#pragma once

#include "dtcore/inc/dtstream.h"

namespace dt
{
    struct _json_value;
    struct _json_object_entry;
    class JsonObjectEntry;

    enum class JsonType
    {
        None,
        Object,
        Array,
        Integer,
        UnsignedInteger,
        Double,
        String,
        Boolean,
        Null
    };

    //////////////////////////////////////////////////////////////////////////

    // This class serves as a wrapper over the _json_value object from the
    // Json library. It allows users to navigate through any type of Json
    // object. You can also manually build your own JsonValue object and 
    // then serialize it as a string.
    class JsonValue : public Serializable
    {
    public:
        // Default constructor. Creates an empty/null value.
        DT_CORE_DLL_ENTRY JsonValue();
        // Create a JsonValue object from a given string. 
        DT_CORE_DLL_ENTRY explicit JsonValue(const String& stringValue);
        DT_CORE_DLL_ENTRY explicit JsonValue(const char* stringValue);
        // Creates a JsonValue of Boolean type, with the given bool value.
        DT_CORE_DLL_ENTRY explicit JsonValue(bool boolVal);
        // Creates a JsonValue of Integer type, with the given integer value.
        DT_CORE_DLL_ENTRY explicit JsonValue(U64 intVal);
        DT_CORE_DLL_ENTRY explicit JsonValue(U32 intVal);
        DT_CORE_DLL_ENTRY explicit JsonValue(U16 intVal);
        DT_CORE_DLL_ENTRY explicit JsonValue(U8 intVal);
        DT_CORE_DLL_ENTRY explicit JsonValue(S64 intVal);
        DT_CORE_DLL_ENTRY explicit JsonValue(S32 intVal);
        DT_CORE_DLL_ENTRY explicit JsonValue(S16 intVal);
        DT_CORE_DLL_ENTRY explicit JsonValue(S8 intVal);
        // Creates a JsonValue of Double type, with the given double value.
        DT_CORE_DLL_ENTRY explicit JsonValue(double doubleVal);
        // Creates a JsonValue of Array type, with the content of the given Vector.
        DT_CORE_DLL_ENTRY explicit JsonValue(const Vector<JsonValue>& arrayVal);
        // Creates a JsonValue of Object type, with the content of the given Vector.
        DT_CORE_DLL_ENTRY explicit JsonValue(const Vector<JsonObjectEntry>& objectVal);
        // Copy constructor.
        DT_CORE_DLL_ENTRY JsonValue(const JsonValue& rhs);
        DT_CORE_DLL_ENTRY JsonValue(JsonValue&& rhs);

        DT_CORE_DLL_ENTRY ~JsonValue();

        // Copy operator.
        DT_CORE_DLL_ENTRY JsonValue& operator=(const JsonValue& rhs);
        // Comparison operators
        DT_CORE_DLL_ENTRY bool operator==(const JsonValue& rhs) const;
        DT_CORE_DLL_ENTRY bool operator!=(const JsonValue& rhs) const;
        DT_CORE_DLL_ENTRY bool operator<(const JsonValue& rhs) const;
        DT_CORE_DLL_ENTRY bool operator>(const JsonValue& rhs) const;
        DT_CORE_DLL_ENTRY bool operator>=(const JsonValue& rhs) const;
        DT_CORE_DLL_ENTRY bool operator<=(const JsonValue& rhs) const;
        DT_CORE_DLL_ENTRY bool operator^(const JsonValue& rhs) const; // contained, return true if all elements on the left are present on the right

        // Math operators
        DT_CORE_DLL_ENTRY JsonValue operator+(const JsonValue& rhs);
        DT_CORE_DLL_ENTRY JsonValue operator-(const JsonValue& rhs);
        DT_CORE_DLL_ENTRY JsonValue operator*(const JsonValue& rhs);
        DT_CORE_DLL_ENTRY JsonValue operator/(const JsonValue& rhs);
        DT_CORE_DLL_ENTRY JsonValue operator%(const JsonValue& rhs);

        // Parses a given Json expression and creates a JsonValue.
        // Returns true if the parsing has succeeded and false
        // otherwise.
        DT_CORE_DLL_ENTRY static bool Parse(const String& jsonString, JsonValue* out);

        // Checks if the current object is an empty/null object (no content).
        DT_CORE_DLL_ENTRY bool IsEmpty() const;
        // Returns the type of the current Json object.
        DT_CORE_DLL_ENTRY JsonType GetType() const;

        // Returns the boolean content of a Boolean type JsonValue.
        // Logs an error if the object type is not Boolean.
        DT_CORE_DLL_ENTRY bool GetBool() const;
        // Returns the integer content of an Integer type JsonValue.
        // Logs an error if the object type is not Integer.
        DT_CORE_DLL_ENTRY U64 GetU64() const;
        DT_CORE_DLL_ENTRY U32 GetU32() const;
        DT_CORE_DLL_ENTRY U16 GetU16() const;
        DT_CORE_DLL_ENTRY U8 GetU8() const;
        DT_CORE_DLL_ENTRY S64 GetS64() const;
        DT_CORE_DLL_ENTRY S32 GetS32() const;
        DT_CORE_DLL_ENTRY S16 GetS16() const;
        DT_CORE_DLL_ENTRY S8 GetS8() const;
        // Returns the double content of a Double type JsonValue.
        // Logs an error if the object type is not Double.
        DT_CORE_DLL_ENTRY double GetDouble() const;
        // Returns the string content of a String type JsonValue.
        // Logs an error if the object type is not String.
        DT_CORE_DLL_ENTRY String GetString() const;
        // Returns the number of members or length of an Object or Array type JsonValue.
        // Logs an error if the object type is not Object or Array.
        DT_CORE_DLL_ENTRY int GetLength() const;
        // Returns a value at a given index of an Array type JsonValue.
        // Logs an error if the object type is not Array.
        DT_CORE_DLL_ENTRY JsonValue GetArrayValue(unsigned int index) const;
        // Returns a member name and value tuple of an Object type JsonValue.
        // Logs an error if the object type is not Object.
        DT_CORE_DLL_ENTRY JsonObjectEntry GetObjectEntry(unsigned int index) const;
        // Returns a member name and value tuple of an Object type JsonValue.
        // Logs an error if the object type is not Object.
        DT_CORE_DLL_ENTRY JsonObjectEntry GetObjectEntry(const String& name) const;

        // Serializes the current object in a valid Json string.
        DT_CORE_DLL_ENTRY String ToString() const;

        // Serialize implementation override for the Serializable interface.
        DT_CORE_DLL_ENTRY virtual void Serialize(U8 version, Stream& stream) override;
        DT_CORE_DLL_ENTRY virtual U8 GetSerializeVersion() const override { return 2; }

    private:
        friend class JsonObjectEntry;
        friend class StreamJsonInput;

        JsonValue(_json_value* externalJsonValue);

        _json_value* GetExternalJsonValue() const { return m_ExternalJsonValue; }
        void FreeExternalJsonValue();

    private:
        _json_value* m_ExternalJsonValue;
        bool m_IsParsedValue;
    };

    // Stringify the Json value
    DT_CORE_DLL_ENTRY String& operator<<(String& out, const JsonValue& obj);

    //////////////////////////////////////////////////////////////////////////

    // A class that represents a wrapper on the Json library object _json_object_entry.
    // It's basically a <name, value> tuple representing a member of an Object type
    // JsonValue. This can be used for retrieving or creating an Object type JsonValue.
    class JsonObjectEntry
    {
    public:
        DT_CORE_DLL_ENTRY JsonObjectEntry(const String& name, const JsonValue& value);

        // Fetches the name of the Json Object member.
        DT_CORE_DLL_ENTRY const String& GetName() const { return m_Name; }
        // Fetches the Json value of the Json Object member.
        DT_CORE_DLL_ENTRY const JsonValue& GetValue() const { return m_Value; }

    private:
        friend JsonValue;

        JsonObjectEntry(const _json_object_entry& objEntry);

    private:
        String m_Name;
        JsonValue m_Value;
    };

}