core/render/blocknote.go

package render

import (
	"context"
	"encoding/json"
	"fmt"
	"html"
	"strings"

	"git.dev.alexdunmow.com/block/core/blocks"
	"github.com/google/uuid"
)

// BlockNoteToHTML converts a BlockNote document (map with "blocks" key) to HTML.
func BlockNoteToHTML(ctx context.Context, doc map[string]any) string {
	rawBlocks := blocksFromRaw(doc["blocks"])
	if len(rawBlocks) == 0 {
		return ""
	}
	return renderBlocks(ctx, rawBlocks)
}

func renderBlocks(ctx context.Context, blocks []map[string]any) string {
	var sb strings.Builder
	var currentListType string
	var listItems []map[string]any

	flushList := func() {
		if len(listItems) == 0 {
			return
		}
		tag := "ul"
		listStyle := "list-disc"
		if currentListType == "numberedListItem" {
			tag = "ol"
			listStyle = "list-decimal"
		}
		fmt.Fprintf(&sb, "<%s class=\"my-4 pl-6 space-y-2 %s\">\n", tag, listStyle)
		for _, item := range listItems {
			content := inlineContentFromRaw(item["content"])
			childrenHTML := renderChildren(ctx, item["children"])
			sb.WriteString("<li>")
			sb.WriteString(renderInlineContent(content, false))
			if childrenHTML != "" {
				sb.WriteString(childrenHTML)
			}
			sb.WriteString("</li>\n")
		}
		fmt.Fprintf(&sb, "</%s>\n", tag)
		listItems = nil
		currentListType = ""
	}

	for _, blockMap := range blocks {
		blockType, _ := blockMap["type"].(string)

		if blockType == "bulletListItem" || blockType == "numberedListItem" {
			if currentListType != "" && currentListType != blockType {
				flushList()
			}
			currentListType = blockType
			listItems = append(listItems, blockMap)
			continue
		}

		flushList()
		sb.WriteString(renderBlock(ctx, blockMap))
	}

	flushList()
	return sb.String()
}

func inlineContentFromRaw(raw any) []map[string]any {
	switch v := raw.(type) {
	case []any:
		items := make([]map[string]any, 0, len(v))
		for _, item := range v {
			if m, ok := item.(map[string]any); ok {
				items = append(items, m)
			}
		}
		return items
	case []map[string]any:
		return v
	case string:
		if v == "" {
			return nil
		}
		return []map[string]any{{"type": "text", "text": v}}
	default:
		return nil
	}
}

func blocksFromRaw(raw any) []map[string]any {
	switch v := raw.(type) {
	case []any:
		items := make([]map[string]any, 0, len(v))
		for _, item := range v {
			if m, ok := item.(map[string]any); ok {
				items = append(items, m)
			}
		}
		return items
	case []map[string]any:
		return v
	default:
		return nil
	}
}

func textAlignClass(props map[string]any) string {
	if props == nil {
		return ""
	}
	align, _ := props["textAlignment"].(string)
	switch align {
	case "left":
		return "text-left"
	case "center":
		return "text-center"
	case "right":
		return "text-right"
	case "justify":
		return "text-justify"
	default:
		return ""
	}
}

func safeClassToken(value string) string {
	for _, r := range value {
		if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || r == '-' {
			continue
		}
		return ""
	}
	return value
}

func isHexDigit(c rune) bool {
	return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')
}

func colorValueToClass(value string, prefix string) string {
	if value == "" || value == "default" {
		return ""
	}

	if after, ok := strings.CutPrefix(value, "hex:"); ok {
		hex := after
		if len(hex) != 7 && len(hex) != 4 {
			return ""
		}
		for i, r := range hex {
			if i == 0 && r == '#' {
				continue
			}
			if !isHexDigit(r) {
				return ""
			}
		}
		return fmt.Sprintf("%s-[%s]", prefix, hex)
	}

	if after, ok := strings.CutPrefix(value, "custom:"); ok {
		name := safeClassToken(after)
		if name == "" {
			return ""
		}
		return fmt.Sprintf("%s-[hsl(var(--color-%s))]", prefix, name)
	}

	value = safeClassToken(value)
	if value == "" {
		return ""
	}
	return fmt.Sprintf("%s-%s", prefix, value)
}

func renderBlock(ctx context.Context, block map[string]any) string {
	blockType, _ := block["type"].(string)
	props, _ := block["props"].(map[string]any)
	content := inlineContentFromRaw(block["content"])
	childrenHTML := renderChildren(ctx, block["children"])

	var sb strings.Builder

	switch blockType {
	case "paragraph":
		classNames := "my-4"
		if alignClass := textAlignClass(props); alignClass != "" {
			classNames += " " + alignClass
		}
		fmt.Fprintf(&sb, "<p class=\"%s\">", classNames)
		sb.WriteString(renderInlineContent(content, false))
		if childrenHTML != "" {
			sb.WriteString(childrenHTML)
		}
		sb.WriteString("</p>\n")

	case "heading":
		level := 2
		if l, ok := props["level"].(float64); ok {
			level = int(l)
		} else if l, ok := props["level"].(int); ok {
			level = l
		}
		if level < 1 {
			level = 1
		}
		if level > 6 {
			level = 6
		}
		classNames := "mt-8 mb-4 font-bold"
		if alignClass := textAlignClass(props); alignClass != "" {
			classNames += " " + alignClass
		}
		fmt.Fprintf(&sb, "<h%d class=\"%s\">", level, classNames)
		sb.WriteString(renderInlineContent(content, false))
		if childrenHTML != "" {
			sb.WriteString(childrenHTML)
		}
		fmt.Fprintf(&sb, "</h%d>\n", level)

	case "quote":
		classNames := "my-4 border-l-4 border-border pl-4 text-muted-foreground"
		if alignClass := textAlignClass(props); alignClass != "" {
			classNames += " " + alignClass
		}
		fmt.Fprintf(&sb, "<blockquote class=\"%s\">", classNames)
		sb.WriteString(renderInlineContent(content, false))
		if childrenHTML != "" {
			sb.WriteString(childrenHTML)
		}
		sb.WriteString("</blockquote>\n")

	case "checkListItem":
		checked := false
		if c, ok := props["checked"].(bool); ok {
			checked = c
		}
		checkedAttr := ""
		if checked {
			checkedAttr = " checked"
		}
		fmt.Fprintf(&sb, `<div class="check-list-item my-2 flex items-start gap-2"><input type="checkbox" disabled%s><span>`, checkedAttr)
		sb.WriteString(renderInlineContent(content, false))
		sb.WriteString("</span>")
		if childrenHTML != "" {
			fmt.Fprintf(&sb, `<div class="pl-6">%s</div>`, childrenHTML)
		}
		sb.WriteString("</div>\n")

	case "toggleListItem":
		openAttr := ""
		if open, ok := props["open"].(bool); ok && open {
			openAttr = " open"
		}
		fmt.Fprintf(&sb, `<details class="my-4"%s>`, openAttr)
		sb.WriteString(`<summary class="cursor-pointer font-medium">`)
		sb.WriteString(renderInlineContent(content, false))
		sb.WriteString("</summary>")
		if childrenHTML != "" {
			fmt.Fprintf(&sb, `<div class="pl-6 mt-2">%s</div>`, childrenHTML)
		}
		sb.WriteString("</details>\n")

	case "codeBlock":
		lang := ""
		if l, ok := props["language"].(string); ok {
			lang = l
		}
		fmt.Fprintf(&sb, `<pre class="my-4"><code class="language-%s">`, html.EscapeString(lang))
		sb.WriteString(renderInlineContent(content, false))
		sb.WriteString("</code></pre>\n")

	case "image":
		url := ""
		caption := ""
		alt := ""
		if u, ok := props["url"].(string); ok {
			url = u
		}
		if c, ok := props["caption"].(string); ok {
			caption = c
		}
		if a, ok := props["alt"].(string); ok {
			alt = a
		}
		if alt == "" {
			alt = caption
		}
		sb.WriteString(`<figure class="my-6">`)
		fmt.Fprintf(&sb, `<img src="%s" alt="%s" />`, html.EscapeString(url), html.EscapeString(alt))
		if caption != "" {
			fmt.Fprintf(&sb, "<figcaption>%s</figcaption>", html.EscapeString(caption))
		}
		sb.WriteString("</figure>\n")

	case "video":
		url := ""
		caption := ""
		if u, ok := props["url"].(string); ok {
			url = u
		}
		if c, ok := props["caption"].(string); ok {
			caption = c
		}
		sb.WriteString(`<figure class="my-6">`)
		fmt.Fprintf(&sb, `<video src="%s" controls></video>`, html.EscapeString(url))
		if caption != "" {
			fmt.Fprintf(&sb, "<figcaption>%s</figcaption>", html.EscapeString(caption))
		}
		sb.WriteString("</figure>\n")

	case "audio":
		url := ""
		caption := ""
		if u, ok := props["url"].(string); ok {
			url = u
		}
		if c, ok := props["caption"].(string); ok {
			caption = c
		}
		sb.WriteString(`<figure class="my-6">`)
		fmt.Fprintf(&sb, `<audio src="%s" controls></audio>`, html.EscapeString(url))
		if caption != "" {
			fmt.Fprintf(&sb, "<figcaption>%s</figcaption>", html.EscapeString(caption))
		}
		sb.WriteString("</figure>\n")

	case "file":
		url := ""
		name := ""
		caption := ""
		if u, ok := props["url"].(string); ok {
			url = u
		}
		if n, ok := props["name"].(string); ok {
			name = n
		}
		if c, ok := props["caption"].(string); ok {
			caption = c
		}
		if name == "" {
			name = url
		}
		sb.WriteString(`<div class="my-4 rounded border border-border p-4">`)
		if url != "" {
			fmt.Fprintf(&sb, `<a class="text-primary underline" href="%s">`, html.EscapeString(url))
			sb.WriteString(html.EscapeString(name))
			sb.WriteString("</a>")
		} else {
			sb.WriteString(html.EscapeString(name))
		}
		if caption != "" {
			fmt.Fprintf(&sb, `<p class="mt-2 text-sm text-muted-foreground">%s</p>`, html.EscapeString(caption))
		}
		sb.WriteString("</div>\n")

	case "table":
		sb.WriteString(`<div class="overflow-x-auto my-6"><table class="min-w-full border-collapse border border-border">`)
		if tableContent, ok := block["content"].(map[string]any); ok {
			if rows, ok := tableContent["rows"].([]any); ok && len(rows) > 0 {
				renderTableRow := func(row any, isHeader bool) {
					if rowMap, ok := row.(map[string]any); ok {
						if cells, ok := rowMap["cells"].([]any); ok {
							for _, cell := range cells {
								cellTag := "td"
								cellClass := "px-4 py-2 text-sm"
								if isHeader {
									cellTag = "th"
									cellClass = "px-4 py-3 text-left text-sm font-semibold"
								}
								fmt.Fprintf(&sb, "<%s class=\"%s\">", cellTag, cellClass)
								sb.WriteString(renderInlineContent(inlineContentFromRaw(cell), false))
								fmt.Fprintf(&sb, "</%s>", cellTag)
							}
						}
					}
				}
				sb.WriteString("<thead><tr class=\"bg-muted\">")
				renderTableRow(rows[0], true)
				sb.WriteString("</tr></thead>")
				if len(rows) > 1 {
					sb.WriteString("<tbody>")
					for _, row := range rows[1:] {
						sb.WriteString("<tr class=\"border-b border-border\">")
						renderTableRow(row, false)
						sb.WriteString("</tr>")
					}
					sb.WriteString("</tbody>")
				}
			}
		}
		sb.WriteString("</table></div>\n")

	case "embed":
		if resolver := blocks.GetEmbedResolver(ctx); resolver != nil {
			blockID := ""
			if v, ok := props["blockId"].(string); ok {
				blockID = v
			}
			dataSource := ""
			if v, ok := props["dataSource"].(string); ok {
				dataSource = v
			}
			layout := "full"
			if v, ok := props["layout"].(string); ok && v != "" {
				layout = v
			}
			if blockID != "" {
				if parsedID, err := uuid.Parse(blockID); err == nil {
					sb.WriteString(resolver.RenderEmbed(ctx, parsedID, dataSource, layout))
				}
			}
		}

	case "statement":
		sb.WriteString("<div class=\"bn-statement\">\n")
		if len(content) > 0 {
			sb.WriteString("<p>")
			sb.WriteString(renderInlineContent(content, false))
			sb.WriteString("</p>\n")
		}
		if childrenHTML != "" {
			sb.WriteString(childrenHTML)
		}
		sb.WriteString("</div>\n")

	case "humanProof":
		if hp := blocks.GetHumanProofBanner(ctx); hp != nil {
			sb.WriteString(blocks.RenderHumanProofBanner(hp))
			sb.WriteByte('\n')
		}

	case "references":
		sb.WriteString("<div class=\"bn-references\">\n")
		sb.WriteString("<div class=\"bn-references-label\">References</div>\n")
		sb.WriteString("<ol>\n")
		if itemsJSON, ok := props["items"].(string); ok && itemsJSON != "" {
			var items []map[string]string
			if err := json.Unmarshal([]byte(itemsJSON), &items); err == nil {
				for _, item := range items {
					text := html.EscapeString(item["text"])
					url := item["url"]
					if text == "" {
						continue
					}
					if url != "" {
						fmt.Fprintf(&sb, "<li><a href=\"%s\">%s</a></li>\n", html.EscapeString(url), text)
					} else {
						fmt.Fprintf(&sb, "<li>%s</li>\n", text)
					}
				}
			}
		}
		sb.WriteString("</ol>\n</div>\n")

	default:
		if len(content) > 0 || childrenHTML != "" {
			sb.WriteString("<div>")
			sb.WriteString(renderInlineContent(content, false))
			if childrenHTML != "" {
				sb.WriteString(childrenHTML)
			}
			sb.WriteString("</div>\n")
		}
	}

	return sb.String()
}

func renderChildren(ctx context.Context, children any) string {
	blocks := blocksFromRaw(children)
	if len(blocks) == 0 {
		return ""
	}
	return renderBlocks(ctx, blocks)
}

func renderInlineContent(content []map[string]any, insideLink bool) string {
	var sb strings.Builder
	for _, itemMap := range content {
		itemType, _ := itemMap["type"].(string)
		text, _ := itemMap["text"].(string)
		styles, _ := itemMap["styles"].(map[string]any)

		switch itemType {
		case "text":
			isCode := false
			if styles != nil {
				if c, ok := styles["code"].(bool); ok && c {
					isCode = true
				}
			}
			var rendered string
			if insideLink || isCode {
				rendered = html.EscapeString(text)
			} else {
				rendered = autolinkText(text)
			}
			if styles != nil {
				if bold, ok := styles["bold"].(bool); ok && bold {
					rendered = "<strong>" + rendered + "</strong>"
				}
				if italic, ok := styles["italic"].(bool); ok && italic {
					rendered = "<em>" + rendered + "</em>"
				}
				if underline, ok := styles["underline"].(bool); ok && underline {
					rendered = "<u>" + rendered + "</u>"
				}
				if strike, ok := styles["strike"].(bool); ok && strike {
					rendered = "<s>" + rendered + "</s>"
				}
				if strike, ok := styles["strikethrough"].(bool); ok && strike {
					rendered = "<s>" + rendered + "</s>"
				}
				if isCode {
					rendered = "<code>" + rendered + "</code>"
				}

				var colorClasses []string
				if textColor, ok := styles["textColor"].(string); ok && textColor != "" && textColor != "default" {
					if class := colorValueToClass(textColor, "text"); class != "" {
						colorClasses = append(colorClasses, class)
					}
				}
				if bgColor, ok := styles["backgroundColor"].(string); ok && bgColor != "" && bgColor != "default" {
					if class := colorValueToClass(bgColor, "bg"); class != "" {
						colorClasses = append(colorClasses, class)
					}
				}

				if len(colorClasses) > 0 {
					rendered = fmt.Sprintf(`<span class="%s">%s</span>`, strings.Join(colorClasses, " "), rendered)
				}
			}
			sb.WriteString(rendered)

		case "link":
			href, _ := itemMap["href"].(string)
			linkContent := inlineContentFromRaw(itemMap["content"])
			if href == "" {
				sb.WriteString(renderInlineContent(linkContent, insideLink))
				break
			}
			fmt.Fprintf(&sb, `<a href="%s">`, html.EscapeString(href))
			sb.WriteString(renderInlineContent(linkContent, true))
			sb.WriteString("</a>")

		case "hardBreak":
			sb.WriteString("<br />")

		default:
			if text != "" {
				if insideLink {
					sb.WriteString(html.EscapeString(text))
				} else {
					sb.WriteString(autolinkText(text))
				}
				break
			}
			if rawContent, ok := itemMap["content"]; ok {
				sb.WriteString(renderInlineContent(inlineContentFromRaw(rawContent), insideLink))
			}
		}
	}
	return sb.String()
}

// autolinkText escapes plain text for HTML output and wraps any https:// URL
// substring in <a href="..." rel="noopener">URL</a>. Bare domains, www. and
// http:// URLs are intentionally not auto-linked.
//
// Trailing sentence punctuation (.,;:!?'") is excluded from the linked URL.
// Closing parens, brackets and braces are kept inside the URL only when
// balanced with an opener inside the URL itself — so
//   "(see https://example.com)" links only "https://example.com"
//   "https://en.wikipedia.org/wiki/Foo_(bar)" keeps the trailing paren.
func autolinkText(text string) string {
	const scheme = "https://"
	var sb strings.Builder
	rest := text
	for {
		idx := strings.Index(rest, scheme)
		if idx < 0 {
			sb.WriteString(html.EscapeString(rest))
			return sb.String()
		}
		sb.WriteString(html.EscapeString(rest[:idx]))

		// Scan forward until whitespace or a URL-terminating delimiter.
		end := idx + len(scheme)
		for end < len(rest) {
			c := rest[end]
			if c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '<' || c == '>' || c == '"' || c == '\'' {
				break
			}
			end++
		}
		// Walk back over trailing characters that should sit outside the link,
		// preserving paren/bracket/brace balance.
		urlEnd := end
		for urlEnd > idx+len(scheme) {
			last := rest[urlEnd-1]
			if last == '.' || last == ',' || last == ';' || last == ':' || last == '!' || last == '?' || last == '"' || last == '\'' {
				urlEnd--
				continue
			}
			candidate := rest[idx:urlEnd]
			if last == ')' && strings.Count(candidate, ")") > strings.Count(candidate, "(") {
				urlEnd--
				continue
			}
			if last == ']' && strings.Count(candidate, "]") > strings.Count(candidate, "[") {
				urlEnd--
				continue
			}
			if last == '}' && strings.Count(candidate, "}") > strings.Count(candidate, "{") {
				urlEnd--
				continue
			}
			break
		}
		url := rest[idx:urlEnd]
		tail := rest[urlEnd:end]

		if url == scheme {
			sb.WriteString(html.EscapeString(rest[idx:end]))
		} else {
			escaped := html.EscapeString(url)
			sb.WriteString(`<a href="`)
			sb.WriteString(escaped)
			sb.WriteString(`" rel="noopener">`)
			sb.WriteString(escaped)
			sb.WriteString(`</a>`)
			if tail != "" {
				sb.WriteString(html.EscapeString(tail))
			}
		}

		rest = rest[end:]
	}
}