#include <vector>
#include <functional>
#include <iostream>
#include <yaml-cpp/yaml.h>
#include <sdskv-client.h>
#include <bake-client.h>
#include <ch-placement.h>
#include "hepnos/Exception.hpp"
#include "hepnos/DataStore.hpp"
#include "hepnos/DataSet.hpp"
#include "private/DataStoreImpl.hpp"

namespace hepnos {

////////////////////////////////////////////////////////////////////////////////////////////
// DataStore implementation
////////////////////////////////////////////////////////////////////////////////////////////

DataStore::DataStore(const std::string& configFile) 
: m_impl(std::make_unique<DataStore::Impl>(this)) {
    m_impl->init(configFile);
}

DataStore::DataStore(DataStore&& other)
: m_impl(std::move(other.m_impl)) {}

DataStore& DataStore::operator=(DataStore&& other) {
    if(&other == this) return *this;
    if(m_impl) {
        m_impl->cleanup();
    }
    m_impl = std::move(other.m_impl);
}
    
DataStore::~DataStore() {
    if(m_impl) {
        m_impl->cleanup();
    }
}

DataStore::iterator DataStore::find(const std::string& datasetName) {
    int ret;
    if(datasetName.find('/') != std::string::npos
    || datasetName.find('%') != std::string::npos) {
        throw Exception("Invalid character ('/' or '%') in dataset name");
    }
    std::vector<char> data;
    bool b = m_impl->load(1, "", datasetName, data);
    if(!b) {
        return m_impl->m_end;
    }
    return iterator(DataSet(this, 1, datasetName));
}

DataSet DataStore::operator[](const std::string& datasetName) const {
    auto it = find(datasetName);
    return std::move(*it);
}

DataStore::const_iterator DataStore::find(const std::string& datasetName) const {
    DataStore::iterator it = const_cast<DataStore*>(this)->find(datasetName);
    return it;
}

DataStore::iterator DataStore::begin() {
    DataSet ds(this, 1, "", "");
    ds = ds.next();
    if(ds.valid()) return iterator(std::move(ds));
    else return end();
}

DataStore::const_iterator DataStore::begin() const {
    iterator it = const_cast<DataStore*>(this)->begin();
    return const_iterator(std::move(it));
}

DataStore::iterator DataStore::end() {
    return m_impl->m_end;
}

DataStore::const_iterator DataStore::end() const {
    return m_impl->m_end;
}

DataStore::const_iterator DataStore::cbegin() const {
    return const_cast<DataStore*>(this)->begin();
}

DataStore::const_iterator DataStore::cend() const {
    return const_cast<DataStore*>(this)->end();
}

DataStore::iterator DataStore::lower_bound(const std::string& lb) {
    std::string lb2 = lb;
    size_t s = lb2.size();
    lb2[s-1] -= 1; // sdskv_list_keys's start_key is exclusive
    iterator it = find(lb2);
    if(it != end()) {
        // we found something before the specified lower bound
        ++it;
        return it;
    }
    DataSet ds(this, 1, "", lb2);
    ds = ds.next();
    if(!ds.valid()) return end();
    else return iterator(std::move(ds));
}

DataStore::const_iterator DataStore::lower_bound(const std::string& lb) const {
    iterator it = const_cast<DataStore*>(this)->lower_bound(lb);
    return it;
}

DataStore::iterator DataStore::upper_bound(const std::string& ub) {
    DataSet ds(this, 1, "", ub);
    ds = ds.next();
    if(!ds.valid()) return end();
    else return iterator(std::move(ds));
}

DataStore::const_iterator DataStore::upper_bound(const std::string& ub) const {
    iterator it = const_cast<DataStore*>(this)->upper_bound(ub);
    return it;
}

DataSet DataStore::createDataSet(const std::string& name) {
    if(name.find('/') != std::string::npos
    || name.find('%') != std::string::npos) {
        throw Exception("Invalid character ('/' or '%') in dataset name");
    }
    m_impl->store(1, "", name, std::vector<char>());
    return DataSet(this, 1, "", name);
}
#if 0
bool DataStore::load(uint8_t level, const std::string& containerName,
        const std::string& objectName, std::vector<char>& data) const {
    int ret;
    // build full name
    std::stringstream ss;
    if(!containerName.empty())
        ss << containerName << "/";
    ss << objectName;
    // hash the name to get the provider id
    long unsigned provider_idx = 0;
    if(level != 0) {
        uint64_t h = std::hash<std::string>()(containerName);
        ch_placement_find_closest(m_impl->m_chi_sdskv, h, 1, &provider_idx);
    } else {
        // use the complete name for final objects (level 255)
        uint64_t h = std::hash<std::string>()(ss.str());
        ch_placement_find_closest(m_impl->m_chi_sdskv, h, 1, &provider_idx);
    }
    // make corresponding datastore entry
    DataStoreEntryPtr entry = make_datastore_entry(level, ss.str());
    auto ph = m_impl->m_sdskv_ph[provider_idx];
    auto db_id = m_impl->m_sdskv_db[provider_idx];
    // find the size of the value, as a way to check if the key exists
    hg_size_t vsize;
    std::cerr << "[LOG] load (level=" << (int)level
        << ", container=\"" << containerName << "\", object=\""
        << objectName << "\")" << std::endl;
    ret = sdskv_length(ph, db_id, entry->raw(), entry->length(), &vsize);
    if(ret == SDSKV_ERR_UNKNOWN_KEY) {
        return false;
    }
    if(ret != SDSKV_SUCCESS) {
        throw Exception("Error occured when calling sdskv_length");
    }
    // read the value
    data.resize(vsize);
    ret = sdskv_get(ph, db_id, entry->raw(), entry->length(), data.data(), &vsize);
    if(ret != SDSKV_SUCCESS) {
        throw Exception("Error occured when calling sdskv_get");
    }
    return true;
}

bool DataStore::store(uint8_t level, const std::string& containerName,
        const std::string& objectName, const std::vector<char>& data) {
    // build full name
    std::stringstream ss;
    if(!containerName.empty())
        ss << containerName << "/";
    ss << objectName;
    // hash the name to get the provider id
    long unsigned provider_idx = 0;
    if(level != 0) {
        uint64_t h = std::hash<std::string>()(containerName);
        ch_placement_find_closest(m_impl->m_chi_sdskv, h, 1, &provider_idx);
    } else {
        // use the complete name for final objects (level 0)
        uint64_t h = std::hash<std::string>()(ss.str());
        ch_placement_find_closest(m_impl->m_chi_sdskv, h, 1, &provider_idx);
    }
    // make corresponding datastore entry
    DataStoreEntryPtr entry = make_datastore_entry(level, ss.str());
    auto ph = m_impl->m_sdskv_ph[provider_idx];
    auto db_id = m_impl->m_sdskv_db[provider_idx];
    std::cerr << "[LOG] store (level=" << (int)level
        << ", container=\"" << containerName << "\", object=\""
        << objectName << "\")" << std::endl;
    int ret = sdskv_put(ph, db_id, entry->raw(), entry->length(), data.data(), data.size());
    if(ret != SDSKV_SUCCESS) {
        throw Exception("Could not put key/value pair in SDSKV (sdskv_put error)");
    }
    return true;
}

size_t DataStore::nextKeys(uint8_t level, const std::string& containerName,
        const std::string& lower,
        std::vector<std::string>& keys, size_t maxKeys) const {
    int ret;
    if(level == 0) return 0; // cannot iterate at object level
    // build full name from lower bound key
    std::stringstream ss;
    if(!containerName.empty())
        ss << containerName << "/";
    ss << lower;
    // hash the name to get the provider id
    long unsigned provider_idx = 0;
    uint64_t h = std::hash<std::string>()(containerName);
    ch_placement_find_closest(m_impl->m_chi_sdskv, h, 1, &provider_idx);
    // make an entry for the lower bound
    DataStoreEntryPtr lb_entry = make_datastore_entry(level, ss.str());
    // create data structures to receive keys
    std::vector<DataStoreEntryPtr> keys_ent;
    std::vector<void*>             keys_ptr(maxKeys);
    std::vector<hg_size_t>         keys_len(maxKeys);
    for(unsigned i=0; i < maxKeys; i++) {
        keys_ent.push_back(make_datastore_entry(level, 1024));
        keys_ptr[i] = keys_ent[i]->raw();
        keys_len[i] = sizeof(DataStoreEntry) + 1024;
    }
    // get provider and database
    auto ph = m_impl->m_sdskv_ph[provider_idx];
    auto db_id = m_impl->m_sdskv_db[provider_idx];
    // issue an sdskv_list_keys
    hg_size_t max_keys = maxKeys;
    std::cerr << "[LOG] list keys (level=" << (int)level
        << ", container=\"" << containerName << "\", greaterthan=\""
        << lower << "\")" << std::endl;
    ret = sdskv_list_keys(ph, db_id, lb_entry->raw(), lb_entry->length(),
                          keys_ptr.data(), keys_len.data(), &max_keys);
    if(ret != HG_SUCCESS) {
        throw Exception("Error occured when calling sdskv_list_keys");
    }
    unsigned i = max_keys - 1;
    if(max_keys == 0) return 0;
    // remove keys that don't have the same level or the same prefix
    std::string prefix = containerName + "/";
    keys.resize(0);
    for(unsigned i = 0; i < max_keys; i++) {
        if(keys_ent[i]->m_level != level) {
            max_keys = i;
            break;
        }
        if(!containerName.empty()) {
            size_t lenpre = prefix.size();
            size_t lenstr = strlen(keys_ent[i]->m_fullname);
            if(lenstr < lenpre) {
                max_keys = i;
                break;
            }
            if(strncmp(prefix.c_str(), keys_ent[i]->m_fullname, lenpre) != 0) {
                max_keys = i;
                break;
            }
        }
        keys.push_back(keys_ent[i]->m_fullname);
    }
    // set the resulting keys
    return max_keys;
}
#endif
////////////////////////////////////////////////////////////////////////////////////////////
// DataStore::const_iterator::Impl implementation
////////////////////////////////////////////////////////////////////////////////////////////

class DataStore::const_iterator::Impl {
    public:
        DataSet    m_current_dataset;

        Impl()
        : m_current_dataset()
        {}

        Impl(const DataSet& dataset)
        : m_current_dataset(dataset)
        {}

        Impl(DataSet&& dataset)
        : m_current_dataset(std::move(dataset))
        {}

        Impl(const Impl& other)
        : m_current_dataset(other.m_current_dataset) 
        {}

        bool operator==(const Impl& other) const {
            return m_current_dataset == other.m_current_dataset;
        }
};

////////////////////////////////////////////////////////////////////////////////////////////
// DataStore::const_iterator::Impl implementation
////////////////////////////////////////////////////////////////////////////////////////////

DataStore::const_iterator::const_iterator()
: m_impl(std::make_unique<Impl>()) {}

DataStore::const_iterator::const_iterator(const DataSet& dataset)
: m_impl(std::make_unique<Impl>(dataset)) {}

DataStore::const_iterator::const_iterator(DataSet&& dataset)
: m_impl(std::make_unique<Impl>(std::move(dataset))) {}

DataStore::const_iterator::~const_iterator() {}

DataStore::const_iterator::const_iterator(const DataStore::const_iterator& other) 
: m_impl(std::make_unique<Impl>(*other.m_impl)) {}

DataStore::const_iterator::const_iterator(DataStore::const_iterator&& other) 
: m_impl(std::move(other.m_impl)) {}

DataStore::const_iterator& DataStore::const_iterator::operator=(const DataStore::const_iterator& other) {
    if(&other == this) return *this;
    m_impl = std::make_unique<Impl>(*other.m_impl);
    return *this;
}

DataStore::const_iterator& DataStore::const_iterator::operator=(DataStore::const_iterator&& other) {
    if(&other == this) return *this;
    m_impl = std::move(other.m_impl);
    return *this;
}

DataStore::const_iterator::self_type DataStore::const_iterator::operator++() {
    if(!m_impl) {
        throw Exception("Trying to increment an invalid iterator");
    }
    m_impl->m_current_dataset = m_impl->m_current_dataset.next();
    return *this;
}

DataStore::const_iterator::self_type DataStore::const_iterator::operator++(int) {
    const_iterator copy = *this;
    ++(*this);
    return copy;
}

const DataStore::const_iterator::reference DataStore::const_iterator::operator*() {
    if(!m_impl) {
        throw Exception("Trying to dereference an invalid iterator");
    }
    return m_impl->m_current_dataset;
}

const DataStore::const_iterator::pointer DataStore::const_iterator::operator->() {
    if(!m_impl) return nullptr;
    return &(m_impl->m_current_dataset);
}

bool DataStore::const_iterator::operator==(const self_type& rhs) const {
    if(!m_impl && !rhs.m_impl)  return true;
    if(m_impl  && !rhs.m_impl)  return false;
    if(!m_impl && rhs.m_impl)   return false;
    return *m_impl == *(rhs.m_impl);
}

bool DataStore::const_iterator::operator!=(const self_type& rhs) const {
    return !(*this == rhs);
}

////////////////////////////////////////////////////////////////////////////////////////////
// DataStore::iterator implementation
////////////////////////////////////////////////////////////////////////////////////////////

DataStore::iterator::iterator(const DataSet& current)
: const_iterator(current) {}

DataStore::iterator::iterator(DataSet&& current)
: const_iterator(std::move(current)) {}

DataStore::iterator::iterator()
: const_iterator() {}

DataStore::iterator::~iterator() {}

DataStore::iterator::iterator(const DataStore::iterator& other)
: const_iterator(other) {}

DataStore::iterator::iterator(DataStore::iterator&& other) 
: const_iterator(std::move(other)) {}

DataStore::iterator& DataStore::iterator::operator=(const DataStore::iterator& other) {
    if(this == &other) return *this;
    m_impl = std::make_unique<Impl>(*other.m_impl);
    return *this;
}

DataStore::iterator& DataStore::iterator::operator=(DataStore::iterator&& other) {
    if(this == &other) return *this;
    m_impl = std::move(other.m_impl);
    return *this;
}

DataStore::iterator::reference DataStore::iterator::operator*() {
    return const_cast<reference>(const_iterator::operator*());
}

DataStore::iterator::pointer DataStore::iterator::operator->() {
    return const_cast<pointer>(const_iterator::operator->());
}

}