// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.16
// +build go1.16

package web

import (
	"bytes"

	"github.com/yuin/goldmark"
	"github.com/yuin/goldmark/parser"
	"github.com/yuin/goldmark/renderer/html"
)

// renderMarkdown converts a limited and opinionated flavor of Markdown (compliant with
// CommonMark 0.29) to HTML for the purposes of Go websites.
//
// The Markdown source may contain raw HTML,
// but Go templates have already been processed.
func renderMarkdown(src []byte) ([]byte, error) {
	// parser.WithHeadingAttribute allows custom ids on headings.
	// html.WithUnsafe allows use of raw HTML, which we need for tables.
	md := goldmark.New(
		goldmark.WithParserOptions(parser.WithHeadingAttribute()),
		goldmark.WithRendererOptions(html.WithUnsafe()))
	var buf bytes.Buffer
	if err := md.Convert(src, &buf); err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}