scraper.go

package main

import (
	"context"
	"database/sql"
	"log"
	"strings"
	"sync"
	"time"

	"github.com/Suryarpan/rss-agg/internal/database"
	"github.com/google/uuid"
)

func startScraping(
	db *database.Queries,
	concurrency int,
	timeBetweenRequest time.Duration,
) {
	log.Printf("Scraping on %v goroutines every %s duration\n", concurrency, timeBetweenRequest)
	ticker := time.NewTicker(timeBetweenRequest)
	for ; ; <-ticker.C {
		feeds, err := db.GetNextFeedsToFetch(context.Background(), int32(concurrency))
		if err != nil {
			log.Println("error while fetching feeds:", err)
			continue
		}

		wg := &sync.WaitGroup{}
		for _, feed := range feeds {
			wg.Add(1)
			go scrapeFeed(db, wg, feed)
		}
		wg.Wait()
	}
}

func scrapeFeed(db *database.Queries, wg *sync.WaitGroup, feed database.Feed) {
	defer wg.Done()
	_, err := db.MarkFeedFecthed(context.Background(), feed.ID)
	if err != nil {
		log.Println("error marking feed as fetched:", err)
		return
	}
	rssFeed, err := urlToFeed(feed.Url)
	if err != nil {
		log.Println("Error fetching feed:", err)
		return
	}
	for _, item := range rssFeed.Channel.Item {
		description := sql.NullString{
			String: item.Description,
			Valid: item.Description != "",
		}
		pubTime, err := time.Parse(time.RFC1123Z, item.PubDate)
		if err != nil {
			log.Printf("couldn't parse date %v with err %v\n", item.PubDate, err)
		}
		_, err = db.CreatePost(context.Background(), database.CreatePostParams{
			ID:        uuid.New(),
			CreatedAt: time.Now().UTC(),
			UpdatedAt: time.Now().UTC(),
			Title:     item.Title,
			Description: description,
			PublishedAt: pubTime,
			Url: item.Link,
			FeedID: feed.ID,
		})
		if err != nil {
			if strings.Contains(err.Error(), "duplicate key") {
				continue
			}
			log.Println("failed to create post:", err)
		}
	}
	log.Printf("Feed %s collected, %v posts found", feed.Name, len(rssFeed.Channel.Item))
}