unified_log_context.h

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// BSD 3-Clause License
// Copyright (c) 2025, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
#pragma once
 
#include <kcenon/logger/interfaces/log_entry.h>
#include <kcenon/logger/logger_export.h>
#include <kcenon/logger/otlp/otel_context.h>
 
#include <optional>
#include <shared_mutex>
#include <string>
#include <string_view>
#include <unordered_map>
#include <variant>
#include <vector>
 
namespace kcenon::logger {
 
using context_value = std::variant<std::monostate, bool, int64_t, double, std::string>;
 
enum class context_category : uint8_t {
    custom = 0,   
    trace = 1,    
    request = 2,  
    otel = 3      
};
 
class LOGGER_SYSTEM_API unified_log_context {
public:
    unified_log_context() = default;
 
    unified_log_context(const unified_log_context& other);
 
    unified_log_context(unified_log_context&& other) noexcept;
 
    unified_log_context& operator=(const unified_log_context& other);
 
    unified_log_context& operator=(unified_log_context&& other) noexcept;
 
    ~unified_log_context() = default;
 
    // =========================================================================
    // Setters
    // =========================================================================
 
    unified_log_context& set(std::string_view key,
                             context_value value,
                             context_category category = context_category::custom);
 
    unified_log_context& set_trace(std::string_view trace_id,
                                   std::string_view span_id,
                                   std::optional<std::string_view> parent_span_id = std::nullopt);
 
    unified_log_context& set_request(std::string_view request_id,
                                     std::optional<std::string_view> correlation_id = std::nullopt);
 
    unified_log_context& set_otel(const otlp::otel_context& ctx);
 
    // =========================================================================
    // Getters
    // =========================================================================
 
    [[nodiscard]] std::optional<context_value> get(std::string_view key) const;
 
    template <typename T>
    [[nodiscard]] std::optional<T> get_as(std::string_view key) const {
        auto value = get(key);
        if (!value) {
            return std::nullopt;
        }
        if (auto* ptr = std::get_if<T>(&*value)) {
            return *ptr;
        }
        return std::nullopt;
    }
 
    [[nodiscard]] std::string get_string(std::string_view key,
                                         std::string_view default_value = "") const;
 
    [[nodiscard]] std::optional<context_category> get_category(std::string_view key) const;
 
    // =========================================================================
    // Query methods
    // =========================================================================
 
    [[nodiscard]] bool has(std::string_view key) const;
 
    [[nodiscard]] bool empty() const;
 
    [[nodiscard]] size_t size() const;
 
    [[nodiscard]] std::vector<std::string> keys() const;
 
    [[nodiscard]] std::vector<std::string> keys(context_category category) const;
 
    // =========================================================================
    // Removal
    // =========================================================================
 
    void remove(std::string_view key);
 
    void clear();
 
    void clear(context_category category);
 
    // =========================================================================
    // Export
    // =========================================================================
 
    [[nodiscard]] log_fields to_fields() const;
 
    unified_log_context& merge(const unified_log_context& other, bool overwrite = true);
 
private:
    struct entry {
        context_value value;
        context_category category;
    };
 
    mutable std::shared_mutex mutex_;
    std::unordered_map<std::string, entry> data_;
};
 
}  // namespace kcenon::logger