dnswatcher/internal/watcher/watcher.go

// Package watcher provides the main monitoring orchestrator and scheduler.
package watcher

import (
	"context"
	"log/slog"

	"go.uber.org/fx"

	"sneak.berlin/go/dnswatcher/internal/config"
	"sneak.berlin/go/dnswatcher/internal/logger"
	"sneak.berlin/go/dnswatcher/internal/notify"
	"sneak.berlin/go/dnswatcher/internal/portcheck"
	"sneak.berlin/go/dnswatcher/internal/resolver"
	"sneak.berlin/go/dnswatcher/internal/state"
	"sneak.berlin/go/dnswatcher/internal/tlscheck"
)

// Params contains dependencies for Watcher.
type Params struct {
	fx.In

	Logger    *logger.Logger
	Config    *config.Config
	State     *state.State
	Resolver  *resolver.Resolver
	PortCheck *portcheck.Checker
	TLSCheck  *tlscheck.Checker
	Notify    *notify.Service
}

// Watcher orchestrates all monitoring checks on a schedule.
type Watcher struct {
	log       *slog.Logger
	config    *config.Config
	state     *state.State
	resolver  *resolver.Resolver
	portCheck *portcheck.Checker
	tlsCheck  *tlscheck.Checker
	notify    *notify.Service
	cancel    context.CancelFunc
}

// New creates a new Watcher instance.
func New(
	lifecycle fx.Lifecycle,
	params Params,
) (*Watcher, error) {
	watcher := &Watcher{
		log:       params.Logger.Get(),
		config:    params.Config,
		state:     params.State,
		resolver:  params.Resolver,
		portCheck: params.PortCheck,
		tlsCheck:  params.TLSCheck,
		notify:    params.Notify,
	}

	lifecycle.Append(fx.Hook{
		OnStart: func(startCtx context.Context) error {
			ctx, cancel := context.WithCancel(startCtx)
			watcher.cancel = cancel

			go watcher.Run(ctx)

			return nil
		},
		OnStop: func(_ context.Context) error {
			if watcher.cancel != nil {
				watcher.cancel()
			}

			return nil
		},
	})

	return watcher, nil
}

// Run starts the monitoring loop.
func (w *Watcher) Run(ctx context.Context) {
	w.log.Info(
		"watcher starting",
		"domains", len(w.config.Domains),
		"hostnames", len(w.config.Hostnames),
		"dnsInterval", w.config.DNSInterval,
		"tlsInterval", w.config.TLSInterval,
	)

	// Stub: wait for context cancellation.
	// Implementation will add initial check + periodic scheduling.
	<-ctx.Done()
	w.log.Info("watcher stopped")
}