/**
 * @file RefString.h
 * @author apio (cloudapio.eu)
 * @brief Reference-counted, trivially-copyable, immutable string type.
 *
 * @copyright Copyright (c) 2024, the Luna authors.
 *
 */

#pragma once
#include <luna/Hash.h>
#include <luna/Result.h>
#include <luna/SharedPtr.h>
#include <luna/String.h>
#include <luna/StringView.h>
#include <stdarg.h>

class RefString
{
    typedef const char* ConstIterator;

  public:
    /* Constructs an empty String. */
    RefString();

    RefString(RefString&&);

    RefString(const RefString&);

    RefString& operator=(const RefString&);

    bool operator==(const RefString& other) const
    {
        return !compare(this, &other);
    }

    ~RefString() = default;

    /* Creates a copy of a specific segment of this String and returns it. */
    Result<RefString> substring(usize begin, usize size) const;

    /* Splits a String with a delimiter. */
    Result<Vector<RefString>> split(StringView delim) const
    {
        return view().ref_split(delim);
    }

    /* Splits a String into two parts with a delimiter. */
    Result<Vector<RefString>> split_once(char delim) const
    {
        return view().ref_split_once(delim);
    }

    /* Creates a single String consisting of a list of strings separated by a delimiter. */
    static Result<RefString> join(const Vector<RefString>& vec, StringView delim);

    /* Creates a single String consisting of a list of strings separated by a delimiter. */
    static Result<RefString> join(const Vector<StringView>& vec, StringView delim);

    static Result<RefString> format(StringView fmt, ...);
    static Result<RefString> vformat(StringView fmt, va_list ap);

    static Result<RefString> from_cstring(const char* str);
    static Result<RefString> from_string_view(StringView str);
    static Result<RefString> from_string(const String& str);

    static int compare(const RefString* a, const RefString* b);

    const char* chars() const;

    usize length() const
    {
        return m_string_data ? m_string_data->length : 0;
    }

    bool is_empty() const
    {
        return length() == 0;
    }

    StringView view() const
    {
        return { chars(), length() };
    }

    const char& operator[](usize) const;

    ConstIterator begin() const
    {
        return chars();
    }

    ConstIterator end() const
    {
        return begin() + length();
    }

  private:
    struct RefStringData : public Shareable
    {
        char* string { nullptr };
        usize length { 0 };

        RefStringData(char* s, usize l) : Shareable(), string(s), length(l)
        {
        }

        ~RefStringData()
        {
            if (string) free_impl(string);
        }
    };

    SharedPtr<RefStringData> m_string_data { nullptr };

    static Result<RefString> adopt(char* c_str);
    static Result<RefString> adopt(char* c_str, usize length);
};

template <> u64 hash(const RefString& value, u64 salt);