integration/Source/Integration/StringDecoder.h

#pragma once

#include "CoreMinimal.h"
#include "lpx-basebuffer.hpp"

#include "StringDecoder.generated.h"

class FlxStreamBufferCore {
private:
	bool err_eof_on_read_;
	bool err_string_too_long_;
	bool err_integer_truncated_;
protected:

    void *basebuffer_malloc(size_t size) { return malloc(size); }
    void basebuffer_free(void *p) { free(p); }
    void clear_error_flags() { err_eof_on_read_ = err_string_too_long_ = err_integer_truncated_ = false; }
	void raise_eof_on_read() { err_eof_on_read_ = true; }
    void raise_string_too_long() { err_string_too_long_ = true; }
	void raise_integer_truncated() { err_integer_truncated_ = true; }

public:
	bool get_err_eof_on_read() const { return err_eof_on_read_; }
	bool get_err_string_too_long() const { return err_string_too_long_; }
	bool get_err_integer_truncated() const { return err_integer_truncated_; }
	bool any_error() const { return err_eof_on_read_ || err_string_too_long_ || err_integer_truncated_; }
};

class FlxStreamBuffer : public BaseBuffer<FlxStreamBufferCore, std::string> {
public:
    using BaseBuffer::BaseBuffer;
    using BaseBuffer::write_string;

    void write_string(const FString &str) {
	    FTCHARToUTF8 utf8str(str);
        write_string(std::string_view(utf8str.Get(), utf8str.Length()));
    }

    void write_fname(const FName &name) {
	    FTCHARToUTF8 utf8str(name.ToString());
        write_string(std::string_view(utf8str.Get(), utf8str.Length()));
    }

    void write_string(const char *s) {
        write_string(std::string_view(s));
    }

    void write_fvector(const FVector &xyz) {
        write_double(xyz.X);
        write_double(xyz.Y);
        write_double(xyz.Z);
    }

    FVector read_fvector() {
        double x = read_double();
        double y = read_double();
        double z = read_double();
        return FVector(x, y, z);
    }

    FString read_fstring() {
        std::string_view s = read_string_view();
	    return FString(s.size(), (const UTF8CHAR *)s.data());
    }

    FName read_fname() {
        std::string_view s = read_string_view();
        return FName(s.size(), (const UTF8CHAR *)s.data(), FNAME_Add);
    }
};

/////////////////////////////////////////////////////////////////
//
// These are the types that can actually be packed into
// a serialized buffer.
//
/////////////////////////////////////////////////////////////////

UENUM(BlueprintType)
enum class ElxLuaValueType : uint8 {
    None,
    String,
	Name,
    Float,
    Boolean,
    Vector
};


/////////////////////////////////////////////////////////////////
//
// This class stores an array of values that were returned by Lua.
//
/////////////////////////////////////////////////////////////////

UCLASS(MinimalAPI)
class UlxLuaValues : public UObject
{
    GENERATED_BODY()

private:
    // The raw serialized data returned by Lua.
    //
    std::string Serialized;

    // For each chunk, the type of the chunk.
    //
    TArray<ElxLuaValueType> Types;

    // For each chunk, a pointer to the serialized data.
    //
    TArray<std::string_view> Data;

    // The current cursor.
    //
    int Cursor;

private:
    // Clear everything.
    //
    void Empty();

    // Compare two types.  If they aren't equal, log an error and return false.
    //
    static bool CheckType(ElxLuaValueType Type, ElxLuaValueType Desired);

public:
    UlxLuaValues() { Cursor = 0; }

    // Copies the data, and then preprocesses it to make sure
    // it's all valid.  If it's not valid, returns false.
    // 
    bool Initialize(std::string_view data);

    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
    FString DebugString() const;

    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
    int Length() const { return Types.Num(); }

    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
    int GetCursor() const { return Cursor; }

    UFUNCTION(BlueprintCallable, Category = "Luprex|Lua Value Array")
    void SetCursor(int n) { Cursor = n; }

    
private: 
    //
    // Functions that get values from the array, random access.
    //

    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
    ElxLuaValueType GetType(int n) const;
    
    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
    bool IsType(int n, ElxLuaValueType Type) const { return GetType(n) == Type; }
    
    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
    FString GetString(int n) const;
	
    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
	FName GetName(int n) const;
	
    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
	double GetFloat(int n) const;

    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
	int GetInt(int n) const;

    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
	FVector GetVector(int n) const;

    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
	FVector2D GetVector2D(int n) const;

    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
	bool GetBoolean(int n) const;

    //
    // Functions that get values from the array using the cursor.
    //

public:
    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
    ElxLuaValueType NextType() const { return GetType(Cursor); }
    
    UFUNCTION(BlueprintPure, Category = "Luprex|Lua Value Array")
    bool IsNextType(ElxLuaValueType Type) const { return IsType(Cursor, Type); }
    
    UFUNCTION(BlueprintCallable, Category = "Luprex|Lua Value Array")
    FString ReadString() { return GetString(Cursor++); }
	
    UFUNCTION(BlueprintCallable, Category = "Luprex|Lua Value Array")
	FName ReadName() { return GetName(Cursor++); }
	
    UFUNCTION(BlueprintCallable, Category = "Luprex|Lua Value Array")
	double ReadFloat() { return GetFloat(Cursor++); }

    UFUNCTION(BlueprintCallable, Category = "Luprex|Lua Value Array")
	int ReadInt() { return GetInt(Cursor++); }

    UFUNCTION(BlueprintCallable, Category = "Luprex|Lua Value Array")
	FVector ReadVector() { return GetVector(Cursor++); }

    UFUNCTION(BlueprintCallable, Category = "Luprex|Lua Value Array")
	FVector2D ReadVector2D() { return GetVector2D(Cursor++); }

    UFUNCTION(BlueprintCallable, Category = "Luprex|Lua Value Array")
	bool ReadBoolean() { return GetBoolean(Cursor++); }
};