priv impl and scaffold for driver

include/bb_expantions.hpp

@@ -5,6 +5,8 @@
 
 #include <stdint.h>
 
+#define EXPANDER_DEVICE_NAME_MAX_LEN 32
+
 /// The expantion device ids in the BLK_BOX ecosystem.
 enum class BlkBoxExpantion: uint16_t {
     NONE = 0,

include/bbnow_driver.hpp

@@ -0,0 +1,74 @@
+/// Generic code for driving a BBNOW interface.
+
+#ifndef _BBNOW_DRIVER_HPP
+#define _BBNOW_DRIVER_HPP
+
+#include <array>
+#include <cstdint>
+#include <span>
+#include <string>
+#include <vector>
+
+#include "esp_err.h"
+
+#include "bb_expantions.hpp"
+#include "bbnow_pub.hpp"
+#include "bbnow_priv.hpp"
+
+class BBNowDriver {
+public:
+    using MacAddress = std::array<uint8_t, 6>;
+
+    struct PairedExpander {
+        MacAddress mac;
+        std::string name;
+        BlkBoxExpantion type;
+    };
+
+    static constexpr uint8_t DEFAULT_CHANNEL = 6;
+
+    static esp_err_t init();
+    static esp_err_t deinit();
+
+    static esp_err_t send_pub(const BBNowPubPacket& packet);
+    static bool has_pub();
+    static bool recv_pub(BBNowPubPacket& packet);
+
+    static esp_err_t send_priv(
+        const MacAddress& destination,
+        const BBNowPrivPacket& packet
+    );
+    static bool has_priv();
+    static bool recv_priv(
+        MacAddress& source,
+        BBNowPrivPacket& packet
+    );
+
+    /// Broadcast a discovery packet.
+    static size_t send_discovery(
+        BlkBoxExpantion type
+    );
+
+    static esp_err_t pair_expander(
+        BlkBoxExpantion type,
+        const MacAddress& mac
+    );
+
+    static esp_err_t unpair_expander(
+        const MacAddress& mac
+    );
+
+    static std::span<const PairedExpander> get_paired_expanders();
+
+private:
+    static constexpr MacAddress BROADCAST_MAC = {
+        0xff, 0xff, 0xff,
+        0xff, 0xff, 0xff
+    };
+
+    static bool initialized_;
+
+    static std::vector<PairedExpander> paired_expanders;
+};
+
+#endif /* _BBNOW_DRIVER_HPP */

include/bbnow_priv.hpp

@@ -4,9 +4,49 @@
 #define _BBNOW_PRIV_H
 
 #include <stdint.h>
+#include <vector>
+#include <optional>
+#include <span>
+#include <variant>
 
-#define EXPANDER_DEVICE_NAME_MAX_LEN 32
+#include "bb_expantions.hpp"
 
+///////////////////////////////////////
+// ACK                              //
+/////////////////////////////////////
+/// The data associated with the `ACK` type.
+struct BBNowPrivAckData {
+};
+
+///////////////////////////////////////
+// DISCOVERY RESPONSE               //
+/////////////////////////////////////
+/// The data associated with the `DISCOVERY_RESPONSE` type.
+struct BBNowPrivDiscoveryResponseData {
+    BlkBoxExpantion expantion_type{};
+};
+
+///////////////////////////////////////
+// EXPANDER MESSAGE                 //
+/////////////////////////////////////
+/// The data associated with the `EXPANDER_MESSAGE` type.
+struct BBNowPrivExpanderMessageData {
+    // TODO: this should get flattened into a concrete type, an enum over the expander types.
+    std::vector<uint8_t> data;
+};
+
+///////////////////////////////////////
+// INFO QUERY                       //
+/////////////////////////////////////
+/// The data associated with the `INFO_QUERY` type.
+struct BBNowPrivInfoQueryData {
+    uint8_t battery_percentage;
+    // TODO: add other status fields that may be useful to query.
+};
+
+///////////////////////////////////////
+// PRIV PACKET                      //
+/////////////////////////////////////
 /// The packet type for `BBNowPrivPacket`s.
 enum class BBNowPrivPacketType: uint16_t {
     NONE = 0,
@@ -14,7 +54,93 @@ enum class BBNowPrivPacketType: uint16_t {
     // TODO: we will need to add more here for handshaking in the future.
     DISCOVERY_RESPONSE = 2,
     EXPANDER_MESSAGE = 3,
-    MAX = 3,
+    INFO_QUERY = 4,
+    MAX = 4,
+};
+
+/// The data field for the packet.
+using BBNowPrivPacketData = std::variant<
+    std::monostate,
+    BBNowPrivAckData,
+    BBNowPrivDiscoveryResponseData,
+    BBNowPrivExpanderMessageData,
+    BBNowPrivInfoQueryData
+>;
+
+struct BBNowPrivPacket {
+    /// ACK packet size.
+    const static size_t ACK_PACKET_SIZE = 4;
+    static_assert(
+        ACK_PACKET_SIZE == sizeof(BBNowPrivPacketType) + sizeof(uint16_t),
+        "ACK packet size should match it's data size"
+    );
+
+    /// Discovery response packet size.
+    const static size_t DISCOVERY_RESPONSE_PACKET_SIZE = 6;
+    static_assert(
+        DISCOVERY_RESPONSE_PACKET_SIZE == sizeof(BBNowPrivPacketType) +
+        sizeof(uint16_t) +
+        sizeof(BBNowPrivDiscoveryResponseData),
+        "Discovery response packet size should match it's data size"
+    );
+
+    /// Info query packet size.
+    const static size_t INFO_QUERY_PACKET_SIZE = 5;
+    static_assert(
+        INFO_QUERY_PACKET_SIZE ==
+            sizeof(BBNowPrivPacketType) +
+            sizeof(uint16_t) +
+            sizeof(BBNowPrivInfoQueryData),
+        "Info query packet size should match its data size"
+    );
+
+    /// The type of packet this is.
+    BBNowPrivPacketType packet_type{};
+
+    /// Sequence number associated with this packet.
+    uint16_t sequence{};
+
+    /// The data held by the packet.
+    BBNowPrivPacketData packet_data{};
+
+    /// The size of the serialized packet (in bytes).
+    size_t serialize_size() const;
+
+    /// Serializes the packet to a vector.
+    std::vector<uint8_t> serialize() const;
+
+    /// Serializes the packet into the given vector.
+    ///
+    /// Returns the number of bytes written into the buffer.
+    size_t serialize_into(std::vector<uint8_t>& buf) const;
+
+    /// Deserializes a packet from the given bytes.
+    static std::optional<BBNowPrivPacket>
+    deserialize(std::span<const uint8_t> bytes);
+
+    /// Constructs an empty packet.
+    BBNowPrivPacket() = default;
+
+    /// Constructs a new `ACK` packet.
+    static BBNowPrivPacket new_ack(uint16_t sequence);
+
+    /// Constructs a new `DISCOVERY_RESPONSE` packet.
+    static BBNowPrivPacket new_discovery_response(
+        uint16_t sequence,
+        BBNowPrivDiscoveryResponseData data
+    );
+
+    /// Constructs a new `EXPANDER_MESSAGE` packet.
+    static BBNowPrivPacket new_expander_message(
+        uint16_t sequence,
+        BBNowPrivExpanderMessageData data
+    );
+
+    /// Constructs a new `INFO_QUERY` packet.
+    static BBNowPrivPacket new_info_query(
+        uint16_t sequence, 
+        BBNowPrivInfoQueryData data
+    );
 };
 
 #endif /* _BBNOW_PRIV_H */

include/bbnow_pub.hpp

@@ -7,6 +7,7 @@
 #include <vector>
 #include <optional>
 #include <span>
+#include <variant>
 
 #include "bb_expantions.hpp"
 
@@ -30,10 +31,11 @@ enum class BBNowPubPacketType: uint16_t {
     MAX = 1,
 };
 
-/// The data field for the packet
-union BlkBoxNowPubPacketData {
-    BlkBoxNowPubDiscoveryData discovery;
-};
+/// The data field for the packet.
+using BlkBoxNowPubPacketData = std::variant<
+    std::monostate,
+    BlkBoxNowPubDiscoveryData
+>;
 
 struct BBNowPubPacket {
     // "bbnp" in ascii