#include <cassert>
#include <Common/Exception.h>

#include <Interpreters/MutationsInterpreter.h>
#include <Interpreters/getColumnFromBlock.h>
#include <Interpreters/inplaceBlockConversions.h>
#include <Storages/StorageFactory.h>
#include <Storages/StorageMemory.h>
#include <Storages/MemorySettings.h>
#include <DataTypes/ObjectUtils.h>
#include <Columns/ColumnObject.h>

#include <IO/WriteHelpers.h>
#include <Processors/Sources/SourceWithProgress.h>
#include <QueryPipeline/Pipe.h>
#include <Processors/Sinks/SinkToStorage.h>
#include <Processors/Executors/PullingPipelineExecutor.h>
#include <Parsers/ASTCreateQuery.h>

#include <Common/FileChecker.h>
#include <Compression/CompressedReadBuffer.h>
#include <Compression/CompressedReadBufferFromFile.h>
#include <Compression/CompressedWriteBuffer.h>
#include <Backups/IBackup.h>
#include <Backups/IBackupEntriesBatch.h>
#include <Backups/IRestoreTask.h>
#include <IO/copyData.h>
#include <IO/createReadBufferFromFileBase.h>
#include <Poco/TemporaryFile.h>


namespace DB
{

namespace ErrorCodes
{
    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}


class MemorySource : public SourceWithProgress
{
    using InitializerFunc = std::function<void(std::shared_ptr<const Blocks> &)>;
public:

    MemorySource(
        Names column_names_,
        const StorageSnapshotPtr & storage_snapshot,
        std::shared_ptr<const Blocks> data_,
        std::shared_ptr<std::atomic<size_t>> parallel_execution_index_,
        InitializerFunc initializer_func_ = {})
        : SourceWithProgress(storage_snapshot->getSampleBlockForColumns(column_names_))
        , column_names_and_types(storage_snapshot->getColumnsByNames(
            GetColumnsOptions(GetColumnsOptions::All).withSubcolumns().withExtendedObjects(), column_names_))
        , data(data_)
        , parallel_execution_index(parallel_execution_index_)
        , initializer_func(std::move(initializer_func_))
    {
    }

    String getName() const override { return "Memory"; }

protected:
    Chunk generate() override
    {
        if (initializer_func)
        {
            initializer_func(data);
            initializer_func = {};
        }

        size_t current_index = getAndIncrementExecutionIndex();

        if (!data || current_index >= data->size())
        {
            return {};
        }

        const Block & src = (*data)[current_index];

        Columns columns;
        size_t num_columns = column_names_and_types.size();
        columns.reserve(num_columns);

        auto name_and_type = column_names_and_types.begin();
        for (size_t i = 0; i < num_columns; ++i)
        {
            columns.emplace_back(tryGetColumnFromBlock(src, *name_and_type));
            ++name_and_type;
        }

        fillMissingColumns(columns, src.rows(), column_names_and_types, /*metadata_snapshot=*/ nullptr);
        assert(std::all_of(columns.begin(), columns.end(), [](const auto & column) { return column != nullptr; }));

        return Chunk(std::move(columns), src.rows());
    }

private:
    size_t getAndIncrementExecutionIndex()
    {
        if (parallel_execution_index)
        {
            return (*parallel_execution_index)++;
        }
        else
        {
            return execution_index++;
        }
    }

    const NamesAndTypesList column_names_and_types;
    size_t execution_index = 0;
    std::shared_ptr<const Blocks> data;
    std::shared_ptr<std::atomic<size_t>> parallel_execution_index;
    InitializerFunc initializer_func;
};


class MemorySink : public SinkToStorage
{
public:
    MemorySink(
        StorageMemory & storage_,
        const StorageMetadataPtr & metadata_snapshot_)
        : SinkToStorage(metadata_snapshot_->getSampleBlock())
        , storage(storage_)
        , storage_snapshot(storage_.getStorageSnapshot(metadata_snapshot_))
    {
    }

    String getName() const override { return "MemorySink"; }

    void consume(Chunk chunk) override
    {
        auto block = getHeader().cloneWithColumns(chunk.getColumns());
        storage_snapshot->metadata->check(block, true);
        if (!storage_snapshot->object_columns.empty())
        {
            auto columns = storage_snapshot->metadata->getColumns().getAllPhysical().filter(block.getNames());
            auto extended_storage_columns = storage_snapshot->getColumns(
                GetColumnsOptions(GetColumnsOptions::AllPhysical).withExtendedObjects());

            convertObjectsToTuples(columns, block, extended_storage_columns);
        }

        if (storage.compress)
        {
            Block compressed_block;
            for (const auto & elem : block)
                compressed_block.insert({ elem.column->compress(), elem.type, elem.name });

            new_blocks.emplace_back(compressed_block);
        }
        else
        {
            new_blocks.emplace_back(block);
        }
    }

    void onFinish() override
    {
        size_t inserted_bytes = 0;
        size_t inserted_rows = 0;

        for (const auto & block : new_blocks)
        {
            inserted_bytes += block.allocatedBytes();
            inserted_rows += block.rows();
        }

        std::lock_guard lock(storage.mutex);

        auto new_data = std::make_unique<Blocks>(*(storage.data.get()));
        new_data->insert(new_data->end(), new_blocks.begin(), new_blocks.end());

        storage.data.set(std::move(new_data));
        storage.total_size_bytes.fetch_add(inserted_bytes, std::memory_order_relaxed);
        storage.total_size_rows.fetch_add(inserted_rows, std::memory_order_relaxed);
    }

private:
    Blocks new_blocks;

    StorageMemory & storage;
    StorageSnapshotPtr storage_snapshot;
};


StorageMemory::StorageMemory(
    const StorageID & table_id_,
    ColumnsDescription columns_description_,
    ConstraintsDescription constraints_,
    const String & comment,
    bool compress_)
    : IStorage(table_id_), data(std::make_unique<const Blocks>()), compress(compress_)
{
    StorageInMemoryMetadata storage_metadata;
    storage_metadata.setColumns(std::move(columns_description_));
    storage_metadata.setConstraints(std::move(constraints_));
    storage_metadata.setComment(comment);
    setInMemoryMetadata(storage_metadata);
}

StorageSnapshotPtr StorageMemory::getStorageSnapshot(const StorageMetadataPtr & metadata_snapshot) const
{
    auto snapshot_data = std::make_unique<SnapshotData>();
    snapshot_data->blocks = data.get();

    if (!hasObjectColumns(metadata_snapshot->getColumns()))
        return std::make_shared<StorageSnapshot>(*this, metadata_snapshot, ColumnsDescription{}, std::move(snapshot_data));

    auto object_columns = getObjectColumns(
        snapshot_data->blocks->begin(),
        snapshot_data->blocks->end(),
        metadata_snapshot->getColumns(),
        [](const auto & block) -> const auto & { return block.getColumnsWithTypeAndName(); });

    return std::make_shared<StorageSnapshot>(*this, metadata_snapshot, object_columns, std::move(snapshot_data));
}

Pipe StorageMemory::read(
    const Names & column_names,
    const StorageSnapshotPtr & storage_snapshot,
    SelectQueryInfo & /*query_info*/,
    ContextPtr /*context*/,
    QueryProcessingStage::Enum /*processed_stage*/,
    size_t /*max_block_size*/,
    unsigned num_streams)
{
    storage_snapshot->check(column_names);

    const auto & snapshot_data = assert_cast<const SnapshotData &>(*storage_snapshot->data);
    auto current_data = snapshot_data.blocks;

    if (delay_read_for_global_subqueries)
    {
        /// Note: for global subquery we use single source.
        /// Mainly, the reason is that at this point table is empty,
        /// and we don't know the number of blocks are going to be inserted into it.
        ///
        /// It may seem to be not optimal, but actually data from such table is used to fill
        /// set for IN or hash table for JOIN, which can't be done concurrently.
        /// Since no other manipulation with data is done, multiple sources shouldn't give any profit.

        return Pipe(std::make_shared<MemorySource>(
            column_names,
            storage_snapshot,
            nullptr /* data */,
            nullptr /* parallel execution index */,
            [current_data](std::shared_ptr<const Blocks> & data_to_initialize)
            {
                data_to_initialize = current_data;
            }));
    }

    size_t size = current_data->size();

    if (num_streams > size)
        num_streams = size;

    Pipes pipes;

    auto parallel_execution_index = std::make_shared<std::atomic<size_t>>(0);

    for (size_t stream = 0; stream < num_streams; ++stream)
    {
        pipes.emplace_back(std::make_shared<MemorySource>(column_names, storage_snapshot, current_data, parallel_execution_index));
    }

    return Pipe::unitePipes(std::move(pipes));
}


SinkToStoragePtr StorageMemory::write(const ASTPtr & /*query*/, const StorageMetadataPtr & metadata_snapshot, ContextPtr /*context*/)
{
    return std::make_shared<MemorySink>(*this, metadata_snapshot);
}


void StorageMemory::drop()
{
    data.set(std::make_unique<Blocks>());
    total_size_bytes.store(0, std::memory_order_relaxed);
    total_size_rows.store(0, std::memory_order_relaxed);
}

static inline void updateBlockData(Block & old_block, const Block & new_block)
{
    for (const auto & it : new_block)
    {
        auto col_name = it.name;
        auto & col_with_type_name = old_block.getByName(col_name);
        col_with_type_name.column = it.column;
    }
}

void StorageMemory::checkMutationIsPossible(const MutationCommands & /*commands*/, const Settings & /*settings*/) const
{
    /// Some validation will be added
}

void StorageMemory::mutate(const MutationCommands & commands, ContextPtr context)
{
    std::lock_guard lock(mutex);
    auto metadata_snapshot = getInMemoryMetadataPtr();
    auto storage = getStorageID();
    auto storage_ptr = DatabaseCatalog::instance().getTable(storage, context);

    /// When max_threads > 1, the order of returning blocks is uncertain,
    /// which will lead to inconsistency after updateBlockData.
    auto new_context = Context::createCopy(context);
    new_context->setSetting("max_streams_to_max_threads_ratio", 1);
    new_context->setSetting("max_threads", 1);

    auto interpreter = std::make_unique<MutationsInterpreter>(storage_ptr, metadata_snapshot, commands, new_context, true);
    auto pipeline = interpreter->execute();
    PullingPipelineExecutor executor(pipeline);

    Blocks out;
    Block block;
    while (executor.pull(block))
    {
        if (compress)
            for (auto & elem : block)
                elem.column = elem.column->compress();

        out.push_back(block);
    }

    std::unique_ptr<Blocks> new_data;

    // all column affected
    if (interpreter->isAffectingAllColumns())
    {
        new_data = std::make_unique<Blocks>(out);
    }
    else
    {
        /// just some of the column affected, we need update it with new column
        new_data = std::make_unique<Blocks>(*(data.get()));
        auto data_it = new_data->begin();
        auto out_it = out.begin();

        while (data_it != new_data->end())
        {
            /// Mutation does not change the number of blocks
            assert(out_it != out.end());

            updateBlockData(*data_it, *out_it);
            ++data_it;
            ++out_it;
        }

        assert(out_it == out.end());
    }

    size_t rows = 0;
    size_t bytes = 0;
    for (const auto & buffer : *new_data)
    {
        rows += buffer.rows();
        bytes += buffer.bytes();
    }
    total_size_bytes.store(bytes, std::memory_order_relaxed);
    total_size_rows.store(rows, std::memory_order_relaxed);
    data.set(std::move(new_data));
}


void StorageMemory::truncate(
    const ASTPtr &, const StorageMetadataPtr &, ContextPtr, TableExclusiveLockHolder &)
{
    data.set(std::make_unique<Blocks>());
    total_size_bytes.store(0, std::memory_order_relaxed);
    total_size_rows.store(0, std::memory_order_relaxed);
}


class MemoryBackupEntriesBatch : public shared_ptr_helper<MemoryBackupEntriesBatch>, public IBackupEntriesBatch
{
private:
    friend struct shared_ptr_helper<MemoryBackupEntriesBatch>;

    MemoryBackupEntriesBatch(
        const StorageMetadataPtr & metadata_snapshot_, const std::shared_ptr<const Blocks> blocks_, UInt64 max_compress_block_size_)
        : IBackupEntriesBatch({"data.bin", "index.mrk", "sizes.json"})
        , metadata_snapshot(metadata_snapshot_)
        , blocks(blocks_)
        , max_compress_block_size(max_compress_block_size_)
    {
    }

    static constexpr const size_t kDataBinPos = 0;
    static constexpr const size_t kIndexMrkPos = 1;
    static constexpr const size_t kSizesJsonPos = 2;
    static constexpr const size_t kSize = 3;

    void initialize()
    {
        std::call_once(initialized_flag, [this]()
        {
            temp_dir_owner.emplace();
            auto temp_dir = temp_dir_owner->path();
            fs::create_directories(temp_dir);

            /// Writing data.bin
            constexpr char data_file_name[] = "data.bin";
            String data_file_path = temp_dir + "/" + data_file_name;
            IndexForNativeFormat index;
            {
                auto data_out_compressed = std::make_unique<WriteBufferFromFile>(data_file_path);
                CompressedWriteBuffer data_out{*data_out_compressed, CompressionCodecFactory::instance().getDefaultCodec(), max_compress_block_size};
                NativeWriter block_out{data_out, 0, metadata_snapshot->getSampleBlock(), false, &index};
                for (const auto & block : *blocks)
                    block_out.write(block);
            }

            /// Writing index.mrk
            constexpr char index_file_name[] = "index.mrk";
            String index_file_path = temp_dir + "/" + index_file_name;
            {
                auto index_out_compressed = std::make_unique<WriteBufferFromFile>(index_file_path);
                CompressedWriteBuffer index_out{*index_out_compressed};
                index.write(index_out);
            }

            /// Writing sizes.json
            constexpr char sizes_file_name[] = "sizes.json";
            String sizes_file_path = temp_dir + "/" + sizes_file_name;
            FileChecker file_checker{sizes_file_path};
            file_checker.update(data_file_path);
            file_checker.update(index_file_path);
            file_checker.save();

            file_paths[kDataBinPos] = data_file_path;
            file_sizes[kDataBinPos] = file_checker.getFileSize(data_file_path);

            file_paths[kIndexMrkPos] = index_file_path;
            file_sizes[kIndexMrkPos] = file_checker.getFileSize(index_file_path);

            file_paths[kSizesJsonPos] = sizes_file_path;
            file_sizes[kSizesJsonPos] = fs::file_size(sizes_file_path);

            /// We don't need to keep `blocks` any longer.
            blocks.reset();
            metadata_snapshot.reset();
        });
    }

    std::unique_ptr<ReadBuffer> getReadBuffer(size_t index) override
    {
        initialize();
        return createReadBufferFromFileBase(file_paths[index], {});
    }

    UInt64 getSize(size_t index) override
    {
        initialize();
        return file_sizes[index];
    }

    StorageMetadataPtr metadata_snapshot;
    std::shared_ptr<const Blocks> blocks;
    UInt64 max_compress_block_size;
    std::once_flag initialized_flag;
    std::optional<Poco::TemporaryFile> temp_dir_owner;
    std::array<String, kSize> file_paths;
    std::array<UInt64, kSize> file_sizes;
};


BackupEntries StorageMemory::backup(ContextPtr context, const ASTs & partitions)
{
    if (!partitions.empty())
        throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Table engine {} doesn't support partitions", getName());

    return MemoryBackupEntriesBatch::create(getInMemoryMetadataPtr(), data.get(), context->getSettingsRef().max_compress_block_size)
        ->getBackupEntries();
}


class MemoryRestoreTask : public IRestoreTask
{
public:
    MemoryRestoreTask(
        std::shared_ptr<StorageMemory> storage_, const BackupPtr & backup_, const String & data_path_in_backup_, ContextMutablePtr context_)
        : storage(storage_), backup(backup_), data_path_in_backup(data_path_in_backup_), context(context_)
    {
    }

    RestoreTasks run() override
    {
        /// Our data are in the StripeLog format.

        /// Reading index.mrk
        IndexForNativeFormat index;
        {
            String index_file_path = data_path_in_backup + "index.mrk";
            auto backup_entry = backup->readFile(index_file_path);
            auto in = backup_entry->getReadBuffer();
            CompressedReadBuffer compressed_in{*in};
            index.read(compressed_in);
        }

        /// Reading data.bin
        Blocks new_blocks;
        size_t new_bytes = 0;
        size_t new_rows = 0;
        {
            String data_file_path = data_path_in_backup + "data.bin";
            auto backup_entry = backup->readFile(data_file_path);
            std::unique_ptr<ReadBuffer> in = backup_entry->getReadBuffer();
            std::optional<Poco::TemporaryFile> temp_data_copy;
            if (!dynamic_cast<ReadBufferFromFileBase *>(in.get()))
            {
                temp_data_copy.emplace();
                auto temp_data_copy_out = std::make_unique<WriteBufferFromFile>(temp_data_copy->path());
                copyData(*in, *temp_data_copy_out);
                temp_data_copy_out.reset();
                in = createReadBufferFromFileBase(temp_data_copy->path(), {});
            }
            std::unique_ptr<ReadBufferFromFileBase> in_from_file{static_cast<ReadBufferFromFileBase *>(in.release())};
            CompressedReadBufferFromFile compressed_in{std::move(in_from_file)};
            NativeReader block_in{compressed_in, 0, index.blocks.begin(), index.blocks.end()};

            while (auto block = block_in.read())
            {
                new_bytes += block.bytes();
                new_rows += block.rows();
                new_blocks.push_back(std::move(block));
            }
        }

        /// Append old blocks with the new ones.
        auto old_blocks = storage->data.get();
        Blocks old_and_new_blocks = *old_blocks;
        old_and_new_blocks.insert(old_and_new_blocks.end(), std::make_move_iterator(new_blocks.begin()), std::make_move_iterator(new_blocks.end()));

        /// Finish restoring.
        storage->data.set(std::make_unique<Blocks>(std::move(old_and_new_blocks)));
        storage->total_size_bytes += new_bytes;
        storage->total_size_rows += new_rows;

        return {};
    }

private:
    std::shared_ptr<StorageMemory> storage;
    BackupPtr backup;
    String data_path_in_backup;
    ContextMutablePtr context;
};


RestoreTaskPtr StorageMemory::restoreFromBackup(ContextMutablePtr context, const ASTs & partitions, const BackupPtr & backup, const String & data_path_in_backup, const StorageRestoreSettings &)
{
    if (!partitions.empty())
        throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Table engine {} doesn't support partitions", getName());

    return std::make_unique<MemoryRestoreTask>(
        typeid_cast<std::shared_ptr<StorageMemory>>(shared_from_this()), backup, data_path_in_backup, context);
}


std::optional<UInt64> StorageMemory::totalRows(const Settings &) const
{
    /// All modifications of these counters are done under mutex which automatically guarantees synchronization/consistency
    /// When run concurrently we are fine with any value: "before" or "after"
    return total_size_rows.load(std::memory_order_relaxed);
}

std::optional<UInt64> StorageMemory::totalBytes(const Settings &) const
{
    return total_size_bytes.load(std::memory_order_relaxed);
}

void registerStorageMemory(StorageFactory & factory)
{
    factory.registerStorage("Memory", [](const StorageFactory::Arguments & args)
    {
        if (!args.engine_args.empty())
            throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
                "Engine {} doesn't support any arguments ({} given)",
                args.engine_name, args.engine_args.size());

        bool has_settings = args.storage_def->settings;
        MemorySettings settings;
        if (has_settings)
            settings.loadFromQuery(*args.storage_def);

        return StorageMemory::create(args.table_id, args.columns, args.constraints, args.comment, settings.compress);
    },
    {
        .supports_settings = true,
        .supports_parallel_insert = true,
    });
}

}