#include <AggregateFunctions/AggregateFunctionFactory.h>
#include <Columns/ColumnTuple.h>
#include <Columns/ColumnsNumber.h>
#include <DataStreams/BlocksBlockInputStream.h>
#include <DataStreams/ExpressionBlockInputStream.h>
#include <DataStreams/FilterBlockInputStream.h>
#include <DataStreams/IBlockOutputStream.h>
#include <DataStreams/MaterializingBlockInputStream.h>
#include <DataStreams/NullBlockInputStream.h>
#include <DataStreams/OneBlockInputStream.h>
#include <DataStreams/SquashingBlockInputStream.h>
#include <DataStreams/copyData.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypeDateTime.h>
#include <DataTypes/DataTypesNumber.h>
#include <Functions/FunctionFactory.h>
#include <Functions/FunctionsWindow.h>
#include <Interpreters/AddDefaultDatabaseVisitor.h>
#include <Interpreters/Context.h>
#include <Interpreters/InDepthNodeVisitor.h>
#include <Interpreters/InterpreterAlterQuery.h>
#include <Interpreters/InterpreterDropQuery.h>
#include <Interpreters/InterpreterSelectQuery.h>
#include <Interpreters/getTableExpressions.h>
#include <Parsers/ASTAlterQuery.h>
#include <Parsers/ASTAssignment.h>
#include <Parsers/ASTAsterisk.h>
#include <Parsers/ASTCreateQuery.h>
#include <Parsers/ASTDropQuery.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTSelectQuery.h>
#include <Parsers/ASTSubquery.h>
#include <Parsers/ASTTablesInSelectQuery.h>
#include <Parsers/ASTWatchQuery.h>
#include <Parsers/formatAST.h>
#include <Storages/StorageFactory.h>
#include <Common/typeid_cast.h>

#include <Storages/WindowView/StorageWindowView.h>
#include <Storages/WindowView/WindowViewBlockInputStream.h>
#include <Storages/WindowView/BlocksListInputStream.h>
#include <Storages/WindowView/WindowViewProxyStorage.h>


namespace DB
{
namespace ErrorCodes
{
    extern const int LOGICAL_ERROR;
    extern const int INCORRECT_QUERY;
    extern const int TABLE_WAS_NOT_DROPPED;
    extern const int QUERY_IS_NOT_SUPPORTED_IN_WINDOW_VIEW;
    extern const int SUPPORT_IS_DISABLED;
    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}

namespace
{
    const auto RESCHEDULE_MS = 500;

    class ParserStageMergeableOneMatcher
    {
    public:
        using Visitor = InDepthNodeVisitor<ParserStageMergeableOneMatcher, true>;

        struct Data
        {
            ASTPtr window_function;
            String window_column_name;
            bool is_tumble = false;
            bool is_hop = false;
        };

        static bool needChildVisit(ASTPtr & node, const ASTPtr &)
        {
            if (node->as<ASTFunction>())
                return false;
            return true;
        }

        static void visit(ASTPtr & ast, Data & data)
        {
            if (const auto * t = ast->as<ASTFunction>())
                visit(*t, ast, data);
        }

    private:
        static void visit(const ASTFunction & node, ASTPtr & node_ptr, Data & data)
        {
            if (node.name == "TUMBLE")
            {
                if (!data.window_function)
                {
                    data.is_tumble = true;
                    data.window_column_name = node.getColumnName();
                    data.window_function = node.clone();
                }
                else if (serializeAST(node) != serializeAST(*data.window_function))
                    throw Exception("WINDOW VIEW only support ONE WINDOW FUNCTION", ErrorCodes::QUERY_IS_NOT_SUPPORTED_IN_WINDOW_VIEW);
            }
            else if (node.name == "HOP")
            {
                if (!data.window_function)
                {
                    data.is_hop = true;
                    data.window_function = node.clone();
                    auto ptr_ = node.clone();
                    std::static_pointer_cast<ASTFunction>(ptr_)->setAlias("");
                    auto arrayJoin = makeASTFunction("arrayJoin", ptr_);
                    arrayJoin->alias = node.alias;
                    data.window_column_name = arrayJoin->getColumnName();
                    node_ptr = arrayJoin;
                }
                else if (serializeAST(node) != serializeAST(*data.window_function))
                    throw Exception("WINDOW VIEW only support ONE WINDOW FUNCTION", ErrorCodes::QUERY_IS_NOT_SUPPORTED_IN_WINDOW_VIEW);
            }
        }
    };

    static inline String generateInnerTableName(const String & table_name) { return ".inner." + table_name; }

    static ASTPtr generateDeleteRetiredQuery(StorageID inner_table_id, UInt32 timestamp)
    {
        auto function_equal = makeASTFunction(
            "less", std::make_shared<ASTIdentifier>("____w_end"), std::make_shared<ASTLiteral>(timestamp));

        auto alterCommand = std::make_shared<ASTAlterCommand>();
        alterCommand->type = ASTAlterCommand::DELETE;
        alterCommand->predicate = function_equal;
        alterCommand->children.push_back(alterCommand->predicate);

        auto alterCommandList = std::make_shared<ASTAlterCommandList>();
        alterCommandList->add(alterCommand);

        auto alterQuery = std::make_shared<ASTAlterQuery>();
        alterQuery->database = inner_table_id.database_name;
        alterQuery->table = inner_table_id.table_name;
        alterQuery->set(alterQuery->command_list, alterCommandList);
        return alterQuery;
    }

    static std::shared_ptr<ASTSelectQuery> generateFetchColumnsQuery(const StorageID & inner_storage)
    {
        auto res_query = std::make_shared<ASTSelectQuery>();
        auto select = std::make_shared<ASTExpressionList>();
        select->children.push_back(std::make_shared<ASTAsterisk>());
        res_query->setExpression(ASTSelectQuery::Expression::SELECT, select);

        auto tableInSelectQuery = std::make_shared<ASTTablesInSelectQuery>();
        auto tableInSelectQueryElement = std::make_shared<ASTTablesInSelectQueryElement>();
        res_query->setExpression(ASTSelectQuery::Expression::TABLES, std::make_shared<ASTTablesInSelectQuery>());
        auto tables = res_query->tables();
        auto tables_elem = std::make_shared<ASTTablesInSelectQueryElement>();
        auto table_expr = std::make_shared<ASTTableExpression>();
        tables->children.push_back(tables_elem);
        tables_elem->table_expression = table_expr;
        tables_elem->children.push_back(table_expr);
        table_expr->database_and_table_name = createTableIdentifier(inner_storage.database_name, inner_storage.table_name);
        table_expr->children.push_back(table_expr->database_and_table_name);

        return res_query;
    }
}

static void extractDependentTable(ASTSelectQuery & query, String & select_database_name, String & select_table_name)
{
    auto db_and_table = getDatabaseAndTable(query, 0);
    ASTPtr subquery = extractTableExpression(query, 0);

    if (!db_and_table && !subquery)
        return;

    if (db_and_table)
    {
        select_table_name = db_and_table->table;

        if (db_and_table->database.empty())
        {
            db_and_table->database = select_database_name;
            AddDefaultDatabaseVisitor visitor(select_database_name);
            visitor.visit(query);
        }
        else
            select_database_name = db_and_table->database;
    }
    else if (auto * ast_select = subquery->as<ASTSelectWithUnionQuery>())
    {
        if (ast_select->list_of_selects->children.size() != 1)
            throw Exception("UNION is not supported for WINDOW VIEW", ErrorCodes::QUERY_IS_NOT_SUPPORTED_IN_WINDOW_VIEW);

        auto & inner_query = ast_select->list_of_selects->children.at(0);

        extractDependentTable(inner_query->as<ASTSelectQuery &>(), select_database_name, select_table_name);
    }
    else
        throw Exception(
            "Logical error while creating StorageWindowView."
            " Could not retrieve table name from select query.",
            DB::ErrorCodes::LOGICAL_ERROR);
}

void StorageWindowView::checkTableCanBeDropped() const
{
    auto table_id = getStorageID();
    Dependencies dependencies = global_context.getDependencies(table_id);
    if (!dependencies.empty())
    {
        StorageID dependent_table_id = dependencies.front();
        throw Exception("Table has dependency " + dependent_table_id.getNameForLogs(), ErrorCodes::TABLE_WAS_NOT_DROPPED);
    }
}

static void executeDropQuery(ASTDropQuery::Kind kind, Context & global_context, const StorageID & target_table_id)
{
    if (global_context.tryGetTable(target_table_id))
    {
        /// We create and execute `drop` query for internal table.
        auto drop_query = std::make_shared<ASTDropQuery>();
        drop_query->database = target_table_id.database_name;
        drop_query->table = target_table_id.table_name;
        drop_query->kind = kind;
        ASTPtr ast_drop_query = drop_query;
        InterpreterDropQuery drop_interpreter(ast_drop_query, global_context);
        drop_interpreter.execute();
    }
}

void StorageWindowView::drop(TableStructureWriteLockHolder &)
{
    auto table_id = getStorageID();
    global_context.removeDependency(select_table_id, table_id);

    if (has_inner_table)
        executeDropQuery(ASTDropQuery::Kind::Drop, global_context, inner_table_id);

    std::lock_guard lock(mutex);
    is_dropped = true;
    condition.notify_all();
}

inline void StorageWindowView::clearInnerTable()
{
    //delete fired blocks
    UInt32 timestamp_now = std::time(nullptr);
    UInt32 w_lower_bound = getWindowLowerBound(timestamp_now, -1);
    if (has_inner_table)
    {
        auto sql = generateDeleteRetiredQuery(inner_table_id, w_lower_bound);
        InterpreterAlterQuery alt_query(sql, global_context);
        alt_query.execute();
    }
    else
    {
        std::lock_guard lock(mutex);
        for (BlocksListPtr mergeable_block : *mergeable_blocks)
        {
            mergeable_block->remove_if([&w_lower_bound](Block & block_)
            {
                auto & column_ = block_.getByName("____w_end").column;
                const auto & data = static_cast<const ColumnUInt32 &>(*column_).getData();
                for (size_t i = 0; i < column_->size(); ++i)
                {
                    if (data[i] >= w_lower_bound)
                        return false;
                }
                return true;
            });
        }
        mergeable_blocks->remove_if([](BlocksListPtr & ptr) { return ptr->size() == 0; });
    }
}

inline void StorageWindowView::flushToTable()
{
    //write into dependent table
    StoragePtr target_table = getTargetTable();
    auto _blockInputStreamPtr = getNewBlocksInputStreamPtr();
    auto _lock = target_table->lockStructureForShare(true, global_context.getCurrentQueryId());
    auto stream = target_table->write(getInnerQuery(), global_context);
    copyData(*_blockInputStreamPtr, *stream);
}

std::shared_ptr<ASTCreateQuery> StorageWindowView::generateInnerTableCreateQuery(const ASTCreateQuery & inner_create_query, const String & database_name, const String & table_name)
{
    /// We will create a query to create an internal table.
    auto manual_create_query = std::make_shared<ASTCreateQuery>();
    manual_create_query->database = database_name;
    manual_create_query->table = table_name;

    auto new_columns_list = std::make_shared<ASTColumns>();

    auto storage = getParentStorage();
    auto sample_block_
        = InterpreterSelectQuery(getInnerQuery(), global_context, storage, SelectQueryOptions(QueryProcessingStage::WithMergeableState))
              .getSampleBlock();

    auto columns_list = std::make_shared<ASTExpressionList>();
    for (auto & column_ : sample_block_.getColumnsWithTypeAndName())
    {
        ParserIdentifierWithOptionalParameters parser;
        String sql = column_.type->getName();
        ASTPtr ast = parseQuery(parser, sql.data(), sql.data() + sql.size(), "data type", 0);
        auto column_dec = std::make_shared<ASTColumnDeclaration>();
        column_dec->name = column_.name;
        column_dec->type = ast;
        columns_list->children.push_back(column_dec);
    }
    auto column_fire_status = std::make_shared<ASTColumnDeclaration>();
    column_fire_status->name = "____w_end";
    column_fire_status->type = std::make_shared<ASTIdentifier>("DateTime");
    columns_list->children.push_back(column_fire_status);

    new_columns_list->set(new_columns_list->columns, columns_list);
    manual_create_query->set(manual_create_query->columns_list, new_columns_list);
    manual_create_query->set(manual_create_query->storage, inner_create_query.storage->ptr());

    return manual_create_query;
}

UInt32 StorageWindowView::getWindowLowerBound(UInt32 time_sec, int window_id_skew)
{
    switch (window_kind)
    {
#define CASE_WINDOW_KIND(KIND) \
    case IntervalKind::KIND: \
    { \
        UInt32 res = ToStartOfTransform<IntervalKind::KIND>::execute(time_sec, window_num_units, time_zone); \
        if (window_id_skew != 0) \
            return AddTime<IntervalKind::KIND>::execute(res, window_id_skew * window_num_units, time_zone); \
        else \
            return res; \
    }
        CASE_WINDOW_KIND(Second)
        CASE_WINDOW_KIND(Minute)
        CASE_WINDOW_KIND(Hour)
        CASE_WINDOW_KIND(Day)
        CASE_WINDOW_KIND(Week)
        CASE_WINDOW_KIND(Month)
        CASE_WINDOW_KIND(Quarter)
        CASE_WINDOW_KIND(Year)
#undef CASE_WINDOW_KIND
    }
    __builtin_unreachable();
}

UInt32 StorageWindowView::getWindowUpperBound(UInt32 time_sec, int window_id_skew)
{
    switch (window_kind)
    {
#define CASE_WINDOW_KIND(KIND) \
    case IntervalKind::KIND: \
    { \
        UInt32 start = ToStartOfTransform<IntervalKind::KIND>::execute(time_sec, window_num_units, time_zone); \
        UInt32 res = AddTime<IntervalKind::KIND>::execute(start, window_num_units, time_zone); \
        if (window_id_skew != 0) \
            return AddTime<IntervalKind::KIND>::execute(res, window_id_skew * window_num_units, time_zone); \
        else \
            return res; \
    }
        CASE_WINDOW_KIND(Second)
        CASE_WINDOW_KIND(Minute)
        CASE_WINDOW_KIND(Hour)
        CASE_WINDOW_KIND(Day)
        CASE_WINDOW_KIND(Week)
        CASE_WINDOW_KIND(Month)
        CASE_WINDOW_KIND(Quarter)
        CASE_WINDOW_KIND(Year)
#undef CASE_WINDOW_KIND
    }
    __builtin_unreachable();
}

void StorageWindowView::threadFuncClearInnerTable()
{
    while (!shutdown_called)
    {
        try
        {
            clearInnerTable();
            sleep(inner_table_clear_interval);
        }
        catch (...)
        {
            tryLogCurrentException(__PRETTY_FUNCTION__);
            break;
        }
    }
    if (!shutdown_called)
        innerTableClearTask->scheduleAfter(RESCHEDULE_MS);
}

void StorageWindowView::threadFuncToTable()
{
    while (!shutdown_called && !target_table_id.empty())
    {
        std::unique_lock lock(flushTableMutex);
        UInt64 timestamp_usec = static_cast<UInt64>(Poco::Timestamp().epochMicroseconds());
        UInt64 w_end = static_cast<UInt64>(getWindowUpperBound(static_cast<UInt32>(timestamp_usec / 1000000))) * 1000000;
        condition.wait_for(lock, std::chrono::microseconds(w_end - timestamp_usec));
        try
        {
            flushToTable();
        }
        catch (...)
        {
            tryLogCurrentException(__PRETTY_FUNCTION__);
            break;
        }
    }
    if (!shutdown_called)
        toTableTask->scheduleAfter(RESCHEDULE_MS);
}

BlockInputStreams StorageWindowView::watch(
    const Names & /*column_names*/,
    const SelectQueryInfo & query_info,
    const Context & /*context*/,
    QueryProcessingStage::Enum & processed_stage,
    size_t /*max_block_size*/,
    const unsigned /*num_streams*/)
{
    if (!target_table_id.empty())
        throw Exception("WATCH query is disabled for " + getName() + " when constructed with 'TO' clause.", ErrorCodes::INCORRECT_QUERY);

    if (active_ptr.use_count() > 1)
        throw Exception("WATCH query is already attached, WINDOW VIEW only supports attaching one watch query.", ErrorCodes::INCORRECT_QUERY);

    ASTWatchQuery & query = typeid_cast<ASTWatchQuery &>(*query_info.query);

    bool has_limit = false;
    UInt64 limit = 0;

    if (query.limit_length)
    {
        has_limit = true;
        limit = safeGet<UInt64>(typeid_cast<ASTLiteral &>(*query.limit_length).value);
    }

    auto reader = std::make_shared<WindowViewBlockInputStream>(
        std::static_pointer_cast<StorageWindowView>(shared_from_this()),
        active_ptr,
        has_limit,
        limit);

    processed_stage = QueryProcessingStage::Complete;

    return {reader};
}

Block StorageWindowView::getHeader() const
{
    if (!sample_block)
    {
        auto storage = global_context.getTable(select_table_id);
        sample_block = InterpreterSelectQuery(getInnerQuery(), global_context, storage, SelectQueryOptions(QueryProcessingStage::Complete))
                           .getSampleBlock();
        for (size_t i = 0; i < sample_block.columns(); ++i)
            sample_block.safeGetByPosition(i).column = sample_block.safeGetByPosition(i).column->convertToFullColumnIfConst();
    }

    return sample_block;
}

StorageWindowView::StorageWindowView(
    const StorageID & table_id_,
    Context & local_context,
    const ASTCreateQuery & query,
    const ColumnsDescription & columns_,
    bool attach_)
    : IStorage(table_id_)
    , global_context(local_context.getGlobalContext())
    , time_zone(DateLUT::instance())
{
    setColumns(columns_);

    if (!query.select)
        throw Exception("SELECT query is not specified for " + getName(), ErrorCodes::INCORRECT_QUERY);

    /// Default value, if only table name exist in the query
    if (query.select->list_of_selects->children.size() != 1)
        throw Exception("UNION is not supported for Window View", ErrorCodes::QUERY_IS_NOT_SUPPORTED_IN_WINDOW_VIEW);

    auto inner_query_ = query.select->list_of_selects->children.at(0);

    ASTSelectQuery & select_query = typeid_cast<ASTSelectQuery &>(*inner_query_);
    String select_database_name = local_context.getCurrentDatabase();
    String select_table_name;
    extractDependentTable(select_query, select_database_name, select_table_name);
    select_table_id = StorageID(select_database_name, select_table_name);
    inner_query = innerQueryParser(select_query);

    /// If the table is not specified - use the table `system.one`
    if (select_table_name.empty())
    {
        select_database_name = "system";
        select_table_name = "one";
    }

    global_context.addDependency(select_table_id, table_id_);

    if (!query.to_table.empty())
        target_table_id = StorageID(query.to_database, query.to_table);

    is_temporary = query.temporary;
    inner_table_clear_interval = local_context.getSettingsRef().window_view_inner_table_clean_interval.totalSeconds();

    mergeable_blocks = std::make_shared<std::list<BlocksListPtr>>();

    active_ptr = std::make_shared<bool>(true);

    has_inner_table = query.storage;

    if (query.storage)
    {
        if (attach_)
        {
            inner_table_id = StorageID(table_id_.database_name, generateInnerTableName(table_id_.table_name));
        }
        else
        {
            if(query.storage->engine->name != "MergeTree")
                throw Exception(
                    "The ENGINE of WindowView must be MergeTree family of table engines including the engines with replication support",
                    ErrorCodes::INCORRECT_QUERY);

            auto manual_create_query
                = generateInnerTableCreateQuery(query, table_id_.database_name, generateInnerTableName(table_id_.table_name));
            InterpreterCreateQuery create_interpreter(manual_create_query, local_context);
            create_interpreter.setInternal(true);
            create_interpreter.execute();
            inner_storage = global_context.getTable(manual_create_query->database, manual_create_query->table);
            inner_table_id = inner_storage->getStorageID();
        }
        fetch_column_query = generateFetchColumnsQuery(inner_table_id);
    }

    toTableTask = global_context.getSchedulePool().createTask(getStorageID().getFullTableName(), [this] { threadFuncToTable(); });
    innerTableClearTask = global_context.getSchedulePool().createTask(getStorageID().getFullTableName(), [this] { threadFuncClearInnerTable(); });
    toTableTask->deactivate();
    innerTableClearTask->deactivate();
}


ASTPtr StorageWindowView::innerQueryParser(ASTSelectQuery & query)
{
    if (!query.groupBy())
        throw Exception("GROUP BY query is required for " + getName(), ErrorCodes::INCORRECT_QUERY);

    // parse stage mergeable
    ASTPtr result = query.clone();
    ASTPtr expr_list = result;
    ParserStageMergeableOneMatcher::Data stageMergeableOneData;
    ParserStageMergeableOneMatcher::Visitor(stageMergeableOneData).visit(expr_list);
    if (!stageMergeableOneData.is_tumble && !stageMergeableOneData.is_hop)
        throw Exception("WINDOW FUNCTION is not specified for " + getName(), ErrorCodes::INCORRECT_QUERY);
    window_column_name = stageMergeableOneData.window_column_name;

    // parser window function
    ASTFunction & window_function = typeid_cast<ASTFunction &>(*stageMergeableOneData.window_function);
    const auto & arguments = window_function.arguments->children;
    const auto & interval_p1 = std::static_pointer_cast<ASTFunction>(arguments.at(1));
    if (!interval_p1 || !startsWith(interval_p1->name, "toInterval"))
        throw Exception("Illegal type of last argument of function " + interval_p1->name + " should be Interval", ErrorCodes::ILLEGAL_COLUMN);

    String interval_str = interval_p1->name.substr(10);
    if (interval_str == "Second")
        window_kind = IntervalKind::Second;
    else if (interval_str == "Minute")
        window_kind = IntervalKind::Minute;
    else if (interval_str == "Hour")
        window_kind = IntervalKind::Hour;
    else if (interval_str == "Day")
        window_kind = IntervalKind::Day;
    else if (interval_str == "Week")
        window_kind = IntervalKind::Week;
    else if (interval_str == "Month")
        window_kind = IntervalKind::Month;
    else if (interval_str == "Quarter")
        window_kind = IntervalKind::Quarter;
    else if (interval_str == "Year")
        window_kind = IntervalKind::Year;

    const auto & interval_units_p1 = std::static_pointer_cast<ASTLiteral>(interval_p1->children.front()->children.front());

    window_num_units = stoi(interval_units_p1->value.get<String>());
    return result;
}

void StorageWindowView::writeIntoWindowView(StorageWindowView & window_view, const Block & block, const Context & context)
{
    BlockInputStreams streams = {std::make_shared<OneBlockInputStream>(block)};
    auto window_proxy_storage = std::make_shared<WindowViewProxyStorage>(
        StorageID("", "WindowViewProxyStorage"), window_view.getParentStorage(), std::move(streams), QueryProcessingStage::FetchColumns);
    InterpreterSelectQuery select_block(
        window_view.getInnerQuery(), context, window_proxy_storage, QueryProcessingStage::WithMergeableState);

    auto data_mergeable_stream = std::make_shared<MaterializingBlockInputStream>(select_block.execute().in);


    if (window_view.has_inner_table)
    {
        auto stream = window_view.getInnerStorage()->write(window_view.getInnerQuery(), context);
        while (Block block_ = data_mergeable_stream->read())
        {
            const ColumnTuple * column_tuple
                = checkAndGetColumn<ColumnTuple>(block_.getByName(window_view.window_column_name).column.get());
            block_.insert({column_tuple->getColumnPtr(1), std::make_shared<DataTypeDateTime>(), "____w_end"});
            stream->write(block_);
        }
    }
    else
    {
        BlocksListPtr new_mergeable_blocks = std::make_shared<BlocksList>();
        while (Block block_ = data_mergeable_stream->read())
        {
            const ColumnTuple * column_tuple
                = checkAndGetColumn<ColumnTuple>(block_.getByName(window_view.window_column_name).column.get());
            block_.insert({column_tuple->getColumnPtr(1), std::make_shared<DataTypeDateTime>(), "____w_end"});
            new_mergeable_blocks->push_back(block_);
        }
        if (!new_mergeable_blocks->empty())
        {
            std::unique_lock lock(window_view.mutex);
            window_view.getMergeableBlocksList()->push_back(new_mergeable_blocks);
        }
    }
    // window_view.condition.notify_all();
}

StoragePtr StorageWindowView::getTargetTable() const
{
    return global_context.getTable(target_table_id);
}

StoragePtr StorageWindowView::tryGetTargetTable() const
{
    return global_context.tryGetTable(target_table_id);
}

void StorageWindowView::startup()
{
    // Start the working thread
    if (!target_table_id.empty())
        toTableTask->activateAndSchedule();
    innerTableClearTask->activateAndSchedule();
}

void StorageWindowView::shutdown()
{
    bool expected = false;
    if (!shutdown_called.compare_exchange_strong(expected, true))
        return;
    toTableTask->deactivate();
    innerTableClearTask->deactivate();
}

StorageWindowView::~StorageWindowView()
{
    shutdown();
}

BlockInputStreamPtr StorageWindowView::getNewBlocksInputStreamPtr()
{
    if (has_inner_table)
        return getNewBlocksInputStreamPtrInnerTable();

    if (mergeable_blocks->empty())
        return {std::make_shared<NullBlockInputStream>(getHeader())};

    UInt32 timestamp_now = std::time(nullptr);
    UInt32 w_upper_bound = getWindowUpperBound(timestamp_now);

    BlockInputStreams from;
    auto sample_block_ = mergeable_blocks->front()->front().cloneEmpty();
    BlockInputStreamPtr stream = std::make_shared<BlocksListInputStream>(mergeable_blocks, sample_block_, mutex,w_upper_bound);
    from.push_back(std::move(stream));
    auto proxy_storage = std::make_shared<WindowViewProxyStorage>(
        StorageID("", "WindowViewProxyStorage"), getParentStorage(), std::move(from), QueryProcessingStage::WithMergeableState);

    InterpreterSelectQuery select(getInnerQuery(), global_context, proxy_storage, QueryProcessingStage::Complete);
    BlockInputStreamPtr data = std::make_shared<MaterializingBlockInputStream>(select.execute().in);
    return data;
}

BlockInputStreamPtr StorageWindowView::getNewBlocksInputStreamPtrInnerTable()
{
    // Fetch and filter data can be fired
    UInt32 timestamp_now = std::time(nullptr);
    UInt32 w_end = getWindowUpperBound(timestamp_now);

    auto & storage = getInnerStorage();
    InterpreterSelectQuery fetch(fetch_column_query, global_context, storage, SelectQueryOptions(QueryProcessingStage::FetchColumns));

    ColumnsWithTypeAndName columns_;
    columns_.emplace_back(nullptr, std::make_shared<DataTypeDateTime>(), "____w_end");

    ExpressionActionsPtr add_column_actions = std::make_shared<ExpressionActions>(columns_, global_context);
    add_column_actions->add(ExpressionAction::addColumn({std::make_shared<DataTypeDateTime>()->createColumnConst(1, toField(w_end)), std::make_shared<DataTypeDateTime>(), "____w_end_now"}));
    auto add_column_instream = std::make_shared<ExpressionBlockInputStream>(fetch.execute().in, add_column_actions);

    columns_.emplace_back(nullptr, std::make_shared<DataTypeDateTime>(), "____w_end_now");
    const auto & function_equals = FunctionFactory::instance().get("equals", global_context);
    ExpressionActionsPtr apply_function_actions = std::make_shared<ExpressionActions>(columns_, global_context);
    apply_function_actions->add(ExpressionAction::applyFunction(function_equals, Names{"____w_end", "____w_end_now"}, "____filter"));

    auto stream = std::make_shared<FilterBlockInputStream>(add_column_instream, apply_function_actions, "____filter");

    BlockInputStreams from;
    from.push_back(std::move(stream));
    auto proxy_storage = std::make_shared<WindowViewProxyStorage>(
        StorageID("", "WindowViewProxyStorage"), getParentStorage(), std::move(from), QueryProcessingStage::WithMergeableState);

    InterpreterSelectQuery select(getInnerQuery(), global_context, proxy_storage, QueryProcessingStage::Complete);

    BlockInputStreamPtr data = std::make_shared<MaterializingBlockInputStream>(select.execute().in);
    return data;
}

void registerStorageWindowView(StorageFactory & factory)
{
    factory.registerStorage("WindowView", [](const StorageFactory::Arguments & args)
    {
        if (!args.attach && !args.local_context.getSettingsRef().allow_experimental_window_view)
            throw Exception(
                "Experimental WINDOW VIEW feature is not enabled (the setting 'allow_experimental_window_view')",
                ErrorCodes::SUPPORT_IS_DISABLED);

        return StorageWindowView::create(args.table_id, args.local_context, args.query, args.columns, args.attach);
    });
}

}