Add syntax highlighting. Fixes #28

2 files changed, 130 insertions, 15 deletions

diff --git a/ui/messages/htmlmessage.go b/ui/messages/htmlmessage.go
index 51678ba..0ffb6c9 100644
--- a/ui/messages/htmlmessage.go
+++ b/ui/messages/htmlmessage.go
@@ -72,23 +72,23 @@ func (hw *HTMLMessage) Height() int {
 }
 
 func (hw *HTMLMessage) PlainText() string {
-	// FIXME
-	return "Plaintext unavailable"
+	return hw.Root.PlainText()
 }
 
 func (hw *HTMLMessage) NotificationContent() string {
-	// FIXME
-	return "Notification content unavailable"
+	return hw.Root.PlainText()
 }
 
 type HTMLEntity struct {
 	// Permanent variables
-	Tag      string
-	Text     string
-	Style    tcell.Style
-	Children []*HTMLEntity
-	Block    bool
-	Indent   int
+	Tag       string
+	Text      string
+	Style     tcell.Style
+	Children  []*HTMLEntity
+	Block     bool
+	Indent    int
+
+	DefaultHeight int
 
 	// Non-permanent variables (calculated buffer data)
 	buffer    []string
@@ -130,8 +130,9 @@ func (he *HTMLEntity) Draw(screen mauview.Screen) {
 func (he *HTMLEntity) String() string {
 	var buf strings.Builder
 	buf.WriteString("&HTMLEntity{\n")
-	_, _ = fmt.Fprintf(&buf, `    Tag="%s", Style=%d, Block=%t, Indent=%d, startX=%d, height=%d,\n`,
+	_, _ = fmt.Fprintf(&buf, `    Tag="%s", Style=%d, Block=%t, Indent=%d, startX=%d, height=%d,`,
 		he.Tag, he.Style, he.Block, he.Indent, he.startX, he.height)
+	buf.WriteRune('\n')
 	_, _ = fmt.Fprintf(&buf, `    Buffer=["%s"]`, strings.Join(he.buffer, "\", \""))
 	if len(he.Text) > 0 {
 		buf.WriteString(",\n")
@@ -150,6 +151,27 @@ func (he *HTMLEntity) String() string {
 	return buf.String()
 }
 
+func (he *HTMLEntity) PlainText() string {
+	if len(he.Children) == 0 {
+		return he.Text
+	}
+	var buf strings.Builder
+	buf.WriteString(he.Text)
+	newlined := false
+	for _, child := range he.Children {
+		if child.Block && !newlined {
+			buf.WriteRune('\n')
+		}
+		newlined = false
+		buf.WriteString(child.PlainText())
+		if child.Block {
+			buf.WriteRune('\n')
+			newlined = true
+		}
+	}
+	return buf.String()
+}
+
 func (he *HTMLEntity) calculateBuffer(width, startX int, bare bool) int {
 	he.startX = startX
 	if he.Block {
@@ -178,6 +200,7 @@ func (he *HTMLEntity) calculateBuffer(width, startX int, bare bool) int {
 		text := he.Text
 		textStartX := he.startX
 		for {
+			// TODO add option no wrap and character wrap options
 			extract := runewidth.Truncate(text, width-textStartX, "")
 			extract, wordWrapped := trim(extract, text, bare)
 			if !wordWrapped && textStartX > 0 {
@@ -210,7 +233,10 @@ func (he *HTMLEntity) calculateBuffer(width, startX int, bare bool) int {
 			textStartX = 0
 		}
 	}
-	return 0
+	if len(he.Text) == 0 && len(he.Children) == 0 {
+		he.height = he.DefaultHeight
+	}
+	return he.startX
 }
 
 func trim(extract, full string, bare bool) (string, bool) {
diff --git a/ui/messages/parser/htmlparser.go b/ui/messages/parser/htmlparser.go
index 9a9c2d1..688deb3 100644
--- a/ui/messages/parser/htmlparser.go
+++ b/ui/messages/parser/htmlparser.go
@@ -23,6 +23,9 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/alecthomas/chroma"
+	"github.com/alecthomas/chroma/lexers"
+	"github.com/alecthomas/chroma/styles"
 	"github.com/lucasb-eyer/go-colorful"
 	"golang.org/x/net/html"
 
@@ -216,18 +219,102 @@ func (parser *htmlParser) linkToEntity(node *html.Node, stripLinebreak bool) *me
 			}
 		}
 	}
-	// TODO add click action for links
+	// TODO add click action and underline on hover for links
 	return entity
 }
 
-func (parser *htmlParser) codeblockToEntity(node *html.Node) *messages.HTMLEntity {
+func (parser *htmlParser) imageToEntity(node *html.Node) *messages.HTMLEntity {
+	alt := parser.getAttribute(node, "alt")
+	if len(alt) == 0 {
+		alt = parser.getAttribute(node, "title")
+		if len(alt) == 0 {
+			alt = "[inline image]"
+		}
+	}
+	entity := &messages.HTMLEntity{
+		Tag:  "img",
+		Text: alt,
+	}
+	// TODO add click action and underline on hover for inline images
+	return entity
+}
+
+func colourToColor(colour chroma.Colour) tcell.Color {
+	if !colour.IsSet() {
+		return tcell.ColorDefault
+	}
+	return tcell.NewRGBColor(int32(colour.Red()), int32(colour.Green()), int32(colour.Blue()))
+}
+
+func styleEntryToStyle(se chroma.StyleEntry) tcell.Style {
+	return tcell.StyleDefault.
+		Bold(se.Bold == chroma.Yes).
+		Italic(se.Italic == chroma.Yes).
+		Underline(se.Underline == chroma.Yes).
+		Foreground(colourToColor(se.Colour)).
+		Background(colourToColor(se.Background))
+}
+
+func (parser *htmlParser) syntaxHighlight(text, language string) *messages.HTMLEntity {
+	lexer := lexers.Get(language)
+	if lexer == nil {
+		return nil
+	}
+	iter, err := lexer.Tokenise(nil, text)
+	if err != nil {
+		return nil
+	}
+	style := styles.SolarizedDark
+	tokens := iter.Tokens()
+	children := make([]*messages.HTMLEntity, len(tokens))
+	for i, token := range tokens {
+		if token.Value == "\n" {
+			children[i] = &messages.HTMLEntity{Block: true, Tag: "br"}
+		} else {
+			children[i] = &messages.HTMLEntity{
+				Tag:   token.Type.String(),
+				Text:  token.Value,
+				Style: styleEntryToStyle(style.Get(token.Type)),
+
+				DefaultHeight: 1,
+			}
+		}
+	}
 	return &messages.HTMLEntity{
 		Tag:      "pre",
-		Children: parser.nodeToEntities(node.FirstChild, false),
 		Block:    true,
+		Children: children,
 	}
 }
 
+func (parser *htmlParser) codeblockToEntity(node *html.Node) *messages.HTMLEntity {
+	entity := &messages.HTMLEntity{
+		Tag:   "pre",
+		Block: true,
+	}
+	// TODO allow disabling syntax highlighting
+	if node.FirstChild.Type == html.ElementNode && node.FirstChild.Data == "code" {
+		text := (&messages.HTMLEntity{
+			Children: parser.nodeToEntities(node.FirstChild.FirstChild, false),
+		}).PlainText()
+		attr := parser.getAttribute(node.FirstChild, "class")
+		var lang string
+		for _, class := range strings.Split(attr, " ") {
+			if strings.HasPrefix(class, "language-") {
+				lang = class[len("language-"):]
+				break
+			}
+		}
+		if len(lang) != 0 {
+			if parsed := parser.syntaxHighlight(text, lang); parsed != nil {
+				return parsed
+			}
+		}
+	}
+	entity.Children = parser.nodeToEntities(node.FirstChild, false)
+	return entity
+}
+
 func (parser *htmlParser) tagNodeToEntity(node *html.Node, stripLinebreak bool) *messages.HTMLEntity {
 	switch node.Data {
 	case "blockquote":
@@ -242,6 +329,8 @@ func (parser *htmlParser) tagNodeToEntity(node *html.Node, stripLinebreak bool)
 		return parser.basicFormatToEntity(node, stripLinebreak)
 	case "a":
 		return parser.linkToEntity(node, stripLinebreak)
+	case "img":
+		return parser.imageToEntity(node)
 	case "pre":
 		return parser.codeblockToEntity(node)
 	default: