#pragma once

#include <Storages/MutationCommands.h>
#include <Interpreters/Context_fwd.h>
#include <Storages/StorageInMemoryMetadata.h>


namespace DB
{

/// Alter conversions which should be applied on-fly for part.
/// Built from of the most recent mutation commands for part.
/// Now only ALTER RENAME COLUMN is applied.
class AlterConversions : private WithContext, boost::noncopyable
{
public:
    AlterConversions() = default;

    AlterConversions(StorageMetadataPtr metadata_snapshot_, ContextPtr context_)
        : WithContext(context_)
        , metadata_snapshot(std::move(metadata_snapshot_))
    {
    }

    struct RenamePair
    {
        std::string rename_to;
        std::string rename_from;
    };

    void addMutationCommand(const MutationCommand & command);
    const std::vector<RenamePair> & getRenameMap() const { return rename_map; }

    /// Column was renamed (lookup by value in rename_map)
    bool columnHasNewName(const std::string & old_name) const;
    /// Get new name for column (lookup by value in rename_map)
    std::string getColumnNewName(const std::string & old_name) const;
    /// Is this name is new name of column (lookup by key in rename_map)
    bool isColumnRenamed(const std::string & new_name) const;
    /// Get column old name before rename (lookup by key in rename_map)
    std::string getColumnOldName(const std::string & new_name) const;

    static bool isSupportedDataMutation(MutationCommand::Type type);
    static bool isSupportedMetadataMutation(MutationCommand::Type type);

private:
    /// Rename map new_name -> old_name.
    std::vector<RenamePair> rename_map;
    StorageMetadataPtr metadata_snapshot;
};

using AlterConversionsPtr = std::shared_ptr<const AlterConversions>;

}