feat(core): declare in-game command parser and dispatcher interface

core/include/vf/Command.h

@@ -0,0 +1,115 @@
+#pragma once
+
+#include <cstdint>
+#include <functional>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "Container.h"
+#include "Item.h"
+#include "Math.h"
+#include "Mob.h"
+#include "StructureGen.h"
+#include "Survival.h"
+#include "TimeOfDay.h"
+#include "Weather.h"
+#include "World.h"
+
+namespace vf {
+
+enum class GameRuleType : uint8_t { Bool, Int };
+
+struct GameRuleValue {
+    GameRuleType type = GameRuleType::Bool;
+    bool boolValue = false;
+    int intValue = 0;
+};
+
+class GameRules {
+public:
+    GameRules();
+
+    bool has(const std::string& name) const;
+    const GameRuleValue* find(const std::string& name) const;
+
+    bool boolValue(const std::string& name) const;
+    int intValue(const std::string& name) const;
+
+    bool setBool(const std::string& name, bool value);
+    bool setInt(const std::string& name, int value);
+
+    const std::vector<std::string>& names() const { return order; }
+
+private:
+    void define(const std::string& name, const GameRuleValue& value);
+
+    std::unordered_map<std::string, GameRuleValue> rules;
+    std::vector<std::string> order;
+};
+
+// Everything a command may read or mutate. References point at state owned by the
+// caller so command effects outlive a single dispatch. The Weather state machine
+// exposes no public setter, so a forced weather target is recorded on the context
+// for the world simulation to honour instead of being written into Weather.
+struct CommandContext {
+    World& world;
+    TimeOfDay& time;
+    Weather& weather;
+    Container& inventory;
+    SurvivalState& player;
+    std::vector<Creature>& creatures;
+    GameRules& rules;
+
+    Vec3 callerPos{0.0f, 0.0f, 0.0f};
+    uint32_t seed = 0u;
+
+    int worldMinY = 0;
+    int worldMaxY = 256;
+    int horizontalLimit = 30000000;
+    long long maxVolume = 32768;
+    int locateChunkRadius = 128;
+
+    bool weatherForced = false;
+    WeatherState forcedWeather = WeatherState::Clear;
+    long long forcedWeatherDuration = 0;
+};
+
+struct CommandResult {
+    bool ok = false;
+    std::string message;
+    int affected = 0;
+    bool hasPosition = false;
+    Vec3i position{0, 0, 0};
+};
+
+using CommandHandler = std::function<CommandResult(CommandContext&, const std::vector<std::string>&)>;
+
+class CommandDispatcher {
+public:
+    CommandDispatcher();
+
+    void registerCommand(const std::string& name, CommandHandler handler);
+    bool hasCommand(const std::string& name) const;
+    std::vector<std::string> commandNames() const;
+
+    CommandResult execute(CommandContext& context, const std::string& line) const;
+
+private:
+    std::unordered_map<std::string, CommandHandler> handlers;
+};
+
+std::vector<std::string> tokenizeCommand(const std::string& line);
+bool parseIntArg(const std::string& token, int& out);
+bool parseCoordArg(const std::string& token, int base, int& out);
+bool parseBlockName(const std::string& token, Block& out);
+bool parseItemName(const std::string& token, ItemId& out);
+bool parseSpeciesName(const std::string& token, Species& out);
+bool parseStructureName(const std::string& token, StructureGenKind& out);
+
+const char* blockDisplayName(Block block);
+const char* itemDisplayName(ItemId item);
+const char* speciesDisplayName(Species species);
+const char* structureDisplayName(StructureGenKind kind);
+
+} // namespace vf