/** @file
 *****************************************************************************

 Declaration of interfaces for:
 - a R1CS constraint,
 - a R1CS variable assignment, and
 - a R1CS constraint system.

 See r1cs.hpp .

 *****************************************************************************
 * @author     This file is part of libsnark, developed by SCIPR Lab
 *             and contributors (see AUTHORS).
 * @copyright  MIT license (see LICENSE file)
 *****************************************************************************/

#ifndef R1CS_TCC_
#define R1CS_TCC_

#include "r1cs/r1cs.hpp"

#include <algorithm>
#include <cassert>
#include <set>
#include "common/utils.hpp"
#include "common/profiling.hpp"
#include "algebra/fields/bigint.hpp"

namespace libsnark {

template<typename FieldT>
r1cs_constraint<FieldT>::r1cs_constraint(const linear_combination<FieldT> &a,
                                         const linear_combination<FieldT> &b,
                                         const linear_combination<FieldT> &c) :
    a(a), b(b), c(c)
{
}

template<typename FieldT>
r1cs_constraint<FieldT>::r1cs_constraint(const std::initializer_list<linear_combination<FieldT> > A,
                                         const std::initializer_list<linear_combination<FieldT> > B,
                                         const std::initializer_list<linear_combination<FieldT> > C)
{
    for (auto lc_A : A)
    {
        a.terms.insert(a.terms.end(), lc_A.terms.begin(), lc_A.terms.end());
    }
    for (auto lc_B : B)
    {
        b.terms.insert(b.terms.end(), lc_B.terms.begin(), lc_B.terms.end());
    }
    for (auto lc_C : C)
    {
        c.terms.insert(c.terms.end(), lc_C.terms.begin(), lc_C.terms.end());
    }
}

template<typename FieldT>
bool r1cs_constraint<FieldT>::operator==(const r1cs_constraint<FieldT> &other) const
{
    return (this->a == other.a &&
            this->b == other.b &&
            this->c == other.c);
}

template<typename FieldT>
std::ostream& operator<<(std::ostream &out, const r1cs_constraint<FieldT> &c)
{
    out << c.a;
    out << c.b;
    out << c.c;

    return out;
}

template<typename FieldT>
std::istream& operator>>(std::istream &in, r1cs_constraint<FieldT> &c)
{
    in >> c.a;
    in >> c.b;
    in >> c.c;

    return in;
}

template<typename FieldT>
bool r1cs_constraint_system<FieldT>::is_valid() const
{
    if (this->num_inputs > this->num_vars) return false;

    for (size_t c = 0; c < constraints.size(); ++c)
    {
        if (!(constraints[c].a.is_valid(this->num_vars) &&
              constraints[c].b.is_valid(this->num_vars) &&
              constraints[c].c.is_valid(this->num_vars)))
        {
            return false;
        }
    }

    return true;
}

template<typename FieldT>
void dump_r1cs_constraint(const r1cs_constraint<FieldT> &c, const r1cs_variable_assignment<FieldT> &w,
                          const std::map<size_t, std::string> &variable_annotations)
{
    printf("terms for a:\n"); c.a.print_with_assignment(w, variable_annotations);
    printf("terms for b:\n"); c.b.print_with_assignment(w, variable_annotations);
    printf("terms for c:\n"); c.c.print_with_assignment(w, variable_annotations);
}

template<typename FieldT>
bool r1cs_constraint_system<FieldT>::is_satisfied(const r1cs_variable_assignment<FieldT> &w) const
{
    assert(w.size() == num_vars);

    for (size_t c = 0; c < constraints.size(); ++c)
    {
        FieldT ares = constraints[c].a.evaluate(w);
        FieldT bres = constraints[c].b.evaluate(w);
        FieldT cres = constraints[c].c.evaluate(w);
        if (!(ares*bres == cres))
        {
#ifdef DEBUG
            auto it = constraint_annotations.find(c);
            printf("constraint %zu (%s) unsatisfied\n", c, (it == constraint_annotations.end() ? "no annotation" : it->second.c_str()));
            printf("<a,(1,x)> = "); ares.print();
            printf("<b,(1,x)> = "); bres.print();
            printf("<c,(1,x)> = "); cres.print();
            printf("constraint was:\n");
            dump_r1cs_constraint(constraints[c], w, variable_annotations);
#endif // DEBUG
            return false;
        }
    }

    return true;
}

template<typename FieldT>
void r1cs_constraint_system<FieldT>::add_constraint(const r1cs_constraint<FieldT> &c)
{
    constraints.emplace_back(c);
}

template<typename FieldT>
void r1cs_constraint_system<FieldT>::add_constraint(const r1cs_constraint<FieldT> &c, const std::string &annotation)
{
#ifdef DEBUG
    constraint_annotations[constraints.size()] = annotation;
#endif
    constraints.emplace_back(c);
}

template<typename FieldT>
void r1cs_constraint_system<FieldT>::swap_AB_if_beneficial()
{
    enter_block("Call to r1cs_constraint_system::swap_AB_if_beneficial");

    enter_block("Estimate densities");
    bit_vector touched_by_A(this->num_vars + 1, false), touched_by_B(this->num_vars + 1, false);

    for (size_t i = 0; i < this->constraints.size(); ++i)
    {
        for (size_t j = 0; j < this->constraints[i].a.terms.size(); ++j)
        {
            touched_by_A[this->constraints[i].a.terms[j].index] = true;
        }

        for (size_t j = 0; j < this->constraints[i].b.terms.size(); ++j)
        {
            touched_by_B[this->constraints[i].b.terms[j].index] = true;
        }
    }

    size_t non_zero_A_count = 0, non_zero_B_count = 0;
    for (size_t i = 0; i < this->num_vars + 1; ++i)
    {
        non_zero_A_count += touched_by_A[i] ? 1 : 0;
        non_zero_B_count += touched_by_B[i] ? 1 : 0;
    }

    if (!inhibit_profiling_info)
    {
        print_indent(); printf("* Non-zero A-count (estimate): %zu\n", non_zero_A_count);
        print_indent(); printf("* Non-zero B-count (estimate): %zu\n", non_zero_B_count);
    }
    leave_block("Estimate densities");

    if (non_zero_B_count > non_zero_A_count)
    {
        enter_block("Perform the swap");
        for (size_t i = 0; i < this->constraints.size(); ++i)
        {
            std::swap(this->constraints[i].a, this->constraints[i].b);
        }
        leave_block("Perform the swap");
    }
    else
    {
        print_indent(); printf("Swap is not beneficial, not performing\n");
    }

    leave_block("Call to r1cs_constraint_system::swap_AB_if_beneficial");
}

template<typename FieldT>
bool r1cs_constraint_system<FieldT>::operator==(const r1cs_constraint_system<FieldT> &other) const
{
    return (this->constraints == other.constraints &&
            this->num_inputs == other.num_inputs &&
            this->num_vars == other.num_vars);
}

template<typename FieldT>
std::ostream& operator<<(std::ostream &out, const r1cs_constraint_system<FieldT> &cs)
{
    out << cs.num_inputs << "\n";
    out << cs.num_vars << "\n";

    out << cs.constraints.size() << "\n";
    for (const r1cs_constraint<FieldT>& c : cs.constraints)
    {
        out << c;
    }

    return out;
}

template<typename FieldT>
std::istream& operator>>(std::istream &in, r1cs_constraint_system<FieldT> &cs)
{
    in >> cs.num_inputs;
    in >> cs.num_vars;

    cs.constraints.clear();

    size_t s;
    in >> s;

    char b;
    in.read(&b, 1);

    cs.constraints.reserve(s);

    for (size_t i = 0; i < s; ++i)
    {
        r1cs_constraint<FieldT> c;
        in >> c;
        cs.constraints.emplace_back(c);
    }

    return in;
}

template<typename FieldT>
void r1cs_constraint_system<FieldT>::report_statistics() const
{
#ifdef DEBUG
    for (size_t i = 0; i < constraints.size(); ++i)
    {
        auto &constr = constraints[i];
        bool a_is_const = true;
        for (auto &t : constr.a.terms)
        {
            a_is_const = a_is_const && (t.index == 0);
        }

        bool b_is_const = true;
        for (auto &t : constr.b.terms)
        {
            b_is_const = b_is_const && (t.index == 0);
        }

        if (a_is_const || b_is_const)
        {
            auto it = constraint_annotations.find(i);
            printf("%s\n", (it == constraint_annotations.end() ? FORMAT("", "constraint_%zu", i) : it->second).c_str());
        }
    }
#endif
}

} // libsnark
#endif // R1CS_TCC_