database_cursor.h

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// BSD 3-Clause License
// Copyright (c) 2021-2025, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
#pragma once
 
#include <kcenon/pacs/storage/pacs_database_adapter.h>
 
#ifdef PACS_WITH_DATABASE_SYSTEM
 
#include <kcenon/pacs/storage/instance_record.h>
#include <kcenon/pacs/storage/patient_record.h>
#include <kcenon/pacs/storage/series_record.h>
#include <kcenon/pacs/storage/study_record.h>
 
#include <kcenon/common/patterns/result.h>
 
#include <cstdint>
#include <memory>
#include <optional>
#include <string>
#include <variant>
#include <vector>
 
namespace kcenon::pacs::services {
 
template <typename T>
using Result = kcenon::common::Result<T>;
 
using VoidResult = kcenon::common::VoidResult;
 
using query_record = std::variant<storage::patient_record, storage::study_record,
                                  storage::series_record, storage::instance_record>;
 
class database_cursor {
public:
    enum class record_type { patient, study, series, instance };
 
    ~database_cursor();
 
    // Non-copyable
    database_cursor(const database_cursor&) = delete;
    auto operator=(const database_cursor&) -> database_cursor& = delete;
 
    // Movable
    database_cursor(database_cursor&& other) noexcept;
    auto operator=(database_cursor&& other) noexcept -> database_cursor&;
 
    // =========================================================================
    // Factory Methods
    // =========================================================================
 
    [[nodiscard]] static auto create_patient_cursor(
        std::shared_ptr<storage::pacs_database_adapter> db,
        const storage::patient_query& query) -> Result<std::unique_ptr<database_cursor>>;
 
    [[nodiscard]] static auto create_study_cursor(
        std::shared_ptr<storage::pacs_database_adapter> db,
        const storage::study_query& query) -> Result<std::unique_ptr<database_cursor>>;
 
    [[nodiscard]] static auto create_series_cursor(
        std::shared_ptr<storage::pacs_database_adapter> db,
        const storage::series_query& query) -> Result<std::unique_ptr<database_cursor>>;
 
    [[nodiscard]] static auto create_instance_cursor(
        std::shared_ptr<storage::pacs_database_adapter> db,
        const storage::instance_query& query) -> Result<std::unique_ptr<database_cursor>>;
 
 
    // =========================================================================
    // Cursor Operations
    // =========================================================================
 
    [[nodiscard]] auto has_more() const noexcept -> bool;
 
    [[nodiscard]] auto fetch_next() -> std::optional<query_record>;
 
    [[nodiscard]] auto fetch_batch(size_t batch_size) -> std::vector<query_record>;
 
    [[nodiscard]] auto position() const noexcept -> size_t;
 
    [[nodiscard]] auto type() const noexcept -> record_type;
 
    [[nodiscard]] auto reset() -> VoidResult;
 
    // =========================================================================
    // Cursor State
    // =========================================================================
 
    [[nodiscard]] auto serialize() const -> std::string;
 
private:
    database_cursor(std::vector<query_record> results, record_type type);
 
    [[nodiscard]] static auto parse_patient_row(
        const storage::database_row& row) -> storage::patient_record;
 
    [[nodiscard]] static auto parse_study_row(
        const storage::database_row& row) -> storage::study_record;
 
    [[nodiscard]] static auto parse_series_row(
        const storage::database_row& row) -> storage::series_record;
 
    [[nodiscard]] static auto parse_instance_row(
        const storage::database_row& row) -> storage::instance_record;
 
    static void add_dicom_condition(
        database::query_builder& builder,
        const std::string& field,
        const std::string& value);
 
    std::vector<query_record> results_;
 
    [[nodiscard]] static auto to_like_pattern(std::string_view pattern) -> std::string;
 
    [[nodiscard]] static auto contains_dicom_wildcards(std::string_view pattern) -> bool;
 
    record_type type_;
 
    size_t position_{0};
 
    bool has_more_{true};
 
    bool stepped_{false};
};
 
}  // namespace kcenon::pacs::services
 
#endif  // PACS_WITH_DATABASE_SYSTEM