/********************************************************
 *  ██████╗  ██████╗████████╗██╗
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 *  ╚═════╝  ╚═════╝   ╚═╝   ╚══════╝
 * Geophysical Computational Tools & Library (GCTL)
 *
 * Copyright (c) 2023  Yi Zhang (yizhang-geo@zju.edu.cn)
 *
 * GCTL is distributed under a dual licensing scheme. You can redistribute 
 * it and/or modify it under the terms of the GNU Lesser General Public 
 * License as published by the Free Software Foundation, either version 2 
 * of the License, or (at your option) any later version. You should have 
 * received a copy of the GNU Lesser General Public License along with this 
 * program. If not, see <http://www.gnu.org/licenses/>.
 * 
 * If the terms and conditions of the LGPL v.2. would prevent you from using 
 * the GCTL, please consider the option to obtain a commercial license for a 
 * fee. These licenses are offered by the GCTL's original author. As a rule, 
 * licenses are provided "as-is", unlimited in time for a one time fee. Please 
 * send corresponding requests to: yizhang-geo@zju.edu.cn. Please do not forget 
 * to include some description of your company and the realm of its activities. 
 * Also add information on how to contact you by electronic and paper mail.
 ******************************************************/

#ifndef _GCTL_COMMON_GRADIENT_H
#define _GCTL_COMMON_GRADIENT_H

#include "lcg.h"

namespace gctl
{
    class common_gradient : public lcg_solver
    {
    public:
        common_gradient(); ///< 构造函数

        /**
         * @brief Construct a new common_gradient object
         * 
         * @param Ln Number of loss functions
         * @param Mn Number of model parameters
         */
        common_gradient(size_t Ln, size_t Mn);

        virtual ~common_gradient(); ///< 析构函数

        virtual void LCG_Ax(const array<double> &x, array<double> &ax); ///< 计算Ax

        /**
         * @brief Configure the solver's setups
         * 
         * @param para LCG solver parameters
         */
        void set_solver(const lcg_para &para);

        /**
         * @brief Set the weights for the loss functions.
         * 
         * The number of weights equal to the number of the loss functions.
         * The bigger weights is the calculated gradient is more dependent
         * on the corresponding gradients.
         */
        void set_weights(const _1d_array &w);

        /**
         * @brief Initialize the common_gradient object
         * 
         * @param Ln Number of loss functions
         * @param Mn Number of model parameters
         */
        void init(size_t Ln, size_t Mn);

        /**
         * @brief Fill the model gradient
         *
         * @param id Loss function index
         * @param fx Objective value
         * @param g Model gradient
         */
        void fill_model_gradient(size_t id, double fx, const _1d_array &g);

        /**
         * @brief Get the conflict free gradient
         * 
         * @param normalized Normalize the output gradient
         * @param fixed_w Fixed weights
         * @return Calculated model gradient
         */
        const _1d_array &get_common_gradient(bool normalized = true, bool fixed_w = true);

        /**
         * @brief Save the recorded weights.
         * 
         * @param file Output file name
         */
        void save_records(std::string file);

    private:
        bool zero_iter_;
        size_t Ln_, Mn_; // Ln_: loss_func number，Mn_: model number
        _2d_matrix G_; // kernel martix
        _1d_array B_, g_, t_, x_; // variables of the linear system
        _1d_array gm_, w_; // gradient module and functions' weight
        _1d_array fx_, fx0_; // functions' value, initial functions' value
        array<bool> filled_; // new gradient filled for the current round of evaluation
        std::vector<array<double> > rcd_wgts_; // weights records
        std::vector<array<double> > rcd_fxs_; // fx records
    };
};

#endif // _GCTL_COMMON_GRADIENT_H