cmd/feed2mdir/main.go

   1 /*
   2 feeder  -- newsfeeds aggregator
   3 Copyright (C) 2022 Sergey Matveev <stargrave@stargrave.org>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, version 3 of the License.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 package main
  19
  20 import (
  21         "crypto/sha512"
  22         "encoding/base64"
  23         "encoding/hex"
  24         "flag"
  25         "fmt"
  26         "log"
  27         "mime"
  28         "os"
  29         "path"
  30         "strings"
  31         "time"
  32
  33         "github.com/mmcdole/gofeed"
  34 )
  35
  36 func main() {
  37         maxEntries := flag.Uint("max-entries", 0, "Max entries to process (0=unlimited)")
  38         flag.Parse()
  39         mdir := flag.Arg(0)
  40         fp := gofeed.NewParser()
  41         feed, err := fp.Parse(os.Stdin)
  42         if err != nil {
  43                 log.Fatalln(err)
  44         }
  45
  46         guids := make(map[string]struct{}, len(feed.Items))
  47         useGUID := true
  48         for _, item := range feed.Items {
  49                 if _, exists := guids[item.GUID]; exists {
  50                         useGUID = false
  51                         break
  52                 } else {
  53                         guids[item.GUID] = struct{}{}
  54                 }
  55         }
  56
  57         h := sha512.New()
  58         news := 0
  59         var when *time.Time
  60         now := time.Now()
  61         latest := &time.Time{}
  62         for n, item := range feed.Items {
  63                 if *maxEntries > 0 && n == int(*maxEntries) {
  64                         break
  65                 }
  66                 when = nil
  67                 if item.PublishedParsed != nil {
  68                         when = item.PublishedParsed
  69                 } else if item.UpdatedParsed != nil {
  70                         when = item.UpdatedParsed
  71                 } else {
  72                         when = &now
  73                 }
  74                 if latest.Before(*when) {
  75                         latest = when
  76                 }
  77                 var what string
  78                 if len(item.Content) == 0 {
  79                         what = item.Description
  80                 } else {
  81                         what = item.Content
  82                 }
  83                 what = strings.TrimPrefix(what, "<![CDATA[")
  84                 what = strings.TrimSuffix(what, "]]>")
  85                 h.Reset()
  86                 if useGUID {
  87                         h.Write([]byte(item.GUID))
  88                 } else {
  89                         h.Write([]byte(item.Title))
  90                         h.Write([]byte{0})
  91                         h.Write([]byte(what))
  92                 }
  93                 fn := hex.EncodeToString(h.Sum(nil)[:sha512.Size/2])
  94                 exists := false
  95                 for _, d := range []string{"cur", "new"} {
  96                         entries, err := os.ReadDir(path.Join(mdir, d))
  97                         if err != nil {
  98                                 log.Fatalln(err)
  99                         }
 100                         for _, entry := range entries {
 101                                 if strings.HasPrefix(entry.Name(), fn) {
 102                                         exists = true
 103                                         break
 104                                 }
 105                         }
 106                 }
 107                 if exists {
 108                         continue
 109                 }
 110                 fn = path.Join(mdir, "new", fn)
 111                 fd, err := os.OpenFile(fn, os.O_WRONLY|os.O_CREATE|os.O_EXCL, os.FileMode(0666))
 112                 if err != nil {
 113                         log.Fatalln(err)
 114                 }
 115                 fd.WriteString("From: \"" + feed.Title + "\" <feeder@localhost\n")
 116                 fd.WriteString("Date: " + when.UTC().Format(time.RFC1123Z) + "\n")
 117                 fd.WriteString("Subject: " + mime.BEncoding.Encode("UTF-8", item.Title) + "\n")
 118                 fd.WriteString("MIME-Version: 1.0\n")
 119                 fd.WriteString("Content-Type: text/html; charset=utf-8\n")
 120                 fd.WriteString("Content-Transfer-Encoding: base64\n")
 121                 for _, author := range item.Authors {
 122                         if len(author.Name) > 0 {
 123                                 fd.WriteString("X-Author: " + author.Name + "\n")
 124                         }
 125                 }
 126                 for _, link := range item.Links {
 127                         fd.WriteString("X-URL: " + link + "\n")
 128                 }
 129                 for _, enc := range item.Enclosures {
 130                         fd.WriteString("X-Enclosure: " + enc.URL + "\n")
 131                 }
 132                 if len(item.Categories) > 0 {
 133                         fd.WriteString("X-Categories: " + strings.Join(item.Categories, ", ") + "\n")
 134                 }
 135                 fd.WriteString("\n")
 136                 what = base64.StdEncoding.EncodeToString([]byte(what))
 137                 for i := 0; i < len(what); i += 72 {
 138                         b := i + 72
 139                         if b > len(what) {
 140                                 b = len(what)
 141                         }
 142                         fd.WriteString(what[i:b] + "\n")
 143                 }
 144                 fd.Close()
 145                 if err = os.Chtimes(fn, *when, *when); err != nil {
 146                         log.Fatalln(err)
 147                 }
 148                 news++
 149         }
 150         for _, d := range []string{"cur", "new"} {
 151                 if err = os.Chtimes(path.Join(mdir, d), *latest, *latest); err != nil {
 152                         log.Fatalln(err)
 153                 }
 154         }
 155         fmt.Println(feed.Title)
 156 }