/* dht.h - BEP-5 KRPC codec and bounded IPv4 get_peers traversal. */
#ifndef NAUT_DHT_H
#define NAUT_DHT_H

#include "naut/common.h"
#include "naut/tracker.h"

#define NAUT_DHT_ID_LEN 20
#define NAUT_DHT_MAX_NODES 256
#define NAUT_DHT_MAX_PEERS 256

typedef struct {
    uint8_t id[NAUT_DHT_ID_LEN];
    uint8_t ip[4];
    uint16_t port;
} naut_dht_node;

typedef enum {
    NAUT_DHT_RESPONSE,
    NAUT_DHT_ERROR
} naut_dht_message_type;

typedef struct {
    naut_dht_message_type type;
    uint8_t transaction[8];
    size_t transaction_len;
    uint8_t id[NAUT_DHT_ID_LEN];
    bool has_id;
    uint8_t token[64];
    size_t token_len;
    naut_dht_node *nodes;
    size_t num_nodes;
    naut_peer_addr *peers;
    size_t num_peers;
    int error_code;
} naut_dht_response;

naut_err naut_dht_build_ping(const uint8_t *tx, size_t tx_len,
                             const uint8_t id[20],
                             uint8_t **out, size_t *out_len);
naut_err naut_dht_build_find_node(const uint8_t *tx, size_t tx_len,
                                  const uint8_t id[20],
                                  const uint8_t target[20],
                                  uint8_t **out, size_t *out_len);
naut_err naut_dht_build_get_peers(const uint8_t *tx, size_t tx_len,
                                  const uint8_t id[20],
                                  const uint8_t info_hash[20],
                                  uint8_t **out, size_t *out_len);
naut_err naut_dht_build_announce_peer(const uint8_t *tx, size_t tx_len,
                                      const uint8_t id[20],
                                      const uint8_t info_hash[20],
                                      uint16_t port, bool implied_port,
                                      const void *token, size_t token_len,
                                      uint8_t **out, size_t *out_len);

naut_err naut_dht_parse_response(const uint8_t *data, size_t len,
                                 naut_dht_response *out);
void     naut_dht_response_free(naut_dht_response *response);

/* Query bootstrap endpoints ("host:port") and iteratively follow returned
 * compact nodes until peers are found or the bounded traversal is exhausted. */
naut_err naut_dht_get_peers(const char *const *bootstrap, size_t num_bootstrap,
                            const uint8_t info_hash[20],
                            naut_peer_addr **peers, size_t *num_peers);

#endif /* NAUT_DHT_H */