feat: scaffold initial RSS reader project with Go backend and React frontend

internal/parser/parser.go

@@ -0,0 +1,129 @@
+package parser
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/mmcdole/gofeed"
+	"github.com/haopengzhan/rsspipe/internal/models"
+)
+
+type FetchResult struct {
+	NotModified  bool
+	ETag         string
+	LastModified string
+	Title        string
+	SiteURL      string
+	Entries      []models.FeedEntry
+}
+
+type Parser struct {
+	client *http.Client
+}
+
+func NewParser() *Parser {
+	return &Parser{
+		client: &http.Client{
+			Timeout: 8 * time.Second,
+		},
+	}
+}
+
+func (p *Parser) FetchFeed(ctx context.Context, feedURL, etag, lastModified string) (*FetchResult, error) {
+	req, err := http.NewRequestWithContext(ctx, "GET", feedURL, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	req.Header.Set("User-Agent", "RSSPipe/1.0 (+https://github.com/haopengzhan/rsspipe)")
+	req.Header.Set("Accept", "application/rss+xml, application/atom+xml, application/xml, text/xml, application/json;q=0.9, */*;q=0.8")
+
+	if etag != "" {
+		req.Header.Set("If-None-Match", etag)
+	}
+	if lastModified != "" {
+		req.Header.Set("If-Modified-Since", lastModified)
+	}
+
+	resp, err := p.client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to fetch url: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == http.StatusNotModified {
+		return &FetchResult{NotModified: true}, nil
+	}
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return nil, fmt.Errorf("server returned HTTP status %d", resp.StatusCode)
+	}
+
+	newETag := resp.Header.Get("ETag")
+	newLastModified := resp.Header.Get("Last-Modified")
+
+	bodyBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	fp := gofeed.NewParser()
+	feed, err := fp.ParseString(string(bodyBytes))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse feed content: %w", err)
+	}
+
+	result := &FetchResult{
+		NotModified:  false,
+		ETag:         newETag,
+		LastModified: newLastModified,
+		Title:        feed.Title,
+		SiteURL:      feed.Link,
+		Entries:      make([]models.FeedEntry, 0, len(feed.Items)),
+	}
+
+	for _, item := range feed.Items {
+		guid := item.GUID
+		if guid == "" {
+			guid = item.Link
+		}
+		if guid == "" {
+			guid = item.Title
+		}
+
+		pubDate := time.Now().UTC()
+		if item.PublishedParsed != nil {
+			pubDate = item.PublishedParsed.UTC()
+		} else if item.UpdatedParsed != nil {
+			pubDate = item.UpdatedParsed.UTC()
+		}
+
+		content := item.Content
+		if strings.TrimSpace(content) == "" {
+			content = item.Description
+		}
+
+		author := ""
+		if item.Author != nil {
+			author = item.Author.Name
+		}
+
+		entry := models.FeedEntry{
+			GUID:        guid,
+			URL:         item.Link,
+			Title:       item.Title,
+			Author:      author,
+			Content:     content,
+			RawContent:  item.Description,
+			PublishedAt: pubDate,
+			Metadata:    make(map[string]interface{}),
+		}
+		result.Entries = append(result.Entries, entry)
+	}
+
+	return result, nil
+}