(reader);
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m_Commander = reader.ReadEntity<Mobile>();
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if (version < 5)
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{
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LastAtrophy = Core.Now;
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}
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if (version < 4)
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{
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var time = reader.ReadDateTime();
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if (m_LastBroadcasts.Length > 0)
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{
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m_LastBroadcasts[0] = time;
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}
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}
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Tithe = reader.ReadEncodedInt();
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Silver = reader.ReadEncodedInt();
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var memberCount = reader.ReadEncodedInt();
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Members = [];
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for (var i = 0; i < memberCount; ++i)
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{
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var pl = new PlayerState(reader, m_Faction, Members);
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if (pl.Mobile != null)
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{
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Members.Add(pl);
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}
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}
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m_Faction.State = this;
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m_Faction.ZeroRankOffset = Members.Count;
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Members.Sort();
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for (var i = Members.Count - 1; i >= 0; i--)
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{
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var player = Members[i];
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if (player.KillPoints <= 0)
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{
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m_Faction.ZeroRankOffset = i;
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}
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else
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{
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player.RankIndex = i;
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}
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}
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// The loop above only assigns RankIndex to members with kill points, and nothing
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// computes rank on read, so rank everyone now that the ordering has settled.
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foreach (var player in Members)
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{
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player.UpdateRank();
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}
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FactionItems = [];
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if (version >= 2)
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{
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var factionItemCount = reader.ReadEncodedInt();
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for (var i = 0; i < factionItemCount; ++i)
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{
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var factionItem = new FactionItem(reader, m_Faction);
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Timer.StartTimer(factionItem.CheckAttach); // sandbox attachment
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}
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}
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Traps = [];
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if (version >= 3)
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{
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var factionTrapCount = reader.ReadEncodedInt();
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for (var i = 0; i < factionTrapCount; ++i)
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{
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if (reader.ReadEntity<Item>() is BaseFactionTrap trap && !trap.CheckDecay())
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{
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Traps.Add(trap);
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}
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}
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}
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break;
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}
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}
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if (version < 1)
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{
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Election = new Election(m_Faction);
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}
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}
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public DateTime LastAtrophy { get; set; }
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public bool FactionMessageReady
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{
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get
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{
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for (var i = 0; i < m_LastBroadcasts.Length; ++i)
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{
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if (Core.Now >= m_LastBroadcasts[i] + BroadcastPeriod)
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{
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return true;
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}
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}
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return false;
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}
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}
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public bool IsAtrophyReady => Core.Now >= LastAtrophy + TimeSpan.FromHours(47.0);
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public List<FactionItem> FactionItems { get; set; }
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public List<BaseFactionTrap> Traps { get; set; }
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public Election Election { get; set; }
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public Mobile Commander
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{
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get => m_Commander;
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set
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{
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m_Commander?.InvalidateProperties();
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m_Commander = value;
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if (m_Commander != null)
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{
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m_Commander.SendLocalizedMessage(1042227); // You have been elected Commander of your faction
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m_Commander.InvalidateProperties();
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var pl = PlayerState.Find(m_Commander);
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if (pl?.Finance != null)
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{
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pl.Finance.Finance = null;
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}
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if (pl?.Sheriff != null)
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{
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pl.Sheriff.Sheriff = null;
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}
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}
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}
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}
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public int Tithe { get; set; }
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public int Silver { get; set; }
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public List<PlayerState> Members { get; set; }
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public int CheckAtrophy()
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{
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if (Core.Now < LastAtrophy + TimeSpan.FromHours(47.0))
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{
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return 0;
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}
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var distrib = 0;
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LastAtrophy = Core.Now;
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var members = new List<PlayerState>(Members);
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for (var i = 0; i < members.Count; ++i)
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{
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var ps = members[i];
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if (ps.IsActive)
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{
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ps.IsActive = false;
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continue;
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}
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if (ps.KillPoints > 0)
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{
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var atrophy = (ps.KillPoints + 9) / 10;
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ps.KillPoints -= atrophy;
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distrib += atrophy;
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}
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}
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return distrib;
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}
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public void RegisterBroadcast()
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{
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for (var i = 0; i < m_LastBroadcasts.Length; ++i)
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{
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if (Core.Now >= m_LastBroadcasts[i] + BroadcastPeriod)
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{
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m_LastBroadcasts[i] = Core.Now;
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break;
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}
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}
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}
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public void Serialize(IGenericWriter writer)
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{
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writer.WriteEncodedInt(5); // version
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writer.Write(LastAtrophy);
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writer.WriteEncodedInt(m_LastBroadcasts.Length);
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for (var i = 0; i < m_LastBroadcasts.Length; ++i)
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{
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writer.Write(m_LastBroadcasts[i]);
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}
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Election.Serialize(writer);
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Faction.WriteReference(writer, m_Faction);
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writer.Write(m_Commander);
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writer.WriteEncodedInt(Tithe);
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writer.WriteEncodedInt(Silver);
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writer.WriteEncodedInt(Members.Count);
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for (var i = 0; i < Members.Count; ++i)
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{
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var pl = Members[i];
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pl.Serialize(writer);
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}
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writer.WriteEncodedInt(FactionItems.Count);
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for (var i = 0; i < FactionItems.Count; ++i)
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{
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FactionItems[i].Serialize(writer);
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}
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writer.WriteEncodedInt(Traps.Count);
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for (var i = 0; i < Traps.Count; ++i)
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{
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writer.Write(Traps[i]);
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}
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}
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}
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