feat: Improved opengraph defaults.

html.odin

@@ -0,0 +1,137 @@
+package main
+
+import "core:strings"
+
+strip_html_tags :: proc(s: string, allocator := context.allocator) -> string {
+	sb := strings.builder_make(allocator)
+	defer strings.builder_destroy(&sb)
+
+	in_tag := false
+	start := 0
+	for i in 0 ..< len(s) {
+		if s[i] == '<' && !in_tag {
+			if i > start {
+				strings.write_string(&sb, s[start:i])
+			}
+			in_tag = true
+		} else if s[i] == '>' && in_tag {
+			in_tag = false
+			start = i + 1
+		}
+	}
+	if start == 0 {
+		return s
+	}
+	if !in_tag && start < len(s) {
+		strings.write_string(&sb, s[start:])
+	}
+	return strings.to_string(sb)
+}
+
+unescape_html :: proc(s: string) -> string {
+	sb := strings.builder_make()
+	defer strings.builder_destroy(&sb)
+
+	start := 0
+	for i in 0 ..< len(s) {
+		if s[i] != '&' {
+			continue
+		}
+		semi := strings.index(s[i:], ";")
+		if semi < 0 {
+			break
+		}
+		entity := s[i : i + semi + 1]
+		replacement := ""
+		switch entity {
+		case "&amp;":  replacement = "&"
+		case "&lt;":   replacement = "<"
+		case "&gt;":   replacement = ">"
+		case "&quot;": replacement = "\""
+		case "&#39;", "&apos;": replacement = "'"
+		case: continue
+		}
+		if i > start {
+			strings.write_string(&sb, s[start:i])
+		}
+		strings.write_string(&sb, replacement)
+		start = i + semi + 1
+	}
+	if start == 0 {
+		return s
+	}
+	if start < len(s) {
+		strings.write_string(&sb, s[start:])
+	}
+	return strings.to_string(sb)
+}
+
+// generate_summary produces a plain-text summary of an HTML fragment.
+// Blocks (paragraphs, headings, list items) are extracted, their tags
+// stripped, entities decoded, and accumulated word-by-word until the
+// max_words threshold is crossed — at which point the rest of the
+// current block is included before stopping. Mirrors Hugo's default
+// summary behavior.
+generate_summary :: proc(html: string, max_words: int = 70) -> string {
+	separated, _ := strings.replace_all(html, "</p>", "\n\n", context.temp_allocator)
+	separated, _ = strings.replace_all(separated, "</h1>", "\n\n")
+	separated, _ = strings.replace_all(separated, "</h2>", "\n\n")
+	separated, _ = strings.replace_all(separated, "</h3>", "\n\n")
+	separated,_ = strings.replace_all(separated, "</h4>", "\n\n")
+	separated, _ = strings.replace_all(separated, "</h5>", "\n\n")
+	separated, _ = strings.replace_all(separated, "</h6>", "\n\n")
+	separated, _ = strings.replace_all(separated, "</li>", "\n\n")
+	separated, _ = strings.replace_all(separated, "</blockquote>", "\n\n")
+
+	stripped := strip_html_tags(separated, context.temp_allocator)
+	plain := unescape_html(stripped)
+
+	blocks := strings.split(plain, "\n\n", allocator = context.temp_allocator)
+	defer delete(blocks)
+
+	sb := strings.builder_make(context.temp_allocator)
+	defer strings.builder_destroy(&sb)
+
+	word_count := 0
+	first := true
+	for raw_block in blocks {
+		block := strings.trim_space(raw_block)
+		if len(block) == 0 {
+			continue
+		}
+
+		// Collapse internal whitespace to single spaces.
+		block_sb := strings.builder_make(context.temp_allocator)
+		has_content := false
+		in_space := true
+		for c in block {
+			if c == ' ' || c == '\t' || c == '\n' || c == '\r' {
+				in_space = true
+			} else {
+				if in_space && has_content {
+					strings.write_byte(&block_sb, ' ')
+				}
+				strings.write_rune(&block_sb, c)
+				in_space = false
+				has_content = true
+			}
+		}
+		collapsed := strings.to_string(block_sb)
+		words := strings.split(collapsed, " ", allocator = context.temp_allocator)
+
+		if !first && word_count > 0 {
+			strings.write_byte(&sb, ' ')
+		}
+		strings.write_string(&sb, collapsed)
+		word_count += len(words)
+		first = false
+
+		delete(words)
+
+		if word_count >= max_words {
+			break
+		}
+	}
+
+	return strings.to_string(sb)
+}