/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2017 Pantelis Sopasakis (https://alphaville.github.io),
 *                    Krina Menounou (https://www.linkedin.com/in/krinamenounou), 
 *                    Panagiotis Patrinos (http://homes.esat.kuleuven.be/~ppatrino)
 * Copyright (c) 2012 Brendan O'Donoghue (bodonoghue85@gmail.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * 
 */
#ifndef LINSYS_H_GUARD
#define LINSYS_H_GUARD

#ifdef __cplusplus
extern "C" {
#endif

    /* 
     * YOUR LINEAR SYSTEM SOLVER MUST IMPLEMENT THESE METHODS AND scs_private_data
     * STRUCT 
     */

    /* 
     * private data structs (that you define) containing any necessary data to solve
     * linear system, etc. 
     */

    /* 
     * this defines the matrix A, only the linear system solver interacts with this
     * struct 
     */

    /**
     * Structure supporting sparse matrices in CSC format.
     * 
     * \sa \ref page_sparse_matrices "Sparse matrices documentation"
     */
    typedef struct scs_a_data_matrix ScsAMatrix;

    /** 
     * Stores the necessary private workspace, only the linear system solver
     * interacts with this struct 
     */
    typedef struct scs_private_data ScsPrivWorkspace;

    /** 
     * initialize scs_linsys_priv_workspace structure and perform any necessary preprocessing 
     */
    ScsPrivWorkspace *scs_init_priv(
            const ScsAMatrix *A,
            const ScsSettings *stgs);

    /** 
     * Solves <code>[d->RHO_X * I  A' ; A  -I] x = b</code> for <code>x</code>, 
     * stores result in <code>b</code>, <code>s</code> contains
     * warm-start, <code>iter</code> is current scs iteration count 
     * 
     * @param A sparse matrix A
     * @param stgs user-specified settings
     * @param p private structure
     * @param b right hand side
     * @param s initial guess
     * @param iter 
     * 
     * @return on success, returns 0
     */
    scs_int scs_solve_lin_sys(
            const ScsAMatrix *A,
            const ScsSettings *stgs,
            ScsPrivWorkspace *p,
            scs_float *b,
            const scs_float *s,
            scs_int iter);
    /** 
     * Frees scs_linsys_priv_workspace structure and allocated memory in it.
     */
    void scs_free_priv(ScsPrivWorkspace *p);

    /** 
     * Performs <code>y += A'*x</code>
     */
    void scs_accum_by_a_trans(
            const ScsAMatrix *A,
            ScsPrivWorkspace *p,
            const scs_float *x,
            scs_float *y);

    /** 
     * Performs <code>y += A*x</code>
     */
    void scs_accum_by_a(
            const ScsAMatrix *A,
            ScsPrivWorkspace *p,
            const scs_float *x,
            scs_float *y);

    /** 
     * Returns negative num if input data is invalid 
     */
    scs_int scs_validate_linsys(
            const ScsAMatrix *A);

    /** 
     * Returns string describing method, can return null, if not null free will be
     * called on output 
     */
    char *scs_get_linsys_method(
            const ScsAMatrix *A,
            const ScsSettings *stgs);

    /** 
     * Returns string containing summary information about linear system solves, can
     * return null, if not null free will be called on output 
     */
    char *scs_get_linsys_summary(
            ScsPrivWorkspace *p,
            const ScsInfo *info);

    /* Normalization routines, used if d->NORMALIZE is true */
    /** 
     * normalizes A matrix, sets <code>w->E</code> and <code>w->D</code> 
     * diagonal scaling matrices,<code>Anew = d->SCALE * (D^-1)*A*(E^-1)</code> 
     * (different to paper which is <code>D*A*E</code>) D and E must be all 
     * positive entries, D must satisfy cone boundaries must set 
     * (<code>w->meanNormRowA</code> = mean of norms of rows of normalized A) 
     * THEN scale resulting <code>A</code> by <code>d->SCALE</code>.
     */
    void scs_normalize_a(
            ScsAMatrix *A,
            const ScsSettings *stgs,
            const ScsCone *k,
            ScsScaling *scal);

    /** 
     * unnormalizes \c A matrix, unnormalizes by <code>w->D</code> and <code>w->E</code> 
     * and <code>d->SCALE</code>.
     */
    void scs_unnormalize_a(
            ScsAMatrix *A,
            const ScsSettings *stgs,
            const ScsScaling *scal);

    /** 
     * Frees the memory allocated in ScsAMatrix.
     */
    void scs_free_a_matrix(ScsAMatrix *A);
    
    /**
     * Whether the solution of the linear system is based on 
     * an indirect method.
     * 
     * @return \c 1 if indirect, \c 0 otherwise
     */
    scs_int scs_linsys_is_indirect(void);
    
    /**
     * Total number of CG iterations if an indirect method is used,
     * \c -1 otherwise
     * 
     * @param priv private workspace structure
     * @return total CG iterations
     */
    scs_int scs_linsys_total_cg_iters(ScsPrivWorkspace *priv);
    
    /**
     * Returns the total solve time for the linear system (in \c ms).
     * 
     * @param priv private workspace structure
     * @return solve time in \c ms
     */
    scs_float scs_linsys_total_solve_time_ms(ScsPrivWorkspace *priv);

#ifdef COPYAMATRIX

    /** 
     * copies <code>A</code> (instead of in-place normalization), returns 
     * <code>0</code> for failure, allocates memory for <code>dstp</code>.
     */
    scs_int scs_copy_a_matrix(
            ScsAMatrix **dstp,
            const ScsAMatrix *src);
#endif

#ifdef __cplusplus
}
#endif

#endif