// Package proto defines all wire types shared between the daemon and anchor.
// Everything on the wire is newline-delimited JSON.
// Binary data (keys, signatures) is hex-encoded; signaling boxes are base64.
package proto

import "time"

// ── Identity ──────────────────────────────────────────────────────────────────

// PeerID is a peer's stable identity: lowercase hex of the 32-byte Ed25519 public key (64 chars).
// This IS the peer — display names are advisory only and unauthenticated.
type PeerID string

// Short returns the first 16 hex chars grouped in 4s: "a1b2 c3d4 e5f6 0718".
func (p PeerID) Short() string {
	s := string(p)
	if len(s) < 16 {
		return s
	}
	return s[0:4] + " " + s[4:8] + " " + s[8:12] + " " + s[12:16]
}

// PeerInfo is a peer's self-description, included in the hello confirmation.
type PeerInfo struct {
	ID        PeerID    `json:"id"`
	Alias     string    `json:"alias"`      // advisory, not authenticated
	PublicKey string    `json:"public_key"` // Ed25519 pubkey, hex
	CreatedAt time.Time `json:"created_at"`
}

// ── Peer-to-peer message types (over the "yaw" DataChannel) ──────────────────

// MsgType identifies the kind of peer message.
type MsgType string

const (
	MsgChat       MsgType = "chat"
	MsgPeerGossip MsgType = "peer_gossip"
	MsgFileOffer  MsgType = "file_offer"
	MsgFileResp   MsgType = "file_response"
	MsgFileDone   MsgType = "file_done"
	MsgPing       MsgType = "ping"
	MsgPong       MsgType = "pong"
)

// PeerMessage is the top-level container sent over the "yaw" DataChannel.
// File chunks go over a separate binary DataChannel labeled "f:<xid>".
type PeerMessage struct {
	Type MsgType `json:"type"`

	// Only one of these will be set, depending on Type.
	Chat      *ChatMessage  `json:"chat,omitempty"`
	Gossip    *PeerGossip   `json:"gossip,omitempty"`
	FileOffer *FileOffer    `json:"file_offer,omitempty"`
	FileResp  *FileResponse `json:"file_response,omitempty"`
	FileDone  *FileDone     `json:"file_done,omitempty"`
	Seq       *uint64       `json:"seq,omitempty"` // for ping/pong
}

// ChatMessage is a message to a room or a DM.
type ChatMessage struct {
	Mid    string    `json:"mid"`          // random 16-byte hex, for deduplication (YAW/2 §8)
	ID     string    `json:"id"`           // internal uuid, kept for local use
	From   PeerID    `json:"from"`
	To     *PeerID   `json:"to,omitempty"` // nil = broadcast to room
	Room   string    `json:"room"`
	Body   string    `json:"body"`
	SentAt time.Time `json:"sent_at"`
}

// PeerGossip shares known peer addresses.
type PeerGossip struct {
	Peers []GossipEntry `json:"peers"`
}

// GossipEntry is one peer hint shared via gossip.
type GossipEntry struct {
	Peer     PeerInfo  `json:"peer"`
	AddrHint string    `json:"addr_hint"` // IP:port hint, may be behind NAT
	LastSeen time.Time `json:"last_seen"`
}

// FileOffer initiates a file transfer.
type FileOffer struct {
	Mid       string `json:"mid"`        // dedup id
	Xid       string `json:"xid"`        // transfer id, used as DataChannel label "f:<xid>"
	Filename  string `json:"filename"`
	SizeBytes int64  `json:"size_bytes"`
	SHA256    string `json:"sha256"`     // hex
}

// FileResponse accepts or declines a FileOffer.
type FileResponse struct {
	Mid      string `json:"mid"`
	Xid      string `json:"xid"`
	Accepted bool   `json:"accepted"`
}

// FileDone signals that all chunks have been sent. Receiver verifies SHA256.
type FileDone struct {
	Mid    string `json:"mid"`
	Xid    string `json:"xid"`
	SHA256 string `json:"sha256"` // hex
}

// ── DataChannel hello (YAW/2 §6) ─────────────────────────────────────────────

// HelloMessage is the first message sent on the "yaw" DataChannel.
// The signature binds this identity to the specific DTLS session.
type HelloMessage struct {
	Type string   `json:"type"` // always "hello"
	ID   string   `json:"id"`   // hex pubkey
	Nick string   `json:"nick"` // alias
	Caps []string `json:"caps"` // capability list, e.g. ["chat","file"]
	Sig  string   `json:"sig"`  // hex ed25519 sig over HelloBindString
}

// HelloBindString returns the bytes the hello signature covers:
// "yaw/2 bind" || localDTLSFingerprint(32 bytes) || remoteDTLSFingerprint(32 bytes)
func HelloBindString(localFP, remoteFP []byte) []byte {
	buf := []byte("yaw/2 bind")
	buf = append(buf, localFP...)
	buf = append(buf, remoteFP...)
	return buf
}

// ── Signaling payload (sealed inside nacl/box, exchanged via anchor) ──────────

// SignalingKind identifies the kind of sealed signaling payload.
type SignalingKind string

const (
	SigOffer     SignalingKind = "offer"
	SigAnswer    SignalingKind = "answer"
	SigCandidate SignalingKind = "candidate"
	SigBye       SignalingKind = "bye"
)

// SignalingPayload is the JSON plaintext sealed inside a crypto_box (YAW/2 §5).
type SignalingPayload struct {
	Kind  SignalingKind `json:"kind"`
	SDP   string        `json:"sdp,omitempty"`   // offer / answer
	Cand  string        `json:"cand,omitempty"`  // trickle ICE candidate line
	Mid   string        `json:"mid,omitempty"`   // media stream id for candidate
	MLine int           `json:"mline,omitempty"` // media line index
}

// ── Anchor WebSocket wire types (YAW/2 §5) ────────────────────────────────────

// AnchorMsgType identifies anchor WebSocket messages.
type AnchorMsgType string

const (
	AnchorChallenge AnchorMsgType = "challenge"
	AnchorJoin      AnchorMsgType = "join"
	AnchorJoined    AnchorMsgType = "joined"
	AnchorPeerJoin  AnchorMsgType = "peer-join"
	AnchorPeerLeave AnchorMsgType = "peer-leave"
	AnchorTo        AnchorMsgType = "to"
	AnchorFrom      AnchorMsgType = "from"
	AnchorNoPeer    AnchorMsgType = "no-peer"
)

// AnchorMessage covers all WebSocket frames to/from the anchor.
type AnchorMessage struct {
	Type  AnchorMsgType `json:"type"`
	Nonce string        `json:"nonce,omitempty"` // challenge nonce, hex
	ID    string        `json:"id,omitempty"`    // peer hex id
	Net   string        `json:"net,omitempty"`   // hashed network name
	Sig   string        `json:"sig,omitempty"`   // ed25519 sig over (nonce||net), hex
	Peers []string      `json:"peers,omitempty"` // joined: list of peer hex ids in network
	To    string        `json:"to,omitempty"`    // target peer hex id
	From  string        `json:"from,omitempty"`  // sender peer hex id
	Box   string        `json:"box,omitempty"`   // base64 nacl/box sealed payload
}

// ── IPC protocol (daemon ↔ local UI) ─────────────────────────────────────────

// IpcMsgType identifies IPC messages.
type IpcMsgType string

const (
	// Commands (UI → daemon)
	CmdSendMessage  IpcMsgType = "send_message"
	CmdJoinNetwork  IpcMsgType = "join_network"  // fields: network_name (plaintext)
	CmdLeaveNetwork IpcMsgType = "leave_network"
	CmdGetState     IpcMsgType = "get_state"
	CmdSendFile     IpcMsgType = "send_file"

	// Events (daemon → UI)
	EvtMessageReceived  IpcMsgType = "message_received"
	EvtPeerConnected    IpcMsgType = "peer_connected"
	EvtPeerDisconnected IpcMsgType = "peer_disconnected"
	EvtSessionReady     IpcMsgType = "session_ready"   // DataChannel open + hello verified
	EvtIncomingFile     IpcMsgType = "incoming_file"
	EvtFileProgress     IpcMsgType = "file_progress"
	EvtStateSnapshot    IpcMsgType = "state_snapshot"
	EvtError            IpcMsgType = "error"
)

// IpcMessage covers both commands and events.
type IpcMessage struct {
	Type IpcMsgType `json:"type"`

	// send_message
	Room string  `json:"room,omitempty"`
	To   *PeerID `json:"to,omitempty"`
	Body string  `json:"body,omitempty"`

	// join_network / leave_network
	NetworkName string `json:"network_name,omitempty"`

	// send_file
	Path string `json:"path,omitempty"`

	// events
	Peer           *PeerInfo    `json:"peer,omitempty"`
	PeerID         *PeerID      `json:"peer_id,omitempty"`
	Nick           string       `json:"nick,omitempty"`
	Message        *ChatMessage `json:"message,omitempty"`
	Offer          *FileOffer   `json:"offer,omitempty"`
	TransferID     string       `json:"transfer_id,omitempty"`
	BytesReceived  int64        `json:"bytes_received,omitempty"`
	TotalBytes     int64        `json:"total_bytes,omitempty"`
	LocalPeer      *PeerInfo    `json:"local_peer,omitempty"`
	ConnectedPeers []PeerInfo   `json:"connected_peers,omitempty"`
	Rooms          []string     `json:"rooms,omitempty"`
	ErrorMessage   string       `json:"error_message,omitempty"`
}