/***********************************************************************************[SolverTypes.h]
 The MIT License (MIT)

 Copyright (c) 2014-2017, Sam Bayless
 Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
 Copyright (c) 2007-2010, Niklas Sorensson

 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 Monosat_SolverTypes_h
#define Monosat_SolverTypes_h

#include <cassert>

#include "monosat/mtl/IntTypes.h"
#include "monosat/mtl/Alg.h"
#include "monosat/mtl/Vec.h"
#include "monosat/mtl/IntMap.h"
#include "monosat/mtl/Map.h"
#include "monosat/mtl/Alloc.h"

namespace Monosat {

//=================================================================================================
// Variables, literals, lifted booleans, clauses:

// NOTE! Variables are just integers. No abstraction here. They should be chosen from 0..N,
// so that they can be used as array indices.

typedef int Var;
#define var_Undef (-1)
struct Lit;

Lit mkLit(Var var, bool sign = false);

struct Lit {
    int x;

    // Use this as a constructor:
    friend Lit mkLit(Var var, bool sign);

    bool operator==(Lit p) const{
        return x == p.x;
    }

    bool operator!=(Lit p) const{
        return x != p.x;
    }

    bool operator<(Lit p) const{
        return x < p.x;
    } // '<' makes p, ~p adjacent in the ordering.
};

inline Lit mkLit(Var var, bool sign){
    Lit p;
    p.x = var + var + (int) sign;
    return p;
}

inline Lit operator~(Lit p){
    Lit q;
    q.x = p.x ^ 1;
    return q;
}

inline Lit operator^(Lit p, bool b){
    Lit q;
    q.x = p.x ^ (unsigned int) b;
    return q;
}

inline bool sign(Lit p){
    return p.x & 1;
}

inline int var(Lit p){
    return p.x >> 1;
}

// Mapping Literals to and from compact integers suitable for array indexing:
inline int toInt(Var v){
    return v;
}

inline int toInt(Lit p){
    return p.x;
}

inline Lit toLit(int i){
    Lit p;
    p.x = i;
    return p;
}

inline int dimacs(Lit l){
    return sign(l) ? -(var(l) + 1) : (var(l) + 1);
}
//const Lit lit_Undef = mkLit(var_Undef, false);  // }- Useful special constants.
//const Lit lit_Error = mkLit(var_Undef, true );  // }

const Lit lit_Undef = {-2};  // }- Useful special constants.
const Lit lit_Error = {-1};  // }

struct MkIndexLit {
    int operator()(Lit l) const{return l.x;}
};

template<class T>
class VMap : public IntMap<Var, T> {
};

template<class T>
class LMap : public IntMap<Lit, T, MkIndexLit> {
};

class LSet : public IntSet<Lit, MkIndexLit> {
};

//=================================================================================================
// Lifted booleans:
//
// NOTE: this implementation is optimized for the case when comparisons between values are mostly
//       between one variable and one constant. Some care had to be taken to make sure that gcc 
//       does enough constant propagation to produce sensible code, and this appears to be somewhat
//       fragile unfortunately.

#define l_True  (lbool((uint8_t)0)) // gcc does not do constant propagation if these are real constants.
#define l_False (lbool((uint8_t)1))
#define l_Undef (lbool((uint8_t)2))

class lbool {
    uint8_t value;

public:
    explicit lbool(uint8_t v) :
            value(v){
    }

    lbool() :
            value(0){
    }

    explicit lbool(bool x) :
            value(!x){
    }

    bool operator==(lbool b) const{
        return ((b.value & 2) & (value & 2)) | (!(b.value & 2) & (value == b.value));
    }

    bool operator!=(lbool b) const{
        return !(*this == b);
    }

    lbool operator^(bool b) const{
        return lbool((uint8_t) (value ^ (uint8_t) b));
    }

    lbool operator&&(lbool b) const{
        uint8_t sel = (this->value << 1) | (b.value << 3);
        uint8_t v = (0xF7F755F4 >> sel) & 3;
        return lbool(v);
    }

    lbool operator||(lbool b) const{
        uint8_t sel = (this->value << 1) | (b.value << 3);
        uint8_t v = (0xFCFCF400 >> sel) & 3;
        return lbool(v);
    }

    friend int toInt(lbool l);

    friend lbool toLbool(int v);
};

inline int toInt(lbool l){
    return l.value;
}

inline lbool toLbool(int v){
    return lbool((uint8_t) v);
}

//=================================================================================================
// Clause -- a simple class for representing a clause:

class Clause;

typedef RegionAllocator<uint32_t>::Ref CRef;

class Clause {
    struct {
        unsigned mark :2;
        unsigned learnt :1;
        unsigned has_extra :1;
        unsigned reloced :1;
        unsigned derived :1;
        unsigned size :26;
    } header;
    union {
        Lit lit;
        float act;
        uint32_t abs;
        CRef rel;
    } data[0];

    friend class ClauseAllocator;

    // NOTE: This constructor cannot be used directly (doesn't allocate enough memory).
    template<class V>
    Clause(const V& ps, bool use_extra, bool learnt){
        header.mark = 0;
        header.learnt = learnt;
        header.has_extra = use_extra;
        header.reloced = 0;
        header.size = ps.size();
        header.derived = 0;

        for(int i = 0; i < ps.size(); i++)
            data[i].lit = ps[i];

        if(header.has_extra){
            if(header.learnt)
                data[header.size].act = 0;
            else
                calcAbstraction();
        }
    }

public:
    void calcAbstraction(){
        assert(header.has_extra);
        uint32_t abstraction = 0;
        for(int i = 0; i < size(); i++)
            abstraction |= 1 << (var(data[i].lit) & 31);
        data[header.size].abs = abstraction;
    }

    int size() const{
        return header.size;
    }

    //This is NOT safe. Only use this if it is guaranteed that the clause has enough extra allocated space
    void grow(int i){
        assert(i >= 0);
        if(header.has_extra)
            data[header.size + i] = data[header.size];
        header.size += i;
    }

    void shrink(int i){
        assert(i <= size());
        if(header.has_extra)
            data[header.size - i] = data[header.size];
        header.size -= i;
    }

    void pop(){
        shrink(1);
    }

    bool learnt() const{
        return header.learnt;
    }

    bool has_extra() const{
        return header.has_extra;
    }

    uint32_t mark() const{
        return header.mark;
    }

    void mark(uint32_t m){
        header.mark = m;
    }

    const Lit& last() const{
        return data[header.size - 1].lit;
    }

    bool derivedClause() const{
        return header.derived;
    }

    void setDerived(bool t){
        header.derived = t;
    }

    bool reloced() const{
        return header.reloced;
    }

    CRef relocation() const{
        return data[0].rel;
    }

    void relocate(CRef c){
        header.reloced = 1;
        data[0].rel = c;
    }

    // NOTE: somewhat unsafe to change the clause in-place! Must manually call 'calcAbstraction' afterwards for
    //       subsumption operations to behave correctly.
    Lit& operator[](int i){
        return data[i].lit;
    }

    Lit operator[](int i) const{
        return data[i].lit;
    }

    operator const Lit*(void) const{
        return (Lit*) data;
    }

    float& activity(){
        assert(header.has_extra);
        return data[header.size].act;
    }

    uint32_t abstraction() const{
        assert(header.has_extra);
        return data[header.size].abs;
    }

    Lit subsumes(const Clause& other) const;

    void strengthen(Lit p);

    //stl-style begin and end, to support C++11 range-based for loops
    const Lit* begin() const{
        return &data[0].lit;
    }

    const Lit* end() const{
        return &data[size()].lit;
    }
};

//=================================================================================================
// ClauseAllocator -- a simple class for allocating memory for clauses:

const CRef CRef_Undef = RegionAllocator<uint32_t>::Ref_Undef;

class ClauseAllocator : public RegionAllocator<uint32_t> {
    static int clauseWord32Size(int size, bool has_extra){
        return (sizeof(Clause) + (sizeof(Lit) * (size + (int) has_extra))) / sizeof(uint32_t);
    }

public:
    bool extra_clause_field;
    CRef marker_refs;

    CRef makeMarkerReference(){
        return --marker_refs;
    }

    bool isClause(const CRef& cr) const{
        return cr < marker_refs;
    }

    ClauseAllocator(uint32_t start_cap) :
            RegionAllocator<uint32_t>(start_cap), extra_clause_field(false), marker_refs(CRef_Undef){
    }

    ClauseAllocator() :
            extra_clause_field(false), marker_refs(CRef_Undef){
    }

    void moveTo(ClauseAllocator& to){
        to.extra_clause_field = extra_clause_field;
        RegionAllocator<uint32_t>::moveTo(to);
    }

    template<class Lits>
    CRef alloc(const Lits& ps, bool learnt = false){
        static_assert(sizeof(Lit) == sizeof(uint32_t), "");
        static_assert(sizeof(float) == sizeof(uint32_t), "");
        bool use_extra = learnt | extra_clause_field;

        CRef cid = RegionAllocator<uint32_t>::alloc(clauseWord32Size(ps.size(), use_extra));
        new(lea(cid)) Clause(ps, use_extra, learnt);
        return cid;
    }

    // Deref, Load Effective Address (LEA), Inverse of LEA (AEL):
    Clause& operator[](Ref r){
        return (Clause&) RegionAllocator<uint32_t>::operator[](r);
    }

    const Clause& operator[](Ref r) const{
        return (Clause&) RegionAllocator<uint32_t>::operator[](r);
    }

    Clause* lea(Ref r){
        return (Clause*) RegionAllocator<uint32_t>::lea(r);
    }

    const Clause* lea(Ref r) const{
        return (Clause*) RegionAllocator<uint32_t>::lea(r);
    }

    Ref ael(const Clause* t){
        return RegionAllocator<uint32_t>::ael((uint32_t*) t);
    }

    void free(CRef cid){
        if(cid >= marker_refs){
            assert(false);
            return;
        }
        Clause& c = operator[](cid);
        RegionAllocator<uint32_t>::free(clauseWord32Size(c.size(), c.has_extra()));
    }

    void reloc(CRef& cr, ClauseAllocator& to){
        if(cr >= marker_refs){
            return;
        }
        Clause& c = operator[](cr);

        if(c.reloced()){
            cr = c.relocation();
            return;
        }

        cr = to.alloc(c, c.learnt());
        c.relocate(cr);
        to[cr].setDerived(c.derivedClause());
        // Copy extra data-fields:
        // (This could be cleaned-up. Generalize Clause-constructor to be applicable here instead?)
        to[cr].mark(c.mark());
        if(to[cr].learnt())
            to[cr].activity() = c.activity();
        else if(to[cr].has_extra())
            to[cr].calcAbstraction();
    }
};

//=================================================================================================
// OccLists -- a class for maintaining occurence lists with lazy deletion:

template<class Idx, class Vec, class Deleted>
class OccLists {
    vec<Vec> occs;
    vec<char> dirty;
    vec<Idx> dirties;
    Deleted deleted;

public:
    OccLists(const Deleted& d) :
            deleted(d){
    }

    void init(const Idx& idx){
        occs.growTo(toInt(idx) + 1);
        dirty.growTo(toInt(idx) + 1, 0);
        occs[toInt(idx)].clear();
    }

    // Vec&  operator[](const Idx& idx){ return occs[toInt(idx)]; }
    Vec& operator[](const Idx& idx){
        return occs[toInt(idx)];
    }

    Vec& lookup(const Idx& idx){
        if(dirty[toInt(idx)])
            clean(idx);
        return occs[toInt(idx)];
    }

    void cleanAll();

    void clean(const Idx& idx);

    void smudge(const Idx& idx){
        if(dirty[toInt(idx)] == 0){
            dirty[toInt(idx)] = 1;
            dirties.push(idx);
        }
    }

    void clear(bool free = true){
        occs.clear(free);
        dirty.clear(free);
        dirties.clear(free);
    }
};

template<class Idx, class Vec, class Deleted>
void OccLists<Idx, Vec, Deleted>::cleanAll(){
    for(int i = 0; i < dirties.size(); i++)
        // Dirties may contain duplicates so check here if a variable is already cleaned:
        if(dirty[toInt(dirties[i])])
            clean(dirties[i]);
    dirties.clear();
}

template<class Idx, class Vec, class Deleted>
void OccLists<Idx, Vec, Deleted>::clean(const Idx& idx){
    Vec& vec = occs[toInt(idx)];
    int i, j;
    for(i = j = 0; i < vec.size(); i++)
        if(!deleted(vec[i]))
            vec[j++] = vec[i];
    vec.shrink(i - j);
    dirty[toInt(idx)] = 0;
}

//=================================================================================================
// CMap -- a class for mapping clauses to values:

template<class T>
class CMap {
    struct CRefHash {
        uint32_t operator()(CRef cr) const{
            return (uint32_t) cr;
        }
    };

    typedef Map<CRef, T, CRefHash> HashTable;
    HashTable map;

public:
    // Size-operations:
    void clear(){
        map.clear();
    }

    int size() const{
        return map.elems();
    }

    // Insert/Remove/Test mapping:
    void insert(CRef cr, const T& t){
        map.insert(cr, t);
    }

    void growTo(CRef cr, const T& t){
        map.insert(cr, t);
    } // NOTE: for compatibility
    void remove(CRef cr){
        map.remove(cr);
    }

    bool has(CRef cr, T& t){
        return map.peek(cr, t);
    }

    // Vector interface (the clause 'c' must already exist):
    const T& operator[](CRef cr) const{
        return map[cr];
    }

    T& operator[](CRef cr){
        return map[cr];
    }

    // Iteration (not transparent at all at the moment):
    int bucket_count() const{
        return map.bucket_count();
    }

    const vec<typename HashTable::Pair>& bucket(int i) const{
        return map.bucket(i);
    }

    // Move contents to other map:
    void moveTo(CMap& other){
        map.moveTo(other.map);
    }

    // TMP debug:
    void debug(){
        printf(" --- size = %d, bucket_count = %d\n", size(), map.bucket_count());
    }
};

/*_________________________________________________________________________________________________
 |
 |  subsumes : (other : const Clause&)  ->  Lit
 |
 |  Description:
 |       Checks if clause subsumes 'other', and at the same time, if it can be used to simplify 'other'
 |       by subsumption resolution.
 |
 |    Result:
 |       lit_Error  - No subsumption or simplification
 |       lit_Undef  - Clause subsumes 'other'
 |       p          - The literal p can be deleted from 'other'
 |________________________________________________________________________________________________@*/
inline Lit Clause::subsumes(const Clause& other) const{
    //if (other.size() < size() || (extra.abst & ~other.extra.abst) != 0)
    //if (other.size() < size() || (!learnt() && !other.learnt() && (extra.abst & ~other.extra.abst) != 0))
    assert(!header.learnt);
    assert(!other.header.learnt);
    assert(header.has_extra);
    assert(other.header.has_extra);
    if(other.header.size < header.size || (data[header.size].abs & ~other.data[other.header.size].abs) != 0)
        return lit_Error;

    Lit ret = lit_Undef;
    const Lit* c = (const Lit*) (*this);
    const Lit* d = (const Lit*) other;

    for(unsigned i = 0; i < header.size; i++){
        // search for c[i] or ~c[i]
        for(unsigned j = 0; j < other.header.size; j++)
            if(c[i] == d[j])
                goto ok;
            else if(ret == lit_Undef && c[i] == ~d[j]){
                ret = c[i];
                goto ok;
            }

        // did not find it
        return lit_Error;
        ok:;
    }

    return ret;
}

inline void Clause::strengthen(Lit p){
    remove(*this, p);
    calcAbstraction();
}

//=================================================================================================
// Simple iterator classes (for iterating over clauses and top-level assignments):

class ClauseIterator {
    const ClauseAllocator& ca;
    const CRef* crefs;
public:
    ClauseIterator(const ClauseAllocator& _ca, const CRef* _crefs) : ca(_ca), crefs(_crefs){}

    void operator++(){crefs++;}

    const Clause& operator*() const{return ca[*crefs];}

    // NOTE: does not compare that references use the same clause-allocator:
    bool operator==(const ClauseIterator& ci) const{return crefs == ci.crefs;}

    bool operator!=(const ClauseIterator& ci) const{return crefs != ci.crefs;}
};


class TrailIterator {
    const Lit* lits;
public:
    TrailIterator(const Lit* _lits) : lits(_lits){}

    void operator++(){lits++;}

    Lit operator*() const{return *lits;}

    bool operator==(const TrailIterator& ti) const{return lits == ti.lits;}

    bool operator!=(const TrailIterator& ti) const{return lits != ti.lits;}
};
//=================================================================================================
}

#endif
