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/*
  This code provide a templated matrix implementation
 */

#ifndef LBCRYPTO_MATH_MATRIX_H
#define LBCRYPTO_MATH_MATRIX_H

#include "lattice/lat-hal.h"

#include "math/distrgen.h"
#include "math/math-hal.h"
#include "math/nbtheory.h"

#include "utils/inttypes.h"
#include "utils/memory.h"
#include "utils/parallel.h"
#include "utils/serializable.h"
#include "utils/utilities.h"

#include <cmath>
#include <functional>
// #include <iostream>
#include <memory>
#include <string>
#include <utility>
#include <vector>

namespace lbcrypto {

// Forward declaration
class Field2n;

template <class Element>
class Matrix : public Serializable {
public:
    typedef std::vector<std::vector<Element>> data_t;
    typedef std::vector<Element> data_row_t;
    typedef std::function<Element(void)> alloc_func;

    /**
   * Constructor that initializes matrix values using a zero allocator
   *
   * @param &allocZero lambda function for zero initialization.
   * @param &rows number of rows.
   * @param &rows number of columns.
   */
    Matrix(alloc_func allocZero, size_t rows, size_t cols) : data(), rows(rows), cols(cols), allocZero(allocZero) {
        data.resize(rows);
        for (auto row = data.begin(); row != data.end(); ++row) {
            row->reserve(cols);
            for (size_t col = 0; col < cols; ++col) {
                row->push_back(allocZero());
            }
        }
    }

    // TODO: add Clear();

    /**
   * Constructor that initializes matrix values using a distribution generation
   * allocator
   *
   * @param &allocZero lambda function for zero initialization (used for
   * initializing derived matrix objects)
   * @param &rows number of rows.
   * @param &rows number of columns.
   * @param &allocGen lambda function for initialization using a distribution
   * generator.
   */
    Matrix(alloc_func allocZero, size_t rows, size_t cols, alloc_func allocGen);

    /**
   * Constructor of an empty matrix.
   * SetSize must be called on this matrix to use it
   * SetAlloc needs to be called if 0 passed to constructor
   * This mostly exists to support deserializing
   *
   * @param &allocZero lambda function for zero initialization.
   */
    explicit Matrix(alloc_func allocZero = 0) : data(), rows(0), cols(0), allocZero(allocZero) {}

    /**
   * Set the size of a matrix, elements are zeroed out
   *
   * @param rows number of rows
   * @param cols number of colums
   */

    void SetSize(size_t rows, size_t cols) {
        if (this->rows != 0 || this->cols != 0) {
            OPENFHE_THROW("You cannot SetSize on a non-empty matrix");
        }

        this->rows = rows;
        this->cols = cols;

        data.resize(rows);
        for (auto row = data.begin(); row != data.end(); ++row) {
            row->reserve(cols);
            for (size_t col = 0; col < cols; ++col) {
                row->push_back(allocZero());
            }
        }
    }

    /**
   * SetAllocator - set the function to allocate a zero;
   * basically only required for deserializer
   *
   * @param allocZero
   */
    void SetAllocator(alloc_func allocZero) {
        this->allocZero = allocZero;
    }

    /**
   * Copy constructor
   *
   * @param &other the matrix object to be copied
   */
    Matrix(const Matrix<Element>& other) : data(), rows(other.rows), cols(other.cols), allocZero(other.allocZero) {
        deepCopyData(other.data);
    }

    /**
   * Assignment operator
   *
   * @param &other the matrix object whose values are to be copied
   * @return the resulting matrix
   */
    Matrix<Element>& operator=(const Matrix<Element>& other);

    /**
   * In-place change of the current matrix to a matrix of all ones
   *
   * @return the resulting matrix
   */
    Matrix<Element>& Ones() {
        for (size_t row = 0; row < rows; ++row) {
            for (size_t col = 0; col < cols; ++col) {
                data[row][col] = 1;
            }
        }
        return *this;
    }

    /**
   * In-place modulo reduction
   *
   * @return the resulting matrix
   */
    Matrix<Element>& ModEq(const Element& modulus);

    /**
   * modular subtraction
   *
   * @return the resulting matrix
   */
    Matrix<Element>& ModSubEq(Matrix<Element> const& b, const Element& modulus);

    /**
   * Fill matrix using the same element
   *
   * @param &val the element the matrix is filled by
   *
   * @return the resulting matrix
   */
    Matrix<Element>& Fill(const Element& val);

    /**
   * In-place change of the current matrix to Identity matrix
   *
   * @return the resulting matrix
   */
    Matrix<Element>& Identity() {
        for (size_t row = 0; row < rows; ++row) {
            for (size_t col = 0; col < cols; ++col) {
                if (row == col) {
                    data[row][col] = 1;
                }
                else {
                    data[row][col] = 0;
                }
            }
        }
        return *this;
    }

    /**
   * Sets the first row to be powers of two for when the base is two
   *
   * @param base is the base the digits of the matrix are represented in
   * @return the resulting matrix
   */
    template <typename T                          = Element,
              typename std::enable_if<!std::is_same<T, M2DCRTPoly>::value && !std::is_same<T, M4DCRTPoly>::value &&
                                          !std::is_same<T, M6DCRTPoly>::value,
                                      bool>::type = true>
    Matrix<T> GadgetVector(int64_t base = 2) const {
        Matrix<T> g(allocZero, rows, cols);
        auto base_matrix = allocZero();
        size_t k         = cols / rows;
        base_matrix      = base;
        g(0, 0)          = 1;
        for (size_t i = 1; i < k; i++) {
            g(0, i) = g(0, i - 1) * base_matrix;
        }
        for (size_t row = 1; row < rows; row++) {
            for (size_t i = 0; i < k; i++) {
                g(row, i + row * k) = g(0, i);
            }
        }
        return g;
    }

    template <typename T                          = Element,
              typename std::enable_if<std::is_same<T, M2DCRTPoly>::value || std::is_same<T, M4DCRTPoly>::value ||
                                          std::is_same<T, M6DCRTPoly>::value,
                                      bool>::type = true>
    Matrix<T> GadgetVector(int64_t base = 2) const {
        Matrix<T> g(allocZero, rows, cols);
        auto base_matrix = allocZero();
        base_matrix      = base;
        size_t bk        = 1;

        auto params = g(0, 0).GetParams()->GetParams();

        uint64_t digitCount = (uint64_t)ceil(log2(params[0]->GetModulus().ConvertToDouble()) / log2(base));

        for (size_t k = 0; k < digitCount; k++) {
            for (size_t i = 0; i < params.size(); i++) {
                NativePoly temp(params[i]);
                temp = bk;
                g(0, k + i * digitCount).SetElementAtIndex(i, std::move(temp));
            }
            bk *= base;
        }

        size_t kCols = cols / rows;
        for (size_t row = 1; row < rows; row++) {
            for (size_t i = 0; i < kCols; i++) {
                g(row, i + row * kCols) = g(0, i);
            }
        }
        return g;
    }

    /**
   * Computes the infinity norm
   *
   * @return the norm in double format
   */
    template <typename T                          = Element,
              typename std::enable_if<std::is_same<T, double>::value || std::is_same<T, int>::value ||
                                          std::is_same<T, int64_t>::value || std::is_same<T, Field2n>::value,
                                      bool>::type = true>
    double Norm() const {
        OPENFHE_THROW("Norm not defined for this type");
    }

    template <typename T                          = Element,
              typename std::enable_if<!std::is_same<T, double>::value && !std::is_same<T, int>::value &&
                                          !std::is_same<T, int64_t>::value && !std::is_same<T, Field2n>::value,
                                      bool>::type = true>
    double Norm() const {
        double retVal = 0.0;
        double locVal = 0.0;
        for (size_t row = 0; row < rows; ++row) {
            for (size_t col = 0; col < cols; ++col) {
                locVal = data[row][col].Norm();
                if (locVal > retVal) {
                    retVal = locVal;
                }
            }
        }
        return retVal;
    }

    /**
   * Matrix multiplication
   *
   * @param &other the multiplier matrix
   * @return the result of multiplication
   */
    Matrix<Element> Mult(Matrix<Element> const& other) const;

    /**
   * Operator for matrix multiplication
   *
   * @param &other the multiplier matrix
   * @return the result of multiplication
   */
    Matrix<Element> operator*(Matrix<Element> const& other) const {
        return Mult(other);
    }

    /**
   * Multiplication of matrix by a scalar
   *
   * @param &other the multiplier element
   * @return the result of multiplication
   */
    Matrix<Element> ScalarMult(Element const& other) const {
        Matrix<Element> result(*this);
#pragma omp parallel for
        for (size_t col = 0; col < result.cols; ++col) {
            for (size_t row = 0; row < result.rows; ++row) {
                result.data[row][col] = result.data[row][col] * other;
            }
        }

        return result;
    }

    /**
   * Operator for scalar multiplication
   *
   * @param &other the multiplier element
   * @return the result of multiplication
   */
    Matrix<Element> operator*(Element const& other) const {
        return ScalarMult(other);
    }

    /**
   * Equality check
   *
   * @param &other the matrix object to compare to
   * @return the boolean result
   */
    bool Equal(Matrix<Element> const& other) const {
        if (rows != other.rows || cols != other.cols) {
            return false;
        }

        for (size_t i = 0; i < rows; ++i) {
            for (size_t j = 0; j < cols; ++j) {
                if (data[i][j] != other.data[i][j]) {
                    return false;
                }
            }
        }
        return true;
    }

    /**
   * Operator for equality check
   *
   * @param &other the matrix object to compare to
   * @return the boolean result
   */
    bool operator==(Matrix<Element> const& other) const {
        return Equal(other);
    }

    /**
   * Operator for non-equality check
   *
   * @param &other the matrix object to compare to
   * @return the boolean result
   */
    bool operator!=(Matrix<Element> const& other) const {
        return !Equal(other);
    }

    /**
   * Get property to access the data as a vector of vectors
   *
   * @return the data as vector of vectors
   */
    const data_t& GetData() const {
        return data;
    }

    /**
   * Get property to access the number of rows in the matrix
   *
   * @return the number of rows
   */
    size_t GetRows() const {
        return rows;
    }

    /**
   * Get property to access the number of columns in the matrix
   *
   * @return the number of columns
   */
    size_t GetCols() const {
        return cols;
    }

    /**
   * Get property to access the zero allocator for the matrix
   *
   * @return the lambda function corresponding to the element zero allocator
   */
    alloc_func GetAllocator() const {
        return allocZero;
    }

    /**
   * Sets the evaluation or coefficient representation for all ring elements
   * that support the SetFormat method
   *
   * @param &format the enum value corresponding to coefficient or evaluation
   * representation
   */
    void SetFormat(Format format);

    /**
   * Matrix addition
   *
   * @param &other the matrix to be added
   * @return the resulting matrix
   */
    Matrix<Element> Add(Matrix<Element> const& other) const {
        if (rows != other.rows || cols != other.cols) {
            OPENFHE_THROW("Addition operands have incompatible dimensions");
        }
        Matrix<Element> result(*this);
#pragma omp parallel for
        for (size_t j = 0; j < cols; ++j) {
            for (size_t i = 0; i < rows; ++i) {
                result.data[i][j] += other.data[i][j];
            }
        }
        return result;
    }

    /**
   * Operator for matrix addition
   *
   * @param &other the matrix to be added
   * @return the resulting matrix
   */
    Matrix<Element> operator+(Matrix<Element> const& other) const {
        return this->Add(other);
    }

    /**
   * Operator for in-place addition
   *
   * @param &other the matrix to be added
   * @return the resulting matrix (same object)
   */
    Matrix<Element>& operator+=(Matrix<Element> const& other);

    /**
   * Matrix substraction
   *
   * @param &other the matrix to be substracted
   * @return the resulting matrix
   */
    Matrix<Element> Sub(Matrix<Element> const& other) const {
        if (rows != other.rows || cols != other.cols) {
            OPENFHE_THROW("Subtraction operands have incompatible dimensions");
        }
        Matrix<Element> result(allocZero, rows, other.cols);
#pragma omp parallel for
        for (size_t j = 0; j < cols; ++j) {
            for (size_t i = 0; i < rows; ++i) {
                result.data[i][j] = data[i][j] - other.data[i][j];
            }
        }

        return result;
    }

    /**
   * Operator for matrix substraction
   *
   * @param &other the matrix to be substracted
   * @return the resulting matrix
   */
    Matrix<Element> operator-(Matrix<Element> const& other) const {
        return this->Sub(other);
    }

    /**
   * Operator for in-place matrix substraction
   *
   * @param &other the matrix to be substracted
   * @return the resulting matrix (same object)
   */
    Matrix<Element>& operator-=(Matrix<Element> const& other);

    /**
   * Matrix transposition
   *
   * @return the resulting matrix
   */
    Matrix<Element> Transpose() const;

    // YSP The signature of this method needs to be changed in the future
    /**
   * Matrix determinant - found using Laplace formula with complexity O(d!),
   * where d is the dimension
   *
   * @param *result where the result is stored
   */
    void Determinant(Element* result) const;
    // Element Determinant() const;

    /**
   * Cofactor matrix - the matrix of determinants of the minors A_{ij}
   * multiplied by -1^{i+j}
   *
   * @return the cofactor matrix for the given matrix
   */
    Matrix<Element> CofactorMatrix() const;

    /**
   * Add rows to bottom of the matrix
   *
   * @param &other the matrix to be added to the bottom of current matrix
   * @return the resulting matrix
   */
    Matrix<Element>& VStack(Matrix<Element> const& other);

    /**
   * Add columns the right of the matrix
   *
   * @param &other the matrix to be added to the right of current matrix
   * @return the resulting matrix
   */
    Matrix<Element>& HStack(Matrix<Element> const& other);

    /**
   * Matrix indexing operator - writeable instance of the element
   *
   * @param &row row index
   * @param &col column index
   * @return the element at the index
   */
    Element& operator()(size_t row, size_t col) {
        return data[row][col];
    }

    /**
   * Matrix indexing operator - read-only instance of the element
   *
   * @param &row row index
   * @param &col column index
   * @return the element at the index
   */
    Element const& operator()(size_t row, size_t col) const {
        return data[row][col];
    }

    /**
   * Matrix row extractor
   *
   * @param &row row index
   * @return the row at the index
   */
    Matrix<Element> ExtractRow(size_t row) const {
        Matrix<Element> result(this->allocZero, 1, this->cols);
        int i = 0;
        for (auto& elem : this->GetData()[row]) {
            result(0, i) = elem;
            i++;
        }
        return result;
        // return *this;
    }

    /**
   * Matrix column extractor
   *
   * @param &col col index
   * @return the col at the index
   */
    Matrix<Element> ExtractCol(size_t col) const {
        Matrix<Element> result(this->allocZero, this->rows, 1);
        for (size_t i = 0; i < this->rows; i++) {
            result(i, 0) = data[i][col];
        }
        return result;
        // return *this;
    }

    /**
   * Matrix rows extractor in a range from row_start to row_and; inclusive
   *
   * @param &row_start &row_end row indices
   * @return the rows in the range delimited by indices inclusive
   */
    inline Matrix<Element> ExtractRows(size_t row_start, size_t row_end) const {
        Matrix<Element> result(this->allocZero, row_end - row_start + 1, this->cols);

        for (usint row = row_start; row < row_end + 1; row++) {
            int i = 0;

            for (auto elem = this->GetData()[row].begin(); elem != this->GetData()[row].end(); ++elem) {
                result(row - row_start, i) = *elem;
                i++;
            }
        }

        return result;
    }

    friend std::ostream& operator<<(std::ostream& os, const Matrix<Element>& m) {
        os << "[ ";
        for (size_t row = 0; row < m.GetRows(); ++row) {
            os << "[ ";
            for (size_t col = 0; col < m.GetCols(); ++col) {
                os << m(row, col) << " ";
            }
            os << "]\n";
        }
        os << " ]\n";
        return os;
    }

    /**
   * Call switch format for each (ring) element
   *
   */
    void SwitchFormat();
#define NOT_AN_ELEMENT_MATRIX(T)                   \
    template <>                                    \
    void Matrix<T>::SwitchFormat() {               \
        OPENFHE_THROW("Not a matrix of Elements"); \
    }

    /*
   * Multiply the matrix by a vector whose elements are all 1's.  This causes
   * the elements of each row of the matrix to be added and placed into the
   * corresponding position in the output vector.
   */
    Matrix<Element> MultByUnityVector() const;

    /*
   * Multiply the matrix by a vector of random 1's and 0's, which is the same as
   * adding select elements in each row together. Return a vector that is a rows
   * x 1 matrix.
   */
    Matrix<Element> MultByRandomVector(std::vector<int> ranvec) const;

    template <class Archive>
    void save(Archive& ar, std::uint32_t const version) const {
        ar(::cereal::make_nvp("d", data));
        ar(::cereal::make_nvp("r", rows));
        ar(::cereal::make_nvp("c", cols));
    }

    template <class Archive>
    void load(Archive& ar, std::uint32_t const version) {
        if (version > SerializedVersion()) {
            OPENFHE_THROW("serialized object version " + std::to_string(version) +
                          " is from a later version of the library");
        }
        ar(::cereal::make_nvp("d", data));
        ar(::cereal::make_nvp("r", rows));
        ar(::cereal::make_nvp("c", cols));

        // users will need to SetAllocator for any newly deserialized matrix
    }

    std::string SerializedObjectName() const override {
        return "Matrix";
    }
    static uint32_t SerializedVersion() {
        return 1;
    }

private:
    data_t data;
    uint32_t rows;
    uint32_t cols;
    alloc_func allocZero;
    // mutable int NUM_THREADS = 1;

    // deep copy of data - used for copy constructor
    void deepCopyData(data_t const& src) {
        data.clear();
        data.resize(src.size());
        for (size_t row = 0; row < src.size(); ++row) {
            for (auto elem = src[row].begin(); elem != src[row].end(); ++elem) {
                data[row].push_back(*elem);
            }
        }
    }
};

/**
 * Operator for scalar multiplication of matrix
 *
 * @param &e element
 * @param &M matrix
 * @return the resulting matrix
 */
template <class Element>
Matrix<Element> operator*(Element const& e, Matrix<Element> const& M) {
    return M.ScalarMult(e);
}

/**
 * Generates a matrix of rotations. See pages 7-8 of
 * https://eprint.iacr.org/2013/297
 *
 * @param &inMat the matrix of power-of-2 cyclotomic ring elements to be rotated
 * @return the resulting matrix of big binary integers
 */
template <typename Element>
Matrix<typename Element::Integer> Rotate(Matrix<Element> const& inMat);

/**
 *  Each element becomes a square matrix with columns of that element's
 *  rotations in coefficient form. See pages 7-8 of
 * https://eprint.iacr.org/2013/297
 *
 * @param &inMat the matrix of power-of-2 cyclotomic ring elements to be rotated
 * @return the resulting matrix of big binary integers
 */
template <typename Element>
Matrix<typename Element::Vector> RotateVecResult(Matrix<Element> const& inMat);

/**
 *  Stream output operator
 *
 * @param &os stream
 * @param &m matrix to be outputted
 * @return the chained stream
 */
template <class Element>
std::ostream& operator<<(std::ostream& os, const Matrix<Element>& m);

/**
 * Gives the Choleshky decomposition of the input matrix.
 * The assumption is that covariance matrix does not have large coefficients
 * because it is formed by discrete gaussians e and s; this implies int32_t can
 * be used This algorithm can be further improved - see the Darmstadt paper
 * section 4.4 http://eprint.iacr.org/2013/297.pdf
 *
 * @param &input the matrix for which the Cholesky decomposition is to be
 * computed
 * @return the resulting matrix of floating-point numbers
 */
Matrix<double> Cholesky(const Matrix<int32_t>& input);

void Cholesky(const Matrix<int32_t>& input, Matrix<double>& result);

/**
 * Convert a matrix of integers from BigInteger to int32_t
 * Convert from Z_q to [-q/2, q/2]
 *
 * @param &input the input matrix
 * @param &modulus the ring modulus
 * @return the resulting matrix of int32_t
 */
Matrix<int32_t> ConvertToInt32(const Matrix<BigInteger>& input, const BigInteger& modulus);

/**
 * Convert a matrix of BigVector to int32_t
 * Convert from Z_q to [-q/2, q/2]
 *
 * @param &input the input matrix
 * @param &modulus the ring modulus
 * @return the resulting matrix of int32_t
 */
Matrix<int32_t> ConvertToInt32(const Matrix<BigVector>& input, const BigInteger& modulus);

/**
 * Split a vector of int32_t into a vector of ring elements with ring dimension
 * n
 *
 * @param &other the input matrix
 * @param &n the ring dimension
 * @param &params Poly element params
 * @return the resulting matrix of Poly
 */
template <typename Element>
Matrix<Element> SplitInt64IntoElements(Matrix<int64_t> const& other, size_t n,
                                       const std::shared_ptr<typename Element::Params> params);

#define SPLIT64_FOR_TYPE(T)                                                              \
    template <>                                                                          \
    Matrix<T> SplitInt64IntoElements(Matrix<int64_t> const& other, size_t n,             \
                                     const std::shared_ptr<typename T::Params> params) { \
        auto zero_alloc = T::Allocator(params, Format::COEFFICIENT);                     \
        size_t rows     = other.GetRows() / n;                                           \
        Matrix<T> result(zero_alloc, rows, 1);                                           \
        for (size_t row = 0; row < rows; ++row) {                                        \
            std::vector<int64_t> values(n);                                              \
            for (size_t i = 0; i < n; ++i)                                               \
                values[i] = other(row * n + i, 0);                                       \
            result(row, 0) = values;                                                     \
        }                                                                                \
        return result;                                                                   \
    }

/**
 * Another method for splitting a vector of int32_t into a vector of ring
 * elements with ring dimension n
 *
 * @param &other the input matrix
 * @param &n the ring dimension
 * @param &params Poly element params
 * @return the resulting matrix of Poly
 */
template <typename Element>
Matrix<Element> SplitInt32AltIntoElements(Matrix<int32_t> const& other, size_t n,
                                          const std::shared_ptr<typename Element::Params> params);

#define SPLIT32ALT_FOR_TYPE(T)                                                              \
    template <>                                                                             \
    Matrix<T> SplitInt32AltIntoElements(Matrix<int32_t> const& other, size_t n,             \
                                        const std::shared_ptr<typename T::Params> params) { \
        auto zero_alloc = T::Allocator(params, Format::COEFFICIENT);                        \
        size_t rows     = other.GetRows();                                                  \
        Matrix<T> result(zero_alloc, rows, 1);                                              \
        for (size_t row = 0; row < rows; ++row) {                                           \
            std::vector<int32_t> values(n);                                                 \
            for (size_t i = 0; i < n; ++i)                                                  \
                values[i] = other(row, i);                                                  \
            result(row, 0) = values;                                                        \
        }                                                                                   \
        return result;                                                                      \
    }

/**
 * Split a vector of int64_t into a vector of ring elements with ring dimension
 * n
 *
 * @param &other the input matrix
 * @param &n the ring dimension
 * @param &params Poly element params
 * @return the resulting matrix of Poly
 */
template <typename Element>
Matrix<Element> SplitInt64AltIntoElements(Matrix<int64_t> const& other, size_t n,
                                          const std::shared_ptr<typename Element::Params> params);

#define SPLIT64ALT_FOR_TYPE(T)                                                              \
    template <>                                                                             \
    Matrix<T> SplitInt64AltIntoElements(Matrix<int64_t> const& other, size_t n,             \
                                        const std::shared_ptr<typename T::Params> params) { \
        auto zero_alloc = T::Allocator(params, Format::COEFFICIENT);                        \
        size_t rows     = other.GetRows();                                                  \
        Matrix<T> result(zero_alloc, rows, 1);                                              \
        for (size_t row = 0; row < rows; ++row) {                                           \
            std::vector<int64_t> values(n);                                                 \
            for (size_t i = 0; i < n; ++i)                                                  \
                values[i] = other(row, i);                                                  \
            result(row, 0) = values;                                                        \
        }                                                                                   \
        return result;                                                                      \
    }

}  // namespace lbcrypto
#endif  // LBCRYPTO_MATH_MATRIX_H
