/*
 * libfud
 * Copyright 2024 Dominick Allen
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef FUD_STRING_HPP
#define FUD_STRING_HPP

#include "fud_status.hpp"
#include "fud_string_view.hpp"
#include "fud_utf8.hpp"

#include <climits>
#include <cstddef>

static_assert(CHAR_BIT == 8);

namespace fud {

constexpr size_t SSO_BUF_LENGTH = 15;
constexpr size_t SSO_BUF_SIZE = SSO_BUF_LENGTH + 1;

class String {
  public:
    String() = default;
    explicit String(const utf8* cString);
    explicit String(const char* cString);
    String(const String& rhs);
    String(String&& rhs);
    ~String();

    String& operator=(const String& rhs);
    String& operator=(String&& rhs);

    [[nodiscard]] constexpr size_t length() const
    {
        return m_length;
    }

    [[nodiscard]] constexpr bool empty() const
    {
        return m_length == 0;
    }

    [[nodiscard]] constexpr size_t size() const
    {
        return m_length + 1;
    }

    [[nodiscard]] constexpr size_t capacity() const
    {
        return m_capacity - 1;
    }

    /** \brier The underlying data, guaranteed to have c string representation. */
    [[nodiscard]] constexpr const utf8* data() const
    {
        return isLarge() ? m_data : m_buffer.data();
    }

    /** \brier The underlying data as an explicit c string. */
    [[nodiscard]] inline const char* c_str() const
    {
        return isLarge() ? reinterpret_cast<const char*>(m_data) : reinterpret_cast<const char*>(m_buffer.data());
    }

    /** \brier The underlying data, guaranteed to have c string representation. */
    [[nodiscard]] constexpr utf8* data()
    {
        return isLarge() ? m_data : m_buffer.data();
    }

    /** \brier The underlying data as an explicit c string. */
    [[nodiscard]] inline char* c_str()
    {
        return isLarge() ? reinterpret_cast<char*>(m_data) : reinterpret_cast<char*>(m_buffer.data());
    }

    [[nodiscard]] bool nullTerminated() const;

    [[nodiscard]] bool valid() const;

    [[nodiscard]] bool utf8Valid() const;

    FudStatus nullTerminate();

    FudStatus reserve(size_t newCapacity);

    [[nodiscard]] std::optional<utf8> back();

    [[nodiscard]] constexpr size_t remainingLength() const
    {
        if (m_length >= m_capacity) {
            return 0;
        }

        return m_capacity - 1U - m_length;
    }

    [[nodiscard]] inline StringView asView() const {
        return StringView(*this);
    }

    FudStatus pushBack(char letter);

    FudStatus pushBack(utf8 letter);

    FudStatus pushBack(const FudUtf8& letter);

    std::optional<utf8> pop();

    FudStatus append(const char* source);

    FudStatus append(const String& source);

    FudStatus append(StringView source);

    [[nodiscard]] String catenate(const String& rhs) const;

    [[nodiscard]] String catenate(const char* rhs) const;

    [[nodiscard]] bool compare(const String& rhs) const;

    const utf8* begin() const;

    const utf8* end() const;

  private:
    void cleanup();
    FudStatus resize(size_t newCapacity);

    using BufType = Array<utf8, SSO_BUF_SIZE>;
    union {
        BufType m_buffer{BufType::constFill(0)};
        utf8* m_data;
    };
    size_t m_length{0};
    size_t m_capacity{SSO_BUF_SIZE};

    [[nodiscard]] constexpr bool isLarge() const
    {
        return m_capacity > SSO_BUF_SIZE;
    }
};

} // namespace fud

#endif