/*
 * Copyright (C) 2014 ScyllaDB
 */

/*
 * This file is part of Scylla.
 *
 * Scylla is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Scylla is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Scylla.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include <iosfwd>

#include "mutation_partition.hh"
#include "keys.hh"
#include "schema.hh"
#include "dht/i_partitioner.hh"
#include "hashing.hh"
#include "mutation_fragment.hh"

#include <seastar/util/optimized_optional.hh>

class mutation final {
private:
    struct data {
        schema_ptr _schema;
        dht::decorated_key _dk;
        mutation_partition _p;

        data(dht::decorated_key&& key, schema_ptr&& schema);
        data(partition_key&& key, schema_ptr&& schema);
        data(schema_ptr&& schema, dht::decorated_key&& key, const mutation_partition& mp);
        data(schema_ptr&& schema, dht::decorated_key&& key, mutation_partition&& mp);
    };
    std::unique_ptr<data> _ptr;
private:
    mutation() = default;
    explicit operator bool() const { return bool(_ptr); }
    friend class optimized_optional<mutation>;
public:
    mutation(schema_ptr schema, dht::decorated_key key)
        : _ptr(std::make_unique<data>(std::move(key), std::move(schema)))
    { }
    mutation(schema_ptr schema, partition_key key_)
        : _ptr(std::make_unique<data>(std::move(key_), std::move(schema)))
    { }
    mutation(schema_ptr schema, dht::decorated_key key, const mutation_partition& mp)
        : _ptr(std::make_unique<data>(std::move(schema), std::move(key), mp))
    { }
    mutation(schema_ptr schema, dht::decorated_key key, mutation_partition&& mp)
        : _ptr(std::make_unique<data>(std::move(schema), std::move(key), std::move(mp)))
    { }
    mutation(const mutation& m)
        : _ptr(std::make_unique<data>(schema_ptr(m.schema()), dht::decorated_key(m.decorated_key()), m.partition()))
    { }
    mutation(mutation&&) = default;
    mutation& operator=(mutation&& x) = default;
    mutation& operator=(const mutation& m);

    void set_static_cell(const column_definition& def, atomic_cell_or_collection&& value);
    void set_static_cell(const bytes& name, const data_value& value, api::timestamp_type timestamp, ttl_opt ttl = {});
    void set_clustered_cell(const clustering_key& key, const bytes& name, const data_value& value, api::timestamp_type timestamp, ttl_opt ttl = {});
    void set_clustered_cell(const clustering_key& key, const column_definition& def, atomic_cell_or_collection&& value);
    void set_cell(const clustering_key_prefix& prefix, const bytes& name, const data_value& value, api::timestamp_type timestamp, ttl_opt ttl = {});
    void set_cell(const clustering_key_prefix& prefix, const column_definition& def, atomic_cell_or_collection&& value);

    // Upgrades this mutation to a newer schema. The new schema must
    // be obtained using only valid schema transformation:
    //  * primary key column count must not change
    //  * column types may only change to those with compatible representations
    //
    // After upgrade, mutation's partition should only be accessed using the new schema. User must
    // ensure proper isolation of accesses.
    //
    // Strong exception guarantees.
    //
    // Note that the conversion may lose information, it's possible that m1 != m2 after:
    //
    //   auto m2 = m1;
    //   m2.upgrade(s2);
    //   m2.upgrade(m1.schema());
    //
    void upgrade(const schema_ptr&);

    const partition_key& key() const { return _ptr->_dk._key; };
    const dht::decorated_key& decorated_key() const { return _ptr->_dk; };
    dht::ring_position ring_position() const { return { decorated_key() }; }
    const dht::token& token() const { return _ptr->_dk._token; }
    const schema_ptr& schema() const { return _ptr->_schema; }
    const mutation_partition& partition() const { return _ptr->_p; }
    mutation_partition& partition() { return _ptr->_p; }
    const utils::UUID& column_family_id() const { return _ptr->_schema->id(); }
    // Consistent with hash<canonical_mutation>
    bool operator==(const mutation&) const;
    bool operator!=(const mutation&) const;
public:
    // The supplied partition_slice must be governed by this mutation's schema
    query::result query(const query::partition_slice&,
        query::result_options opts = query::result_options::only_result(),
        gc_clock::time_point now = gc_clock::now(),
        uint32_t row_limit = query::max_rows) &&;

    // The supplied partition_slice must be governed by this mutation's schema
    // FIXME: Slower than the r-value version
    query::result query(const query::partition_slice&,
        query::result_options opts = query::result_options::only_result(),
        gc_clock::time_point now = gc_clock::now(),
        uint32_t row_limit = query::max_rows) const&;

    // The supplied partition_slice must be governed by this mutation's schema
    void query(query::result::builder& builder,
        const query::partition_slice& slice,
        gc_clock::time_point now = gc_clock::now(),
        uint32_t row_limit = query::max_rows) &&;

    // See mutation_partition::live_row_count()
    size_t live_row_count(gc_clock::time_point query_time = gc_clock::time_point::min()) const;

    void apply(mutation&&);
    void apply(const mutation&);
    void apply(const mutation_fragment&);

    mutation operator+(const mutation& other) const;
    mutation& operator+=(const mutation& other);
    mutation& operator+=(mutation&& other);

    // Returns a subset of this mutation holding only information relevant for given clustering ranges.
    // Range tombstones will be trimmed to the boundaries of the clustering ranges.
    mutation sliced(const query::clustering_row_ranges&) const;
private:
    friend std::ostream& operator<<(std::ostream& os, const mutation& m);
};

struct mutation_equals_by_key {
    bool operator()(const mutation& m1, const mutation& m2) const {
        return m1.schema() == m2.schema()
                && m1.decorated_key().equal(*m1.schema(), m2.decorated_key());
    }
};

struct mutation_hash_by_key {
    size_t operator()(const mutation& m) const {
        auto dk_hash = std::hash<dht::decorated_key>();
        return dk_hash(m.decorated_key());
    }
};

struct mutation_decorated_key_less_comparator {
    bool operator()(const mutation& m1, const mutation& m2) const;
};

using mutation_opt = optimized_optional<mutation>;

// Consistent with operator==()
// Consistent across the cluster, so should not rely on particular
// serialization format, only on actual data stored.
template<>
struct appending_hash<mutation> {
    template<typename Hasher>
    void operator()(Hasher& h, const mutation& m) const {
        const schema& s = *m.schema();
        feed_hash(h, m.key(), s);
        m.partition().feed_hash(h, s);
    }
};

inline
void apply(mutation_opt& dst, mutation&& src) {
    if (!dst) {
        dst = std::move(src);
    } else {
        dst->apply(std::move(src));
    }
}

inline
void apply(mutation_opt& dst, mutation_opt&& src) {
    if (src) {
        apply(dst, std::move(*src));
    }
}

// Returns a range into partitions containing mutations covered by the range.
// partitions must be sorted according to decorated key.
// range must not wrap around.
boost::iterator_range<std::vector<mutation>::const_iterator> slice(
    const std::vector<mutation>& partitions,
    const dht::partition_range&);

class flat_mutation_reader;

// Reads a single partition from a reader. Returns empty optional if there are no more partitions to be read.
future<mutation_opt> read_mutation_from_flat_mutation_reader(flat_mutation_reader& reader, db::timeout_clock::time_point timeout);
