Add dep

vendor/maunium.net/go/gomatrix/format/htmlparser.go

@@ -0,0 +1,256 @@
+package format
+
+import (
+	"fmt"
+	"math"
+	"regexp"
+	"strings"
+
+	"golang.org/x/net/html"
+	"strconv"
+)
+
+var MatrixToURL = regexp.MustCompile("^(?:https?://)?(?:www\\.)?matrix\\.to/#/([#@!+].*)(?:/(\\$.+))?")
+
+type TextConverter func(string) string
+
+type HTMLParser struct {
+	PillConverter           func(mxid, eventID string) string
+	TabsToSpaces            int
+	Newline                 string
+	BoldConverter           TextConverter
+	ItalicConverter         TextConverter
+	StrikethroughConverter  TextConverter
+	UnderlineConverter      TextConverter
+	MonospaceBlockConverter TextConverter
+	MonospaceConverter      TextConverter
+}
+
+type TaggedString struct {
+	string
+	tag string
+}
+
+func (parser *HTMLParser) getAttribute(node *html.Node, attribute string) string {
+	for _, attr := range node.Attr {
+		if attr.Key == attribute {
+			return attr.Val
+		}
+	}
+	return ""
+}
+
+func Digits(num int) int {
+	return int(math.Floor(math.Log10(float64(num))) + 1)
+}
+
+func (parser *HTMLParser) listToString(node *html.Node, stripLinebreak bool) string {
+	ordered := node.Data == "ol"
+	taggedChildren := parser.nodeToTaggedStrings(node.FirstChild, stripLinebreak)
+	counter := 1
+	indentLength := 0
+	if ordered {
+		start := parser.getAttribute(node, "start")
+		if len(start) > 0 {
+			counter, _ = strconv.Atoi(start)
+		}
+
+		longestIndex := (counter - 1) + len(taggedChildren)
+		indentLength = Digits(longestIndex)
+	}
+	indent := strings.Repeat(" ", indentLength+2)
+	var children []string
+	for _, child := range taggedChildren {
+		if child.tag != "li" {
+			continue
+		}
+		var prefix string
+		if ordered {
+			indexPadding := indentLength - Digits(counter)
+			prefix = fmt.Sprintf("%d. %s", counter, strings.Repeat(" ", indexPadding))
+		} else {
+			prefix = "● "
+		}
+		str := prefix + child.string
+		counter++
+		parts := strings.Split(str, "\n")
+		for i, part := range parts[1:] {
+			parts[i+1] = indent + part
+		}
+		str = strings.Join(parts, "\n")
+		children = append(children, str)
+	}
+	return strings.Join(children, "\n")
+}
+
+func (parser *HTMLParser) basicFormatToString(node *html.Node, stripLinebreak bool) string {
+	str := parser.nodeToTagAwareString(node.FirstChild, stripLinebreak)
+	switch node.Data {
+	case "b", "strong":
+		if parser.BoldConverter != nil {
+			return parser.BoldConverter(str)
+		}
+		return fmt.Sprintf("**%s**", str)
+	case "i", "em":
+		if parser.ItalicConverter != nil {
+			return parser.ItalicConverter(str)
+		}
+		return fmt.Sprintf("_%s_", str)
+	case "s", "del":
+		if parser.StrikethroughConverter != nil {
+			return parser.StrikethroughConverter(str)
+		}
+		return fmt.Sprintf("~~%s~~", str)
+	case "u", "ins":
+		if parser.UnderlineConverter != nil {
+			return parser.UnderlineConverter(str)
+		}
+	case "tt", "code":
+		if parser.MonospaceConverter != nil {
+			return parser.MonospaceConverter(str)
+		}
+	}
+	return str
+}
+
+func (parser *HTMLParser) headerToString(node *html.Node, stripLinebreak bool) string {
+	children := parser.nodeToStrings(node.FirstChild, stripLinebreak)
+	length := int(node.Data[1] - '0')
+	prefix := strings.Repeat("#", length) + " "
+	return prefix + strings.Join(children, "")
+}
+
+func (parser *HTMLParser) blockquoteToString(node *html.Node, stripLinebreak bool) string {
+	str := parser.nodeToTagAwareString(node.FirstChild, stripLinebreak)
+	childrenArr := strings.Split(strings.TrimSpace(str), "\n")
+	for index, child := range childrenArr {
+		childrenArr[index] = "> " + child
+	}
+	return strings.Join(childrenArr, "\n")
+}
+
+func (parser *HTMLParser) linkToString(node *html.Node, stripLinebreak bool) string {
+	str := parser.nodeToTagAwareString(node.FirstChild, stripLinebreak)
+	href := parser.getAttribute(node, "href")
+	if len(href) == 0 {
+		return str
+	}
+	match := MatrixToURL.FindStringSubmatch(href)
+	if len(match) == 2 || len(match) == 3 {
+		if parser.PillConverter != nil {
+			mxid := match[1]
+			eventID := ""
+			if len(match) == 3 {
+				eventID = match[2]
+			}
+			return parser.PillConverter(mxid, eventID)
+		}
+		return str
+	}
+	return fmt.Sprintf("%s (%s)", str, href)
+}
+
+func (parser *HTMLParser) tagToString(node *html.Node, stripLinebreak bool) string {
+	switch node.Data {
+	case "blockquote":
+		return parser.blockquoteToString(node, stripLinebreak)
+	case "ol", "ul":
+		return parser.listToString(node, stripLinebreak)
+	case "h1", "h2", "h3", "h4", "h5", "h6":
+		return parser.headerToString(node, stripLinebreak)
+	case "br":
+		return parser.Newline
+	case "b", "strong", "i", "em", "s", "del", "u", "ins", "tt", "code":
+		return parser.basicFormatToString(node, stripLinebreak)
+	case "a":
+		return parser.linkToString(node, stripLinebreak)
+	case "p":
+		return parser.nodeToTagAwareString(node.FirstChild, stripLinebreak) + "\n"
+	case "pre":
+		var preStr string
+		if node.FirstChild != nil && node.FirstChild.Type == html.ElementNode && node.FirstChild.Data == "code" {
+			preStr = parser.nodeToString(node.FirstChild.FirstChild, false)
+		} else {
+			preStr = parser.nodeToString(node.FirstChild, false)
+		}
+		if parser.MonospaceBlockConverter != nil {
+			return parser.MonospaceBlockConverter(preStr)
+		}
+		return preStr
+	default:
+		return parser.nodeToTagAwareString(node.FirstChild, stripLinebreak)
+	}
+}
+
+func (parser *HTMLParser) singleNodeToString(node *html.Node, stripLinebreak bool) TaggedString {
+	switch node.Type {
+	case html.TextNode:
+		if stripLinebreak {
+			node.Data = strings.Replace(node.Data, "\n", "", -1)
+		}
+		return TaggedString{node.Data, "text"}
+	case html.ElementNode:
+		return TaggedString{parser.tagToString(node, stripLinebreak), node.Data}
+	case html.DocumentNode:
+		return TaggedString{parser.nodeToTagAwareString(node.FirstChild, stripLinebreak), "html"}
+	default:
+		return TaggedString{"", "unknown"}
+	}
+}
+
+func (parser *HTMLParser) nodeToTaggedStrings(node *html.Node, stripLinebreak bool) (strs []TaggedString) {
+	for ; node != nil; node = node.NextSibling {
+		strs = append(strs, parser.singleNodeToString(node, stripLinebreak))
+	}
+	return
+}
+
+var BlockTags = []string{"p", "h1", "h2", "h3", "h4", "h5", "h6", "ol", "ul", "pre", "blockquote", "div", "hr", "table"}
+
+func (parser *HTMLParser) isBlockTag(tag string) bool {
+	for _, blockTag := range BlockTags {
+		if tag == blockTag {
+			return true
+		}
+	}
+	return false
+}
+
+func (parser *HTMLParser) nodeToTagAwareString(node *html.Node, stripLinebreak bool) string {
+	strs := parser.nodeToTaggedStrings(node, stripLinebreak)
+	var output strings.Builder
+	for _, str := range strs {
+		tstr := str.string
+		if parser.isBlockTag(str.tag) {
+			tstr = fmt.Sprintf("\n%s\n", tstr)
+		}
+		output.WriteString(tstr)
+	}
+	return strings.TrimSpace(output.String())
+}
+
+func (parser *HTMLParser) nodeToStrings(node *html.Node, stripLinebreak bool) (strs []string) {
+	for ; node != nil; node = node.NextSibling {
+		strs = append(strs, parser.singleNodeToString(node, stripLinebreak).string)
+	}
+	return
+}
+
+func (parser *HTMLParser) nodeToString(node *html.Node, stripLinebreak bool) string {
+	return strings.Join(parser.nodeToStrings(node, stripLinebreak), "")
+}
+
+func (parser *HTMLParser) Parse(htmlData string) string {
+	if parser.TabsToSpaces >= 0 {
+		htmlData = strings.Replace(htmlData, "\t", strings.Repeat(" ", parser.TabsToSpaces), -1)
+	}
+	node, _ := html.Parse(strings.NewReader(htmlData))
+	return parser.nodeToTagAwareString(node, true)
+}
+
+func HTMLToText(html string) string {
+	return (&HTMLParser{
+		TabsToSpaces: 4,
+		Newline:      "\n",
+	}).Parse(html)
+}