package store

import (
	"context"
	"encoding/json"
	"time"
)

// ClusterNode represents a registered node in the cluster registry.
type ClusterNode struct {
	NodeID       string          `json:"node_id"`
	Endpoint     string          `json:"endpoint"`
	Seq          int             `json:"seq"`
	RegisteredAt time.Time       `json:"registered_at"`
	Heartbeat    time.Time       `json:"heartbeat"`
	Stats        json.RawMessage `json:"stats"`
}

// ClusterStore manages the node_registry table for cluster self-assembly.
// Postgres-only — SQLite deployments set this to nil.
type ClusterStore interface {
	// Register inserts or re-registers a node (idempotent).
	Register(ctx context.Context, nodeID, endpoint string) error

	// Heartbeat updates the node's heartbeat timestamp and stats.
	// Returns rows affected — 0 means the node was swept (self-eviction).
	Heartbeat(ctx context.Context, nodeID string, stats json.RawMessage) (int64, error)

	// SweepStale deletes nodes whose heartbeat is older than threshold.
	SweepStale(ctx context.Context, threshold time.Duration) (int64, error)

	// ListNodes returns all registered nodes ordered by sequence.
	ListNodes(ctx context.Context) ([]ClusterNode, error)

	// Deregister removes a node (best-effort cleanup on shutdown).
	Deregister(ctx context.Context, nodeID string) error
}