rssfetch/cmd/root.go

/*
Copyright © 2024 filifa

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package cmd

import (
	"fmt"
	"html"
	"log"
	"os"
	"strings"
	"text/template"

	"github.com/mmcdole/gofeed"
	"github.com/spf13/cobra"
)

var output string

// formatItem returns an individual item formatted as a string for printing.
func formatItem(item *gofeed.Item, tmpl *template.Template) (string, error) {
	b := new(strings.Builder)
	err := tmpl.Execute(b, item)
	return html.UnescapeString(b.String()), err
}

// parseFeeds parses the feeds at the given urls in parallel and returns them,
// along with any parsing errors.
func parseFeeds(urls []string) ([]*gofeed.Feed, []error) {
	fp := gofeed.NewParser()
	feeds := make([]*gofeed.Feed, len(urls))
	errs := make([]error, len(urls))
	done := make(chan int)

	for i, url := range urls {
		go func(i int, url string) {
			feed, err := fp.ParseURL(url)
			feeds[i] = feed
			errs[i] = err
			done <- i
		}(i, url)
	}

	for i := 0; i < len(urls); i++ {
		<-done
	}

	return feeds, errs
}

func rssfetch(cmd *cobra.Command, urls []string) {
	tmpl, err := template.New("out").Parse(output)
	if err != nil {
		log.Fatal(err)
	}

	feeds, errs := parseFeeds(urls)
	for _, err := range errs {
		if err != nil {
			log.Fatal(err)
		}
	}

	for _, feed := range feeds {
		for _, item := range feed.Items {
			out, err := formatItem(item, tmpl)
			if err != nil {
				log.Fatal(err)
			}
			fmt.Printf("%s", out)
		}
	}
}

// rootCmd represents the base command when called without any subcommands
var rootCmd = &cobra.Command{
	Use:   "rssfetch <url> [url ...]",
	Short: "rssfetch outputs items contained in rss feeds",
	Long: `rssfetch outputs items contained in rss feeds.
You can specify the output format with the -o flag. For instance, -o "{{.Title}}" will only output the title of each item.`,
	Run:  rssfetch,
	Args: cobra.MinimumNArgs(1),
}

// Execute adds all child commands to the root command and sets flags appropriately.
// This is called by main.main(). It only needs to happen once to the rootCmd.
func Execute() {
	err := rootCmd.Execute()
	if err != nil {
		os.Exit(1)
	}
}

func init() {
	// Here you will define your flags and configuration settings.
	// Cobra supports persistent flags, which, if defined here,
	// will be global for your application.

	// rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.rssfetch.yaml)")

	// Cobra also supports local flags, which will only run
	// when this action is called directly.
	rootCmd.Flags().StringVarP(&output, "output", "o", "{{.Title}}\n\n{{.Description}}\n\n{{.Link}}\n", "output format")
}