/******************************************
Copyright (c) 2016, Mate Soos

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 __WATCHARRAY_H__
#define __WATCHARRAY_H__

#include <stdlib.h>
#include "watched.h"
#include <vector>

namespace CMSat {
using std::vector;

struct watch_array;

struct Elem
{
    Elem() :
        num(0)
        , offset(0)
    {}

    uint32_t num:8;
    uint32_t offset:24;
    uint32_t size = 0;
    uint32_t alloc = 0;
    //uint32_t accessed = 0;

    void print_stat() const
    {
        cout
        << "c elem."
        << " num: " << num
        << " offset:" << offset
        << " size" << size
        << " alloc" << alloc
        << endl;
    }
};

struct Mem
{
    uint32_t alloc = 0;
    Watched* base_ptr = NULL;
    uint32_t next_space_offset = 0;
};

struct OffsAndNum
{
    OffsAndNum() :
        offset(0)
        , num(0)
    {}

    OffsAndNum(uint32_t _offset, uint32_t _num) :
        offset(_offset)
        , num(_num)
    {}

    uint32_t offset;
    uint32_t num;
};

struct watch_subarray
{
    vector<Elem>::iterator base_at;
    watch_array* base;
    explicit watch_subarray(vector<Elem>::iterator _base_at, watch_array* _base) :
        base_at(_base_at)
        , base(_base)
    {}

    Watched& operator[](const uint32_t at);
    void clear();
    uint32_t size() const;
    bool empty() const;
    Watched* begin();
    Watched* end();
    const Watched* begin() const;
    const Watched* end() const;
    void shrink(const uint32_t num);
    void shrink_(const uint32_t num);
    void push(const Watched& watched);
    void get_space_for_push();

    typedef Watched* iterator;
    typedef const Watched* const_iterator;
};

struct watch_subarray_const
{
    vector<Elem>::const_iterator base_at;
    const watch_array* base;
    explicit watch_subarray_const(vector<Elem>::const_iterator _base_at, const watch_array* _base) :
        base_at(_base_at)
        , base(_base)
    {}

    watch_subarray_const(const watch_subarray& other) :
        base_at(other.base_at)
        , base(other.base)
    {}

    void print_stat() const;
    const Watched& operator[](const uint32_t at) const;
    uint32_t size() const;
    bool empty() const;
    const Watched* begin() const;
    const Watched* end() const;
    typedef const Watched* const_iterator;
};

struct watch_array
{
    const static size_t WATCH_MIN_SIZE_ONE_ALLOC_FIRST = 1ULL*1000ULL*1000ULL;
    const static size_t WATCH_MIN_SIZE_ONE_ALLOC_LATER = 50ULL*1000ULL*1000ULL;
    const static size_t WATCH_MAX_SIZE_ONE_ALLOC = (1ULL<<24)-1;

    vector<Elem> watches;
    vector<Mem> mems;
    size_t free_mem_used = 0;
    size_t free_mem_not_used = 0;

    //at least 2**N elements in there
    vector<vector<OffsAndNum> > free_mem;

    watch_array()
    {
        //We need at least 1
        Mem new_mem;
        size_t elems = WATCH_MIN_SIZE_ONE_ALLOC_FIRST;
        new_mem.base_ptr = (Watched*)malloc(elems*sizeof(Watched));
        new_mem.alloc = elems;
        mems.push_back(new_mem);

        free_mem.resize(20);
    }

    ~watch_array()
    {
        for(size_t i = 0; i < mems.size(); i++) {
            free(mems[i].base_ptr);
        }
    }

    uint32_t get_suitable_base(uint32_t elems)
    {
        //print_stat();

        assert(mems.size() > 0);
        size_t last_alloc = mems[0].alloc;
        for(size_t i = 0; i < mems.size(); i++) {
            if (mems[i].next_space_offset + elems < mems[i].alloc) {
                return i;
            }
            last_alloc = mems[i].alloc;
        }
        assert(mems.size() < 255);

        Mem new_mem;
        new_mem.alloc = std::max<size_t>(3*last_alloc, WATCH_MIN_SIZE_ONE_ALLOC_LATER);
        new_mem.alloc = std::min<size_t>(3*last_alloc, WATCH_MAX_SIZE_ONE_ALLOC);
        new_mem.base_ptr = (Watched*)malloc(new_mem.alloc*sizeof(Watched));
        assert(new_mem.base_ptr != NULL);
        mems.push_back(new_mem);
        return mems.size()-1;
    }

    bool find_free_space(OffsAndNum& toret, uint32_t size)
    {
        size_t bucket = get_bucket(size);
        if (free_mem.size() <= bucket
            || free_mem[bucket].empty()
        ) {
            free_mem_not_used++;
            return false;
        }

        toret = free_mem[bucket].back();
        free_mem[bucket].pop_back();
        free_mem_used++;
        return true;
    }

    OffsAndNum get_space(uint32_t elems)
    {
        OffsAndNum toret;
        if (find_free_space(toret, elems))
            return toret;

        uint32_t num = get_suitable_base(elems);
        Mem& mem = mems[num];
        assert(mem.next_space_offset + elems < mem.alloc);

        uint32_t off_to_ret = mem.next_space_offset;
        mem.next_space_offset += elems;

        toret = OffsAndNum(off_to_ret, num);
        return toret;
    }

    size_t extra_space_during_consolidate(size_t orig_size)
    {
        if (orig_size == 1)
            return 2;

        unsigned bucket = get_bucket(orig_size);
        if (2U<<bucket == orig_size)
            return orig_size;
        else
            return 2U<<(bucket+1);
    }

    size_t total_needed_during_consolidate()
    {
        size_t total_needed = 0;
        for(size_t i = 0; i < watches.size(); i++) {
            if (watches[i].size != 0) {
                total_needed += extra_space_during_consolidate(watches[i].size);
            }
        }
        total_needed *= 1.2;
        total_needed = std::max<size_t>(total_needed, WATCH_MIN_SIZE_ONE_ALLOC_FIRST);

        return total_needed;
    }

    void consolidate();
    void print_stat(bool detailed = false) const;

    unsigned get_bucket(unsigned size)
    {
        //assert(size >= 2);
        int at = ((int)((sizeof(unsigned)*8))-__builtin_clz(size))-2;
        //assert(at >= 0);
        return at;
    }

    void delete_offset(uint32_t num, uint32_t offs, uint32_t size)
    {
        size_t bucket = get_bucket(size);
        //assert(size == 2U<<bucket);

        if (bucket >= free_mem.size()) {
            return;
        }

        free_mem[bucket].push_back(OffsAndNum(offs, num));
    }

    size_t mem_used_alloc() const
    {
        size_t total = 0;
        for(size_t i = 0; i < mems.size(); i++) {
            total += mems[i].alloc*sizeof(Watched);
        }
        return total;
    }

    size_t mem_used_array() const
    {
        size_t total = 0;
        total += watches.capacity() * sizeof(Elem);
        total += mems.capacity() * sizeof(Mem);
        return total;
    }

    watch_subarray operator[](size_t at)
    {
        assert(watches.size() > at);
        return watch_subarray(watches.begin() + at, this);
    }

    watch_subarray_const operator[](size_t at) const
    {
        assert(watches.size() > at);
        return watch_subarray_const(watches.begin() + at, this);
    }

    void resize(const size_t new_size)
    {
        watches.resize(new_size);
    }

    uint32_t size() const
    {
        return watches.size();
    }

    void shrink_to_fit()
    {
        watches.shrink_to_fit();
    }

    void prefetch(const size_t at) const
    {
        __builtin_prefetch(mems[watches[at].num].base_ptr + watches[at].offset);
    }

    struct iterator
    {
        vector<Elem>::iterator it;
        watch_array* base;
        explicit iterator(vector<Elem>::iterator _it, watch_array* _base) :
            it(_it)
            , base(_base)
        {}

        iterator operator++()
        {
            ++it;
            return *this;
        }

        watch_subarray operator*()
        {
            return watch_subarray(it, base);
        }

        bool operator==(const iterator& it2) const
        {
            return it == it2.it;
        }

        bool operator!=(const iterator& it2) const
        {
            return it != it2.it;
        }

        friend size_t operator-(const iterator& lhs, const iterator& rhs);
    };

    struct const_iterator
    {
        vector<Elem>::const_iterator it;
        const watch_array* base;
        explicit const_iterator(vector<Elem>::const_iterator _it, const watch_array* _base) :
            it(_it)
            , base(_base)
        {}

        const_iterator(const iterator& other) :
            it(other.it)
            , base(other.base)
        {}

        const_iterator operator++()
        {
            ++it;
            return *this;
        }

        const watch_subarray_const operator*() const
        {
            return watch_subarray_const(it, base);
        }

        bool operator==(const const_iterator& it2) const
        {
            return it == it2.it;
        }

        bool operator!=(const const_iterator& it2) const
        {
            return it != it2.it;
        }

        friend size_t operator-(const const_iterator& lhs, const const_iterator& rhs);
    };

    iterator begin()
    {
        return iterator(watches.begin(), this);
    }

    iterator end()
    {
        return iterator(watches.end(), this);
    }

    const_iterator begin() const
    {
        return const_iterator(watches.begin(), this);
    }

    const_iterator end() const
    {
        return const_iterator(watches.end(), this);
    }

    void fitToSize()
    {
        //TODO shirnk
    }
};

inline size_t operator-(const watch_array::iterator& lhs, const watch_array::iterator& rhs)
{
    return lhs.it-rhs.it;
}

inline size_t operator-(const watch_array::const_iterator& lhs, const watch_array::const_iterator& rhs)
{
    return lhs.it-rhs.it;
}

inline Watched& watch_subarray::operator[](const uint32_t at)
{
    //base_at->accessed++;
    return *(begin() + at);
}

inline void watch_subarray::clear()
{
    base_at->size = 0;
}

inline uint32_t watch_subarray::size() const
{
    return base_at->size;
}

inline bool watch_subarray::empty() const
{
    return size() == 0;
}

inline Watched* watch_subarray::begin()
{
    return base->mems[base_at->num].base_ptr + base_at->offset;
}

inline Watched* watch_subarray::end()
{
    return begin() + size();
}

inline const Watched* watch_subarray::begin() const
{
    return base->mems[base_at->num].base_ptr + base_at->offset;
}

inline const Watched* watch_subarray::end() const
{
    return begin() + size();
}

inline void watch_subarray::shrink(const uint32_t num)
{
    base_at->size -= num;
}

inline void watch_subarray::shrink_(const uint32_t num)
{
    shrink(num);
}

inline void watch_subarray::get_space_for_push()
{
    uint32_t new_alloc = std::max<uint32_t>(base_at->alloc*2, 2U);
    OffsAndNum off_and_num = base->get_space(new_alloc);

    //Copy
    if (base_at->size > 0) {
        Watched* newptr = base->mems[off_and_num.num].base_ptr + off_and_num.offset;
        Watched* oldptr = begin();
        memmove(newptr, oldptr, size() * sizeof(Watched));
        base->delete_offset(base_at->num, base_at->offset, base_at->alloc);
    }

    //Update
    base_at->num = off_and_num.num;
    base_at->offset = off_and_num.offset;
    base_at->alloc = new_alloc;
}

inline void watch_subarray::push(const Watched& watched)
{
    //Make space
    if (base_at->alloc <= base_at->size) {
        get_space_for_push();
    }

    //There is enough space
    //assert(base_at->alloc > base_at->size);

    //Append to the end
    operator[](size()) = watched;
    base_at->size++;
}

inline const Watched& watch_subarray_const::operator[](const uint32_t at) const
{
    return *(begin() + at);
}
inline uint32_t watch_subarray_const::size() const
{
    return base_at->size;
}

inline bool watch_subarray_const::empty() const
{
    return size() == 0;
}
inline const Watched* watch_subarray_const::begin() const
{
    return base->mems[base_at->num].base_ptr + base_at->offset;
}

inline const Watched* watch_subarray_const::end() const
{
    return begin() + size();
}

inline void watch_subarray_const::print_stat() const
{
    base->print_stat();
    base_at->print_stat();
}

inline void swap(watch_subarray a, watch_subarray b)
{
    Elem tmp;
    tmp = *(a.base_at);
    *(a.base_at) = *(b.base_at);
    *(b.base_at) = tmp;
}


} //End of namespace

#endif //__WATCHARRAY_H__