1 files changed, 114 insertions, 0 deletions
diff --git a/include/data/data.hpp b/include/data/data.hpp
new file mode 100644
index 0000000..46156cd
--- /dev/null
+++ b/include/data/data.hpp
@@ -0,0 +1,114 @@
+#pragma once
+
+#include <chrono>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include <nlohmann/json.hpp>
+#include <openssl/evp.h>
+#include <openssl/sha.h>
+
+namespace nostr
+{
+namespace data
+{
+/**
+ * @brief A Nostr event.
+ * @remark All data transmitted over the Nostr protocol is encoded in JSON blobs.  This struct
+ * is common to every Nostr event kind.  The significance of each event is determined by the
+ * `tags` and `content` fields.
+*/
+struct Event
+{
+    std::string id; ///< SHA-256 hash of the event data.
+    std::string pubkey; ///< Public key of the event creator.
+    std::time_t createdAt; ///< Unix timestamp of the event creation.
+    int kind; ///< Event kind.
+    std::vector<std::vector<std::string>> tags; ///< Arbitrary event metadata.
+    std::string content; ///< Event content.
+    std::string sig; ///< Event signature created with the private key of the event creator.
+
+    /**
+     * @brief Serializes the event to a JSON object.
+     * @returns A stringified JSON object representing the event.
+     * @throws `std::invalid_argument` if the event object is invalid.
+     */
+    std::string serialize();
+
+    /**
+     * @brief Deserializes the event from a JSON string.
+     * @param jsonString A stringified JSON object representing the event.
+     * @returns An event instance created from the JSON string.
+     */
+    static Event fromString(std::string jsonString);
+
+    /**
+     * @brief Deserializes the event from a JSON object.
+     * @param j A JSON object representing the event.
+     * @returns An event instance created from the JSON object.
+     */
+    static Event fromJson(nlohmann::json j);
+
+    /**
+     * @brief Compares two events for equality.
+     * @remark Two events are considered equal if they have the same ID, since the ID is uniquely
+     * generated from the event data.  If the `id` field is empty for either event, the comparison
+     * function will throw an exception.
+     */
+    bool operator==(const Event& other) const;
+
+private:
+    /**
+     * @brief Validates the event.
+     * @throws `std::invalid_argument` if the event object is invalid.
+     * @remark The `createdAt` field defaults to the present if it is not already set.
+     */
+    void validate();
+
+    /**
+     * @brief Generates an ID for the event.
+     * @param serializedData The serialized JSON string of all of the event data except the ID and
+     * the signature.
+     * @return A valid Nostr event ID.
+     * @remark The ID is a 32-bytes lowercase hex-encoded sha256 of the serialized event data.
+     */
+    std::string generateId(std::string serializedData) const;
+};
+
+/**
+ * @brief A set of filters for querying Nostr relays.
+ * @remark The `limit` field should always be included to keep the response size reasonable.  The
+ * `since` field is not required, and the `until` field will default to the present.  At least one
+ * of the other fields must be set for a valid filter.
+ */
+struct Filters
+{
+    std::vector<std::string> ids; ///< Event IDs.
+    std::vector<std::string> authors; ///< Event author npubs.
+    std::vector<int> kinds; ///< Kind numbers.
+    std::unordered_map<std::string, std::vector<std::string>> tags; ///< Tag names mapped to lists of tag values.
+    std::time_t since; ///< Unix timestamp.  Matching events must be newer than this.
+    std::time_t until; ///< Unix timestamp.  Matching events must be older than this.
+    int limit; ///< The maximum number of events the relay should return on the initial query.
+
+    /**
+     * @brief Serializes the filters to a JSON object.
+     * @param subscriptionId A string up to 64 chars in length that is unique per relay connection.
+     * @returns A stringified JSON object representing the filters.
+     * @throws `std::invalid_argument` if the filter object is invalid.
+     * @remarks The Nostr client is responsible for managing subscription IDs.  Responses from the
+     * relay will be organized by subscription ID.
+     */
+    std::string serialize(std::string& subscriptionId);
+
+private:
+    /**
+     * @brief Validates the filters.
+     * @throws `std::invalid_argument` if the filter object is invalid.
+     * @remark The `until` field defaults to the present if it is not already set.
+     */
+    void validate();
+};
+} // namespace data
+} // namespace nostr