syntax = "proto3";
// per https://developers.google.com/protocol-buffers/docs/proto3

// We are not placing any of these defs inside a package, because if you do the resulting nanopb version is super verbose
// package mesh;

option java_package = "com.geeksville.mesh";
option java_outer_classname = "MeshProtos";

/**
MESH RADIO PROTOCOL

Old TODO notes on the mesh radio protocol, merge into real docs below...

for each named group we have a pre-shared key known by all group members and wrapped around the device.
you can only be in one group at a time (FIXME?!)
To join the group we read a qr code with the preshared key and ParamsCodeEnum.  that gets sent via
bluetooth to the device.  ParamsCodeEnum maps to a set of various radio params (regulatory region,
center freq, SF, bandwidth, bitrate, power etc...) so all members of the mesh can have their radios set the same way.

once in that group, we can talk between 254 node numbers.
to get our node number (and announce our presence in the channel) we pick a random node number and
broadcast as that node with WANT-NODENUM(my globally unique name).  If anyone on the channel has
seen someone _else_ using that name within the last 24 hrs(?) they reply with DENY-NODENUM.
Note: we might receive multiple denies.  Note: this allows others to speak up for some other node
that might be saving battery right now.
Any time we hear from another node (for any message type), we add that node number to the unpickable
list.  To dramatically decrease the odds a node number we request is already used by someone.
If no one denies within TBD seconds, we assume that we have that node number.  As long as we keep
talking to folks at least once every 24 hrs, others should remember we have it.

Once we have a node number we can broadcast POSITION-UPDATE(my globally unique name, lat, lon, alt,
amt battery remaining).  All receivers will use this to a) update the mapping of who is at what
node nums, b) the time of last rx, c) position.  If we haven't heard from that node in a while we
reply to that node (only) with our current POSITION_UPDATE state - so that node (presumably just
rejoined the network) can build a map of all participants.

We will periodically broadcast POSITION-UPDATE as needed based on distance moved or a periodic minimum heartbeat.

If user wants to send a text they can SEND_TEXT(dest user, short text message).  Dest user is a
node number, or 0xff for broadcast.
*/

/*
Protobuf build instructions:

protoc -I=. --java_out /tmp mesh.proto

To generate Nanopb c code
/home/kevinh/packages/nanopb-0.4.0-linux-x86/generator-bin/protoc --nanopb_out=/tmp -I=app/src/main/proto mesh.proto

Nanopb binaries available here: https://jpa.kapsi.fi/nanopb/download/ use nanopb 0.4.0

*/

// a gps position
message Position {
    double latitude = 1;
    double longitude = 2;
    int32 altitude = 3;
    int32 battery_level = 4; // 1-100 (0 means not provided)

    /// This is usually not sent over the mesh (to save space), but it is sent from the phone so that the local device can set its RTC
    /// If it is sent over the mesh (because there are devices on the mesh without GPS), it will only be sent by devices which has a
    /// hardware GPS clock.
    uint32 time = 6; // seconds since 1970
}

// a data message to forward to an external app (or possibly also be consumed internally in the case of CLEAR_TEXT and CLEAR_READACK
message Data {
    enum Type {
        /// A message sent from a device outside of the mesh, in a form the mesh does not understand
        SIGNAL_OPAQUE = 0; // NOTE: This must be 0, because it is documented in IMeshService.aidl to be so

        /// a simple UTF-8 text message, which even the little micros in the mesh can understand and show on their screen
        /// eventually in some circumstances even signal might send messages in this form (see below)
        CLEAR_TEXT = 1;

        /// a message receive acknowledgement, sent in cleartext - allows radio to show user that a message has been read by the recipient, optional
        CLEAR_READACK = 2;

        /// Not yet used but eventually:
        /// SIGNAL_CLEAR_DATA = 3; // Unencrypted at the signal level, relying on the radio crypt only (to keep size small), but contains Signal control data radios don't care about (ie non text)
    }

    Type typ = 1; // required
    bytes payload = 2; // required
}

/* Broadcast when a newly powered mesh node wants to find a node num it can use
// Sent from the phone over bluetooth to set the user id for the owner of this node.
// Also sent from nodes to each other when a new node signs on (so all clients can have this info)

The algorithm is as follows:
* when a node starts up, it broadcasts their user and the normal flow is for all other nodes to reply with their User as well (so the new node can build its node db)
* If a node ever receives a User (not just the first broadcast) message where the sender node number equals our node number, that indicates a collision has occurred and the following steps should happen:

If the receiving node (that was already in the mesh)'s macaddr is LOWER than the new User who just tried to sign in: it gets to keep its nodenum.  We send a broadcast message
of OUR User (we use a broadcast so that the other node can receive our message, considering we have the same id - it also serves to let observers correct their nodedb) - this case is rare so it should be okay.

If any node receives a User where the macaddr is GTE than their local macaddr, they have been vetoed and should pick a new random nodenum (filtering against whatever it knows about the nodedb) and
rebroadcast their User.

A few nodenums are reserved and will never be requested:
0xff - broadcast
0 through 3 - for future use

*/
message User {
    string id = 1; // a globally unique ID string for this user.  In the case of Signal that would mean +16504442323, for the default macaddr derived id it would be !<6 hexidecimal bytes>
    string long_name = 2; // A full name for this user, i.e. "Kevin Hester"
    string short_name = 3; // A VERY short name, ideally two characters.  Suitable for a tiny OLED screen
    bytes macaddr = 4; // This is the addr of the radio.  Not populated by the phone, but added by the esp32 when broadcasting
}

// The payload portion fo a packet, this is the actual bytes that are sent inside a radio packet (because from/to are broken out by the comms library)
message SubPacket {
    oneof variant {
        Position position = 1;

        Data data = 3;
        User user = 4;
    }

    /// Not normally used, but for testing a sender can request that recipient responds in kind (i.e. if it received a position, it should unicast back its position).  
    // Note: that if you set this on a broadcast you will receive many replies.
    bool want_response = 5;
}

// Note: For simplicity reasons (and that we want to keep over the radio packets very small, we now assume that there is only _one_
// SubPacket in each MeshPacket).  That might change in the far future, but for now that's the case.
// A packet sent over our mesh.
// NOTE: this raw payload does not include the from and to addresses, which are stripped off
// and passed into the mesh library code separately.
//message MeshPayload {
//    repeated SubPacket subPackets = 3;
//}

// A full packet sent/received over the mesh
message MeshPacket {
    int32 from = 1;
    int32 to = 2;

    // See note above:
    // MeshPayload payloads = 4;
    SubPacket payload = 3;

    /// The time this message was received by the esp32 (secs since 1970).  Note: this field is _never_ sent on the radio link itself (to save space)
    /// Times are typically not sent over the mesh, but they will be added to any Packet (chain of SubPacket)
    /// sent to the phone (so the phone can know exact time of reception)
    uint32 rx_time = 4;
}

/// Shared constants between device and phone
enum Constants {
    Unused = 0; // First enum must be zero, and we are just using this enum to pass int constants between two very different environments
}

// Full settings (center freq, spread factor, pre-shared secret key etc...) needed to configure a radio for speaking on a particlar channel
// This information can be encoded as a QRcode/url so that other users can configure their radio to join the same channel.
message ChannelSettings {
    int32 tx_power = 1;

    // FIXME - change this to an integer for easier user comprehension and smaller bitsize
    uint32 channel_num = 2;

    enum ModemConfig {
        // Note: these mappings must match ModemConfigChoice in the device code.
        Bw125Cr45Sf128 = 0; ///< Bw = 125 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Default medium range
        Bw500Cr45Sf128 = 1; ///< Bw = 500 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Fast+short range
        Bw31_25Cr48Sf512 = 2; ///< Bw = 31.25 kHz, Cr = 4/8, Sf = 512chips/symbol, CRC on. Slow+long range
        Bw125Cr48Sf4096 = 3; ///< Bw = 125 kHz, Cr = 4/8, Sf = 4096chips/symbol, CRC on. Slow+long range
    }

    /// This value replaces bandwidth/spread_factor/coding_rate.  If you'd like to experiment with other options
    /// add them to MeshRadio.cpp in the device code.
    ModemConfig modem_config = 3;
    // uint32 bandwidth = 5;
    // int32 spread_factor = 6;
    // int32 coding_rate = 7;

    /// A simple preshared key for now for crypto.  At first I'm using 128 bit (16 byte) block for the Speck crypto
    /// but for beta we'll want something more carefully thought through.  I want to keep the QR code small
    bytes psk = 4;

    /// A SHORT name that will be packed into the URL.  Less than 12 bytes.  Something for end users to call the channel
    string name = 5;
}

// The entire set of user settable/readable settings for our radio device.  Includes both the current channel settings
// and any preferences the user has set for behavior of their node
message RadioConfig {

    message UserPreferences {
        // We should send our position this often (but only if it has changed significantly)
        uint32 position_broadcast_secs = 1;

        // Send our owner info at least this often (also we always send once at boot - to rejoin the mesh)
        uint32 send_owner_interval = 2;

        /// If we miss this many owner messages from a node, we declare the node offline (defaults to 3 - to allow for some lost packets)
        uint32 num_missed_to_fail = 3;

        /// see sw-design.md
        uint32 wait_bluetooth_secs = 4;
        uint32 screen_on_secs = 5;
        uint32 phone_timeout_secs = 6;
        uint32 phone_sds_timeout_sec = 7;
        uint32 mesh_sds_timeout_secs = 8;
        uint32 sds_secs = 9;
        uint32 ls_secs = 10;
        uint32 min_wake_secs = 11;

        // If true, radio should not try to be smart about what packets to queue to the phone
        bool keep_all_packets = 100;

        // If true, we will try to capture all the packets sent on the mesh, not just the ones destined to our node.
        bool promiscuous_mode = 101;
    }

    UserPreferences preferences = 1;
    ChannelSettings channel_settings = 2;
}

/**

The bluetooth to device link:

Old BTLE protocol docs from TODO, merge in above and make real docs...

use protocol buffers, and NanoPB

messages from device to phone:
POSITION_UPDATE (..., time)
TEXT_RECEIVED(from, text, time)
OPAQUE_RECEIVED(from, payload, time) (for signal messages or other applications)

messages from phone to device:
SET_MYID(id, human readable long, human readable short) (send down the unique ID string used for this node, a human readable string shown for that id, and a very short human readable string suitable for oled screen)
SEND_OPAQUE(dest, payload) (for signal messages or other applications)
SEND_TEXT(dest, text)
Get all nodes() (returns list of nodes, with full info, last time seen, loc, battery level etc)
SET_CONFIG (switches device to a new set of radio params and preshared key, drops all existing nodes, force our node to rejoin this new group)

*/

// Full information about a node on the mesh
message NodeInfo {
    int32 num = 1; // the node number
    User user = 2;

    /// This position data will also contain a time last seen
    Position position = 3;

    /// Returns the Signal-to-noise ratio (SNR) of the last received message, as measured
    /// by the receiver.
    /// return SNR of the last received message in dB
    int32 snr = 5;

    /// Returns the last measured frequency error.
    /// The LoRa receiver estimates the frequency offset between the receiver centre frequency
    /// and that of the received LoRa signal. This function returns the estimates offset (in Hz) 
    /// of the last received message. Caution: this measurement is not absolute, but is measured 
    /// relative to the local receiver's oscillator. 
    /// Apparent errors may be due to the transmitter, the receiver or both.
    /// \return The estimated centre frequency offset in Hz of the last received message. 
    int32 frequency_error = 6;
}

/**
Unique local debugging info for this node

Note: we don't include position or the user info, because that will come in the 

Sent to the phone in response to WantNodes.
*/
message MyNodeInfo {
    /// Tells the phone what our node number is, can be -1 if we've not yet joined a mesh.
    int32 my_node_num = 1;

    /// if false it would be great if the phone can help provide gps coordinates
    bool has_gps = 2;

    /// # of legal channels (set at build time in the device flash image)
    int32 num_channels = 3;

    /// The region code for my radio (US, CN, etc...)
    string region = 4;

    /// TBEAM, HELTEC, etc...
    string hw_model = 5;

    /// 0.0.5 etc...
    string firmware_version = 6;

    /// FIXME - add useful debugging state (queue depths etc)
}

// This message is never sent over the wire, but it is used for serializing DB state to flash in the device code
// FIXME, since we write this each time we enter deep sleep (and have infinite flash) it would be better to use some sort of append only data
// structure for the receive queue and use the preferences store for the other stuff
message DeviceState {
    RadioConfig radio = 1;

    /// Tells the phone what our node number is, can be -1 if we've not yet joined a mesh.
    MyNodeInfo my_node = 2;

    /// My owner info
    User owner = 3;

    repeated NodeInfo node_db = 4;

    /// Received packets saved for delivery to the phone 
    repeated MeshPacket receive_queue = 5;

    enum Version {
        option allow_alias = true;

        /// default value for old files before we added version.
        Unset = 0;

        /// We bump up the integer values in this enum to indicate minimum levels of encodings for saved files
        /// if your file is below the Minimum you should discard it.
        Minimum = 17;

        /// The current value we are using for saved files
        Current = 17;
    };

    /// A version integer used to invalidate old save files when we make incompatible changes
    Version version = 6;

    /// We keep the last received text message (only) stored in the device flash, so we can show it on the screen.  Might be null
    MeshPacket rx_text_message = 7;
}

// packets from the radio to the phone will appear on the fromRadio characteristic.  It will support
// READ and NOTIFY.  When a new packet arrives the device will notify?  possibly identify instead?
// it will sit in that descriptor until consumed by the phone, at which point the next item in the FIFO
// will be populated.  FIXME
message FromRadio {
    // The packet num, used to allow the phone to request missing read packets from the FIFO, see our bluetooth docs
    uint32 num = 1;

    oneof variant {
        MeshPacket packet = 2;

        /// Tells the phone what our node number is, can be -1 if we've not yet joined a mesh.
        // No longer sent in fromRadio, instead there is a mynodeinfo characteristic
        // MyNodeInfo my_info = 3;

        /// One packet is sent for each node in the on radio DB
        // Note: this is no longer in FromRadio because, there is now a bluetooth nodeinfo characteristic
        // after sending wantnodes that characteristic starts over with the first node in our DB
        // NodeInfo node_info = 4;
    }
}

// packets/commands to the radio will be written (reliably) to the toRadio characteristic.  Once the
// write completes the phone can assume it is handled.
message ToRadio {

    oneof variant {
        MeshPacket packet = 1; // send this packet on the mesh

        //
        // Rare operations
        //
        // All of these have been moved to unique writable bluetooth characteristics

        /// phone wants radio to send full node db to the phone, This is typically the first packet sent
        /// to the radio when the phone gets a bluetooth connection.
        /// The radio will respond by sending back a FromRadio.my_node_num and a series of FromRadio.node_info
        // WantNodes want_nodes = 100;

        //RadioConfig set_radio = 101; // set the radio provisioning for this node
        // User set_owner = 102; // Set the owner for this node
    }
}