/*************************************************************************
 *
 * Copyright 2016 Realm Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 **************************************************************************/

#ifndef REALM_OBJ_HPP
#define REALM_OBJ_HPP

#include <realm/node.hpp>
#include <realm/table_ref.hpp>
#include <realm/keys.hpp>
#include <realm/mixed.hpp>
#include <map>

#define REALM_CLUSTER_IF

namespace realm {

class ClusterTree;
class Replication;
class TableView;
class CollectionBase;
class CascadeState;
class LstBase;
class SetBase;
class ObjList;
struct GlobalKey;

template <class>
class Lst;
template <class>
class Set;
template <class T>
using LstPtr = std::unique_ptr<Lst<T>>;
using LstBasePtr = std::unique_ptr<LstBase>;
template <class T>
using SetPtr = std::unique_ptr<Set<T>>;
using SetBasePtr = std::unique_ptr<SetBase>;
using CollectionBasePtr = std::unique_ptr<CollectionBase>;
using LinkCollectionPtr = std::unique_ptr<ObjList>;

class LnkLst;
using LnkLstPtr = std::unique_ptr<LnkLst>;
class LnkSet;
using LnkSetPtr = std::unique_ptr<LnkSet>;

template <class>
class Set;
class Dictionary;
class DictionaryLinkValues;
using DictionaryPtr = std::unique_ptr<Dictionary>;

namespace _impl {
class DeepChangeChecker;
}

enum JSONOutputMode {
    output_mode_json,       // default / existing implementation for outputting realm to json
    output_mode_xjson,      // extended json as described in the spec
    output_mode_xjson_plus, // extended json as described in the spec with additional modifier used for sync
};

/// The status of an accessor after a call to `update_if_needed()`.
enum class UpdateStatus {
    /// The owning object or column no longer exist, and the accessor could
    /// not be updated. The accessor should be left in a detached state
    /// after this, and further calls to `update_if_needed()` are not
    /// guaranteed to reattach the accessor.
    Detached,

    /// The underlying data of the accessor was changed since the last call
    /// to `update_if_needed()`. The accessor is still valid.
    Updated,

    /// The underlying data of the accessor did not change since the last
    /// call to `update_if_needed()`, and the accessor is still valid in its
    /// current state.
    NoChange,
};

// 'Object' would have been a better name, but it clashes with a class in ObjectStore
class Obj {
public:
    constexpr Obj()
        : m_table(nullptr)
        , m_row_ndx(size_t(-1))
        , m_storage_version(-1)
        , m_valid(false)
    {
    }
    Obj(TableRef table, MemRef mem, ObjKey key, size_t row_ndx);

    TableRef get_table() const noexcept
    {
        return m_table.cast_away_const();
    }

    Allocator& get_alloc() const;

    bool operator==(const Obj& other) const;

    ObjKey get_key() const noexcept
    {
        return m_key;
    }

    GlobalKey get_object_id() const;
    ObjLink get_link() const;

    Replication* get_replication() const;

    // Check if this object is default constructed
    explicit operator bool() const noexcept
    {
        return m_table != nullptr;
    }

    /// Check if the object is still alive
    bool is_valid() const noexcept;
    /// Delete object from table. Object is invalid afterwards.
    void remove();
    /// Invalidate
    ///  - this turns the object into a tombstone if links to the object exist.
    ///  - deletes the object is no links to the object exist.
    ///  - To be used by the Sync client.
    void invalidate();

    template <typename U>
    U get(ColKey col_key) const;

    Mixed get_any(ColKey col_key) const;
    Mixed get_any(StringData col_name) const
    {
        return get_any(get_column_key(col_name));
    }
    Mixed get_any(std::vector<std::string>::iterator path_start, std::vector<std::string>::iterator path_end) const;
    Mixed get_primary_key() const;

    template <typename U>
    U get(StringData col_name) const
    {
        return get<U>(get_column_key(col_name));
    }
    bool is_unresolved(ColKey col_key) const;

    size_t get_link_count(ColKey col_key) const;
    TableRef get_target_table(ColKey col_key) const;

    bool is_null(ColKey col_key) const;
    bool is_null(StringData col_name) const
    {
        return is_null(get_column_key(col_name));
    }
    bool has_backlinks(bool only_strong_links) const;
    size_t get_backlink_count() const;
    size_t get_backlink_count(const Table& origin, ColKey origin_col_key) const;
    ObjKey get_backlink(const Table& origin, ColKey origin_col_key, size_t backlink_ndx) const;
    TableView get_backlink_view(TableRef src_table, ColKey src_col_key);

    // To be used by the query system when a single object should
    // be tested. Will allow a function to be called in the context
    // of the owning cluster.
    template <class T>
    bool evaluate(T func) const;

    void to_json(std::ostream& out, size_t link_depth, const std::map<std::string, std::string>& renames,
                 std::vector<ObjLink>& followed, JSONOutputMode output_mode) const;
    void to_json(std::ostream& out, size_t link_depth, const std::map<std::string, std::string>& renames,
                 JSONOutputMode output_mode = output_mode_json) const
    {
        std::vector<ObjLink> followed;
        to_json(out, link_depth, renames, followed, output_mode);
    }

    std::string to_string() const;

    // Get the path in a minimal format without including object accessors.
    // If you need to obtain additional information for each object in the path,
    // you should use get_fat_path() or traverse_path() instead (see below).
    struct PathElement;
    struct Path {
        TableKey top_table;
        ObjKey top_objkey;
        std::vector<PathElement> path_from_top;
    };
    Path get_path() const;

    // Get the fat path to this object expressed as a vector of fat path elements.
    // each Fat path elements include a Obj allowing for low cost access to the
    // objects data.
    // For a top-level object, the returned vector will be empty.
    // For an embedded object, the vector has the top object as first element,
    // and the embedded object itself is not included in the path.
    struct FatPathElement;
    using FatPath = std::vector<FatPathElement>;
    FatPath get_fat_path() const;

    // For an embedded object, traverse the path leading to this object.
    // The PathSizer is called first to set the size of the path
    // Then there is one call for each object on that path, starting with the top level object
    // The embedded object itself is not considered part of the path.
    // Note: You should never provide the path_index for calls to traverse_path.
    using Visitor = util::FunctionRef<void(const Obj&, ColKey, Mixed)>;
    using PathSizer = util::FunctionRef<void(size_t)>;
    void traverse_path(Visitor v, PathSizer ps, size_t path_index = 0) const;

    template <typename U>
    Obj& set(ColKey col_key, U value, bool is_default = false);
    // Create a new object and link it. If an embedded object
    // is already set, it will be removed. If a non-embedded
    // object is already set, we throw LogicError (to prevent
    // dangling objects, since they do not delete automatically
    // if they are not embedded...)
    Obj create_and_set_linked_object(ColKey col_key, bool is_default = false);
    // Clear all fields of a linked object returning it to its
    // default state. If the object does not exist, create a
    // new object and link it. (To Be Implemented)
    Obj clear_linked_object(ColKey col_key);
    Obj& set_any(ColKey col_key, Mixed value, bool is_default = false);
    Obj& set_any(StringData col_name, Mixed value, bool is_default = false)
    {
        return set_any(get_column_key(col_name), value, is_default);
    }

    template <typename U>
    Obj& set(StringData col_name, U value, bool is_default = false)
    {
        return set(get_column_key(col_name), value, is_default);
    }

    Obj& set_null(ColKey col_key, bool is_default = false);
    Obj& set_null(StringData col_name, bool is_default = false)
    {
        return set_null(get_column_key(col_name), is_default);
    }

    Obj& add_int(ColKey col_key, int64_t value);
    Obj& add_int(StringData col_name, int64_t value)
    {
        return add_int(get_column_key(col_name), value);
    }

    template <typename U>
    Obj& set_list_values(ColKey col_key, const std::vector<U>& values);

    template <typename U>
    std::vector<U> get_list_values(ColKey col_key) const;

    template <class Head, class... Tail>
    Obj& set_all(Head v, Tail... tail);

    // The main algorithm for handling schema migrations if we try to convert
    // from TopLevel* to Embedded, in this case all the orphan objects are deleted
    // and all the objects with multiple backlinks are cloned in order to avoid to
    // get schema violations during the migration.
    // By default this alogirithm is disabled. RealmConfig contains a boolean flag
    // to enable it.
    void handle_multiple_backlinks_during_schema_migration();

    Obj get_linked_object(ColKey link_col_key) const
    {
        return _get_linked_object(link_col_key, get_any(link_col_key));
    }
    Obj get_linked_object(StringData link_col_name) const
    {
        return get_linked_object(get_column_key(link_col_name));
    }
    Obj get_parent_object() const;

    template <typename U>
    Lst<U> get_list(ColKey col_key) const;
    template <typename U>
    LstPtr<U> get_list_ptr(ColKey col_key) const;

    template <typename U>
    Lst<U> get_list(StringData col_name) const
    {
        return get_list<U>(get_column_key(col_name));
    }

    LnkLst get_linklist(ColKey col_key) const;
    LnkLstPtr get_linklist_ptr(ColKey col_key) const;
    LnkLst get_linklist(StringData col_name) const;

    /// Get a type-erased list instance for the given list column.
    ///
    /// Note: For lists of links, this always returns a `LnkLst`, rather than a
    /// `Lst<ObjKey>`. Use `get_list_ptr<ObjKey>(col_key)` to get a list of
    /// links with uncondensed indices.
    LstBasePtr get_listbase_ptr(ColKey col_key) const;

    template <typename U>
    Set<U> get_set(StringData col_name) const
    {
        return get_set<U>(get_column_key(col_name));
    }
    template <typename U>
    Set<U> get_set(ColKey col_key) const;
    template <typename U>
    SetPtr<U> get_set_ptr(ColKey col_key) const;
    LnkSet get_linkset(ColKey col_key) const;
    LnkSet get_linkset(StringData col_name) const;
    LnkSetPtr get_linkset_ptr(ColKey col_key) const;
    SetBasePtr get_setbase_ptr(ColKey col_key) const;
    Dictionary get_dictionary(ColKey col_key) const;
    DictionaryPtr get_dictionary_ptr(ColKey col_key) const;
    Dictionary get_dictionary(StringData col_name) const;

    CollectionBasePtr get_collection_ptr(ColKey col_key) const;
    CollectionBasePtr get_collection_ptr(StringData col_name) const;
    LinkCollectionPtr get_linkcollection_ptr(ColKey col_key) const;

    void assign_pk_and_backlinks(const Obj& other);

    class Internal {
        friend class _impl::DeepChangeChecker;

        static ref_type get_ref(const Obj& obj, ColKey col_key);
    };

private:
    friend class ArrayBacklink;
    friend class CascadeState;
    friend class Cluster;
    friend class ColumnListBase;
    friend class CollectionBase;
    friend class TableView;
    template <class, class>
    friend class Collection;
    template <class>
    friend class CollectionBaseImpl;
    template <class>
    friend class Lst;
    friend class LnkLst;
    friend class Dictionary;
    friend class LinkMap;
    template <class>
    friend class Set;
    friend class Table;
    friend class Transaction;

    mutable TableRef m_table;
    ObjKey m_key;
    mutable MemRef m_mem;
    mutable size_t m_row_ndx;
    mutable uint64_t m_storage_version;
    mutable bool m_valid;

    Allocator& _get_alloc() const noexcept;


    /// Update the accessor. Returns true when the accessor was updated to
    /// reflect new changes to the underlying state.
    bool update() const;
    // update if needed - with and without check of table instance version:
    bool update_if_needed() const;
    bool _update_if_needed() const; // no check, use only when already checked

    /// Update the accessor (and return `UpdateStatus::Detached` if the Obj is
    /// no longer valid, rather than throwing an exception).
    UpdateStatus update_if_needed_with_status() const;

    template <class T>
    bool do_is_null(ColKey::Idx col_ndx) const;

    const ClusterTree* get_tree_top() const;
    ColKey get_column_key(StringData col_name) const;
    ColKey get_primary_key_column() const;
    TableKey get_table_key() const;
    TableRef get_target_table(ObjLink link) const;
    const Spec& get_spec() const;

    template <typename U>
    U _get(ColKey::Idx col_ndx) const;

    ObjKey get_backlink(ColKey backlink_col, size_t backlink_ndx) const;
    // Return all backlinks from a specific backlink column
    std::vector<ObjKey> get_all_backlinks(ColKey backlink_col) const;
    // Return number of backlinks from a specific backlink column
    size_t get_backlink_cnt(ColKey backlink_col) const;
    ObjKey get_unfiltered_link(ColKey col_key) const;

    template <class Val>
    Obj& _set(size_t col_ndx, Val v);
    template <class Head, class... Tail>
    Obj& _set(size_t col_ndx, Head v, Tail... tail);
    ColKey spec_ndx2colkey(size_t col_ndx);
    size_t colkey2spec_ndx(ColKey);
    bool ensure_writeable();
    void sync(Node& arr);
    int_fast64_t bump_content_version();
    void bump_both_versions();
    template <class T>
    void do_set_null(ColKey col_key);

    // Dictionary support
    size_t get_row_ndx() const
    {
        return m_row_ndx;
    }

    Obj _get_linked_object(ColKey link_col_key, Mixed link) const;
    Obj _get_linked_object(StringData link_col_name, Mixed link) const
    {
        return _get_linked_object(get_column_key(link_col_name), link);
    }

    void set_int(ColKey col_key, int64_t value);
    void add_backlink(ColKey backlink_col, ObjKey origin_key);
    bool remove_one_backlink(ColKey backlink_col, ObjKey origin_key);
    void nullify_link(ColKey origin_col, ObjLink target_key) &&;
    // Used when inserting a new link. You will not remove existing links in this process
    void set_backlink(ColKey col_key, ObjLink new_link) const;
    // Used when replacing a link, return true if CascadeState contains objects to remove
    bool replace_backlink(ColKey col_key, ObjLink old_link, ObjLink new_link, CascadeState& state) const;
    // Used when removing a backlink, return true if CascadeState contains objects to remove
    bool remove_backlink(ColKey col_key, ObjLink old_link, CascadeState& state) const;
    template <class T>
    inline void set_spec(T&, ColKey);
    template <class ValueType>
    inline void nullify_single_link(ColKey col, ValueType target);

    void fix_linking_object_during_schema_migration(Obj linking_obj, Obj obj, ColKey opposite_col_key) const;
};

std::ostream& operator<<(std::ostream&, const Obj& obj);

template <>
int64_t Obj::get(ColKey) const;
template <>
bool Obj::get(ColKey) const;

template <>
int64_t Obj::_get(ColKey::Idx col_ndx) const;
template <>
StringData Obj::_get(ColKey::Idx col_ndx) const;
template <>
BinaryData Obj::_get(ColKey::Idx col_ndx) const;
template <>
ObjKey Obj::_get(ColKey::Idx col_ndx) const;

struct Obj::FatPathElement {
    Obj obj;        // Object which embeds...
    ColKey col_key; // Column holding link or link list which embeds...
    Mixed index;    // index into link list or dictionary (or null)
};

struct Obj::PathElement {
    ColKey col_key; // Column holding link or link list which embeds...
    Mixed index;    // index into link list or dictionary (or null)
};

template <>
Obj& Obj::set(ColKey, int64_t value, bool is_default);

template <>
Obj& Obj::set(ColKey, ObjKey value, bool is_default);

template <>
Obj& Obj::set(ColKey, ObjLink value, bool is_default);


template <>
inline Obj& Obj::set(ColKey col_key, int value, bool is_default)
{
    return set(col_key, int_fast64_t(value), is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, uint_fast64_t value, bool is_default)
{
    int_fast64_t value_2 = 0;
    if (REALM_UNLIKELY(util::int_cast_with_overflow_detect(value, value_2))) {
        REALM_TERMINATE("Unsigned integer too big.");
    }
    return set(col_key, value_2, is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, const char* str, bool is_default)
{
    return set(col_key, StringData(str), is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, char* str, bool is_default)
{
    return set(col_key, StringData(str), is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, std::string str, bool is_default)
{
    return set(col_key, StringData(str), is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, realm::null, bool is_default)
{
    return set_null(col_key, is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, util::Optional<bool> value, bool is_default)
{
    return value ? set(col_key, *value, is_default) : set_null(col_key, is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, util::Optional<int64_t> value, bool is_default)
{
    return value ? set(col_key, *value, is_default) : set_null(col_key, is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, util::Optional<float> value, bool is_default)
{
    return value ? set(col_key, *value, is_default) : set_null(col_key, is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, util::Optional<double> value, bool is_default)
{
    return value ? set(col_key, *value, is_default) : set_null(col_key, is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, util::Optional<ObjectId> value, bool is_default)
{
    return value ? set(col_key, *value, is_default) : set_null(col_key, is_default);
}

template <>
inline Obj& Obj::set(ColKey col_key, util::Optional<UUID> value, bool is_default)
{
    return value ? set(col_key, *value, is_default) : set_null(col_key, is_default);
}

template <typename U>
Obj& Obj::set_list_values(ColKey col_key, const std::vector<U>& values)
{
    size_t sz = values.size();
    auto list = get_list<U>(col_key);
    size_t list_sz = list.size();
    if (sz < list_sz) {
        list.resize(sz);
        list_sz = sz;
    }
    size_t i = 0;
    while (i < list_sz) {
        list.set(i, values[i]);
        i++;
    }
    while (i < sz) {
        list.add(values[i]);
        i++;
    }

    return *this;
}

template <typename U>
std::vector<U> Obj::get_list_values(ColKey col_key) const
{
    std::vector<U> values;
    auto list = get_list<U>(col_key);
    for (auto v : list)
        values.push_back(v);

    return values;
}

template <class Val>
inline Obj& Obj::_set(size_t col_ndx, Val v)
{
    return set(spec_ndx2colkey(col_ndx), v);
}

template <class Head, class... Tail>
inline Obj& Obj::_set(size_t col_ndx, Head v, Tail... tail)
{
    set(spec_ndx2colkey(col_ndx), v);
    return _set(col_ndx + 1, tail...);
}

template <class Head, class... Tail>
inline Obj& Obj::set_all(Head v, Tail... tail)
{
    size_t start_index = 0;

    // Avoid trying to set the PK column.
    if (get_primary_key_column()) {
        REALM_ASSERT(colkey2spec_ndx(get_primary_key_column()) == 0);
        start_index = 1;
    }

    return _set(start_index, v, tail...);
}

inline bool Obj::update_if_needed() const
{
    auto current_version = get_alloc().get_storage_version();
    if (current_version != m_storage_version) {
        return update();
    }
    return false;
}

inline int_fast64_t Obj::bump_content_version()
{
    Allocator& alloc = get_alloc();
    return alloc.bump_content_version();
}

inline void Obj::bump_both_versions()
{
    Allocator& alloc = get_alloc();
    alloc.bump_content_version();
    alloc.bump_storage_version();
}

} // namespace realm

#endif // REALM_OBJ_HPP