/*++
Copyright (c) 2017 Microsoft Corporation

Author:

    Lev Nachmanson (levnach)

Revision History:


--*/
#include <string>
#include "util/vector.h"
#include "math/lp/lar_core_solver.h"
#include "math/lp/lar_solution_signature.h"
namespace lp {
lar_core_solver::lar_core_solver(
    lp_settings & settings,
    const column_namer & column_names):
    m_infeasible_sum_sign(0),
    m_r_solver(m_r_A,
               m_right_sides_dummy,
               m_r_x,
               m_r_basis,
               m_r_nbasis,
               m_r_heading,
               m_costs_dummy,
               m_column_types(),
               m_r_lower_bounds(),
               m_r_upper_bounds(),
               settings,
               column_names),
    m_d_solver(m_d_A,
               m_d_right_sides_dummy,
               m_d_x,
               m_d_basis,
               m_d_nbasis,
               m_d_heading,
               m_d_costs_dummy,
               m_column_types(),
               m_d_lower_bounds,
               m_d_upper_bounds,
               settings,
               column_names) {
}    
    
    

void lar_core_solver::calculate_pivot_row(unsigned i) {
    m_r_solver.calculate_pivot_row(i);
}



void lar_core_solver::prefix_r() {
    if (!m_r_solver.m_settings.use_tableau()) {
        m_r_solver.m_copy_of_xB.resize(m_r_solver.m_n());
        m_r_solver.m_ed.resize(m_r_solver.m_m());
        m_r_solver.m_pivot_row.resize(m_r_solver.m_n()); 
        m_r_solver.m_pivot_row_of_B_1.resize(m_r_solver.m_m());
        m_r_solver.m_w.resize(m_r_solver.m_m());
        m_r_solver.m_y.resize(m_r_solver.m_m());
        m_r_solver.m_rows_nz.resize(m_r_solver.m_m(), 0);
        m_r_solver.m_columns_nz.resize(m_r_solver.m_n(), 0); 
        init_column_row_nz_for_r_solver();
    }

    m_r_solver.m_b.resize(m_r_solver.m_m());
    if (m_r_solver.m_settings.simplex_strategy() != simplex_strategy_enum::tableau_rows) {
        if(m_r_solver.m_settings.use_breakpoints_in_feasibility_search)
            m_r_solver.m_breakpoint_indices_queue.resize(m_r_solver.m_n());
        m_r_solver.m_costs.resize(m_r_solver.m_n());
        m_r_solver.m_d.resize(m_r_solver.m_n());
        m_r_solver.set_using_infeas_costs(true);
    }
}

void lar_core_solver::prefix_d() {
    m_d_solver.m_b.resize(m_d_solver.m_m());
    m_d_solver.m_breakpoint_indices_queue.resize(m_d_solver.m_n());
    m_d_solver.m_copy_of_xB.resize(m_d_solver.m_n());
    m_d_solver.m_costs.resize(m_d_solver.m_n());
    m_d_solver.m_d.resize(m_d_solver.m_n());
    m_d_solver.m_ed.resize(m_d_solver.m_m());
    m_d_solver.m_pivot_row.resize(m_d_solver.m_n());
    m_d_solver.m_pivot_row_of_B_1.resize(m_d_solver.m_m());
    m_d_solver.m_w.resize(m_d_solver.m_m());
    m_d_solver.m_y.resize(m_d_solver.m_m());
    m_d_solver.m_steepest_edge_coefficients.resize(m_d_solver.m_n());
    m_d_solver.m_column_norms.clear();
    m_d_solver.m_column_norms.resize(m_d_solver.m_n(), 2);
    m_d_solver.clear_inf_set();
    m_d_solver.resize_inf_set(m_d_solver.m_n());
}

void lar_core_solver::fill_not_improvable_zero_sum_from_inf_row() {
    CASSERT("A_off", m_r_solver.A_mult_x_is_off() == false);
    unsigned bj = m_r_basis[m_r_solver.m_inf_row_index_for_tableau];
    m_infeasible_sum_sign =  m_r_solver.inf_sign_of_column(bj);
    m_infeasible_linear_combination.clear();
    for (auto & rc : m_r_solver.m_A.m_rows[m_r_solver.m_inf_row_index_for_tableau]) {
        m_infeasible_linear_combination.push_back(std::make_pair(rc.coeff(), rc.var()));
    }
}

void lar_core_solver::fill_not_improvable_zero_sum() {
    if (m_r_solver.m_settings.simplex_strategy() == simplex_strategy_enum::tableau_rows) {
        fill_not_improvable_zero_sum_from_inf_row();
        return;
    }
    //  reusing the existing mechanism for row_feasibility_loop
    m_infeasible_sum_sign = m_r_solver.m_settings.use_breakpoints_in_feasibility_search? -1 : 1;
    m_infeasible_linear_combination.clear();
    for (auto j : m_r_solver.m_basis) {
        const mpq & cost_j = m_r_solver.m_costs[j];
        if (!numeric_traits<mpq>::is_zero(cost_j)) {
            m_infeasible_linear_combination.push_back(std::make_pair(cost_j, j));
        }
    }
    // m_costs are expressed by m_d ( additional costs), substructing the latter gives 0
    for (unsigned j = 0; j < m_r_solver.m_n(); j++) {
        if (m_r_solver.m_basis_heading[j] >= 0) continue;
        const mpq & d_j = m_r_solver.m_d[j];
        if (!numeric_traits<mpq>::is_zero(d_j)) {
            m_infeasible_linear_combination.push_back(std::make_pair(-d_j, j));
        }
    }
}

unsigned lar_core_solver::get_number_of_non_ints() const {
    unsigned n = 0;
    for (auto & x : m_r_solver.m_x) {
        if (x.is_int() == false)
            n++;
    }
    return n;
}

void lar_core_solver::solve() {
    TRACE("lar_solver", tout << m_r_solver.get_status() << "\n";);
    lp_assert(m_r_solver.non_basic_columns_are_set_correctly());
    lp_assert(m_r_solver.inf_set_is_correct());
	TRACE("find_feas_stats", tout << "infeasibles = " << m_r_solver.inf_set_size() << ", int_infs = " << get_number_of_non_ints() << std::endl;);
	if (m_r_solver.current_x_is_feasible() && m_r_solver.m_look_for_feasible_solution_only) {
            m_r_solver.set_status(lp_status::OPTIMAL);
            TRACE("lar_solver", tout << m_r_solver.get_status() << "\n";);
            return;
	}
    ++settings().stats().m_need_to_solve_inf;
    CASSERT("A_off", !m_r_solver.A_mult_x_is_off());
    lp_assert((!settings().use_tableau()) || r_basis_is_OK());
    if (need_to_presolve_with_double_solver()) {
        TRACE("lar_solver", tout << "presolving\n";);
        prefix_d();
        lar_solution_signature solution_signature;
        vector<unsigned> changes_of_basis = find_solution_signature_with_doubles(solution_signature);
        if (m_d_solver.get_status() == lp_status::TIME_EXHAUSTED) {
            m_r_solver.set_status(lp_status::TIME_EXHAUSTED);
            return;
        }
        if (settings().use_tableau())
            solve_on_signature_tableau(solution_signature, changes_of_basis);
        else 
            solve_on_signature(solution_signature, changes_of_basis);

        lp_assert(!settings().use_tableau() || r_basis_is_OK());
    } else {
        if (!settings().use_tableau()) {
            TRACE("lar_solver", tout << "no tablau\n";);
            bool snapped = m_r_solver.snap_non_basic_x_to_bound();   
            lp_assert(m_r_solver.non_basic_columns_are_set_correctly());
            if (snapped)
                m_r_solver.solve_Ax_eq_b();
        }
        if (m_r_solver.m_look_for_feasible_solution_only) //todo : should it be set?
            m_r_solver.find_feasible_solution();
        else {
            m_r_solver.solve();
        }
        lp_assert(!settings().use_tableau() || r_basis_is_OK());
    }
    if (m_r_solver.get_status() == lp_status::INFEASIBLE) {
        fill_not_improvable_zero_sum();
    } 
    else if (m_r_solver.get_status() != lp_status::UNBOUNDED) {
        m_r_solver.set_status(lp_status::OPTIMAL);
    }
    lp_assert(r_basis_is_OK());
    lp_assert(m_r_solver.non_basic_columns_are_set_correctly());
    lp_assert(m_r_solver.inf_set_is_correct());

    TRACE("lar_solver", tout << m_r_solver.get_status() << "\n";);
}


}