// Copyright (c) 2016, the SDSL Project Authors.  All rights reserved.
// Please see the AUTHORS file for details.  Use of this source code is governed
// by a BSD license that can be found in the LICENSE file.
/*! \file rank_support_v5.hpp
    \brief rank_support_v5.hpp contains rank_support_v5.5
    \author Simon Gog
*/
#ifndef INCLUDED_SDSL_RANK_SUPPORT_VFIVE
#define INCLUDED_SDSL_RANK_SUPPORT_VFIVE

#include "rank_support.hpp"

//! Namespace for the succinct data structure library.
namespace sdsl {

template <uint8_t, uint8_t>
struct rank_support_trait;

//! A class supporting rank queries in constant time.
/*! \par Space complexity
 *  \f$ 0.0625n\f$ bits for a bit vector of length n bits.
 *
 * The superblock size is 2048. Each superblock is subdivided into
 * 2048/(6*64) = 5 blocks (with some bit remaining). So absolute counts for
 * the superblock add 64/2048 bits on top of each supported bit. Since the
 * first of the 6 relative count values is 0, we can fit the remaining 5
 * (each of width log(2048)=11) in a 64 bit word. The relative counts add
 * another 64/2048 bits bits on top of each supported bit. In total this
 * results in 128/2048= 6.25% overhead.
 *
 * \tparam t_b       Bit pattern `0`,`1`,`10`,`01` which should be ranked.
 * \tparam t_pat_len Length of the bit pattern.
 *
 * @ingroup rank_support_group
 */
template <uint8_t t_b = 1, uint8_t t_pat_len = 1>
class rank_support_v5 : public rank_support {
private:
	static_assert(t_b == 1u or t_b == 0u or t_b == 10u or t_b == 11u,
				  "rank_support_v5: bit pattern must be `0`,`1`,`10` or `01` or `11`");
	static_assert(t_pat_len == 1u or t_pat_len == 2u,
				  "rank_support_v5: bit pattern length must be 1 or 2");

public:
	typedef bit_vector bit_vector_type;
	typedef rank_support_trait<t_b, t_pat_len> trait_type;
	enum { bit_pat = t_b };
	enum { bit_pat_len = t_pat_len };

private:
	//      basic block for interleaved storage of superblockrank and blockrank
	int_vector<64> m_basic_block;

public:
	explicit rank_support_v5(const bit_vector* v = nullptr)
	{
		set_vector(v);
		if (v == nullptr) {
			return;
		} else if (v->empty()) {
			m_basic_block = int_vector<64>(2, 0);
			return;
		}
		size_type basic_block_size = (((v->bit_size() + 63) >> 11) + 1) << 1;
		m_basic_block.resize(basic_block_size); // resize structure for basic_blocks
		if (m_basic_block.empty()) return;
		const uint64_t* data = m_v->data();
		size_type		i, j = 0;
		m_basic_block[0] = m_basic_block[1] = 0;

		uint64_t carry			  = trait_type::init_carry();
		uint64_t sum			  = trait_type::args_in_the_word(*data, carry);
		uint64_t second_level_cnt = 0;
		uint64_t cnt_words		  = 1;
		for (i = 1; i < ((m_v->bit_size() + 63) >> 6); ++i, ++cnt_words) {
			if (cnt_words == 32) {
				j += 2;
				m_basic_block[j - 1] = second_level_cnt;
				m_basic_block[j]	 = m_basic_block[j - 2] + sum;
				second_level_cnt = sum = cnt_words = 0;
			} else if ((cnt_words % 6) == 0) {
				// pack the prefix sum for each 6x64bit block into the second_level_cnt
				second_level_cnt |= sum << (60 - 12 * (cnt_words / 6)); //  48, 36, 24, 12, 0
			}
			sum += trait_type::args_in_the_word(*(++data), carry);
		}

		if ((cnt_words % 6) == 0) {
			second_level_cnt |= sum << (60 - 12 * (cnt_words / 6));
		}
		if (cnt_words == 32) {
			j += 2;
			m_basic_block[j - 1] = second_level_cnt;
			m_basic_block[j]	 = m_basic_block[j - 2] + sum;
			m_basic_block[j + 1] = 0;
		} else {
			m_basic_block[j + 1] = second_level_cnt;
		}
	}

	rank_support_v5(const rank_support_v5&) = default;
	rank_support_v5(rank_support_v5&&)		= default;
	rank_support_v5& operator=(const rank_support_v5&) = default;
	rank_support_v5& operator=(rank_support_v5&&) = default;

	size_type rank(size_type idx) const
	{
		assert(m_v != nullptr);
		assert(idx <= m_v->size());
		const uint64_t* p =
		m_basic_block.data() + ((idx >> 10) & 0xFFFFFFFFFFFFFFFEULL); // (idx/2048)*2
		//                     ( prefix sum of the 6x64bit blocks | (idx%2048)/(64*6) )
		size_type result = *p + ((*(p + 1) >> (60 - 12 * ((idx & 0x7FF) / (64 * 6)))) & 0x7FFULL) +
						   trait_type::word_rank(m_v->data(), idx);
		idx -= (idx & 0x3F);
		uint8_t to_do = ((idx >> 6) & 0x1FULL) % 6;
		--idx;
		while (to_do) {
			result += trait_type::full_word_rank(m_v->data(), idx);
			--to_do;
			idx -= 64;
		}
		return result;
	}

	inline size_type operator()(size_type idx) const { return rank(idx); }
	size_type							  size() const { return m_v->size(); }

	size_type
	serialize(std::ostream& out, structure_tree_node* v = nullptr, std::string name = "") const
	{
		size_type			 written_bytes = 0;
		structure_tree_node* child = structure_tree::add_child(v, name, util::class_name(*this));
		written_bytes += m_basic_block.serialize(out, child, "cumulative_counts");
		structure_tree::add_size(child, written_bytes);
		return written_bytes;
	}

	void load(std::istream& in, const bit_vector* v = nullptr)
	{
		set_vector(v);
		m_basic_block.load(in);
	}

	template <typename archive_t>
	void CEREAL_SAVE_FUNCTION_NAME(archive_t & ar) const
	{
		ar(CEREAL_NVP(m_basic_block));
	}

	template <typename archive_t>
	void CEREAL_LOAD_FUNCTION_NAME(archive_t & ar)
	{
		ar(CEREAL_NVP(m_basic_block));
	}

	bool operator==(const rank_support_v5& other) const noexcept
	{
		return m_basic_block == other.m_basic_block;
	}

	bool operator!=(const rank_support_v5& other) const noexcept
	{
		return !(*this == other);
	}

	void set_vector(const bit_vector* v = nullptr) { m_v = v; }
};

} // end namespace sds

#endif // end file
