package headscale

import (
	"context"
	"fmt"
	"time"

	"go.uber.org/zap"

	"github.com/guildhouse-co/kedge/internal/config"
)

// PeerUpdater is implemented by the mesh manager to receive peer updates.
type PeerUpdater interface {
	AddPeer(pubKey string, endpoint string, allowedIPs []string) error
}

// Client connects to Headscale for mesh peer discovery.
type Client struct {
	cfg     config.HeadscaleConfig
	peers   PeerUpdater
	log     *zap.SugaredLogger
}

// NewClient creates a new Headscale peer discovery client.
func NewClient(cfg config.HeadscaleConfig, peers PeerUpdater, log *zap.SugaredLogger) *Client {
	return &Client{cfg: cfg, peers: peers, log: log}
}

// Run starts the Headscale peer discovery loop.
func (c *Client) Run(ctx context.Context) error {
	if !c.cfg.Enabled {
		c.log.Info("headscale peer discovery disabled")
		<-ctx.Done()
		return nil
	}

	c.log.Infof("starting headscale peer discovery (endpoint: %s, interval: %s)",
		c.cfg.Endpoint, c.cfg.PollInterval)

	ticker := time.NewTicker(c.cfg.PollInterval)
	defer ticker.Stop()

	// Initial discovery.
	if err := c.discoverPeers(ctx); err != nil {
		c.log.Warnw("initial peer discovery failed", "error", err)
	}

	for {
		select {
		case <-ctx.Done():
			return nil
		case <-ticker.C:
			if err := c.discoverPeers(ctx); err != nil {
				c.log.Warnw("peer discovery failed", "error", err)
			}
		}
	}
}

func (c *Client) discoverPeers(ctx context.Context) error {
	// TODO: Call Headscale gRPC API to list nodes in the mesh namespace.
	// For each node, extract WireGuard public key, endpoint, and allowed IPs,
	// then call c.peers.AddPeer() to update the mesh manager.

	_ = ctx
	return fmt.Errorf("headscale peer discovery not yet implemented")
}