// Copyright © 2023 Roberto Hidalgo <event-gateway@un.rob.mx>
// SPDX-License-Identifier: Apache-2.0
package consul

import (
	"context"
	"time"

	"git.rob.mx/nidito/event-gateway/internal/payload"
	"git.rob.mx/nidito/event-gateway/internal/sink"
	"git.rob.mx/nidito/event-gateway/internal/sink/types"
	"github.com/cenkalti/backoff/v4"
	"github.com/hashicorp/consul/api"
)

type watch struct {
	Name      string
	DC        string  `json:"dc"`
	Filter    *string `json:"filter,omitempty"`
	Transform *string `json:"transform,omitempty"`
	Event     types.Event
	lastIndex uint64
	cancel    context.CancelFunc
	client    Client
}

func (c *watch) Watch(client Client) {
	log.Infof("Starting lookup for %s", c.Name)
	bgctx, cancel := context.WithCancel(context.Background())
	c.cancel = cancel
	ctx := backoff.WithContext(backoff.NewExponentialBackOff(), bgctx)

	onUpdateError := func(err error, cooldown time.Duration) {
		log.Errorf("Could not lookup %s, retrying in %vs: %v", c.Name, cooldown.Truncate(time.Second), err)
	}
	c.client = client

	go func() {
		for {
			if err := backoff.RetryNotify(c.fetch, ctx, onUpdateError); err != nil {
				continue
			}
		}
	}()
}

func (c *watch) fetch() error {
	opts := &api.QueryOptions{
		WaitTime:  10 * time.Minute,
		WaitIndex: c.lastIndex,
	}
	evts, meta, err := c.client.List(c.Name, opts)
	if err != nil {
		return err
	}

	c.lastIndex = meta.LastIndex

	for _, evt := range evts {
		log.Infof("Incoming event from source: consul:%s", c.Name)
		ctx := context.WithValue(context.Background(), payload.ContextKey, evt.Payload)
		// ctx = context.WithValue(ctx, "event", "consul:"+c.Name)
		if err := sink.Dispatch(ctx, c.Event); err != nil {
			log.Errorf("could not trigger sink from consul:%s %s\n", c.Name, err)
		}
	}

	return nil
}