/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

package watcher

import (
	"fmt"

	"git.st8l.com/luxolus/kdnotify/config"
	"git.st8l.com/luxolus/kdnotify/fifo"
	n "git.st8l.com/luxolus/kdnotify/schema/notify"
)

type MsgHandler interface {
	ProcessVrrp(n.VrrpMessage) error
}

type EventWatcher struct {
	Events fifo.EventChannel
	Cxt    *config.LibCxt
}

func NewWatcherFifo(cxt *config.LibCxt, path string) (EventWatcher, error) {
	events, err := fifo.NewFifoChannel(cxt, path)
	if err != nil {
		return EventWatcher{}, fmt.Errorf("unable to create watch fifo channel for '%s': %s", path, err)
	}

	return NewWatcher(cxt, &events), nil
}

func NewWatcher(cxt *config.LibCxt, events fifo.EventChannel) EventWatcher {
	cxt = &config.LibCxt{
		Context: cxt.Context,
		Logger:  cxt.Logger.Named("watch"),
	}

	return EventWatcher{
		Events: events,
		Cxt:    cxt,
	}
}

func (w *EventWatcher) Watch(h MsgHandler) error {
	w.watchLoop(w.Events, h)

	return nil
}

func (w *EventWatcher) watchLoop(events fifo.EventChannel, h MsgHandler) {
	log := w.Cxt.Logger.Sugar()

	log.Debug("starting watch")
	for !events.Done() {
		msg, err := events.Next()
		if err != nil {
			if err != fifo.EClosed {
				log.Warnw("event channel closed abnormally", "error", err)
			}
			break
		}
		log.Debugw("incoming VRRP message", "instance", msg.Instance)

		err = h.ProcessVrrp(msg)
		if err != nil {
			log.Warnw("handler failed to process VRRP message", "error", err)
		}
	}
	log.Debug("stopping watch")
}