// Package protocol defines the IOP wire-level message types.
// The transport layer uses 4-byte big-endian length-prefixed frames.
// Each frame carries a JSON-encoded Envelope; Envelope.Payload holds
// the JSON-encoded inner message (RunRequest, RunEvent, etc.).
//
// TODO: replace JSON encoding with protobuf once proto/iop/runtime.proto
// is compiled with protoc-gen-go.
package protocol

const ProtocolVersion uint32 = 1

type MessageType string

const (
	TypeRunRequest          MessageType = "run.request"
	TypeRunEvent            MessageType = "run.event"
	TypeHeartbeat           MessageType = "heartbeat"
	TypeCancelRequest       MessageType = "cancel.request"
	TypeError               MessageType = "error"
	TypeCapabilityRequest   MessageType = "capability.request"
	TypeCapabilityResponse  MessageType = "capability.response"
)

// Envelope is the outer wrapper for every IOP TCP message.
type Envelope struct {
	ProtocolVersion uint32      `json:"protocol_version"`
	RequestID       string      `json:"request_id"`
	RunID           string      `json:"run_id,omitempty"`
	StreamID        string      `json:"stream_id,omitempty"`
	Type            MessageType `json:"type"`
	Payload         []byte      `json:"payload"`
}

// RunRequest initiates a model execution on the node.
type RunRequest struct {
	RunID      string            `json:"run_id"`
	Adapter    string            `json:"adapter,omitempty"`
	Model      string            `json:"model,omitempty"`
	Workspace  string            `json:"workspace,omitempty"`
	Policy     map[string]any    `json:"policy,omitempty"`
	Input      map[string]any    `json:"input"`
	TimeoutSec int               `json:"timeout_sec,omitempty"`
	Metadata   map[string]string `json:"metadata,omitempty"`
}

// RunEvent is a streaming execution event sent from node to client.
type RunEvent struct {
	RunID     string            `json:"run_id"`
	Type      string            `json:"type"` // start | delta | complete | error
	Delta     string            `json:"delta,omitempty"`
	Message   string            `json:"message,omitempty"`
	Error     string            `json:"error,omitempty"`
	Usage     *UsageInfo        `json:"usage,omitempty"`
	Metadata  map[string]string `json:"metadata,omitempty"`
	Timestamp int64             `json:"timestamp"` // unix nano
}

type UsageInfo struct {
	InputTokens  int `json:"input_tokens"`
	OutputTokens int `json:"output_tokens"`
}

// Heartbeat keeps the TCP connection alive.
type Heartbeat struct {
	Timestamp int64 `json:"timestamp"`
}

// CancelRequest asks the node to cancel a running execution.
type CancelRequest struct {
	RunID string `json:"run_id"`
}

// ErrorMsg is returned when a request fails at the transport layer.
type ErrorMsg struct {
	Code    string `json:"code"`
	Message string `json:"message"`
}

// CapabilityRequest asks the node what adapters/models it supports.
type CapabilityRequest struct{}

// CapabilityResponse lists the node's available adapters.
type CapabilityResponse struct {
	NodeID   string         `json:"node_id"`
	Adapters []AdapterInfo  `json:"adapters"`
}

type AdapterInfo struct {
	Name           string   `json:"name"`
	Models         []string `json:"models"`
	MaxConcurrency int      `json:"max_concurrency"`
}