// Package proto defines all wire types shared between the daemon and relay.
// Everything on the wire is newline-delimited JSON.
// Binary data (keys, signatures, ciphertext) is base64url encoded.
package proto

import "time"

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

// PeerID is a peer's stable identity: their Ed25519 public key, base64url encoded.
// This IS the peer — display names are advisory only and unauthenticated.
type PeerID string

// Short returns the first 8 characters, useful for display.
func (p PeerID) Short() string {
	if len(p) < 8 {
		return string(p)
	}
	return string(p)[:8]
}

// PeerInfo is a peer's self-description. Included in the Hello handshake.
type PeerInfo struct {
	ID        PeerID    `json:"id"`
	Alias     string    `json:"alias"`      // advisory, not authenticated
	PublicKey string    `json:"public_key"` // Ed25519 pubkey, base64url
	CreatedAt time.Time `json:"created_at"`
}

// ── Handshake ─────────────────────────────────────────────────────────────────

// Hello is the first message sent on a new TCP connection.
type Hello struct {
	Version      int      `json:"version"`
	Peer         PeerInfo `json:"peer"`
	EphemeralKey string   `json:"ephemeral_key"` // X25519 pubkey, base64url
	Signature    string   `json:"signature"`      // Ed25519 sig over ephemeral_key
}

// HelloAck is the response to Hello, completing the handshake.
type HelloAck struct {
	Peer         PeerInfo `json:"peer"`
	EphemeralKey string   `json:"ephemeral_key"`
	Signature    string   `json:"signature"`
	RelayCapable bool     `json:"relay_capable"`
}

// ── Encrypted envelope ────────────────────────────────────────────────────────

// Envelope wraps all post-handshake messages.
// The payload is ChaCha20-Poly1305 encrypted.
type Envelope struct {
	Nonce   string `json:"nonce"`   // 12 bytes, base64url
	Payload string `json:"payload"` // ciphertext, base64url
}

// ── Peer-to-peer message types ────────────────────────────────────────────────

// MsgType identifies the kind of peer message inside an Envelope.
type MsgType string

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

// PeerMessage is the top-level container decoded from inside an Envelope.
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"`
	FileChunk *FileChunk    `json:"file_chunk,omitempty"`
	Seq       *uint64       `json:"seq,omitempty"` // for ping/pong
}

// ChatMessage is a message to a room or a DM.
type ChatMessage struct {
	ID     string    `json:"id"`
	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, may be behind NAT
	LastSeen time.Time `json:"last_seen"`
}

// FileOffer initiates a file transfer.
type FileOffer struct {
	TransferID string `json:"transfer_id"`
	Filename   string `json:"filename"`
	SizeBytes  int64  `json:"size_bytes"`
	SHA256     string `json:"sha256"`
}

// FileResponse accepts or declines a FileOffer.
type FileResponse struct {
	TransferID string `json:"transfer_id"`
	Accepted   bool   `json:"accepted"`
}

// FileChunk is one piece of a file transfer.
type FileChunk struct {
	TransferID string `json:"transfer_id"`
	Seq        uint32 `json:"seq"`
	Data       string `json:"data"` // base64url
	IsLast     bool   `json:"is_last"`
}

// ── Relay protocol ────────────────────────────────────────────────────────────

// RelayMsgType identifies relay wire messages.
type RelayMsgType string

const (
	RelayRegister  RelayMsgType = "register"
	RelayForward   RelayMsgType = "forward"
	RelayListPeers RelayMsgType = "list_peers"
	RelayForwarded RelayMsgType = "forwarded"
	RelayPeerList  RelayMsgType = "peer_list"
	RelayError     RelayMsgType = "error"
)

// RelayMessage is used for both client→relay and relay→client.
type RelayMessage struct {
	Type RelayMsgType `json:"type"`

	// register
	Peer      *PeerInfo `json:"peer,omitempty"`
	Signature string    `json:"signature,omitempty"`

	// forward / forwarded
	To       *PeerID   `json:"to,omitempty"`
	From     *PeerID   `json:"from,omitempty"`
	Envelope *Envelope `json:"envelope,omitempty"`

	// peer_list
	Peers []GossipEntry `json:"peers,omitempty"`

	// error
	Message string `json:"message,omitempty"`
}

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

// IpcMsgType identifies IPC messages.
type IpcMsgType string

const (
	// Commands (UI → daemon)
	CmdSendMessage IpcMsgType = "send_message"
	CmdConnect     IpcMsgType = "connect"
	CmdGetState    IpcMsgType = "get_state"
	CmdSendFile    IpcMsgType = "send_file"

	// Events (daemon → UI)
	EvtMessageReceived  IpcMsgType = "message_received"
	EvtPeerConnected    IpcMsgType = "peer_connected"
	EvtPeerDisconnected IpcMsgType = "peer_disconnected"
	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"`

	// connect
	Addr string `json:"addr,omitempty"`

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

	// events
	Peer           *PeerInfo    `json:"peer,omitempty"`
	PeerID         *PeerID      `json:"peer_id,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"`
}