import { unified } from "unified"
import remarkStringify from "remark-stringify"
import remarkGfm from "remark-gfm"
import remarkFrontmatter from "remark-frontmatter"
import type { Ast } from "./schemas.js"

/**
 * Serialize an mdast-shaped AST (Root) back to a Markdown string.
 * - GFM is enabled by default for table/task-list/strikethrough serialization.
 * - Output always ends with a newline to follow CommonMark/remark canonical formatting.
 *
 * @example
 * ```ts
 * import { parseMarkdown, serializeAst } from "@opral/markdown-wc/ast"
 *
 * const markdown = serializeAst(parseMarkdown("# Heading"))
 * // => "# Heading\n"
 * ```
 */
export function serializeAst(ast: Ast): string {
	const processor = unified()
		.use(remarkStringify as any, {
			bullet: "-",
			listItemIndent: "one",
			rule: "-",
			ruleRepetition: 3,
			ruleSpaces: false,
			emphasis: "_",
			strong: "*",
			// Keep raw HTML in output for html nodes
			allowDangerousHtml: true,
		})
		.use(remarkGfm as any)
		.use(remarkFrontmatter as any, ["yaml"])

	// unified.stringify expects a compatible mdast Root
	const result = processor.stringify(ast as any) as string
	return result
}

export type { Ast }