Add structured materials, canvas layouts, tags and content permissions

internal/platform/content.go

@@ -0,0 +1,129 @@
+package platform
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/url"
+	"regexp"
+)
+
+type Paragraph struct {
+	ID          string `json:"id"`
+	Text        string `json:"text"`
+	Description string `json:"description,omitempty"`
+}
+type Section struct {
+	ID          string      `json:"id"`
+	Title       string      `json:"title"`
+	Description string      `json:"description,omitempty"`
+	Paragraphs  []Paragraph `json:"paragraphs"`
+}
+type Article struct {
+	Sections []Section `json:"sections"`
+}
+type Image struct {
+	URL    string `json:"url"`
+	Alt    string `json:"alt,omitempty"`
+	Width  int    `json:"width,omitempty"`
+	Height int    `json:"height,omitempty"`
+}
+type CardPart struct {
+	Kind    string   `json:"kind"`
+	Text    *string  `json:"text,omitempty"`
+	Article *Article `json:"article,omitempty"`
+	Image   *Image   `json:"image,omitempty"`
+}
+type Content struct {
+	SchemaVersion int        `json:"schema_version"`
+	Text          *string    `json:"text,omitempty"`
+	Article       *Article   `json:"article,omitempty"`
+	Image         *Image     `json:"image,omitempty"`
+	Parts         []CardPart `json:"parts,omitempty"`
+}
+
+var blockID = regexp.MustCompile(`^[A-Za-z0-9_-]{1,64}$`)
+
+func validArticle(article *Article) bool {
+	if article == nil || len(article.Sections) > 200 {
+		return false
+	}
+	seen := map[string]bool{}
+	total := 0
+	for _, section := range article.Sections {
+		if !blockID.MatchString(section.ID) || seen[section.ID] || len(section.Title) > 300 || len(section.Description) > 10000 {
+			return false
+		}
+		seen[section.ID] = true
+		total += len(section.Paragraphs)
+		if total > 2000 {
+			return false
+		}
+		for _, paragraph := range section.Paragraphs {
+			if !blockID.MatchString(paragraph.ID) || seen[paragraph.ID] || len(paragraph.Text) > 100000 || len(paragraph.Description) > 10000 {
+				return false
+			}
+			seen[paragraph.ID] = true
+		}
+	}
+	return true
+}
+func validImage(image *Image) bool {
+	if image == nil || len(image.URL) > 2048 || len(image.Alt) > 2000 || image.Width < 0 || image.Width > 100000 || image.Height < 0 || image.Height > 100000 {
+		return false
+	}
+	u, err := url.Parse(image.URL)
+	return err == nil && u.Scheme == "https" && u.Hostname() != "" && u.User == nil && u.Fragment == ""
+}
+func validPart(part CardPart) bool {
+	switch part.Kind {
+	case "text":
+		return part.Text != nil && len(*part.Text) <= 100000 && part.Article == nil && part.Image == nil
+	case "article":
+		return part.Text == nil && part.Image == nil && validArticle(part.Article)
+	case "image":
+		return part.Text == nil && part.Article == nil && validImage(part.Image)
+	default:
+		return false
+	}
+}
+func normalizeContent(kind string, raw json.RawMessage) (json.RawMessage, bool) {
+	if raw = bytes.TrimSpace(raw); len(raw) == 0 || raw[0] != '{' {
+		return nil, false
+	}
+	var content Content
+	d := json.NewDecoder(bytes.NewReader(raw))
+	d.DisallowUnknownFields()
+	if d.Decode(&content) != nil || d.Decode(new(any)) != io.EOF {
+		return nil, false
+	}
+	if content.SchemaVersion == 0 {
+		content.SchemaVersion = 1
+	}
+	if content.SchemaVersion != 1 {
+		return nil, false
+	}
+	switch kind {
+	case "text", "article", "image":
+		if len(content.Parts) > 0 || !validPart(CardPart{Kind: kind, Text: content.Text, Article: content.Article, Image: content.Image}) {
+			return nil, false
+		}
+	case "board":
+		if content.Text != nil || content.Article != nil || content.Image != nil || len(content.Parts) > 0 {
+			return nil, false
+		}
+	case "card":
+		if content.Text != nil || content.Article != nil || content.Image != nil || len(content.Parts) < 1 || len(content.Parts) > 20 {
+			return nil, false
+		}
+		for _, part := range content.Parts {
+			if !validPart(part) {
+				return nil, false
+			}
+		}
+	default:
+		return nil, false
+	}
+	out, err := json.Marshal(content)
+	return out, err == nil
+}