/*

 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#include <AK/CharacterTypes.h>

#include <AK/FlyString.h>

#include <AK/HashTable.h>

#include <AK/Memory.h>

#include <AK/StdLibExtras.h>

#include <AK/StringHash.h>

#include <AK/StringImpl.h>

#include <AK/kmalloc.h>

namespace AK {

static StringImpl* s_the_empty_stringimpl = nullptr;

StringImpl& StringImpl::the_empty_stringimpl()

{

    if (!s_the_empty_stringimpl) {

        void* slot = kmalloc(sizeof(StringImpl) + sizeof(char));

        s_the_empty_stringimpl = new (slot) StringImpl(ConstructTheEmptyStringImpl);

    }

    return *s_the_empty_stringimpl;

}

StringImpl::StringImpl(ConstructWithInlineBufferTag, size_t length)

    : m_length(length)

{

}

StringImpl::~StringImpl()

{

    if (m_fly)

        FlyString::did_destroy_impl({}, *this);

}

NonnullRefPtr<StringImpl> StringImpl::create_uninitialized(size_t length, char*& buffer)

{

    VERIFY(length);

    void* slot = kmalloc(allocation_size_for_stringimpl(length));

    VERIFY(slot);

    auto new_stringimpl = adopt_ref(*new (slot) StringImpl(ConstructWithInlineBuffer, length));

    buffer = const_cast<char*>(new_stringimpl->characters());

    buffer[length] = '\0';

    return new_stringimpl;

}

RefPtr<StringImpl> StringImpl::create(char const* cstring, size_t length, ShouldChomp should_chomp)

{

    if (!cstring)

        return nullptr;

    if (should_chomp) {

        while (length) {

            char last_ch = cstring[length - 1];

            if (!last_ch || last_ch == '\n' || last_ch == '\r')

                --length;

            else

                break;

        }

    }

    if (!length)

        return the_empty_stringimpl();

    char* buffer;

    auto new_stringimpl = create_uninitialized(length, buffer);

    memcpy(buffer, cstring, length * sizeof(char));

    return new_stringimpl;

}

RefPtr<StringImpl> StringImpl::create(char const* cstring, ShouldChomp shouldChomp)

{

    if (!cstring)

        return nullptr;

    if (!*cstring)

        return the_empty_stringimpl();

    return create(cstring, strlen(cstring), shouldChomp);

}

RefPtr<StringImpl> StringImpl::create(ReadonlyBytes bytes, ShouldChomp shouldChomp)

{

    return StringImpl::create(reinterpret_cast<char const*>(bytes.data()), bytes.size(), shouldChomp);

}

RefPtr<StringImpl> StringImpl::create_lowercased(char const* cstring, size_t length)

{

    if (!cstring)

        return nullptr;

    if (!length)

        return the_empty_stringimpl();

    char* buffer;

    auto impl = create_uninitialized(length, buffer);

    for (size_t i = 0; i < length; ++i)

        buffer[i] = (char)to_ascii_lowercase(cstring[i]);

    return impl;

}

RefPtr<StringImpl> StringImpl::create_uppercased(char const* cstring, size_t length)

{

    if (!cstring)

        return nullptr;

    if (!length)

        return the_empty_stringimpl();

    char* buffer;

    auto impl = create_uninitialized(length, buffer);

    for (size_t i = 0; i < length; ++i)

        buffer[i] = (char)to_ascii_uppercase(cstring[i]);

    return impl;

}

NonnullRefPtr<StringImpl> StringImpl::to_lowercase() const

{

    for (size_t i = 0; i < m_length; ++i) {

        if (is_ascii_upper_alpha(characters()[i]))

            return create_lowercased(characters(), m_length).release_nonnull();

    }

    return const_cast<StringImpl&>(*this);

}

NonnullRefPtr<StringImpl> StringImpl::to_uppercase() const

{

    for (size_t i = 0; i < m_length; ++i) {

        if (is_ascii_lower_alpha(characters()[i]))

            return create_uppercased(characters(), m_length).release_nonnull();

    }

    return const_cast<StringImpl&>(*this);

}

unsigned StringImpl::case_insensitive_hash() const

{

    return case_insensitive_string_hash(characters(), length());

}

void StringImpl::compute_hash() const

{

    if (!length())

        m_hash = 0;

    else

        m_hash = string_hash(characters(), m_length);

    m_has_hash = true;

}

}