"""
MeshBay protocol constants and message type definitions.

MNP (Mesh Node Protocol) — v0.1
MHP (Mesh Bay Hub Protocol) — v0.1

All wire messages are length-prefixed msgpack (4-byte big-endian length header).
Every message carries a "v" field for protocol version.
"""

from dataclasses import dataclass, field
from typing import Any

MNP_VERSION = "0.1"
MHP_VERSION = "0.1"


# ── MNP message types ─────────────────────────────────────────────────────────

class MNP:
    HANDSHAKE       = "handshake"
    HANDSHAKE_ACK   = "handshake_ack"
    INDEX_SYNC      = "index_sync"       # full Mesh Group Index
    INDEX_DELTA     = "index_delta"      # incremental update
    FILE_REQUEST    = "file_req"         # request chunk(s)
    FILE_CHUNK      = "file_chunk"       # encrypted chunk response
    STREAM_SEGMENT  = "stream_seg"       # HLS/DASH segment
    CHAT_MESSAGE    = "chat_msg"         # Double Ratchet message
    CHAT_ATTACHMENT = "chat_attach"      # attachment metadata
    CHAT_HISTORY    = "chat_hist"       # request message history
    CHAT_HISTORY_RESPONSE = "chat_hist_resp"  # history response with messages
    # GEK_REQUEST / GEK_RESPONSE were removed (NS3, and finding L1): the node must
    # never serve the GEK in plaintext. Members obtain it by unwrapping their own
    # ECIES bundle. The constants lingered after the handlers were deleted, leaving
    # the wire contract looking as though the endpoint still existed.
    FILE_UPLOAD      = "file_upload"       # client pushes file chunk to node
    FILE_UPLOAD_ACK  = "file_upload_ack"   # node acknowledges chunk receipt
    FILE_DELETE      = "file_delete"       # client requests file deletion
    FILE_DELETE_ACK  = "file_delete_ack"   # node confirms deletion
    STREAM_REQUEST   = "stream_req"        # client requests MSE video stream
    STREAM_INIT      = "stream_init"       # node sends codec info + signals stream start
    STREAM_DATA      = "stream_data"       # node sends encrypted fMP4 segment
    STREAM_END       = "stream_end"        # node signals end of stream
    EPHEMERAL_STREAM = "ephemeral_stream"  # reserved — mobile live push
    HANDSHAKE_CHALLENGE  = "handshake_challenge"   # node → client: GEK proof nonce
    HANDSHAKE_RESPONSE   = "handshake_response"    # client → node: HMAC(GEK, nonce)
    ADMIN_CHALLENGE      = "admin_challenge"       # node → client: Ed25519 sign challenge
    ADMIN_RESPONSE       = "admin_response"        # client → node: Ed25519 signature
    GEK_BUNDLE_STORE     = "gek_bundle_store"      # client → node: store wrapped GEK for a user
    GEK_BUNDLE_FETCH     = "gek_bundle_fetch"      # client → node: request own wrapped GEK
    GEK_BUNDLE_RESP      = "gek_bundle_resp"       # node → client: wrapped GEK bundle
    KEYPAIR_BUNDLE_STORE = "keypair_bundle_store"  # client → node: store encrypted keypair bundle
    KEYPAIR_BUNDLE_FETCH = "keypair_bundle_fetch"  # client → node: request own keypair bundle
    KEYPAIR_BUNDLE_RESP  = "keypair_bundle_resp"   # node → client: encrypted keypair bundle


# ── Index entry ───────────────────────────────────────────────────────────────

@dataclass
class IndexEntry:
    id:        str    # blake3 hash of file (hex)
    name:      str    # filename
    path:      str    # path relative to shared directory
    size:      int    # bytes
    type:      str    # video | audio | image | document | archive | other
    added_at:  int    # unix timestamp
    duration:  int | None = None   # seconds, for media
    thumb_hash: str | None = None  # blake3 of thumbnail
    uploader_id: str | None = None  # user_id of who uploaded (None = pre-existing on disk)
    uploader_pk: str | None = None  # Ed25519 public key of uploader (base64 raw 32 bytes)


@dataclass
class IndexDelta:
    base_version: int
    version:      int
    additions:    list[IndexEntry] = field(default_factory=list)
    deletions:    list[str] = field(default_factory=list)  # list of ids


# ── Chunk request/response ────────────────────────────────────────────────────

@dataclass
class ChunkRequest:
    file_id:     str   # blake3 hash of file (hex)
    chunk_index: int

@dataclass
class ChunkResponse:
    chunk_index:    int
    plaintext_size: int
    nonce_b64:      str
    ct_b64:         str
    ct_hash_b64:    str
    pt_hash_b64:    str
    sig_b64:        str
    pk_node_b64:    str
    file_hash_b64:  str