/*++
Copyright (c) 2011 Microsoft Corporation

Module Name:

    simplify_tactic.cpp

Abstract:

    Apply simplification and rewriting rules.

Author:

    Leonardo (leonardo) 2011-11-20

Notes:

--*/
#include "tactic/core/simplify_tactic.h"
#include "ast/rewriter/th_rewriter.h"
#include "ast/ast_pp.h"

struct simplify_tactic::imp {
    ast_manager &   m_manager;
    th_rewriter     m_r;
    unsigned        m_num_steps;

    imp(ast_manager & m, params_ref const & p):
        m_manager(m),
        m_r(m, p),
        m_num_steps(0) {
    }

    ast_manager & m() const { return m_manager; }


    void reset() {
        m_r.reset();
        m_num_steps = 0;
    }

    void collect_statistics(statistics& st) {
        st.update("rewriter.steps", m_num_steps);
    }

    void operator()(goal & g) {
        tactic_report report("simplifier", g);
        m_num_steps = 0;
        if (g.inconsistent())
            return;
        expr_ref   new_curr(m());
        proof_ref  new_pr(m());
        unsigned size = g.size();
        for (unsigned idx = 0; idx < size; idx++) {
            if (g.inconsistent())
                break;
            expr * curr = g.form(idx);
            m_r(curr, new_curr, new_pr);
            m_num_steps += m_r.get_num_steps();
            if (g.proofs_enabled()) {
                proof * pr = g.pr(idx);
                new_pr     = m().mk_modus_ponens(pr, new_pr);
            }
            g.update(idx, new_curr, new_pr, g.dep(idx));
        }
        TRACE("simplifier", g.display(tout););
        g.elim_redundancies();
        TRACE("after_simplifier_detail", g.display_with_dependencies(tout););
    }

    unsigned get_num_steps() const { return m_num_steps; }
};

simplify_tactic::simplify_tactic(ast_manager & m, params_ref const & p):
    m_params(p) {
    m_imp = alloc(imp, m, p);
}

simplify_tactic::~simplify_tactic() {
    dealloc(m_imp);
}

void simplify_tactic::updt_params(params_ref const & p) {
    m_params.append(p);
    m_imp->m_r.updt_params(m_params);
}

void simplify_tactic::get_param_descrs(param_descrs & r) {
    th_rewriter::get_param_descrs(r);
}

void simplify_tactic::operator()(goal_ref const & in, 
                                 goal_ref_buffer & result) {
    try {
        (*m_imp)(*(in.get()));
        in->inc_depth();
        result.push_back(in.get());
        m_clean = false;
    }
    catch (rewriter_exception & ex) {
        throw tactic_exception(ex.what());
    }
}


void simplify_tactic::cleanup() {
    if (m_clean)
        return;
    ast_manager & m = m_imp->m();
    params_ref p = std::move(m_params);
    m_imp->~imp();
    new (m_imp) imp(m, p);
    m_clean = true;
}

void simplify_tactic::collect_statistics(statistics& st) const {
    if (m_imp)
        m_imp->collect_statistics(st);
}

unsigned simplify_tactic::get_num_steps() const {
    return m_imp->get_num_steps();
}

tactic * mk_simplify_tactic(ast_manager & m, params_ref const & p) {
    return clean(alloc(simplify_tactic, m, p));
}

tactic * mk_elim_and_tactic(ast_manager & m, params_ref const & p) {
    params_ref xp = p;
    xp.set_bool("elim_and", true);
    return using_params(mk_simplify_tactic(m, xp), xp);
}