/* file: collection.h */
/*******************************************************************************
* Copyright 2014-2021 Intel Corporation
*
* 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 __COLLECTION_H__
#define __COLLECTION_H__

#include <new>
#include "services/daal_shared_ptr.h"

namespace daal
{
namespace services
{
/**
 * \brief Contains version 1.0 of Intel(R) oneAPI Data Analytics Library interface.
 */
namespace interface1
{
/**
 * @ingroup memory
 * @{
 */

/**
 *  <a name="DAAL-CLASS-SERVICES__COLLECTION"></a>
 *  \brief   Class that implements functionality of the Collection container
 *  \tparam  T  Type of an object stored in the container
 */
template <class T>
class Collection
{
public:
    /**
     *  Default constructor. Sets the size and capacity to 0.
     */
    Collection() : _array(NULL), _size(0), _capacity(0) {}

    /**
     *  Constructor. Creates a collection with n empty elements
     *  \param[in] n Number of elements
     */
    explicit Collection(size_t n) : _array(NULL), _size(0), _capacity(0)
    {
        if (!resize(n))
        {
            return;
        }
        _size = n;
    }

    /**
     *  Constructor. Creates a collection from the array
     *  \param[in] n     Number of elements
     *  \param[in] array Array with elements
     */
    Collection(size_t n, const T * array) : _array(NULL), _size(0), _capacity(0)
    {
        if (!resize(n))
        {
            return;
        }
        for (size_t i = 0; i < n; i++)
        {
            _array[i] = array[i];
        }
        _size = n;
    }

    /**
     *  Copy constructor
     *  \param[in] other Copied collection
     */
    Collection(const Collection<T> & other) : _array(NULL), _size(0), _capacity(0)
    {
        if (!resize(other.capacity()))
        {
            return;
        }
        for (size_t i = 0; i < other.size(); i++)
        {
            this->push_back(other[i]);
        }
    }

    Collection & operator=(const Collection<T> & other)
    {
        if (!resize(other.capacity()))
        {
            return *this;
        }
        _size = 0;
        for (size_t i = 0; i < other.size(); i++)
        {
            this->push_back(other[i]);
        }
        return *this;
    }

    /**
     *  Destructor
     */
    virtual ~Collection()
    {
        for (size_t i = 0; i < _capacity; i++)
        {
            _array[i].~T();
        }

        services::daal_free(_array);
        _array = NULL;
    }

    /**
     *  Size of a collection
     *  \return Size of the collection
     */
    size_t size() const { return _size; }

    /**
     *  Size of an allocated storage
     *  \return Size of the allocated storage
     */
    size_t capacity() const { return _capacity; }

    /**
     *  Element access
     *  \param[in] index Index of an accessed element
     *  \return    Reference to the element
     */
    T & operator[](size_t index) { return _array[index]; }

    /**
    *  Const element access
    *  \param[in] index Index of an accessed element
    *  \return    Reference to the element
    */
    const T & operator[](size_t index) const { return _array[index]; }

    /**
     *  Element access
     *  \param[in] index Index of an accessed element
     *  \return    Reference to the element
     */
    T & get(size_t index) { return _array[index]; }

    /**
    *  Const element access
    *  \param[in] index Index of an accessed element
    *  \return    Reference to the element
    */
    const T & get(size_t index) const { return _array[index]; }

    /**
     *  Returns pointer to the underlying array serving as element storage
     *  \return Pointer to the array
     */
    T * data() { return _array; }

    /**
     *  Returns const pointer to the underlying array serving as element storage
     *  \return Const pointer to the array
     */
    const T * data() const { return _array; }

    /**
     *  Adds an element to the end of a collection
     *  \param[in] x Element to add
     */
    Collection & push_back(const T & x)
    {
        safe_push_back(x);
        return *this;
    }

    /**
     *  Adds an element to the end of a collection
     *  \param[in] x The element to add
     *  \return True if the element was successfully added
     */
    bool safe_push_back(const T & x)
    {
        if (_size >= _capacity)
        {
            if (!_resize())
            {
                return false;
            }
        }
        _array[_size] = x;
        _size++;

        return true;
    }

    /**
     *  Adds an element to the end of a collection
     *  \param[in] x Element to add
     */
    Collection & operator<<(const T & x) { return this->push_back(x); }

    /**
     *  Changes the size of a storage
     *  \param[in] newCapacity Size of a new storage.
     */
    bool resize(size_t newCapacity)
    {
        if (newCapacity <= _capacity)
        {
            return true;
        }
        T * newArray = (T *)services::daal_calloc(sizeof(T) * newCapacity);
        if (!newArray)
        {
            return false;
        }
        for (size_t i = 0; i < newCapacity; i++)
        {
            T * elementMemory = &(newArray[i]);
            ::new (elementMemory) T;
        }

        size_t minSize = newCapacity < _size ? newCapacity : _size;
        for (size_t i = 0; i < minSize; i++)
        {
            newArray[i] = _array[i];
        }

        for (size_t i = 0; i < _capacity; i++)
        {
            _array[i].~T();
        }

        services::daal_free(_array);
        _array    = newArray;
        _capacity = newCapacity;
        return true;
    }

    /**
     *  Clears a collection: removes an array, sets the size and capacity to 0
     */
    void clear()
    {
        for (size_t i = 0; i < _capacity; i++)
        {
            _array[i].~T();
        }

        services::daal_free(_array);

        _array    = NULL;
        _size     = 0;
        _capacity = 0;
    }

    /**
     *  Insert an element into a position
     *  \param[in] pos Position to set
     *  \param[in] x   Element to set
     */
    bool insert(const size_t pos, const T & x)
    {
        if (pos > this->size())
        {
            return true;
        }

        size_t newSize = 1 + this->size();
        if (newSize > _capacity)
        {
            if (!_resize())
            {
                return false;
            }
        }

        size_t tail = _size - pos;
        for (size_t i = 0; i < tail; i++)
        {
            _array[_size - i] = _array[_size - 1 - i];
        }
        _array[pos] = x;
        _size       = newSize;
        return true;
    }

    /**
     *  Insert a collection to another collection into a position
     *  \param[in] pos   Position to see
     *  \param[in] other Collection to set
     */
    bool insert(const size_t pos, Collection<T> & other)
    {
        if (pos > this->size())
        {
            return true;
        }

        size_t newSize = other.size() + this->size();
        if (newSize > _capacity)
        {
            if (!resize(newSize))
            {
                return false;
            }
        }

        size_t length = other.size();
        size_t tail   = _size - pos;
        for (size_t i = 0; i < tail; i++)
        {
            _array[_size + length - 1 - i] = _array[_size - 1 - i];
        }
        for (size_t i = 0; i < length; i++)
        {
            _array[pos + i] = other[i];
        }
        _size = newSize;
        return true;
    }

    /**
     *  Erase an element from a position
     *  \param[in] pos Position to erase
     */
    void erase(size_t pos)
    {
        if (pos >= this->size())
        {
            return;
        }

        _size--;

        for (size_t i = 0; i < _size - pos; i++)
        {
            _array[pos + i] = _array[pos + 1 + i];
        }
    }

private:
    static const size_t _default_capacity = 16;
    bool _resize()
    {
        size_t newCapacity = 2 * _capacity;
        if (_capacity == 0)
        {
            newCapacity = _default_capacity;
        }
        return resize(newCapacity);
    }

protected:
    T * _array;
    size_t _size;
    size_t _capacity;
};

/** @} */
} // namespace interface1

using interface1::Collection;

} // namespace services
} // namespace daal

#endif
