first commit

plugin/markdown/renderer/markdown_renderer.go

@@ -0,0 +1,266 @@
+package renderer
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	gast "github.com/yuin/goldmark/ast"
+	east "github.com/yuin/goldmark/extension/ast"
+
+	mast "github.com/usememos/memos/plugin/markdown/ast"
+)
+
+// MarkdownRenderer renders goldmark AST back to markdown text.
+type MarkdownRenderer struct {
+	buf *bytes.Buffer
+}
+
+// NewMarkdownRenderer creates a new markdown renderer.
+func NewMarkdownRenderer() *MarkdownRenderer {
+	return &MarkdownRenderer{
+		buf: &bytes.Buffer{},
+	}
+}
+
+// Render renders the AST node to markdown and returns the result.
+func (r *MarkdownRenderer) Render(node gast.Node, source []byte) string {
+	r.buf.Reset()
+	r.renderNode(node, source, 0)
+	return r.buf.String()
+}
+
+// renderNode renders a single node and its children.
+func (r *MarkdownRenderer) renderNode(node gast.Node, source []byte, depth int) {
+	switch n := node.(type) {
+	case *gast.Document:
+		r.renderChildren(n, source, depth)
+
+	case *gast.Paragraph:
+		r.renderChildren(n, source, depth)
+		if node.NextSibling() != nil {
+			r.buf.WriteString("\n\n")
+		}
+
+	case *gast.Text:
+		// Text nodes store their content as segments in the source
+		segment := n.Segment
+		r.buf.Write(segment.Value(source))
+		if n.SoftLineBreak() {
+			r.buf.WriteByte('\n')
+		} else if n.HardLineBreak() {
+			r.buf.WriteString("  \n")
+		}
+
+	case *gast.CodeSpan:
+		r.buf.WriteByte('`')
+		r.renderChildren(n, source, depth)
+		r.buf.WriteByte('`')
+
+	case *gast.Emphasis:
+		symbol := "*"
+		if n.Level == 2 {
+			symbol = "**"
+		}
+		r.buf.WriteString(symbol)
+		r.renderChildren(n, source, depth)
+		r.buf.WriteString(symbol)
+
+	case *gast.Link:
+		r.buf.WriteString("[")
+		r.renderChildren(n, source, depth)
+		r.buf.WriteString("](")
+		r.buf.Write(n.Destination)
+		if len(n.Title) > 0 {
+			r.buf.WriteString(` "`)
+			r.buf.Write(n.Title)
+			r.buf.WriteString(`"`)
+		}
+		r.buf.WriteString(")")
+
+	case *gast.AutoLink:
+		url := n.URL(source)
+		if n.AutoLinkType == gast.AutoLinkEmail {
+			r.buf.WriteString("<")
+			r.buf.Write(url)
+			r.buf.WriteString(">")
+		} else {
+			r.buf.Write(url)
+		}
+
+	case *gast.Image:
+		r.buf.WriteString("![")
+		r.renderChildren(n, source, depth)
+		r.buf.WriteString("](")
+		r.buf.Write(n.Destination)
+		if len(n.Title) > 0 {
+			r.buf.WriteString(` "`)
+			r.buf.Write(n.Title)
+			r.buf.WriteString(`"`)
+		}
+		r.buf.WriteString(")")
+
+	case *gast.Heading:
+		r.buf.WriteString(strings.Repeat("#", n.Level))
+		r.buf.WriteByte(' ')
+		r.renderChildren(n, source, depth)
+		if node.NextSibling() != nil {
+			r.buf.WriteString("\n\n")
+		}
+
+	case *gast.CodeBlock, *gast.FencedCodeBlock:
+		r.renderCodeBlock(n, source)
+
+	case *gast.Blockquote:
+		// Render each child line with "> " prefix
+		r.renderBlockquote(n, source, depth)
+		if node.NextSibling() != nil {
+			r.buf.WriteString("\n\n")
+		}
+
+	case *gast.List:
+		r.renderChildren(n, source, depth)
+		if node.NextSibling() != nil {
+			r.buf.WriteString("\n\n")
+		}
+
+	case *gast.ListItem:
+		r.renderListItem(n, source, depth)
+
+	case *gast.ThematicBreak:
+		r.buf.WriteString("---")
+		if node.NextSibling() != nil {
+			r.buf.WriteString("\n\n")
+		}
+
+	case *east.Strikethrough:
+		r.buf.WriteString("~~")
+		r.renderChildren(n, source, depth)
+		r.buf.WriteString("~~")
+
+	case *east.TaskCheckBox:
+		if n.IsChecked {
+			r.buf.WriteString("[x] ")
+		} else {
+			r.buf.WriteString("[ ] ")
+		}
+
+	case *east.Table:
+		r.renderTable(n, source)
+		if node.NextSibling() != nil {
+			r.buf.WriteString("\n\n")
+		}
+
+	// Custom Memos nodes
+	case *mast.TagNode:
+		r.buf.WriteByte('#')
+		r.buf.Write(n.Tag)
+
+	default:
+		// For unknown nodes, try to render children
+		r.renderChildren(n, source, depth)
+	}
+}
+
+// renderChildren renders all children of a node.
+func (r *MarkdownRenderer) renderChildren(node gast.Node, source []byte, depth int) {
+	child := node.FirstChild()
+	for child != nil {
+		r.renderNode(child, source, depth+1)
+		child = child.NextSibling()
+	}
+}
+
+// renderCodeBlock renders a code block.
+func (r *MarkdownRenderer) renderCodeBlock(node gast.Node, source []byte) {
+	if fenced, ok := node.(*gast.FencedCodeBlock); ok {
+		// Fenced code block with language
+		r.buf.WriteString("```")
+		if lang := fenced.Language(source); len(lang) > 0 {
+			r.buf.Write(lang)
+		}
+		r.buf.WriteByte('\n')
+
+		// Write all lines
+		lines := fenced.Lines()
+		for i := 0; i < lines.Len(); i++ {
+			line := lines.At(i)
+			r.buf.Write(line.Value(source))
+		}
+
+		r.buf.WriteString("```")
+		if node.NextSibling() != nil {
+			r.buf.WriteString("\n\n")
+		}
+	} else if codeBlock, ok := node.(*gast.CodeBlock); ok {
+		// Indented code block
+		lines := codeBlock.Lines()
+		for i := 0; i < lines.Len(); i++ {
+			line := lines.At(i)
+			r.buf.WriteString("    ")
+			r.buf.Write(line.Value(source))
+		}
+		if node.NextSibling() != nil {
+			r.buf.WriteString("\n\n")
+		}
+	}
+}
+
+// renderBlockquote renders a blockquote with "> " prefix.
+func (r *MarkdownRenderer) renderBlockquote(node *gast.Blockquote, source []byte, depth int) {
+	// Create a temporary buffer for the blockquote content
+	tempBuf := &bytes.Buffer{}
+	tempRenderer := &MarkdownRenderer{buf: tempBuf}
+	tempRenderer.renderChildren(node, source, depth)
+
+	// Add "> " prefix to each line
+	content := tempBuf.String()
+	lines := strings.Split(strings.TrimRight(content, "\n"), "\n")
+	for i, line := range lines {
+		r.buf.WriteString("> ")
+		r.buf.WriteString(line)
+		if i < len(lines)-1 {
+			r.buf.WriteByte('\n')
+		}
+	}
+}
+
+// renderListItem renders a list item with proper indentation and markers.
+func (r *MarkdownRenderer) renderListItem(node *gast.ListItem, source []byte, depth int) {
+	parent := node.Parent()
+	list, ok := parent.(*gast.List)
+	if !ok {
+		r.renderChildren(node, source, depth)
+		return
+	}
+
+	// Add indentation only for nested lists
+	// Document=0, List=1, ListItem=2 (no indent), nested ListItem=3+ (indent)
+	if depth > 2 {
+		indent := strings.Repeat("  ", depth-2)
+		r.buf.WriteString(indent)
+	}
+
+	// Add list marker
+	if list.IsOrdered() {
+		fmt.Fprintf(r.buf, "%d. ", list.Start)
+		list.Start++ // Increment for next item
+	} else {
+		r.buf.WriteString("- ")
+	}
+
+	// Render content
+	r.renderChildren(node, source, depth)
+
+	// Add newline if there's a next sibling
+	if node.NextSibling() != nil {
+		r.buf.WriteByte('\n')
+	}
+}
+
+// renderTable renders a table in markdown format.
+func (r *MarkdownRenderer) renderTable(table *east.Table, source []byte) {
+	// This is a simplified table renderer
+	// A full implementation would need to handle alignment, etc.
+	r.renderChildren(table, source, 0)
+}

plugin/markdown/renderer/markdown_renderer_test.go

@@ -0,0 +1,176 @@
+package renderer
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/extension"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+
+	"github.com/usememos/memos/plugin/markdown/extensions"
+)
+
+func TestMarkdownRenderer(t *testing.T) {
+	// Create goldmark instance with all extensions
+	md := goldmark.New(
+		goldmark.WithExtensions(
+			extension.GFM,
+			extensions.TagExtension,
+		),
+		goldmark.WithParserOptions(
+			parser.WithAutoHeadingID(),
+		),
+	)
+
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "simple text",
+			input:    "Hello world",
+			expected: "Hello world",
+		},
+		{
+			name:     "paragraph with newlines",
+			input:    "First paragraph\n\nSecond paragraph",
+			expected: "First paragraph\n\nSecond paragraph",
+		},
+		{
+			name:     "emphasis",
+			input:    "This is *italic* and **bold** text",
+			expected: "This is *italic* and **bold** text",
+		},
+		{
+			name:     "headings",
+			input:    "# Heading 1\n\n## Heading 2\n\n### Heading 3",
+			expected: "# Heading 1\n\n## Heading 2\n\n### Heading 3",
+		},
+		{
+			name:     "link",
+			input:    "Check [this link](https://example.com)",
+			expected: "Check [this link](https://example.com)",
+		},
+		{
+			name:     "image",
+			input:    "![alt text](image.png)",
+			expected: "![alt text](image.png)",
+		},
+		{
+			name:     "code inline",
+			input:    "This is `inline code` here",
+			expected: "This is `inline code` here",
+		},
+		{
+			name:     "code block fenced",
+			input:    "```go\nfunc main() {\n}\n```",
+			expected: "```go\nfunc main() {\n}\n```",
+		},
+		{
+			name:     "unordered list",
+			input:    "- Item 1\n- Item 2\n- Item 3",
+			expected: "- Item 1\n- Item 2\n- Item 3",
+		},
+		{
+			name:     "ordered list",
+			input:    "1. First\n2. Second\n3. Third",
+			expected: "1. First\n2. Second\n3. Third",
+		},
+		{
+			name:     "blockquote",
+			input:    "> This is a quote\n> Second line",
+			expected: "> This is a quote\n> Second line",
+		},
+		{
+			name:     "horizontal rule",
+			input:    "Text before\n\n---\n\nText after",
+			expected: "Text before\n\n---\n\nText after",
+		},
+		{
+			name:     "strikethrough",
+			input:    "This is ~~deleted~~ text",
+			expected: "This is ~~deleted~~ text",
+		},
+		{
+			name:     "task list",
+			input:    "- [x] Completed task\n- [ ] Incomplete task",
+			expected: "- [x] Completed task\n- [ ] Incomplete task",
+		},
+		{
+			name:     "tag",
+			input:    "This has #tag in it",
+			expected: "This has #tag in it",
+		},
+		{
+			name:     "multiple tags",
+			input:    "#work #important meeting notes",
+			expected: "#work #important meeting notes",
+		},
+		{
+			name:     "complex mixed content",
+			input:    "# Meeting Notes\n\n**Date**: 2024-01-01\n\n## Attendees\n- Alice\n- Bob\n\n## Discussion\n\nWe discussed #project status.\n\n```python\nprint('hello')\n```",
+			expected: "# Meeting Notes\n\n**Date**: 2024-01-01\n\n## Attendees\n\n- Alice\n- Bob\n\n## Discussion\n\nWe discussed #project status.\n\n```python\nprint('hello')\n```",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Parse the input
+			source := []byte(tt.input)
+			reader := text.NewReader(source)
+			doc := md.Parser().Parse(reader)
+			require.NotNil(t, doc)
+
+			// Render back to markdown
+			renderer := NewMarkdownRenderer()
+			result := renderer.Render(doc, source)
+
+			// For debugging
+			if result != tt.expected {
+				t.Logf("Input:    %q", tt.input)
+				t.Logf("Expected: %q", tt.expected)
+				t.Logf("Got:      %q", result)
+			}
+
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestMarkdownRendererPreservesStructure(t *testing.T) {
+	// Test that parsing and rendering preserves structure
+	md := goldmark.New(
+		goldmark.WithExtensions(
+			extension.GFM,
+			extensions.TagExtension,
+		),
+	)
+
+	inputs := []string{
+		"# Title\n\nParagraph",
+		"**Bold** and *italic*",
+		"- List\n- Items",
+		"#tag #another",
+		"> Quote",
+	}
+
+	renderer := NewMarkdownRenderer()
+
+	for _, input := range inputs {
+		t.Run(input, func(t *testing.T) {
+			source := []byte(input)
+			reader := text.NewReader(source)
+			doc := md.Parser().Parse(reader)
+
+			result := renderer.Render(doc, source)
+
+			// The result should be structurally similar
+			// (may have minor formatting differences)
+			assert.NotEmpty(t, result)
+		})
+	}
+}