mirror of
https://github.com/discourse/discourse.git
synced 2024-12-01 05:04:22 +08:00
362 lines
8.8 KiB
Ruby
362 lines
8.8 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
require "securerandom"
|
|
|
|
class HtmlToMarkdown
|
|
|
|
def initialize(html, opts = {})
|
|
@opts = opts
|
|
|
|
# we're only interested in <body>
|
|
@doc = Nokogiri::HTML5(html).at("body")
|
|
|
|
remove_not_allowed!(@doc)
|
|
remove_hidden!(@doc)
|
|
hoist_line_breaks!(@doc)
|
|
remove_whitespaces!(@doc)
|
|
end
|
|
|
|
def to_markdown
|
|
traverse(@doc)
|
|
.gsub(/\n{2,}/, "\n\n")
|
|
.strip
|
|
end
|
|
|
|
private
|
|
|
|
def remove_not_allowed!(doc)
|
|
allowed = Set.new
|
|
|
|
HtmlToMarkdown.private_instance_methods.each do |m|
|
|
if tag = m.to_s[/^visit_(.+)/, 1]
|
|
allowed << tag
|
|
end
|
|
end
|
|
|
|
@doc.traverse { |node| node.remove if !allowed.include?(node.name) }
|
|
end
|
|
|
|
def remove_hidden!(doc)
|
|
@doc.css("[hidden]").remove
|
|
@doc.css("img[width]").each { |n| n.remove if n["width"].to_i <= 0 }
|
|
@doc.css("img[height]").each { |n| n.remove if n["height"].to_i <= 0 }
|
|
end
|
|
|
|
# When there's a <br> inside an inline element, split the inline element around the <br>
|
|
def hoist_line_breaks!(doc)
|
|
klass = "_" + SecureRandom.hex
|
|
doc.css("br").each { |br| br.add_class(klass) }
|
|
|
|
loop do
|
|
changed = false
|
|
|
|
doc.css("br.#{klass}").each do |br|
|
|
parent = br.parent
|
|
|
|
if parent.description.block?
|
|
br.remove_class(klass)
|
|
else
|
|
before, after = parent.children.slice_when { |n| n == br }.to_a
|
|
|
|
if before.size > 1
|
|
b = Nokogiri::XML::Node.new(parent.name, doc)
|
|
before[0...-1].each { |c| b.add_child(c) }
|
|
parent.previous = b if b.inner_html.present?
|
|
end
|
|
|
|
if after.present?
|
|
a = Nokogiri::XML::Node.new(parent.name, doc)
|
|
after.each { |c| a.add_child(c) }
|
|
parent.next = a if a.inner_html.present?
|
|
end
|
|
|
|
parent.replace(br)
|
|
|
|
changed = true
|
|
end
|
|
end
|
|
|
|
break if !changed
|
|
end
|
|
end
|
|
|
|
# Removes most of the unnecessary white spaces for better markdown conversion
|
|
# Loosely based on the CSS' White Space Processing Rules (https://www.w3.org/TR/css-text-3/#white-space-rules)
|
|
def remove_whitespaces!(node)
|
|
return true if "pre" == node.name
|
|
|
|
node.children.chunk { |n| is_inline?(n) }.each do |inline, nodes|
|
|
if inline
|
|
collapse_spaces!(nodes) && remove_trailing_space!(nodes)
|
|
else
|
|
nodes.each { |n| remove_whitespaces!(n) }
|
|
end
|
|
end
|
|
end
|
|
|
|
def is_inline?(node)
|
|
node.text? || ("br" != node.name && node.description&.inline? && node.children.all? { |n| is_inline?(n) })
|
|
end
|
|
|
|
def collapse_spaces!(nodes, was_space = true)
|
|
nodes.each do |node|
|
|
if node.text?
|
|
text = String.new
|
|
|
|
node.text.chars.each do |c|
|
|
if c[/[[:space:]]/]
|
|
text << " " if !was_space
|
|
was_space = true
|
|
else
|
|
text << c
|
|
was_space = false
|
|
end
|
|
end
|
|
|
|
node.content = text
|
|
else
|
|
node.children.each { |n| was_space = collapse_spaces!([n], was_space) }
|
|
end
|
|
end
|
|
|
|
was_space
|
|
end
|
|
|
|
def remove_trailing_space!(nodes)
|
|
last = nodes[-1]
|
|
|
|
if last.text?
|
|
last.content = last.content[0...-1] if last.content[-1] == " "
|
|
elsif last.children.present?
|
|
remove_trailing_space!(last.children)
|
|
end
|
|
end
|
|
|
|
def traverse(node)
|
|
node.children.map { |n| visit(n) }.join
|
|
end
|
|
|
|
def visit(node)
|
|
visitor = "visit_#{node.name}"
|
|
send(visitor, node) if respond_to?(visitor, true)
|
|
end
|
|
|
|
ALLOWED_IMG_SRCS ||= %w{http:// https:// www.}
|
|
|
|
def allowed_hrefs
|
|
@allowed_hrefs ||= begin
|
|
hrefs = SiteSetting.allowed_href_schemes.split("|").map { |scheme| "#{scheme}:" }.to_set
|
|
ALLOWED_IMG_SRCS.each { |src| hrefs << src }
|
|
hrefs << "mailto:"
|
|
hrefs.to_a
|
|
end
|
|
end
|
|
|
|
def visit_a(node)
|
|
if node["href"].present? && node["href"].starts_with?(*allowed_hrefs)
|
|
"[#{traverse(node)}](#{node["href"]})"
|
|
else
|
|
traverse(node)
|
|
end
|
|
end
|
|
|
|
def visit_img(node)
|
|
return if node["src"].blank?
|
|
|
|
if @opts[:keep_img_tags]
|
|
node.to_html
|
|
elsif @opts[:keep_cid_imgs] && node["src"].starts_with?("cid:")
|
|
node.to_html
|
|
elsif node["src"].starts_with?(*ALLOWED_IMG_SRCS)
|
|
title = node["alt"].presence || node["title"].presence
|
|
width = node["width"].to_i
|
|
height = node["height"].to_i
|
|
dimensions = "|#{width}x#{height}" if width > 0 && height > 0
|
|
"![#{title}#{dimensions}](#{node["src"]})"
|
|
end
|
|
end
|
|
|
|
ALLOWED ||= %w{kbd del ins small big sub sup dl dd dt mark}
|
|
ALLOWED.each do |tag|
|
|
define_method("visit_#{tag}") do |node|
|
|
"<#{tag}>#{traverse(node)}</#{tag}>"
|
|
end
|
|
end
|
|
|
|
def visit_blockquote(node)
|
|
text = traverse(node)
|
|
text.strip!
|
|
text.gsub!(/\n{2,}/, "\n\n")
|
|
text.gsub!(/^/, "> ")
|
|
"\n\n#{text}\n\n"
|
|
end
|
|
|
|
BLOCKS ||= %w{div tr}
|
|
BLOCKS.each do |tag|
|
|
define_method("visit_#{tag}") do |node|
|
|
prefix = node.previous_element&.description&.block? ? "" : "\n"
|
|
"#{prefix}#{traverse(node)}\n"
|
|
end
|
|
end
|
|
|
|
def visit_p(node)
|
|
"\n\n#{traverse(node)}\n\n"
|
|
end
|
|
|
|
TRAVERSABLES ||= %w{aside font span thead tbody tfooter u}
|
|
TRAVERSABLES.each do |tag|
|
|
define_method("visit_#{tag}") do |node|
|
|
traverse(node)
|
|
end
|
|
end
|
|
|
|
def visit_tt(node)
|
|
"`#{traverse(node)}`"
|
|
end
|
|
|
|
def visit_code(node)
|
|
node.ancestors("pre").present? ? traverse(node) : visit_tt(node)
|
|
end
|
|
|
|
def visit_pre(node)
|
|
text = traverse(node)
|
|
fence = text["`"] ? "~~~" : "```"
|
|
code = node.at("code")
|
|
code_class = code ? code["class"] : ""
|
|
lang = code_class ? code_class[/lang-(\w+)/, 1] : ""
|
|
"\n\n#{fence}#{lang}\n#{traverse(node)}\n#{fence}\n\n"
|
|
end
|
|
|
|
def visit_br(node)
|
|
"\n"
|
|
end
|
|
|
|
def visit_hr(node)
|
|
"\n\n---\n\n"
|
|
end
|
|
|
|
def visit_abbr(node)
|
|
title = node["title"].presence
|
|
title_attr = title ? %[ title="#{title}"] : ""
|
|
"<abbr#{title_attr}>#{traverse(node)}</abbr>"
|
|
end
|
|
|
|
def visit_acronym(node)
|
|
visit_abbr(node)
|
|
end
|
|
|
|
(1..6).each do |n|
|
|
define_method("visit_h#{n}") do |node|
|
|
"#{"#" * n} #{traverse(node)}"
|
|
end
|
|
end
|
|
|
|
CELLS ||= %w{th td}
|
|
CELLS.each do |tag|
|
|
define_method("visit_#{tag}") do |node|
|
|
"#{traverse(node)} "
|
|
end
|
|
end
|
|
|
|
def visit_table(node)
|
|
if rows = extract_rows(node)
|
|
headers = rows[0].css("td, th")
|
|
text = "| " + headers.map { |td| traverse(td).gsub(/\n/, "<br>") }.join(" | ") + " |\n"
|
|
text << "| " + (["-"] * headers.size).join(" | ") + " |\n"
|
|
rows[1..-1].each do |row|
|
|
text << "| " + row.css("td").map { |td| traverse(td).gsub(/\n/, "<br>") }.join(" | ") + " |\n"
|
|
end
|
|
"\n\n#{text}\n\n"
|
|
else
|
|
traverse(node)
|
|
end
|
|
end
|
|
|
|
def extract_rows(table)
|
|
return if table.ancestors("table").present?
|
|
return if (rows = table.css("tr")).empty?
|
|
headers_count = rows[0].css("td, th").size
|
|
return if rows[1..-1].any? { |row| row.css("td").size != headers_count }
|
|
rows
|
|
end
|
|
|
|
LISTS ||= %w{ul ol}
|
|
LISTS.each do |tag|
|
|
define_method("visit_#{tag}") do |node|
|
|
prefix = node.previous_element&.description&.block? ? "" : "\n"
|
|
suffix = node.ancestors("ul, ol, li").size > 0 ? "" : "\n"
|
|
"#{prefix}#{traverse(node)}#{suffix}"
|
|
end
|
|
end
|
|
|
|
def visit_li(node)
|
|
text = traverse(node)
|
|
|
|
lists = node.ancestors("ul, ol")
|
|
marker = "ol" == lists[0]&.name ? "1. " : "- "
|
|
indent = (" " * marker.size) * [1, lists.size].max
|
|
suffix = node == node.parent.elements[-1] ? "" : "\n"
|
|
|
|
text.gsub!(/\n{2,}/, "\n\n")
|
|
text.gsub!(/^(?!\s*$)/, indent)
|
|
text.lstrip!
|
|
|
|
"#{marker}#{text}#{suffix}"
|
|
end
|
|
|
|
EMPHASES ||= %w{i em}
|
|
EMPHASES.each do |tag|
|
|
define_method("visit_#{tag}") do |node|
|
|
text = traverse(node)
|
|
|
|
return "" if text.empty?
|
|
return " " if text.blank?
|
|
return "<#{tag}>#{text}</#{tag}>" if text["\n"] || (text["*"] && text["_"])
|
|
|
|
prefix = text[0][" "]
|
|
suffix = text[-1][" "] if text.size > 1
|
|
wrap = text["*"] ? "_" : "*"
|
|
|
|
"#{prefix}#{wrap}#{text.strip}#{wrap}#{suffix}"
|
|
end
|
|
end
|
|
|
|
STRONGS ||= %w{b strong}
|
|
STRONGS.each do |tag|
|
|
define_method("visit_#{tag}") do |node|
|
|
text = traverse(node)
|
|
|
|
return "" if text.empty?
|
|
return " " if text.blank?
|
|
return "<#{tag}>#{text}</#{tag}>" if text["\n"] || (text["*"] && text["_"])
|
|
|
|
prefix = text[0][" "]
|
|
suffix = text[-1][" "] if text.size > 1
|
|
wrap = text["*"] ? "__" : "**"
|
|
|
|
"#{prefix}#{wrap}#{text.strip}#{wrap}#{suffix}"
|
|
end
|
|
end
|
|
|
|
STRIKES ||= %w{s strike}
|
|
STRIKES.each do |tag|
|
|
define_method("visit_#{tag}") do |node|
|
|
text = traverse(node)
|
|
|
|
return "" if text.empty?
|
|
return " " if text.blank?
|
|
return "<#{tag}>#{text}</#{tag}>" if text["\n"] || text["~~"]
|
|
|
|
prefix = text[0][" "]
|
|
suffix = text[-1][" "] if text.size > 1
|
|
|
|
"#{prefix}~~#{text.strip}~~#{suffix}"
|
|
end
|
|
end
|
|
|
|
def visit_text(node)
|
|
node.text
|
|
end
|
|
|
|
end
|