1 fd79aa76 2024-03-28 o // Package hn provides a filesystem interface to items on Hacker News.
  2 fd79aa76 2024-03-28 o package hn
  3 fd79aa76 2024-03-28 o 
  4 fd79aa76 2024-03-28 o import (
  5 fd79aa76 2024-03-28 o 	"bytes"
  6 fd79aa76 2024-03-28 o 	"encoding/json"
  7 fd79aa76 2024-03-28 o 	"fmt"
  8 fd79aa76 2024-03-28 o 	"html"
  9 fd79aa76 2024-03-28 o 	"io"
 10 fd79aa76 2024-03-28 o 	"io/fs"
 11 fd79aa76 2024-03-28 o 	"net/http"
 12 fd79aa76 2024-03-28 o 	"os"
 13 fd79aa76 2024-03-28 o 	"path"
 14 fd79aa76 2024-03-28 o 	"strconv"
 15 fd79aa76 2024-03-28 o 	"strings"
 16 fd79aa76 2024-03-28 o 	"time"
 17 fd79aa76 2024-03-28 o )
 18 fd79aa76 2024-03-28 o 
 19 fd79aa76 2024-03-28 o const APIRoot = "https://hacker-news.firebaseio.com/v0"
 20 fd79aa76 2024-03-28 o 
 21 fd79aa76 2024-03-28 o type Item struct {
 22 fd79aa76 2024-03-28 o 	ID     int
 23 fd79aa76 2024-03-28 o 	Type   string
 24 fd79aa76 2024-03-28 o 	By     string
 25 fd79aa76 2024-03-28 o 	Time   int
 26 fd79aa76 2024-03-28 o 	Text   string
 27 fd79aa76 2024-03-28 o 	Parent int
 28 fd79aa76 2024-03-28 o 	URL    string
 29 fd79aa76 2024-03-28 o 	Title  string
 30 fd79aa76 2024-03-28 o }
 31 fd79aa76 2024-03-28 o 
 32 fd79aa76 2024-03-28 o func (it *Item) Name() string       { return strconv.Itoa(it.ID) }
 33 fd79aa76 2024-03-28 o func (it *Item) Size() int64        { r := toMessage(it); return r.Size() }
 34 fd79aa76 2024-03-28 o func (it *Item) Mode() fs.FileMode  { return 0o444 }
 35 fd79aa76 2024-03-28 o func (it *Item) ModTime() time.Time { return time.Unix(int64(it.Time), 0) }
 36 fd79aa76 2024-03-28 o func (it *Item) IsDir() bool        { return false }
 37 fd79aa76 2024-03-28 o func (it *Item) Sys() any           { return nil }
 38 fd79aa76 2024-03-28 o 
 39 fd79aa76 2024-03-28 o type FS struct {
 40 fd79aa76 2024-03-28 o 	cache fs.FS
 41 fd79aa76 2024-03-28 o }
 42 fd79aa76 2024-03-28 o 
 43 fd79aa76 2024-03-28 o func CacheDirFS(name string) *FS {
 44 fd79aa76 2024-03-28 o 	return &FS{cache: os.DirFS(name)}
 45 fd79aa76 2024-03-28 o }
 46 fd79aa76 2024-03-28 o 
 47 fd79aa76 2024-03-28 o func (fsys *FS) Open(name string) (fs.File, error) {
 48 fd79aa76 2024-03-28 o 	if !fs.ValidPath(name) {
 49 fd79aa76 2024-03-28 o 		return nil, &fs.PathError{"open", name, fs.ErrInvalid}
 50 fd79aa76 2024-03-28 o 	}
 51 fd79aa76 2024-03-28 o 	name = path.Clean(name)
 52 fd79aa76 2024-03-28 o 	switch name {
 53 fd79aa76 2024-03-28 o 	case ".":
 54 fd79aa76 2024-03-28 o 		return nil, fmt.Errorf("TODO")
 55 fd79aa76 2024-03-28 o 	default:
 56 fd79aa76 2024-03-28 o 		if _, err := strconv.Atoi(name); err != nil {
 57 fd79aa76 2024-03-28 o 			return nil, &fs.PathError{"open", name, fs.ErrNotExist}
 58 fd79aa76 2024-03-28 o 		}
 59 fd79aa76 2024-03-28 o 	}
 60 fd79aa76 2024-03-28 o 	if fsys.cache != nil {
 61 fd79aa76 2024-03-28 o 		if f, err := fsys.cache.Open(name); err == nil {
 62 fd79aa76 2024-03-28 o 			return f, nil
 63 fd79aa76 2024-03-28 o 		}
 64 fd79aa76 2024-03-28 o 	}
 65 fd79aa76 2024-03-28 o 
 66 fd79aa76 2024-03-28 o 	u := fmt.Sprintf("%s/item/%s.json", APIRoot, name)
 67 fd79aa76 2024-03-28 o 	resp, err := http.Get(u)
 68 fd79aa76 2024-03-28 o 	if err != nil {
 69 fd79aa76 2024-03-28 o 		return nil, err
 70 fd79aa76 2024-03-28 o 	}
 71 fd79aa76 2024-03-28 o 	if resp.StatusCode != http.StatusOK {
 72 fd79aa76 2024-03-28 o 		return nil, err
 73 fd79aa76 2024-03-28 o 	}
 74 fd79aa76 2024-03-28 o 	return &file{rc: resp.Body}, nil
 75 fd79aa76 2024-03-28 o }
 76 fd79aa76 2024-03-28 o 
 77 fd79aa76 2024-03-28 o type file struct {
 78 fd79aa76 2024-03-28 o 	rc   io.ReadCloser
 79 fd79aa76 2024-03-28 o 	item *Item
 80 fd79aa76 2024-03-28 o 	msg  *bytes.Reader
 81 fd79aa76 2024-03-28 o }
 82 fd79aa76 2024-03-28 o 
 83 fd79aa76 2024-03-28 o func (f *file) Read(p []byte) (int, error) {
 84 fd79aa76 2024-03-28 o 	var n int
 85 fd79aa76 2024-03-28 o 	if f.item == nil {
 86 fd79aa76 2024-03-28 o 		if err := json.NewDecoder(f.rc).Decode(&f.item); err != nil {
 87 fd79aa76 2024-03-28 o 			return n, fmt.Errorf("decode item: %v", err)
 88 fd79aa76 2024-03-28 o 		}
 89 fd79aa76 2024-03-28 o 	}
 90 fd79aa76 2024-03-28 o 	if f.msg == nil {
 91 fd79aa76 2024-03-28 o 		f.msg = toMessage(f.item)
 92 fd79aa76 2024-03-28 o 	}
 93 fd79aa76 2024-03-28 o 	return f.msg.Read(p)
 94 fd79aa76 2024-03-28 o }
 95 fd79aa76 2024-03-28 o 
 96 fd79aa76 2024-03-28 o func (f *file) Stat() (fs.FileInfo, error) { return f.item, nil }
 97 fd79aa76 2024-03-28 o 
 98 fd79aa76 2024-03-28 o func (f *file) Close() error {
 99 fd79aa76 2024-03-28 o 	f.msg = nil
100 fd79aa76 2024-03-28 o 	return f.rc.Close()
101 fd79aa76 2024-03-28 o }
102 fd79aa76 2024-03-28 o 
103 fd79aa76 2024-03-28 o func toMessage(item *Item) *bytes.Reader {
104 fd79aa76 2024-03-28 o 	buf := &bytes.Buffer{}
105 fd79aa76 2024-03-28 o 	fmt.Fprintf(buf, "From: %s\n", item.By)
106 fd79aa76 2024-03-28 o 	fmt.Fprintf(buf, "Message-ID: <%d@news.ycombinator.com>\n", item.ID)
107 fd79aa76 2024-03-28 o 	fmt.Fprintf(buf, "Date: %s\n", time.Unix(int64(item.Time), 0).Format(time.RFC1123Z))
108 fd79aa76 2024-03-28 o 	if item.Parent != 0 {
109 fd79aa76 2024-03-28 o 		fmt.Fprintf(buf, "References: <%d@news.ycombinator.com>\n", item.Parent)
110 fd79aa76 2024-03-28 o 	}
111 fd79aa76 2024-03-28 o 	if item.Title != "" {
112 fd79aa76 2024-03-28 o 		fmt.Fprintf(buf, "Subject: %s\n", item.Title)
113 fd79aa76 2024-03-28 o 	}
114 fd79aa76 2024-03-28 o 	fmt.Fprintln(buf)
115 fd79aa76 2024-03-28 o 	if item.URL != "" {
116 fd79aa76 2024-03-28 o 		fmt.Fprintln(buf, item.URL)
117 fd79aa76 2024-03-28 o 	}
118 fd79aa76 2024-03-28 o 	if item.Text != "" {
119 fd79aa76 2024-03-28 o 		fmt.Fprintln(buf, strings.ReplaceAll(html.UnescapeString(item.Text), "<p>", "\n\n"))
120 fd79aa76 2024-03-28 o 	}
121 fd79aa76 2024-03-28 o 	return bytes.NewReader(buf.Bytes())
122 fd79aa76 2024-03-28 o }