Make HTML rendering more advanced

Also add Python-like HTML parser thing in lib/htmlparser

4 files changed, 259 insertions, 87 deletions

diff --git a/ui/messages/htmlparser.go b/ui/messages/htmlparser.go
index 0475e7a..aa6211e 100644
--- a/ui/messages/htmlparser.go
+++ b/ui/messages/htmlparser.go
@@ -17,120 +17,170 @@
 package messages
 
 import (
+	"fmt"
+	"io"
+	"math"
+	"regexp"
 	"strings"
 
-	"golang.org/x/net/html"
 	"maunium.net/go/gomatrix"
 	"maunium.net/go/gomuks/debug"
+	"maunium.net/go/gomuks/lib/htmlparser"
+	"maunium.net/go/gomuks/matrix/rooms"
 	"maunium.net/go/gomuks/ui/messages/tstring"
+	"maunium.net/go/gomuks/ui/widget"
 	"maunium.net/go/tcell"
 )
 
-// TagArray is a reversed queue for remembering what HTML tags are open.
-type TagArray []string
+var matrixToURL = regexp.MustCompile("^(?:https?://)?(?:www\\.)?matrix\\.to/#/([#@!].*)")
 
-// Pushb converts the given byte array into a string and calls Push().
-func (ta *TagArray) Pushb(tag []byte) {
-	ta.Push(string(tag))
+type MatrixHTMLProcessor struct {
+	text tstring.TString
+
+	indent    string
+	listType  string
+	lineIsNew bool
+	openTags  *TagArray
+
+	room *rooms.Room
 }
 
-// Popb converts the given byte array into a string and calls Pop().
-func (ta *TagArray) Popb(tag []byte) {
-	ta.Pop(string(tag))
+func (parser *MatrixHTMLProcessor) newline() {
+	if !parser.lineIsNew {
+		parser.text = parser.text.Append("\n" + parser.indent)
+		parser.lineIsNew = true
+	}
 }
 
-// Hasb converts the given byte array into a string and calls Has().
-func (ta *TagArray) Hasb(tag []byte) {
-	ta.Has(string(tag))
+func (parser *MatrixHTMLProcessor) Preprocess() {}
+
+func (parser *MatrixHTMLProcessor) HandleText(text string) {
+	style := tcell.StyleDefault
+	for _, tag := range *parser.openTags {
+		switch tag.Tag {
+		case "b", "strong":
+			style = style.Bold(true)
+		case "i", "em":
+			style = style.Italic(true)
+		case "s", "del":
+			style = style.Strikethrough(true)
+		case "u", "ins":
+			style = style.Underline(true)
+		case "a":
+			tag.Text += text
+			return
+		}
+	}
+
+	if parser.openTags.Has("pre", "code") {
+		text = strings.Replace(text, "\n", "", -1)
+	}
+	parser.text = parser.text.AppendStyle(text, style)
+	parser.lineIsNew = false
 }
 
-// HasAfterb converts the given byte array into a string and calls HasAfter().
-func (ta *TagArray) HasAfterb(tag []byte, after int) {
-	ta.HasAfter(string(tag), after)
+func (parser *MatrixHTMLProcessor) HandleStartTag(tagName string, attrs map[string]string) {
+	tag := &TagWithMeta{Tag: tagName}
+	switch tag.Tag {
+	case "h1", "h2", "h3", "h4", "h5", "h6":
+		length := int(tag.Tag[1] - '0')
+		parser.text = parser.text.Append(strings.Repeat("#", length) + " ")
+		parser.lineIsNew = false
+	case "a":
+		tag.Meta, _ = attrs["href"]
+	case "ol", "ul":
+		parser.listType = tag.Tag
+	case "li":
+		indentSize := 2
+		if parser.listType == "ol" {
+			list := parser.openTags.Get(parser.listType)
+			list.Counter++
+			parser.text = parser.text.Append(fmt.Sprintf("%d. ", list.Counter))
+			indentSize = int(math.Log10(float64(list.Counter))+1) + len(". ")
+		} else {
+			parser.text = parser.text.Append("* ")
+		}
+		parser.indent += strings.Repeat(" ", indentSize)
+		parser.lineIsNew = false
+	case "blockquote":
+		parser.indent += "> "
+		parser.text = parser.text.Append("> ")
+		parser.lineIsNew = false
+	}
+	parser.openTags.PushMeta(tag)
 }
 
-// Push adds the given tag to the array.
-func (ta *TagArray) Push(tag string) {
-	*ta = append(*ta, "")
-	copy((*ta)[1:], *ta)
-	(*ta)[0] = tag
+func (parser *MatrixHTMLProcessor) HandleSelfClosingTag(tagName string, attrs map[string]string) {
+	if tagName == "br" {
+		parser.newline()
+	}
 }
 
-// Pop removes the given tag from the array.
-func (ta *TagArray) Pop(tag string) {
-	if (*ta)[0] == tag {
-		// This is the default case and is lighter than append(), so we handle it separately.
-		*ta = (*ta)[1:]
-	} else if index := ta.Has(tag); index != -1 {
-		*ta = append((*ta)[:index], (*ta)[index+1:]...)
+func (parser *MatrixHTMLProcessor) HandleEndTag(tagName string) {
+	tag := parser.openTags.Pop(tagName)
+
+	switch tag.Tag {
+	case "li", "blockquote":
+		indentSize := 2
+		if tag.Tag == "li" && parser.listType == "ol" {
+			list := parser.openTags.Get(parser.listType)
+			indentSize = int(math.Log10(float64(list.Counter))+1) + len(". ")
+		}
+		if len(parser.indent) >= indentSize {
+			parser.indent = parser.indent[0 : len(parser.indent)-indentSize]
+		}
+		// TODO this newline is sometimes not good
+		parser.newline()
+	case "a":
+		match := matrixToURL.FindStringSubmatch(tag.Meta)
+		if len(match) == 2 {
+			pillTarget := match[1]
+			if pillTarget[0] == '@' {
+				if member := parser.room.GetMember(pillTarget); member != nil {
+					parser.text = parser.text.AppendColor(member.DisplayName, widget.GetHashColor(member.DisplayName))
+				} else {
+					parser.text = parser.text.Append(pillTarget)
+				}
+			} else {
+				parser.text = parser.text.Append(pillTarget)
+			}
+		} else {
+			// TODO make text clickable rather than printing URL
+			parser.text = parser.text.Append(fmt.Sprintf("%s (%s)", tag.Text, tag.Meta))
+		}
+		parser.lineIsNew = false
+	case "p", "pre", "ol", "ul", "h1", "h2", "h3", "h4", "h5", "h6", "div":
+		// parser.newline()
 	}
 }
 
-// Has returns the first index where the given tag is, or -1 if it's not in the list.
-func (ta *TagArray) Has(tag string) int {
-	return ta.HasAfter(tag, -1)
+func (parser *MatrixHTMLProcessor) ReceiveError(err error) {
+	if err != io.EOF {
+		debug.Print("Unexpected error parsing HTML:", err)
+	}
 }
 
-// HasAfter returns the first index after the given index where the given tag is,
-// or -1 if the given tag is not on the list after the given index.
-func (ta *TagArray) HasAfter(tag string, after int) int {
-	for i := after + 1; i < len(*ta); i++ {
-		if (*ta)[i] == tag {
-			return i
-		}
+func (parser *MatrixHTMLProcessor) Postprocess() {
+	if len(parser.text) > 0 && parser.text[len(parser.text)-1].Char == '\n' {
+		parser.text = parser.text[:len(parser.text)-1]
 	}
-	return -1
 }
 
 // ParseHTMLMessage parses a HTML-formatted Matrix event into a UIMessage.
-func ParseHTMLMessage(evt *gomatrix.Event) tstring.TString {
-	//textData, _ := evt.Content["body"].(string)
+func ParseHTMLMessage(room *rooms.Room, evt *gomatrix.Event) tstring.TString {
 	htmlData, _ := evt.Content["formatted_body"].(string)
 
-	z := html.NewTokenizer(strings.NewReader(htmlData))
-	text := tstring.NewTString("")
-
-	openTags := &TagArray{}
-
-Loop:
-	for {
-		tt := z.Next()
-		switch tt {
-		case html.ErrorToken:
-			break Loop
-		case html.TextToken:
-			style := tcell.StyleDefault
-			for _, tag := range *openTags {
-				switch tag {
-				case "b", "strong":
-					style = style.Bold(true)
-				case "i", "em":
-					style = style.Italic(true)
-				case "s", "del":
-					style = style.Strikethrough(true)
-				case "u", "ins":
-					style = style.Underline(true)
-				}
-			}
-			text = text.AppendStyle(string(z.Text()), style)
-		case html.SelfClosingTagToken, html.StartTagToken:
-			tagb, _ := z.TagName()
-			tag := string(tagb)
-			switch tag {
-			case "br":
-				debug.Print("BR found")
-				debug.Print(text.String())
-				text = text.Append("\n")
-			default:
-				if tt == html.StartTagToken {
-					openTags.Push(tag)
-				}
-			}
-		case html.EndTagToken:
-			tagb, _ := z.TagName()
-			openTags.Popb(tagb)
-		}
+	processor := &MatrixHTMLProcessor{
+		room:      room,
+		text:      tstring.NewBlankTString(),
+		indent:    "",
+		listType:  "",
+		lineIsNew: true,
+		openTags:  &TagArray{},
 	}
 
-	return text
+	parser := htmlparser.NewHTMLParserFromString(htmlData, processor)
+	parser.Process()
+
+	return processor.text
 }
diff --git a/ui/messages/htmltagarray.go b/ui/messages/htmltagarray.go
new file mode 100644
index 0000000..597f0c7
--- /dev/null
+++ b/ui/messages/htmltagarray.go
@@ -0,0 +1,118 @@
+// gomuks - A terminal Matrix client written in Go.
+// Copyright (C) 2018 Tulir Asokan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package messages
+
+// TagWithMeta is an open HTML tag with some metadata (e.g. list index, a href value).
+type TagWithMeta struct {
+	Tag     string
+	Counter int
+	Meta    string
+	Text    string
+}
+
+// BlankTag is a blank TagWithMeta object.
+var BlankTag = &TagWithMeta{}
+
+// TagArray is a reversed queue for remembering what HTML tags are open.
+type TagArray []*TagWithMeta
+
+// Pushb converts the given byte array into a string and calls Push().
+func (ta *TagArray) Pushb(tag []byte) {
+	ta.Push(string(tag))
+}
+
+// Popb converts the given byte array into a string and calls Pop().
+func (ta *TagArray) Popb(tag []byte) *TagWithMeta {
+	return ta.Pop(string(tag))
+}
+
+// Indexb converts the given byte array into a string and calls Index().
+func (ta *TagArray) Indexb(tag []byte) {
+	ta.Index(string(tag))
+}
+
+// IndexAfterb converts the given byte array into a string and calls IndexAfter().
+func (ta *TagArray) IndexAfterb(tag []byte, after int) {
+	ta.IndexAfter(string(tag), after)
+}
+
+// Push adds the given tag to the array.
+func (ta *TagArray) Push(tag string) {
+	ta.PushMeta(&TagWithMeta{Tag: tag})
+}
+
+// Push adds the given tag to the array.
+func (ta *TagArray) PushMeta(tag *TagWithMeta) {
+	*ta = append(*ta, BlankTag)
+	copy((*ta)[1:], *ta)
+	(*ta)[0] = tag
+}
+
+// Pop removes the given tag from the array.
+func (ta *TagArray) Pop(tag string) (removed *TagWithMeta) {
+	if (*ta)[0].Tag == tag {
+		// This is the default case and is lighter than append(), so we handle it separately.
+		removed = (*ta)[0]
+		*ta = (*ta)[1:]
+	} else if index := ta.Index(tag); index != -1 {
+		removed = (*ta)[index]
+		*ta = append((*ta)[:index], (*ta)[index+1:]...)
+	}
+	return
+}
+
+// Index returns the first index where the given tag is, or -1 if it's not in the list.
+func (ta *TagArray) Index(tag string) int {
+	return ta.IndexAfter(tag, -1)
+}
+
+// IndexAfter returns the first index after the given index where the given tag is,
+// or -1 if the given tag is not on the list after the given index.
+func (ta *TagArray) IndexAfter(tag string, after int) int {
+	for i := after + 1; i < len(*ta); i++ {
+		if (*ta)[i].Tag == tag {
+			return i
+		}
+	}
+	return -1
+}
+
+// Get returns the first occurrence of the given tag, or nil if it's not in the list.
+func (ta *TagArray) Get(tag string) *TagWithMeta {
+	return ta.GetAfter(tag, -1)
+}
+
+// IndexAfter returns the first occurrence of the given tag, or nil if the given
+// tag is not on the list after the given index.
+func (ta *TagArray) GetAfter(tag string, after int) *TagWithMeta {
+	for i := after + 1; i < len(*ta); i++ {
+		if (*ta)[i].Tag == tag {
+			return (*ta)[i]
+		}
+	}
+	return nil
+}
+
+// Has returns whether or not the list has at least one of the given tags.
+func (ta *TagArray) Has(tags ...string) bool {
+	for _, tag := range tags {
+		if index := ta.Index(tag); index != -1 {
+			return true
+		}
+	}
+	return false
+}
diff --git a/ui/messages/parser.go b/ui/messages/parser.go
index d8069c6..80ce5d6 100644
--- a/ui/messages/parser.go
+++ b/ui/messages/parser.go
@@ -36,7 +36,7 @@ func ParseEvent(gmx ifc.Gomuks, room *rooms.Room, evt *gomatrix.Event) UIMessage
 	}
 	switch evt.Type {
 	case "m.room.message":
-		return ParseMessage(gmx, evt)
+		return ParseMessage(gmx, room, evt)
 	case "m.room.member":
 		return ParseMembershipEvent(evt)
 	}
@@ -51,14 +51,14 @@ func unixToTime(unix int64) time.Time {
 	return timestamp
 }
 
-func ParseMessage(gmx ifc.Gomuks, evt *gomatrix.Event) UIMessage {
+func ParseMessage(gmx ifc.Gomuks, room *rooms.Room, evt *gomatrix.Event) UIMessage {
 	msgtype, _ := evt.Content["msgtype"].(string)
 	ts := unixToTime(evt.Timestamp)
 	switch msgtype {
 	case "m.text", "m.notice", "m.emote":
 		format, hasFormat := evt.Content["format"].(string)
 		if hasFormat && format == "org.matrix.custom.html" {
-			text := ParseHTMLMessage(evt)
+			text := ParseHTMLMessage(room, evt)
 			return NewExpandedTextMessage(evt.ID, evt.Sender, msgtype, text, ts)
 		} else {
 			text, _ := evt.Content["body"].(string)
diff --git a/ui/messages/tstring/string.go b/ui/messages/tstring/string.go
index d1ad446..a87d16a 100644
--- a/ui/messages/tstring/string.go
+++ b/ui/messages/tstring/string.go
@@ -25,6 +25,10 @@ import (
 
 type TString []Cell
 
+func NewBlankTString() TString {
+	return make([]Cell, 0)
+}
+
 func NewTString(str string) TString {
 	newStr := make([]Cell, len(str))
 	for i, char := range str {