## 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.
339 lines
No EOL
8.8 KiB
C#
339 lines
No EOL
8.8 KiB
C#
using System;
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using System.Collections.Generic;
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using Server.Mobiles;
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namespace Server.Factions;
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public class PlayerState : IComparable<PlayerState>
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{
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private Town m_Finance;
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private int m_KillPoints;
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private MerchantTitle m_MerchantTitle;
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private RankDefinition m_Rank;
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private int m_RankIndex = -1;
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private Town m_Sheriff;
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public PlayerState(Mobile mob, Faction faction, List<PlayerState> owner)
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{
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Mobile = mob;
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Faction = faction;
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Owner = owner;
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// Owner does not contain this state yet, so the count is short by one; the caller ranks it
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// after inserting.
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SeedLowestRank();
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Attach();
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Invalidate();
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}
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public PlayerState(IGenericReader reader, Faction faction, List<PlayerState> owner)
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{
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Faction = faction;
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Owner = owner;
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var version = reader.ReadEncodedInt();
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switch (version)
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{
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case 1:
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{
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IsActive = reader.ReadBool();
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LastHonorTime = reader.ReadDateTime();
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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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Mobile = reader.ReadEntity<Mobile>();
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m_KillPoints = reader.ReadEncodedInt();
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m_MerchantTitle = (MerchantTitle)reader.ReadEncodedInt();
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Leaving = reader.ReadDateTime();
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break;
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}
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}
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// Members are still being read; FactionState ranks everyone once the ordering settles.
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SeedLowestRank();
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Attach();
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}
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public Mobile Mobile { get; }
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public Faction Faction { get; }
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public List<PlayerState> Owner { get; }
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public MerchantTitle MerchantTitle
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{
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get => m_MerchantTitle;
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set
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{
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m_MerchantTitle = value;
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Invalidate();
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}
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}
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public Town Sheriff
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{
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get => m_Sheriff;
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set
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{
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m_Sheriff = value;
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Invalidate();
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}
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}
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public Town Finance
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{
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get => m_Finance;
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set
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{
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m_Finance = value;
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Invalidate();
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}
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}
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public List<SilverGivenEntry> SilverGiven { get; private set; }
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public int KillPoints
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{
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get => m_KillPoints;
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set
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{
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if (m_KillPoints != value)
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{
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if (value > m_KillPoints)
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{
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if (m_KillPoints <= 0)
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{
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if (value <= 0)
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{
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m_KillPoints = value;
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Invalidate();
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return;
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}
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Owner.Remove(this);
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Owner.Insert(Faction.ZeroRankOffset, this);
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// Direct, not through RankIndex: ZeroRankOffset is mid-update. The
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// UpdateRank() at the end of this setter covers it.
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m_RankIndex = Faction.ZeroRankOffset;
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Faction.ZeroRankOffset++;
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}
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while (m_RankIndex - 1 >= 0)
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{
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var p = Owner[m_RankIndex - 1];
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if (value > p.KillPoints)
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{
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Owner[m_RankIndex] = p;
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Owner[m_RankIndex - 1] = this;
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RankIndex--;
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p.RankIndex++;
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}
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else
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{
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break;
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}
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}
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}
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else
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{
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if (value <= 0)
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{
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if (m_KillPoints <= 0)
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{
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m_KillPoints = value;
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Invalidate();
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return;
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}
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while (m_RankIndex + 1 < Faction.ZeroRankOffset)
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{
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var p = Owner[m_RankIndex + 1];
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Owner[m_RankIndex + 1] = this;
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Owner[m_RankIndex] = p;
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RankIndex++;
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p.RankIndex--;
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}
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m_RankIndex = -1;
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Faction.ZeroRankOffset--;
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}
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else
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{
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while (m_RankIndex + 1 < Faction.ZeroRankOffset)
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{
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var p = Owner[m_RankIndex + 1];
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if (value < p.KillPoints)
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{
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Owner[m_RankIndex + 1] = this;
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Owner[m_RankIndex] = p;
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RankIndex++;
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p.RankIndex--;
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}
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else
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{
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break;
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}
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}
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}
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}
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m_KillPoints = value;
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UpdateRank();
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Invalidate();
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}
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}
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}
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public int RankIndex
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{
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get => m_RankIndex;
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set
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{
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if (m_RankIndex != value)
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{
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m_RankIndex = value;
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UpdateRank();
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Invalidate();
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}
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}
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}
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/// <summary>
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/// Read from PlayerMobile.GetProperties, so it must stay a plain field read -- recomputing or
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/// invalidating here re-enters the property list build. Maintained by <see cref="UpdateRank"/>.
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/// </summary>
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public RankDefinition Rank => m_Rank;
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// Lowest rank (Required 0): correct for an unranked member, and never null, so Rank.Title
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// cannot NRE before the first UpdateRank().
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private void SeedLowestRank()
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{
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var ranks = Faction.Definition.Ranks;
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if (ranks.Length > 0)
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{
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m_Rank = ranks[^1];
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}
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}
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/// <summary>
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/// Recomputes the cached rank. Call whenever <see cref="RankIndex"/>, the faction's
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/// ZeroRankOffset, or the member count changes -- and only once they have settled.
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/// </summary>
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public void UpdateRank()
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{
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var ranks = Faction.Definition.Ranks;
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if (ranks.Length == 0)
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{
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return;
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}
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int percent;
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if (Owner.Count == 1)
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{
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percent = 1000;
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}
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else if (m_RankIndex == -1 || Faction.ZeroRankOffset <= 0)
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{
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percent = 0;
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}
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else
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{
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percent = (Faction.ZeroRankOffset - m_RankIndex) * 1000 / Faction.ZeroRankOffset;
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}
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// Ranks run Required-descending ending at 0, so anything >= 0 matches below. A negative
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// percent (RankIndex out of sync with ZeroRankOffset) would otherwise leave it null.
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m_Rank = ranks[^1];
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for (var i = 0; i < ranks.Length; i++)
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{
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var check = ranks[i];
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if (percent >= check.Required)
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{
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m_Rank = check;
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break;
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}
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}
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}
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public DateTime LastHonorTime { get; set; }
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public DateTime Leaving { get; set; }
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public bool IsLeaving => Leaving > DateTime.MinValue;
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public bool IsActive { get; set; }
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public int CompareTo(PlayerState ps) => (ps?.m_KillPoints ?? 0) - m_KillPoints;
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public bool CanGiveSilverTo(Mobile mob)
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{
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for (var i = 0; i < SilverGiven?.Count; ++i)
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{
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var sge = SilverGiven[i];
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if (sge.IsExpired)
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{
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SilverGiven.RemoveAt(i--);
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}
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else if (sge.GivenTo == mob)
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{
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return false;
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}
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}
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return true;
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}
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public void OnGivenSilverTo(Mobile mob)
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{
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SilverGiven ??= [];
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SilverGiven.Add(new SilverGivenEntry(mob));
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}
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public void Invalidate()
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{
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(Mobile as PlayerMobile)?.InvalidateProperties();
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}
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public void Attach()
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{
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if (Mobile is PlayerMobile mobile)
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{
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mobile.FactionPlayerState = this;
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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(1); // version
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writer.Write(IsActive);
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writer.Write(LastHonorTime);
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writer.Write(Mobile);
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writer.WriteEncodedInt(m_KillPoints);
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writer.WriteEncodedInt((int)m_MerchantTitle);
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writer.Write(Leaving);
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}
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public static PlayerState Find(Mobile mob) => mob is PlayerMobile mobile ? mobile.FactionPlayerState : null;
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} |