#pragma once

#include <string>

#include "common/api.h"
#include "common/arrow/arrow.h"
#include "common/database_lifecycle_manager.h"
#include "common/types/types.h"
#include "kuzu_fwd.h"
#include "processor/result/flat_tuple.h"
#include "query_summary.h"
namespace kuzu {
namespace main {

/**
 * @brief QueryResult stores the result of a query execution.
 */
class QueryResult {
    friend class Connection;
    friend class ClientContext;
    class QueryResultIterator {
    private:
        QueryResult* currentResult;

    public:
        QueryResultIterator() = default;

        explicit QueryResultIterator(QueryResult* startResult) : currentResult(startResult) {}

        void operator++() {
            if (currentResult) {
                currentResult = currentResult->nextQueryResult.get();
            }
        }

        bool isEnd() const { return currentResult == nullptr; }

        bool hasNextQueryResult() const { return currentResult->nextQueryResult != nullptr; }

        QueryResult* getCurrentResult() const { return currentResult; }
    };

public:
    /**
     * @brief Used to create a QueryResult object for the failing query.
     */
    KUZU_API QueryResult();

    explicit QueryResult(const PreparedSummary& preparedSummary);
    /**
     * @brief Deconstructs the QueryResult object.
     */
    KUZU_API ~QueryResult();
    /**
     * @return query is executed successfully or not.
     */
    KUZU_API bool isSuccess() const;
    /**
     * @return error message of the query execution if the query fails.
     */
    KUZU_API std::string getErrorMessage() const;
    /**
     * @return number of columns in query result.
     */
    KUZU_API size_t getNumColumns() const;
    /**
     * @return name of each column in query result.
     */
    KUZU_API std::vector<std::string> getColumnNames() const;
    /**
     * @return dataType of each column in query result.
     */
    KUZU_API std::vector<common::LogicalType> getColumnDataTypes() const;
    /**
     * @return num of tuples in query result.
     */
    KUZU_API uint64_t getNumTuples() const;
    /**
     * @return query summary which stores the execution time, compiling time, plan and query
     * options.
     */
    KUZU_API QuerySummary* getQuerySummary() const;
    /**
     * @return whether there are more tuples to read.
     */
    KUZU_API bool hasNext() const;
    /**
     * @return whether there are more query results to read.
     */
    KUZU_API bool hasNextQueryResult() const;
    /**
     * @return get next query result to read (for multiple query statements).
     */
    KUZU_API QueryResult* getNextQueryResult();

    std::unique_ptr<QueryResult> nextQueryResult;
    /**
     * @return next flat tuple in the query result. Note that to reduce resource allocation, all
     * calls to getNext() reuse the same FlatTuple object. Since its contents will be overwritten,
     * please complete processing a FlatTuple or make a copy of its data before calling getNext()
     * again.
     */
    KUZU_API std::shared_ptr<processor::FlatTuple> getNext();
    /**
     * @return string of first query result.
     */
    KUZU_API std::string toString() const;

    /**
     * @brief Resets the result tuple iterator.
     */
    KUZU_API void resetIterator();

    /**
     * @brief Returns the arrow schema of the query result.
     * @return datatypes of the columns as an arrow schema
     *
     * It is the caller's responsibility to call the release function to release the underlying data
     * If converting to another arrow type, this this is usually handled automatically.
     */
    KUZU_API std::unique_ptr<ArrowSchema> getArrowSchema() const;

    /**
     * @brief Returns the next chunk of the query result as an arrow array.
     * @param chunkSize number of tuples to return in the chunk.
     * @return An arrow array representation of the next chunkSize tuples of the query result.
     *
     * The ArrowArray internally stores an arrow struct with fields for each of the columns.
     * This can be converted to a RecordBatch with arrow's ImportRecordBatch function
     *
     * It is the caller's responsibility to call the release function to release the underlying data
     * If converting to another arrow type, this this is usually handled automatically.
     */
    KUZU_API std::unique_ptr<ArrowArray> getNextArrowChunk(int64_t chunkSize);

    processor::FactorizedTable* getTable() { return factorizedTable.get(); }

    static std::unique_ptr<QueryResult> getQueryResultWithError(const std::string& errorMessage);

private:
    void setColumnHeader(std::vector<std::string> columnNames,
        std::vector<common::LogicalType> columnTypes);
    void initResultTableAndIterator(std::shared_ptr<processor::FactorizedTable> factorizedTable_);
    void validateQuerySucceed() const;
    std::pair<std::unique_ptr<processor::FlatTuple>, std::unique_ptr<processor::FlatTupleIterator>>
    getIterator() const;
    void checkDatabaseClosedOrThrow() const;

private:
    // execution status
    bool success = true;
    std::string errMsg;

    // header information
    std::vector<std::string> columnNames;
    std::vector<common::LogicalType> columnDataTypes;
    // data
    std::shared_ptr<processor::FactorizedTable> factorizedTable;
    std::unique_ptr<processor::FlatTupleIterator> iterator;
    std::shared_ptr<processor::FlatTuple> tuple;

    // execution statistics
    std::unique_ptr<QuerySummary> querySummary;

    // query iterator
    QueryResultIterator queryResultIterator;

    // database life cycle manager
    std::shared_ptr<common::DatabaseLifeCycleManager> dbLifeCycleManager;
};

} // namespace main
} // namespace kuzu
