//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).
//
#include <typeinfo>
#define EXPORT __attribute__((visibility("visible")))
#define IMPORT
#include <assert.h>
#include <memory>
#include <iostream>
#include <stdint.h>
#include "rocksdb/cache.h"
#include "rocksdb/comparator.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include <rocksdb/merge_operator.h>
#include "rocksdb/utilities/db_ttl.h"
#include "merge_operators.h"


#define IS_BIG_ENDIAN (*(uint16_t *)"\0\xff" < 0x100)
#define encodeCollocation(w1, w2, dist) (((uint64_t)dist << 56) | ((uint64_t)w2 << 24) | w1)
#define W1(key) (uint64_t)(key & 0xffffff)
#define W2(key) (uint64_t)((key >> 24) & 0xffffff)
#define DIST(key) (int8_t)((uint64_t)((key >> 56) & 0xff))
using namespace rocksdb;

namespace rocksdb {
  size_t num_merge_operator_calls;
  void resetNumMergeOperatorCalls() { num_merge_operator_calls = 0; }
  
  size_t num_partial_merge_calls;
  void resetNumPartialMergeCalls() { num_partial_merge_calls = 0; }


  inline void EncodeFixed64(char* buf, uint64_t value) {
    if (! IS_BIG_ENDIAN) {
      memcpy(buf, &value, sizeof(value));
    } else {
      buf[0] = value & 0xff;
      buf[1] = (value >> 8) & 0xff;
      buf[2] = (value >> 16) & 0xff;
      buf[3] = (value >> 24) & 0xff;
      buf[4] = (value >> 32) & 0xff;
      buf[5] = (value >> 40) & 0xff;
      buf[6] = (value >> 48) & 0xff;
      buf[7] = (value >> 56) & 0xff;
    }
  }

  inline uint32_t DecodeFixed32(const char* ptr) {
    if (! IS_BIG_ENDIAN) {
      // Load the raw bytes
      uint32_t result;
      memcpy(&result, ptr, sizeof(result));  // gcc optimizes this to a plain load
      return result;
    } else {
      return ((static_cast<uint32_t>(static_cast<unsigned char>(ptr[0])))
              | (static_cast<uint32_t>(static_cast<unsigned char>(ptr[1])) << 8)
              | (static_cast<uint32_t>(static_cast<unsigned char>(ptr[2])) << 16)
              | (static_cast<uint32_t>(static_cast<unsigned char>(ptr[3])) << 24));
    }
  }

  inline uint64_t DecodeFixed64(const char* ptr) {
    if (! IS_BIG_ENDIAN) {
      // Load the raw bytes
      uint64_t result;
      memcpy(&result, ptr, sizeof(result));  // gcc optimizes this to a plain load
      return result;
    } else {
      uint64_t lo = DecodeFixed32(ptr);
      uint64_t hi = DecodeFixed32(ptr + 4);
      return (hi << 32) | lo;
    }
  }


  class CountMergeOperator : public AssociativeMergeOperator {
  public:
    CountMergeOperator() {
      mergeOperator_ = MergeOperators::CreateUInt64AddOperator();
    }

    virtual bool Merge(const Slice& key,
                       const Slice* existing_value,
                       const Slice& value,
                       std::string* new_value,
                       Logger* logger) const override {
      assert(new_value->empty());
      ++num_merge_operator_calls;
      if (existing_value == nullptr) {
        new_value->assign(value.data(), value.size());
        return true;
      }

      return mergeOperator_->PartialMerge(
                                          key,
                                          *existing_value,
                                          value,
                                          new_value,
                                          logger);
    }

    virtual const char* Name() const override {
      return "UInt64AddOperator";
    }

  private:
    std::shared_ptr<MergeOperator> mergeOperator_;
  };
    

  class CollocatorIterator : public Iterator {
  private:
    char prefixc[sizeof(uint64_t)];
    Iterator *base_iterator_;
        
        
  public:
    CollocatorIterator(Iterator* base_iterator)
      : base_iterator_(base_iterator)
    {}

    ~CollocatorIterator();

    void setPrefix(char *prefix) {
      memcpy(prefixc, prefix, sizeof(uint64_t));
    }

    virtual void SeekToFirst() { base_iterator_->SeekToFirst(); }
    virtual void SeekToLast() { base_iterator_->SeekToLast(); }
    virtual void Seek(const rocksdb::Slice& s) { base_iterator_->Seek(s); }
    virtual void Prev() { base_iterator_->Prev(); }
    virtual void Next() { base_iterator_->Next(); }
    virtual Slice key() const;
    virtual Slice value() const;
    virtual Status status() const;
    virtual bool Valid() const;
    bool isValid();
    uint64_t intValue();
    uint64_t intKey();
  
  };

  //  rocksdb::CollocatorIterator::CollocatorIterator(Iterator* base_iterator) {}
    
  bool rocksdb::CollocatorIterator::Valid() const {
    return base_iterator_->Valid() && key().starts_with(std::string(prefixc,3));
  }

  bool rocksdb::CollocatorIterator::isValid() {
    return base_iterator_->Valid() && key().starts_with(std::string(prefixc,3));
  }

  uint64_t rocksdb::CollocatorIterator::intKey() {
    return DecodeFixed64(base_iterator_->key().data());
  }
  
  uint64_t rocksdb::CollocatorIterator::intValue() {
    return DecodeFixed64(base_iterator_->value().data());
  }

  class Collocators {
  private:
    WriteOptions merge_option_; // for merge
    char _one[sizeof(uint64_t)];
    Slice _one_slice;
  
  protected:
    std::shared_ptr<DB> db_;

    WriteOptions put_option_;
    ReadOptions get_option_;
    WriteOptions delete_option_;

    uint64_t default_;

    std::shared_ptr<DB> OpenDb(const char *dbname);

  public:
    Collocators(const char *db_name);
		
    ~Collocators();

    // public interface of Collocators.
    // All four functions return false
    // if the underlying level db operation failed.

    // mapped to a levedb Put
    bool set(const std::string& key, uint64_t value) {
      // just treat the internal rep of int64 as the string
      char buf[sizeof(value)];
      EncodeFixed64(buf, value);
      Slice slice(buf, sizeof(value));
      auto s = db_->Put(put_option_, key, slice);

      if (s.ok()) {
        return true;
      } else {
        std::cerr << s.ToString() << std::endl;
        return false;
      }
    }

    DB *getDb() {
      return db_.get();
    }

    // mapped to a rocksdb Delete
    bool remove(const std::string& key) {
      auto s = db_->Delete(delete_option_, key);

      if (s.ok()) {
        return true;
      } else {
        std::cerr << s.ToString() << std::endl;
        return false;
      }
    }

    // mapped to a rocksdb Get
    bool get(const std::string& key, uint64_t* value) {
      std::string str;
      auto s = db_->Get(get_option_, key, &str);

      if (s.IsNotFound()) {
        // return default value if not found;
        *value = default_;
        return true;
      } else if (s.ok()) {
        // deserialization
        if (str.size() != sizeof(uint64_t)) {
          std::cerr << "value corruption\n";
          return false;
        }
        *value = DecodeFixed64(&str[0]);
        return true;
      } else {
        std::cerr << s.ToString() << std::endl;
        return false;
      }
    }


    uint64_t get(const uint32_t w1, const uint32_t w2, const int8_t dist) {
      char encoded_key[sizeof(uint64_t)];
      EncodeFixed64(encoded_key, encodeCollocation(w1,w2,dist));
      uint64_t value = default_;
      get(std::string(encoded_key, 8), &value);
      return value;
    }

    virtual void inc(const std::string& key) {
      db_->Merge(merge_option_, key, _one_slice);
    }

    void inc(const uint64_t key) {
      char encoded_key[sizeof(uint64_t)];
      EncodeFixed64(encoded_key, key);
      db_->Merge(merge_option_, std::string(encoded_key, 8), _one_slice);
    }

    virtual void inc(const uint32_t w1, const uint32_t w2, const uint8_t dist);
    void dump(uint32_t w1, uint32_t w2, int8_t dist);

   
    // mapped to a rocksdb Merge operation
    virtual bool add(const std::string& key, uint64_t value) {
      char encoded[sizeof(uint64_t)];
      EncodeFixed64(encoded, value);
      Slice slice(encoded, sizeof(uint64_t));
      auto s = db_->Merge(merge_option_, key, slice);

      if (s.ok()) {
        return true;
      } else {
        std::cerr << s.ToString() << std::endl;
        return false;
      }
    }

    CollocatorIterator* SeekIterator(uint64_t w1, uint64_t w2, int8_t dist);
  };

  rocksdb::Collocators::Collocators(const char *db_name) {
    std::cout << "Test merge-based counters... " << db_name << "\n";
    db_ = OpenDb(db_name);
    assert(db_);
    uint64_t one = 1;
    EncodeFixed64(_one, one);
    _one_slice = Slice(_one, sizeof(uint64_t));
  }
  
  rocksdb::CollocatorIterator::~CollocatorIterator() {
    std::cout << "destroying itera\n";
  }

  rocksdb::Collocators::~Collocators() {
    std::cout << "destroying coll\n";
  }

  void rocksdb::Collocators::inc(const uint32_t w1, const uint32_t w2, const uint8_t dist) {
    inc(encodeCollocation(w1, w2, dist));
  }
    
  std::shared_ptr<DB> rocksdb::Collocators::OpenDb(const char *dbname) {
		std::cout << "Test merge-based counters... " << dbname << "\n";
		DB* db;
		Options options;
		options.create_if_missing = true;
		options.merge_operator = std::make_shared<CountMergeOperator>();
		options.max_successive_merges = 0;
		Status s;
		//  DestroyDB(dbname, Options());
		s = DB::Open(options, dbname, &db);
		if (!s.ok()) {
			std::cerr << s.ToString() << std::endl;
			assert(false);
		}
		return std::shared_ptr<DB>(db);
  }

  CollocatorIterator* rocksdb::Collocators::SeekIterator(uint64_t w1, uint64_t w2, int8_t dist) {
    ReadOptions options;
    options.prefix_same_as_start = true;  
    char prefixc[sizeof(uint64_t)];
    EncodeFixed64(prefixc, encodeCollocation(w1, w2, dist));
    Iterator *it = db_->NewIterator(options);
    CollocatorIterator *cit = new CollocatorIterator(it);
    cit->Seek(std::string(prefixc,3));// it->Valid() && it->key().starts_with(std::string(prefixc,3)); it->Next()) {
    cit->setPrefix(prefixc);
    return cit;
  }

	void rocksdb::Collocators::dump(uint32_t w1, uint32_t w2, int8_t dist) {
    auto it = std::unique_ptr<CollocatorIterator>(SeekIterator(w1, w2, dist));
    for (; it->isValid(); it->Next()) {
      uint64_t value = it->intValue();
      uint64_t key = it->intKey();
      std::cout << "w1:" << W1(key) << ", w2:" << W2(key) << ", dist:" << (int32_t) DIST(key) << " - count:" << value << std::endl;
    }
    std::cout << "ready dumping\n";
  }

  rocksdb::Slice rocksdb::CollocatorIterator::key() const { return base_iterator_->key(); }
  rocksdb::Slice rocksdb::CollocatorIterator::value() const { return base_iterator_->value(); }
  rocksdb::Status rocksdb::CollocatorIterator::status() const { return base_iterator_->status(); }

};

typedef rocksdb::Collocators COLLOCATORS;

extern "C" {
	COLLOCATORS *open_collocators(char *dbname) {
		return new rocksdb::Collocators(dbname);
	}
	
	void inc_collocators(COLLOCATORS *db, uint32_t w1, uint32_t w2, int8_t dist) {
		db->inc(w1, w2, dist);
	}

	void dump_collocators(COLLOCATORS *db, uint32_t w1, uint32_t w2, int8_t dist) {
		db->dump(w1, w2, dist);
	}
}