blog.gno

  1// Package blog is a multi-author on-chain blog realm for gno.land.
  2//
  3// Any caller can Publish a post; posts are stored persistently and rendered
  4// newest-first. Each post records its author (the calling address) and the
  5// block height at which it was published.
  6package blog
  7
  8import (
  9	"strconv"
 10	"strings"
 11
 12	"chain"
 13	"chain/markdown"
 14	"chain/runtime"
 15
 16	"gno.land/p/g1magld5ptgzaktqcexxq0pgq5lmdf0kz6re8hlv/kit/store/v0"
 17	"gno.land/p/g1magld5ptgzaktqcexxq0pgq5lmdf0kz6re8hlv/kit/ui/v0"
 18	"gno.land/p/g1magld5ptgzaktqcexxq0pgq5lmdf0kz6re8hlv/md/v0"
 19)
 20
 21// selfPath is this realm's own page. A root-relative link resolves against
 22// the domain, not the realm, so every link back into it names it in full.
 23const selfPath = "/r/moul/x/daily/blog/v1"
 24
 25// Post is a single blog entry. It carries no id field: the id belongs to the
 26// store, which hands it back on lookup and iteration.
 27type Post struct {
 28	Title  string
 29	Body   string
 30	Author address
 31	Height int64
 32}
 33
 34// posts holds every published post. The store keys by seqid, so iteration is
 35// in publication order for any number of posts; v0 kept its own nextID plus a
 36// key() that zero-padded to width 12 and stopped ordering past it.
 37var posts = store.Named("post")
 38
 39// Publish creates a new post authored by the caller and returns its id.
 40// It is a state-mutating exported function, so it takes `cur realm`.
 41func Publish(cur realm, title string, body string) int {
 42	if !cur.IsCurrent() {
 43		panic("blog: spoofed realm")
 44	}
 45	title = strings.TrimSpace(title)
 46	body = strings.TrimSpace(body)
 47	if strings.TrimSpace(markdown.StripBidiAndZeroWidth(title)) == "" {
 48		panic("blog: title must not be empty")
 49	}
 50	if strings.TrimSpace(markdown.StripBidiAndZeroWidth(body)) == "" {
 51		panic("blog: body must not be empty")
 52	}
 53
 54	author := cur.Previous().Address()
 55	id := posts.Add(&Post{
 56		Title:  title,
 57		Body:   body,
 58		Author: author,
 59		Height: runtime.ChainHeight(),
 60	})
 61
 62	chain.Emit(
 63		"PostPublished",
 64		"id", id.String(),
 65		"author", author.String(),
 66	)
 67	return int(id)
 68}
 69
 70// PostCount returns the number of published posts.
 71func PostCount() int {
 72	return posts.Len()
 73}
 74
 75// Render lists all posts newest-first at the root, or a single post's full
 76// text at path "/<id>". Render is NOT a crossing function.
 77func Render(path string) string {
 78	path = strings.TrimSpace(path)
 79	if path == "" || path == "/" {
 80		return renderList()
 81	}
 82	idStr := strings.TrimPrefix(path, "/")
 83	id, ok := store.ParseID(idStr)
 84	if !ok {
 85		return "# Not found\n\nInvalid post path: " + md.InlineCode(path) + "\n\n[← back](" + selfPath + ")\n"
 86	}
 87	v, ok := posts.Get(id)
 88	if !ok {
 89		return "# Not found\n\nNo post with id " + idStr + ".\n\n[← back](" + selfPath + ")\n"
 90	}
 91	return renderPost(v.(*Post))
 92}
 93
 94func renderList() string {
 95	var b strings.Builder
 96	b.WriteString("# 📝 Blog\n\n")
 97	if posts.Len() == 0 {
 98		b.WriteString("_No posts yet. Be the first to `Publish`._\n")
 99		return b.String()
100	}
101	b.WriteString(strconv.Itoa(posts.Len()) + " post(s), newest first.\n\n")
102
103	// Ids ascend with publication, so reverse iteration is newest-first.
104	posts.EachReverse(func(id store.ID, v any) {
105		p := v.(*Post)
106		b.WriteString("## [")
107		b.WriteString(ui.Inline(p.Title))
108		b.WriteString("](" + selfPath + ":/")
109		b.WriteString(id.String())
110		b.WriteString(")\n\n")
111		b.WriteString("by `")
112		b.WriteString(p.Author.String())
113		b.WriteString("` · height ")
114		b.WriteString(strconv.FormatInt(p.Height, 10))
115		b.WriteString("\n\n")
116		b.WriteString(ui.Excerpt(strings.TrimSpace(p.Body), 140))
117		b.WriteString("\n\n---\n\n")
118	})
119	return b.String()
120}
121
122func renderPost(p *Post) string {
123	var b strings.Builder
124	b.WriteString("# ")
125	b.WriteString(ui.Inline(p.Title))
126	b.WriteString("\n\n")
127	b.WriteString("by `")
128	b.WriteString(p.Author.String())
129	b.WriteString("` · height ")
130	b.WriteString(strconv.FormatInt(p.Height, 10))
131	b.WriteString("\n\n")
132	// Anyone may publish, so the body is the caller's text, not this realm's
133	// markdown: each line is escaped, and a blank line still breaks a paragraph.
134	for i, line := range strings.Split(p.Body, "\n") {
135		if i > 0 {
136			b.WriteString("  \n")
137		}
138		b.WriteString(ui.Inline(line))
139	}
140	b.WriteString("\n\n---\n\n[← back to all posts](" + selfPath + ")\n")
141	return b.String()
142}