/*++
Copyright (c) 2012 Microsoft Corporation

Module Name:

    fpa2bv_rewriter.cpp

Abstract:

    Rewriter for converting FPA to BV

Author:

    Christoph (cwinter) 2012-02-09

Notes:

--*/


#include "ast/rewriter/rewriter_def.h"
#include "ast/fpa/fpa2bv_rewriter.h"
#include "params/fpa2bv_rewriter_params.hpp"


fpa2bv_rewriter_cfg::fpa2bv_rewriter_cfg(ast_manager & m, fpa2bv_converter & c, params_ref const & p) :
    m_manager(m),
    m_out(m),
    m_conv(c),
    m_bindings(m)
{
    updt_params(p);
    // We need to make sure that the manager has the BV plugin loaded.
    symbol s_bv("bv");
    if (!m_manager.has_plugin(s_bv))
        m_manager.register_plugin(s_bv, alloc(bv_decl_plugin));
}

void fpa2bv_rewriter_cfg::updt_local_params(params_ref const & _p) {
    fpa2bv_rewriter_params p(_p);
    bool v = p.hi_fp_unspecified();
    m_conv.set_unspecified_fp_hi(v);
}

void fpa2bv_rewriter_cfg::updt_params(params_ref const & p) {
    m_max_memory        = megabytes_to_bytes(p.get_uint("max_memory", UINT_MAX));
    m_max_steps         = p.get_uint("max_steps", UINT_MAX);
    updt_local_params(p);
}

bool fpa2bv_rewriter_cfg::max_steps_exceeded(unsigned num_steps) const {
    return num_steps > m_max_steps;
}


br_status fpa2bv_rewriter_cfg::reduce_app(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
    TRACE("fpa2bv_rw", tout << "func: " << f->get_name() << std::endl;
                       tout << "args: " << std::endl;
                       for (unsigned i = 0; i < num; i++)
                           tout << mk_ismt2_pp(args[i], m()) << std::endl;);

    if (num == 0 && f->get_family_id() == null_family_id && m_conv.is_float(f->get_range())) {
        m_conv.mk_const(f, result);
        return BR_DONE;
    }

    if (num == 0 && f->get_family_id() == null_family_id && m_conv.is_rm(f->get_range())) {
        m_conv.mk_rm_const(f, result);
        return BR_DONE;
    }

    if (m().is_eq(f)) {
        SASSERT(num == 2);
        TRACE("fpa2bv_rw", tout << "(= " << mk_ismt2_pp(args[0], m()) << " " <<
            mk_ismt2_pp(args[1], m()) << ")" << std::endl;);
        SASSERT(args[0]->get_sort() == args[1]->get_sort());
        sort * ds = f->get_domain()[0];
        if (m_conv.is_float(ds)) {
            m_conv.mk_eq(args[0], args[1], result);
            return BR_DONE;
        }
        else if (m_conv.is_rm(ds)) {
            result = m().mk_eq(args[0], args[1]);
            return BR_DONE;
        }
        return BR_FAILED;
    }
    else if (m().is_ite(f)) {
        SASSERT(num == 3);
        if (m_conv.is_float(args[1]) || m_conv.is_rm(args[1])) {
            m_conv.mk_ite(args[0], args[1], args[2], result);
            return BR_DONE;
        }
        return BR_FAILED;
    }
    else if (m().is_distinct(f)) {
        sort * ds = f->get_domain()[0];
        if (m_conv.is_float(ds) || m_conv.is_rm(ds)) {
            m_conv.mk_distinct(f, num, args, result);
            return BR_DONE;
        }
        return BR_FAILED;
    }

    if (m_conv.is_float_family(f)) {
        switch (f->get_decl_kind()) {
        case OP_FPA_RM_NEAREST_TIES_TO_AWAY:
        case OP_FPA_RM_NEAREST_TIES_TO_EVEN:
        case OP_FPA_RM_TOWARD_NEGATIVE:
        case OP_FPA_RM_TOWARD_POSITIVE:
        case OP_FPA_RM_TOWARD_ZERO: m_conv.mk_rounding_mode(f->get_decl_kind(), result); return BR_DONE;
        case OP_FPA_NUM: m_conv.mk_numeral(f, num, args, result); return BR_DONE;
        case OP_FPA_PLUS_INF: m_conv.mk_pinf(f, result); return BR_DONE;
        case OP_FPA_MINUS_INF: m_conv.mk_ninf(f, result); return BR_DONE;
        case OP_FPA_PLUS_ZERO: m_conv.mk_pzero(f, result); return BR_DONE;
        case OP_FPA_MINUS_ZERO: m_conv.mk_nzero(f, result); return BR_DONE;
        case OP_FPA_NAN: m_conv.mk_nan(f, result); return BR_DONE;
        case OP_FPA_ADD: m_conv.mk_add(f, num, args, result); return BR_DONE;
        case OP_FPA_SUB: m_conv.mk_sub(f, num, args, result); return BR_DONE;
        case OP_FPA_NEG: m_conv.mk_neg(f, num, args, result); return BR_DONE;
        case OP_FPA_MUL: m_conv.mk_mul(f, num, args, result); return BR_DONE;
        case OP_FPA_DIV: m_conv.mk_div(f, num, args, result); return BR_DONE;
        case OP_FPA_REM: m_conv.mk_rem(f, num, args, result); return BR_DONE;
        case OP_FPA_ABS: m_conv.mk_abs(f, num, args, result); return BR_DONE;
        case OP_FPA_MIN: m_conv.mk_min(f, num, args, result); return BR_DONE;
        case OP_FPA_MAX: m_conv.mk_max(f, num, args, result); return BR_DONE;
        case OP_FPA_FMA: m_conv.mk_fma(f, num, args, result); return BR_DONE;
        case OP_FPA_SQRT: m_conv.mk_sqrt(f, num, args, result); return BR_DONE;
        case OP_FPA_ROUND_TO_INTEGRAL: m_conv.mk_round_to_integral(f, num, args, result); return BR_DONE;
        case OP_FPA_EQ: m_conv.mk_float_eq(f, num, args, result); return BR_DONE;
        case OP_FPA_LT: m_conv.mk_float_lt(f, num, args, result); return BR_DONE;
        case OP_FPA_GT: m_conv.mk_float_gt(f, num, args, result); return BR_DONE;
        case OP_FPA_LE: m_conv.mk_float_le(f, num, args, result); return BR_DONE;
        case OP_FPA_GE: m_conv.mk_float_ge(f, num, args, result); return BR_DONE;
        case OP_FPA_IS_ZERO: m_conv.mk_is_zero(f, num, args, result); return BR_DONE;
        case OP_FPA_IS_NAN: m_conv.mk_is_nan(f, num, args, result); return BR_DONE;
        case OP_FPA_IS_INF: m_conv.mk_is_inf(f, num, args, result); return BR_DONE;
        case OP_FPA_IS_NORMAL: m_conv.mk_is_normal(f, num, args, result); return BR_DONE;
        case OP_FPA_IS_SUBNORMAL: m_conv.mk_is_subnormal(f, num, args, result); return BR_DONE;
        case OP_FPA_IS_POSITIVE: m_conv.mk_is_positive(f, num, args, result); return BR_DONE;
        case OP_FPA_IS_NEGATIVE: m_conv.mk_is_negative(f, num, args, result); return BR_DONE;
        case OP_FPA_TO_FP: m_conv.mk_to_fp(f, num, args, result); return BR_DONE;
        case OP_FPA_TO_FP_UNSIGNED: m_conv.mk_to_fp_unsigned(f, num, args, result); return BR_DONE;
        case OP_FPA_FP: m_conv.mk_fp(f, num, args, result); return BR_DONE;
        case OP_FPA_TO_UBV: m_conv.mk_to_ubv(f, num, args, result); return BR_DONE;
        case OP_FPA_TO_SBV: m_conv.mk_to_sbv(f, num, args, result); return BR_DONE;
        case OP_FPA_TO_REAL: m_conv.mk_to_real(f, num, args, result); return BR_DONE;
        case OP_FPA_TO_IEEE_BV: m_conv.mk_to_ieee_bv(f, num, args, result); return BR_DONE;

        case OP_FPA_BVWRAP:
        case OP_FPA_BV2RM:
                return BR_FAILED;

        default:
            TRACE("fpa2bv", tout << "unsupported operator: " << f->get_name() << "\n";
                  for (unsigned i = 0; i < num; i++) tout << mk_ismt2_pp(args[i], m()) << std::endl;);
            NOT_IMPLEMENTED_YET();
        }
    }
    else
    {
        SASSERT(!m_conv.is_float_family(f));
        if (m_conv.fu().contains_floats(f)) {
            m_conv.mk_uf(f, num, args, result);
            return BR_DONE;
        }
    }

    return BR_FAILED;
}

bool fpa2bv_rewriter_cfg::pre_visit(expr * t)
{
    TRACE("fpa2bv", tout << "pre_visit: " << mk_ismt2_pp(t, m()) << std::endl;);

    if (is_quantifier(t)) {
        quantifier * q = to_quantifier(t);
        TRACE("fpa2bv", tout << "pre_visit quantifier [" << q->get_id() << "]: " << mk_ismt2_pp(q->get_expr(), m()) << std::endl;);
        sort_ref_vector new_bindings(m_manager);
        for (unsigned i = 0 ; i < q->get_num_decls(); i++)
                new_bindings.push_back(q->get_decl_sort(i));
        SASSERT(new_bindings.size() == q->get_num_decls());
        m_bindings.append(new_bindings);
    }
    return true;
}


bool fpa2bv_rewriter_cfg::reduce_quantifier(
    quantifier * old_q,
    expr * new_body,
    expr * const * new_patterns,
    expr * const * new_no_patterns,
    expr_ref & result,
    proof_ref & result_pr) {
    if (is_lambda(old_q)) {
        return false;
    }
    unsigned curr_sz   = m_bindings.size();
    SASSERT(old_q->get_num_decls() <= curr_sz);
    unsigned num_decls = old_q->get_num_decls();
    unsigned old_sz    = curr_sz - num_decls;
    string_buffer<> name_buffer;
    ptr_buffer<sort> new_decl_sorts;
    sbuffer<symbol>  new_decl_names;
    for (unsigned i = 0; i < num_decls; i++) {
        symbol const & n = old_q->get_decl_name(i);
        sort * s         = old_q->get_decl_sort(i);
        if (m_conv.is_float(s)) {
            unsigned ebits = m_conv.fu().get_ebits(s);
            unsigned sbits = m_conv.fu().get_sbits(s);
            name_buffer.reset();
            name_buffer << n << ".bv";
            new_decl_names.push_back(symbol(name_buffer.c_str()));
            new_decl_sorts.push_back(m_conv.bu().mk_sort(sbits+ebits));
        }
        else if (m_conv.is_rm(s)) {
            name_buffer.reset();
            name_buffer << n << ".bv";
            new_decl_names.push_back(symbol(name_buffer.c_str()));
            new_decl_sorts.push_back(m_conv.bu().mk_sort(3));
        }
        else {
            new_decl_sorts.push_back(s);
            new_decl_names.push_back(n);
        }
    }
    result = m().mk_quantifier(old_q->get_kind(), new_decl_sorts.size(), new_decl_sorts.data(), new_decl_names.data(),
                               new_body, old_q->get_weight(), old_q->get_qid(), old_q->get_skid(),
                               old_q->get_num_patterns(), new_patterns, old_q->get_num_no_patterns(), new_no_patterns);
    result_pr = nullptr;
    if (m().proofs_enabled()) {
        result_pr = m().mk_rewrite(old_q, result);
    }
    m_bindings.shrink(old_sz);
    TRACE("fpa2bv", tout << "reduce_quantifier[" << old_q->get_depth() << "]: " <<
          mk_ismt2_pp(old_q->get_expr(), m()) << std::endl <<
          " new body: " << mk_ismt2_pp(new_body, m()) << std::endl;
          tout << "result = " << mk_ismt2_pp(result, m()) << std::endl;);
    return true;
}

bool fpa2bv_rewriter_cfg::reduce_var(var * t, expr_ref & result, proof_ref & result_pr) {
    if (t->get_idx() >= m_bindings.size())
        return false;
    // unsigned inx = m_bindings.size() - t->get_idx() - 1;

    expr_ref new_exp(m());
    sort * s = t->get_sort();
    if (m_conv.is_float(s)) {
        expr_ref new_var(m());
        unsigned ebits = m_conv.fu().get_ebits(s);
        unsigned sbits = m_conv.fu().get_sbits(s);
        new_var = m().mk_var(t->get_idx(), m_conv.bu().mk_sort(sbits+ebits));
        new_exp = m_conv.fu().mk_fp(m_conv.bu().mk_extract(sbits+ebits-1, sbits+ebits-1, new_var),
                                    m_conv.bu().mk_extract(ebits - 1, 0, new_var),
                                    m_conv.bu().mk_extract(sbits+ebits-2, ebits, new_var));
    }
    else if (m_conv.is_rm(s)) {
        expr_ref new_var(m());
        new_var = m().mk_var(t->get_idx(), m_conv.bu().mk_sort(3));
        new_exp = m_conv.fu().mk_bv2rm(new_var);
    }
    else
        new_exp = m().mk_var(t->get_idx(), s);

    result = new_exp;
    result_pr = nullptr;
    TRACE("fpa2bv", tout << "reduce_var: " << mk_ismt2_pp(t, m()) << " -> " << mk_ismt2_pp(result, m()) << std::endl;);
    return true;
}

template class rewriter_tpl<fpa2bv_rewriter_cfg>;

expr_ref fpa2bv_rewriter::convert_atom(th_rewriter& rw, expr * e) {
    TRACE("t_fpa_detail", tout << "converting atom: " << mk_ismt2_pp(e, m_cfg.m()) << std::endl;);
    expr_ref res(m_cfg.m());
    proof_ref pr(m_cfg.m());
    (*this)(e, res);
    rw(res, res);
    SASSERT(is_app(res));
    SASSERT(m_cfg.m().is_bool(res));
    return res;
}

expr_ref fpa2bv_rewriter::convert_term(th_rewriter& rw, expr * e) {
    SASSERT(fu().is_rm(e) || fu().is_float(e));
    ast_manager& m = m_cfg.m();
    
    expr_ref e_conv(m), res(m);
    proof_ref pr(m);
    
    (*this)(e, e_conv);
    
    TRACE("t_fpa_detail", tout << "term: " << mk_ismt2_pp(e, m) << std::endl;
          tout << "converted term: " << mk_ismt2_pp(e_conv, m) << std::endl;);
    
    if (fu().is_rm(e)) {
        SASSERT(fu().is_bv2rm(e_conv));
        expr_ref bv_rm(m);
        rw(to_app(e_conv)->get_arg(0), bv_rm);
        res = fu().mk_bv2rm(bv_rm);
    }
    else if (fu().is_float(e)) {
        SASSERT(fu().is_fp(e_conv));
        expr_ref sgn(m), sig(m), exp(m);
        m_cfg.m_conv.split_fp(e_conv, sgn, exp, sig);
        rw(sgn);
        rw(exp);
        rw(sig);
        res = fu().mk_fp(sgn, exp, sig);
    }
    else
        UNREACHABLE();
    
    return res;
}

expr_ref fpa2bv_rewriter::convert_conversion_term(th_rewriter& rw, expr * e) {
    SASSERT(to_app(e)->get_family_id() == fu().get_family_id());
    /* This is for the conversion functions fp.to_* */
    expr_ref res(m_cfg.m());
    (*this)(e, res);
    rw(res, res);
    return res;
}

expr_ref fpa2bv_rewriter::convert(th_rewriter& rw, expr * e) {
    ast_manager& m = m_cfg.m();
    expr_ref res(m);
    TRACE("t_fpa", tout << "converting " << mk_ismt2_pp(e, m) << std::endl;);
    
    if (fu().is_fp(e))
        res = e;
    else if (m.is_bool(e))
        res = convert_atom(rw, e);
    else if (fu().is_float(e) || fu().is_rm(e))
        res = convert_term(rw, e);
    else
        res = convert_conversion_term(rw, e);
    
    TRACE("t_fpa_detail", tout << "converted; caching:" << std::endl;
          tout << mk_ismt2_pp(e, m) << std::endl << " -> " << std::endl <<
          mk_ismt2_pp(res, m) << std::endl;);
    
    return res;
}