/* extension.h - BEP-10 transport, BEP-9 metadata, and BEP-11 PEX codecs. */
#ifndef NAUT_EXTENSION_H
#define NAUT_EXTENSION_H

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

#define NAUT_EXT_UT_METADATA 1
#define NAUT_EXT_UT_PEX      2
#define NAUT_METADATA_BLOCK  (16u * 1024u)
#define NAUT_METADATA_MAX    (4u * 1024u * 1024u)

typedef struct {
    uint8_t  ut_metadata;
    uint8_t  ut_pex;
    uint32_t metadata_size;
    uint32_t reqq;
    uint16_t port;
} naut_ext_handshake;

/* Build a complete peer-wire extended message (length, message ID 20,
 * extension ID, payload). The returned buffer is malloc-owned. */
naut_err naut_ext_build_handshake(uint8_t ut_metadata_id, uint8_t ut_pex_id,
                                  uint32_t metadata_size, uint16_t port,
                                  uint8_t **out, size_t *out_len);
naut_err naut_ext_parse_handshake(const uint8_t *payload, size_t len,
                                  naut_ext_handshake *out);

typedef enum {
    NAUT_METADATA_REQUEST = 0,
    NAUT_METADATA_DATA = 1,
    NAUT_METADATA_REJECT = 2
} naut_metadata_type;

typedef struct {
    naut_metadata_type type;
    uint32_t piece;
    uint32_t total_size;
    const uint8_t *data;
    size_t data_len;
} naut_metadata_msg;

naut_err naut_metadata_build(uint8_t ext_id, naut_metadata_type type,
                             uint32_t piece, uint32_t total_size,
                             const void *data, size_t data_len,
                             uint8_t **out, size_t *out_len);
naut_err naut_metadata_parse(const uint8_t *payload, size_t len,
                             naut_metadata_msg *out);

typedef struct {
    naut_peer_addr *added;
    uint8_t        *added_flags;
    size_t          num_added;
    naut_peer_addr *dropped;
    size_t          num_dropped;
} naut_pex_msg;

naut_err naut_pex_build(uint8_t ext_id, const naut_pex_msg *msg,
                        uint8_t **out, size_t *out_len);
naut_err naut_pex_parse(const uint8_t *payload, size_t len, naut_pex_msg *out);
void     naut_pex_free(naut_pex_msg *msg);

/* Fetch and SHA-1 verify a v1 torrent's raw info dictionary from one peer.
 * The returned buffer is malloc-owned. */
naut_err naut_metadata_fetch(const naut_peer_addr *peer,
                             const uint8_t info_hash[20],
                             const uint8_t peer_id[20],
                             uint8_t **info, size_t *info_len);

#endif /* NAUT_EXTENSION_H */