package internal

import (
	log "github.com/sirupsen/logrus"
)

type Crawler interface {
	Start()
	Stop()
	Crawl(url string) error
}

type crawler struct {
	conf    *Config
	tasks   *Dispatcher
	db      Store
	indexer Indexer
	queue   chan string
}

func NewCrawler(conf *Config, tasks *Dispatcher, db Store, indexer Indexer) (Crawler, error) {
	return &crawler{
		conf:    conf,
		tasks:   tasks,
		db:      db,
		indexer: indexer,
		queue:   make(chan string),
	}, nil
}

func (c *crawler) loop() {
	for {
		select {
		case url, ok := <-c.queue:
			if !ok {
				log.Debugf("crawler shutting down...")
				return
			}
			log.Debugf("crawling %s", url)
			uuid, err := c.tasks.Dispatch(NewCrawlTask(c.conf, c.db, c.indexer, url))
			if err != nil {
				log.WithError(err).Error("error creating crawl task for %s", url)
			} else {
				taskURL := URLForTask(c.conf.BaseURL, uuid)
				log.WithField("uuid", uuid).Infof("successfully created crawl task for %s: %s", url, taskURL)
			}
		}
	}
}

func (c *crawler) Crawl(url string) error {
	c.queue <- url
	return nil
}

func (c *crawler) Stop() {
	close(c.queue)
}

func (c *crawler) Start() {
	go c.loop()
}