mirror of
https://github.com/42wim/matterbridge.git
synced 2024-12-20 16:02:01 -08:00
406 lines
9.4 KiB
Go
406 lines
9.4 KiB
Go
package godown
|
|
|
|
import (
|
|
"bytes"
|
|
"fmt"
|
|
"io"
|
|
"regexp"
|
|
"strings"
|
|
|
|
"github.com/mattn/go-runewidth"
|
|
|
|
"golang.org/x/net/html"
|
|
)
|
|
|
|
func isChildOf(node *html.Node, name string) bool {
|
|
node = node.Parent
|
|
return node != nil && node.Type == html.ElementNode && strings.ToLower(node.Data) == name
|
|
}
|
|
|
|
func hasClass(node *html.Node, clazz string) bool {
|
|
for _, attr := range node.Attr {
|
|
if attr.Key == "class" {
|
|
for _, c := range strings.Fields(attr.Val) {
|
|
if c == clazz {
|
|
return true
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
func attr(node *html.Node, key string) string {
|
|
for _, attr := range node.Attr {
|
|
if attr.Key == key {
|
|
return attr.Val
|
|
}
|
|
}
|
|
return ""
|
|
}
|
|
|
|
func br(node *html.Node, w io.Writer, option *Option) {
|
|
node = node.PrevSibling
|
|
if node == nil {
|
|
return
|
|
}
|
|
switch node.Type {
|
|
case html.TextNode:
|
|
text := strings.Trim(node.Data, " \t")
|
|
if text != "" && !strings.HasSuffix(text, "\n") {
|
|
fmt.Fprint(w, "\n")
|
|
}
|
|
case html.ElementNode:
|
|
switch strings.ToLower(node.Data) {
|
|
case "br", "p", "ul", "ol", "div", "blockquote", "h1", "h2", "h3", "h4", "h5", "h6":
|
|
fmt.Fprint(w, "\n")
|
|
}
|
|
}
|
|
}
|
|
|
|
func table(node *html.Node, w io.Writer, option *Option) {
|
|
for tr := node.FirstChild; tr != nil; tr = tr.NextSibling {
|
|
if tr.Type == html.ElementNode && strings.ToLower(tr.Data) == "tbody" {
|
|
node = tr
|
|
break
|
|
}
|
|
}
|
|
var header bool
|
|
var rows [][]string
|
|
for tr := node.FirstChild; tr != nil; tr = tr.NextSibling {
|
|
if tr.Type != html.ElementNode || strings.ToLower(tr.Data) != "tr" {
|
|
continue
|
|
}
|
|
var cols []string
|
|
if !header {
|
|
for th := tr.FirstChild; th != nil; th = th.NextSibling {
|
|
if th.Type != html.ElementNode || strings.ToLower(th.Data) != "th" {
|
|
continue
|
|
}
|
|
var buf bytes.Buffer
|
|
walk(th, &buf, 0, option)
|
|
cols = append(cols, buf.String())
|
|
}
|
|
if len(cols) > 0 {
|
|
rows = append(rows, cols)
|
|
header = true
|
|
continue
|
|
}
|
|
}
|
|
for td := tr.FirstChild; td != nil; td = td.NextSibling {
|
|
if td.Type != html.ElementNode || strings.ToLower(td.Data) != "td" {
|
|
continue
|
|
}
|
|
var buf bytes.Buffer
|
|
walk(td, &buf, 0, option)
|
|
cols = append(cols, buf.String())
|
|
}
|
|
rows = append(rows, cols)
|
|
}
|
|
maxcol := 0
|
|
for _, cols := range rows {
|
|
if len(cols) > maxcol {
|
|
maxcol = len(cols)
|
|
}
|
|
}
|
|
widths := make([]int, maxcol)
|
|
for _, cols := range rows {
|
|
for i := 0; i < maxcol; i++ {
|
|
if i < len(cols) {
|
|
width := runewidth.StringWidth(cols[i])
|
|
if widths[i] < width {
|
|
widths[i] = width
|
|
}
|
|
}
|
|
}
|
|
}
|
|
for i, cols := range rows {
|
|
for j := 0; j < maxcol; j++ {
|
|
fmt.Fprint(w, "|")
|
|
if j < len(cols) {
|
|
width := runewidth.StringWidth(cols[j])
|
|
fmt.Fprint(w, cols[j])
|
|
fmt.Fprint(w, strings.Repeat(" ", widths[j]-width))
|
|
} else {
|
|
fmt.Fprint(w, strings.Repeat(" ", widths[j]))
|
|
}
|
|
}
|
|
fmt.Fprint(w, "|\n")
|
|
if i == 0 && header {
|
|
for j := 0; j < maxcol; j++ {
|
|
fmt.Fprint(w, "|")
|
|
fmt.Fprint(w, strings.Repeat("-", widths[j]))
|
|
}
|
|
fmt.Fprint(w, "|\n")
|
|
}
|
|
}
|
|
fmt.Fprint(w, "\n")
|
|
}
|
|
|
|
var emptyElements = []string{
|
|
"area",
|
|
"base",
|
|
"br",
|
|
"col",
|
|
"embed",
|
|
"hr",
|
|
"img",
|
|
"input",
|
|
"keygen",
|
|
"link",
|
|
"meta",
|
|
"param",
|
|
"source",
|
|
"track",
|
|
"wbr",
|
|
}
|
|
|
|
func raw(node *html.Node, w io.Writer, option *Option) {
|
|
switch node.Type {
|
|
case html.ElementNode:
|
|
fmt.Fprintf(w, "<%s", node.Data)
|
|
for _, attr := range node.Attr {
|
|
fmt.Fprintf(w, " %s=%q", attr.Key, attr.Val)
|
|
}
|
|
found := false
|
|
tag := strings.ToLower(node.Data)
|
|
for _, e := range emptyElements {
|
|
if e == tag {
|
|
found = true
|
|
break
|
|
}
|
|
}
|
|
if found {
|
|
fmt.Fprint(w, "/>")
|
|
} else {
|
|
fmt.Fprint(w, ">")
|
|
for c := node.FirstChild; c != nil; c = c.NextSibling {
|
|
raw(c, w, option)
|
|
}
|
|
fmt.Fprintf(w, "</%s>", node.Data)
|
|
}
|
|
case html.TextNode:
|
|
fmt.Fprint(w, node.Data)
|
|
}
|
|
}
|
|
|
|
func bq(node *html.Node, w io.Writer, option *Option) {
|
|
if node.Type == html.TextNode {
|
|
fmt.Fprint(w, strings.Replace(node.Data, "\u00a0", " ", -1))
|
|
} else {
|
|
for c := node.FirstChild; c != nil; c = c.NextSibling {
|
|
bq(c, w, option)
|
|
}
|
|
}
|
|
}
|
|
|
|
func pre(node *html.Node, w io.Writer, option *Option) {
|
|
if node.Type == html.TextNode {
|
|
fmt.Fprint(w, node.Data)
|
|
} else {
|
|
for c := node.FirstChild; c != nil; c = c.NextSibling {
|
|
pre(c, w, option)
|
|
}
|
|
}
|
|
}
|
|
|
|
func walk(node *html.Node, w io.Writer, nest int, option *Option) {
|
|
if node.Type == html.TextNode {
|
|
if strings.TrimSpace(node.Data) != "" {
|
|
text := regexp.MustCompile(`[[:space:]][[:space:]]*`).ReplaceAllString(strings.Trim(node.Data, "\t\r\n"), " ")
|
|
fmt.Fprint(w, text)
|
|
}
|
|
}
|
|
n := 0
|
|
for c := node.FirstChild; c != nil; c = c.NextSibling {
|
|
switch c.Type {
|
|
case html.CommentNode:
|
|
fmt.Fprint(w, "<!--")
|
|
fmt.Fprint(w, c.Data)
|
|
fmt.Fprint(w, "-->\n")
|
|
case html.ElementNode:
|
|
switch strings.ToLower(c.Data) {
|
|
case "a":
|
|
fmt.Fprint(w, "[")
|
|
walk(c, w, nest, option)
|
|
fmt.Fprint(w, "]("+attr(c, "href")+")")
|
|
case "b", "strong":
|
|
fmt.Fprint(w, "**")
|
|
walk(c, w, nest, option)
|
|
fmt.Fprint(w, "**")
|
|
case "i", "em":
|
|
fmt.Fprint(w, "_")
|
|
walk(c, w, nest, option)
|
|
fmt.Fprint(w, "_")
|
|
case "del":
|
|
fmt.Fprint(w, "~~")
|
|
walk(c, w, nest, option)
|
|
fmt.Fprint(w, "~~")
|
|
case "br":
|
|
br(c, w, option)
|
|
fmt.Fprint(w, "\n\n")
|
|
case "p":
|
|
br(c, w, option)
|
|
walk(c, w, nest, option)
|
|
br(c, w, option)
|
|
fmt.Fprint(w, "\n\n")
|
|
case "code":
|
|
if !isChildOf(c, "pre") {
|
|
fmt.Fprint(w, "`")
|
|
pre(c, w, option)
|
|
fmt.Fprint(w, "`")
|
|
}
|
|
case "pre":
|
|
br(c, w, option)
|
|
var buf bytes.Buffer
|
|
pre(c, &buf, option)
|
|
var lang string
|
|
if option != nil && option.GuessLang != nil {
|
|
if guess, err := option.GuessLang(buf.String()); err == nil {
|
|
lang = guess
|
|
}
|
|
}
|
|
fmt.Fprint(w, "```"+lang+"\n")
|
|
fmt.Fprint(w, buf.String())
|
|
if !strings.HasSuffix(buf.String(), "\n") {
|
|
fmt.Fprint(w, "\n")
|
|
}
|
|
fmt.Fprint(w, "```\n\n")
|
|
case "div":
|
|
br(c, w, option)
|
|
walk(c, w, nest, option)
|
|
fmt.Fprint(w, "\n")
|
|
case "blockquote":
|
|
br(c, w, option)
|
|
var buf bytes.Buffer
|
|
if hasClass(c, "code") {
|
|
bq(c, &buf, option)
|
|
var lang string
|
|
if option != nil && option.GuessLang != nil {
|
|
if guess, err := option.GuessLang(buf.String()); err == nil {
|
|
lang = guess
|
|
}
|
|
}
|
|
fmt.Fprint(w, "```"+lang+"\n")
|
|
fmt.Fprint(w, strings.TrimLeft(buf.String(), "\n"))
|
|
if !strings.HasSuffix(buf.String(), "\n") {
|
|
fmt.Fprint(w, "\n")
|
|
}
|
|
fmt.Fprint(w, "```\n\n")
|
|
} else {
|
|
walk(c, &buf, nest+1, option)
|
|
|
|
if lines := strings.Split(strings.TrimSpace(buf.String()), "\n"); len(lines) > 0 {
|
|
for _, l := range lines {
|
|
fmt.Fprint(w, "> "+strings.TrimSpace(l)+"\n")
|
|
}
|
|
fmt.Fprint(w, "\n")
|
|
}
|
|
}
|
|
case "ul", "ol":
|
|
br(c, w, option)
|
|
var buf bytes.Buffer
|
|
walk(c, &buf, 1, option)
|
|
if lines := strings.Split(strings.TrimSpace(buf.String()), "\n"); len(lines) > 0 {
|
|
for i, l := range lines {
|
|
if i > 0 {
|
|
fmt.Fprint(w, "\n")
|
|
}
|
|
fmt.Fprint(w, strings.Repeat(" ", nest)+l)
|
|
}
|
|
fmt.Fprint(w, "\n")
|
|
}
|
|
case "li":
|
|
br(c, w, option)
|
|
if isChildOf(c, "ul") {
|
|
fmt.Fprint(w, "* ")
|
|
} else if isChildOf(c, "ol") {
|
|
n++
|
|
fmt.Fprint(w, fmt.Sprintf("%d. ", n))
|
|
}
|
|
walk(c, w, nest, option)
|
|
fmt.Fprint(w, "\n")
|
|
case "h1", "h2", "h3", "h4", "h5", "h6":
|
|
br(c, w, option)
|
|
fmt.Fprint(w, strings.Repeat("#", int(rune(c.Data[1])-rune('0')))+" ")
|
|
walk(c, w, nest, option)
|
|
fmt.Fprint(w, "\n\n")
|
|
case "img":
|
|
fmt.Fprint(w, "!["+attr(c, "alt")+"]("+attr(c, "src")+")")
|
|
case "hr":
|
|
br(c, w, option)
|
|
fmt.Fprint(w, "\n---\n\n")
|
|
case "table":
|
|
br(c, w, option)
|
|
table(c, w, option)
|
|
case "style":
|
|
if option != nil && option.Style {
|
|
br(c, w, option)
|
|
raw(c, w, option)
|
|
fmt.Fprint(w, "\n\n")
|
|
}
|
|
case "script":
|
|
if option != nil && option.Script {
|
|
br(c, w, option)
|
|
raw(c, w, option)
|
|
fmt.Fprint(w, "\n\n")
|
|
}
|
|
default:
|
|
if option == nil || option.CustomRules == nil {
|
|
walk(c, w, nest, option)
|
|
break
|
|
}
|
|
|
|
foundCustom := false
|
|
for _, cr := range option.CustomRules {
|
|
if tag, customWalk := cr.Rule(walk); strings.ToLower(c.Data) == tag {
|
|
customWalk(c, w, nest, option)
|
|
foundCustom = true
|
|
}
|
|
}
|
|
|
|
if foundCustom {
|
|
break
|
|
}
|
|
walk(c, w, nest, option)
|
|
}
|
|
default:
|
|
walk(c, w, nest, option)
|
|
}
|
|
}
|
|
}
|
|
|
|
// WalkFunc type is an signature for functions traversing HTML nodes
|
|
type WalkFunc func(node *html.Node, w io.Writer, nest int, option *Option)
|
|
|
|
// CustomRule is an interface to define custom conversion rules
|
|
//
|
|
// Rule method accepts `next WalkFunc` as an argument, which `customRule` should call
|
|
// to let walk function continue parsing the content inside the HTML tag.
|
|
// It returns a tagName to indicate what HTML element this `customRule` handles and the `customRule`
|
|
// function itself, where conversion logic should reside.
|
|
//
|
|
// See example TestRule implementation in godown_test.go
|
|
type CustomRule interface {
|
|
Rule(next WalkFunc) (tagName string, customRule WalkFunc)
|
|
}
|
|
|
|
// Option is optional information for Convert.
|
|
type Option struct {
|
|
GuessLang func(string) (string, error)
|
|
Script bool
|
|
Style bool
|
|
CustomRules []CustomRule
|
|
}
|
|
|
|
// Convert convert HTML to Markdown. Read HTML from r and write to w.
|
|
func Convert(w io.Writer, r io.Reader, option *Option) error {
|
|
doc, err := html.Parse(r)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
walk(doc, w, 0, option)
|
|
fmt.Fprint(w, "\n")
|
|
return nil
|
|
}
|