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package ai.platon.pulsar.skeleton.crawl.parse.html
import ai.platon.pulsar.common.DomUtil
import ai.platon.pulsar.common.NodeWalker
import ai.platon.pulsar.common.Strings
import ai.platon.pulsar.common.config.AppConstants.CACHING_FORBIDDEN_CONTENT
import ai.platon.pulsar.common.config.CapabilityTypes.PARSE_CACHING_FORBIDDEN_POLICY
import ai.platon.pulsar.common.config.ImmutableConfig
import ai.platon.pulsar.common.urls.UrlUtils.resolveURL
import ai.platon.pulsar.persist.HyperlinkPersistable
import ai.platon.pulsar.persist.ParseStatus
import ai.platon.pulsar.persist.WebPage
import ai.platon.pulsar.skeleton.common.EncodingDetector
import ai.platon.pulsar.skeleton.crawl.filter.CrawlFilters
import ai.platon.pulsar.skeleton.crawl.parse.ParseResult
import ai.platon.pulsar.skeleton.crawl.parse.Parser
import com.google.common.collect.Maps
import org.slf4j.LoggerFactory
import org.w3c.dom.Node
import org.w3c.dom.NodeList
import java.net.MalformedURLException
import java.net.URL
import java.util.*
/**
* A very simple DOM parser
*
* A collection of methods for extracting content from DOM trees.
*
* This class holds a few utility methods for pulling content out of DOM nodes,
* such as getLiveLinks, getPageText, etc.
*/
class PrimerParser(val conf: ImmutableConfig) {
private val logger = LoggerFactory.getLogger(Parser::class.java)
private val tracer = logger.takeIf { it.isTraceEnabled }
private val cachingPolicy = conf.get(PARSE_CACHING_FORBIDDEN_POLICY, CACHING_FORBIDDEN_CONTENT)
private var encodingDetector = EncodingDetector(conf)
private val linkParams = HashMap()
init {
// forceTags is used to override configurable tag ignoring, later on
val forceTags = arrayListOf()
linkParams.clear()
linkParams["a"] = LinkParams("a", "href", 1)
linkParams["area"] = LinkParams("area", "href", 0)
if (conf.getBoolean("parser.html.form.use_action", true)) {
linkParams["form"] = LinkParams("form", "action", 1)
if (conf["parser.html.form.use_action"] != null) {
forceTags.add("form")
}
}
linkParams["frame"] = LinkParams("frame", "src", 0)
linkParams["iframe"] = LinkParams("iframe", "src", 0)
linkParams["script"] = LinkParams("script", "src", 0)
linkParams["link"] = LinkParams("link", "href", 0)
linkParams["img"] = LinkParams("img", "src", 0)
// remove unwanted link tags from the linkParams map
val ignoreTags = conf.getStrings("parser.html.outlinks.ignore_tags")
var i = 0
while (i < ignoreTags.size) {
if (!forceTags.contains(ignoreTags[i])) {
linkParams.remove(ignoreTags[i])
}
i++
}
}
fun detectEncoding(page: WebPage) {
val encoding = encodingDetector.sniffEncoding(page)
if (encoding != null && encoding.isNotEmpty()) {
page.encoding = encoding
} else {
logger.warn("Failed to detect encoding, url: " + page.url)
}
}
@Throws(Exception::class)
fun parseHTMLDocument(page: WebPage): ParseContext {
tracer?.trace(
"{}.\tParsing page | {} | {} | {} | {}",
page.id, Strings.compactFormat(page.contentLength),
page.protocolStatus, page.htmlIntegrity, page.url
)
if (page.encoding == null) {
detectEncoding(page)
}
val jsoupParser = JsoupParser(page, conf)
jsoupParser.parse()
return ParseContext(page, jsoupParser.document)
}
private fun initParseResult(metaTags: HTMLMetaTags): ParseResult {
if (metaTags.noIndex) {
return ParseResult(ParseStatus.SUCCESS, ParseStatus.SUCCESS_NO_INDEX)
}
val parseResult = ParseResult(ParseStatus.SUCCESS, ParseStatus.SUCCESS_OK)
if (metaTags.refresh) {
parseResult.minorCode = ParseStatus.SUCCESS_REDIRECT
parseResult.args[ParseStatus.REFRESH_HREF] = metaTags.refreshHref.toString()
parseResult.args[ParseStatus.REFRESH_TIME] = metaTags.refreshTime.toString()
}
return parseResult
}
/**
* This method takes a [StringBuilder] and a DOM [Node], and will
* append all the content text found beneath the DOM node to the
* `StringBuilder`.
*
* If `abortOnNestedAnchors` is true, DOM traversal will be aborted
* and the `StringBuffer` will not contain any text encountered
* after a nested anchor is found.
*
* @return true if nested anchors were found
*/
fun getPageText(sb: StringBuilder, root: Node, abortOnNestedAnchors: Boolean): Boolean {
return getTextHelper(sb, root, abortOnNestedAnchors, 0)
}
/**
* This is a convinience method, equivalent to
* [getPageText(sb, node, false)][.getPageText].
*/
fun getPageText(sb: StringBuilder, root: Node) {
getPageText(sb, root, false)
}
fun getPageText(root: Node): String {
val sb = StringBuilder()
getPageText(sb, root, false)
return sb.toString()
}
fun getPageTitle(root: Node): String {
val sb = StringBuilder()
getPageTitle(sb, root)
return sb.toString()
}
/**
* This method takes a [StringBuffer] and a DOM [Node], and will
* append the content text found beneath the first `title` node to
* the `StringBuffer`.
*
* @return true if a title node was found, false otherwise
*/
private fun getPageTitle(sb: StringBuilder, root: Node): Boolean {
val walker = NodeWalker(root)
while (walker.hasNext()) {
val node = walker.nextNode()
val name = node.nodeName
val type = node.nodeType
// stop after HEAD
if ("body".equals(name, ignoreCase = true)) {
return false
}
if (type == Node.ELEMENT_NODE) {
if ("title".equals(name, ignoreCase = true)) {
getPageText(sb, node)
return true
}
}
}
return false
}
fun getMetadata(root: Node): Map {
val metadata: MutableMap = Maps.newLinkedHashMap()
val sb = StringBuilder()
val walker = NodeWalker(root)
while (walker.hasNext()) {
val currentNode = walker.nextNode()
val nodeName = currentNode.nodeName
val nodeType = currentNode.nodeType
// stop after HEAD
if ("body".equals(nodeName, ignoreCase = true)) {
return metadata
}
if (nodeType == Node.ELEMENT_NODE) {
if ("title".equals(nodeName, ignoreCase = true)) {
sb.setLength(0)
getPageText(sb, currentNode)
metadata["meta-title"] = sb.toString()
} else if ("meta".equals(nodeName, ignoreCase = true)) {
getMetadataFromMetaTag(metadata, root)
}
} // if nodeType ...
}
return metadata
}
private fun getMetadataFromMetaTag(metadata: MutableMap, metaNode: Node) {
var attrValue: String? = DomUtil.getAttribute(metaNode, "name") ?: return
if ("keywords".equals(attrValue, ignoreCase = true)) {
attrValue = DomUtil.getAttribute(metaNode, "content")
if (attrValue != null) {
metadata["meta-keywords"] = attrValue
}
} else if ("description".equals(attrValue, ignoreCase = true)) {
attrValue = DomUtil.getAttribute(metaNode, "content")
if (attrValue != null) {
metadata["meta-description"] = attrValue
}
}
}
/**
* If Node contains a BASE tag then it's HREF is returned.
*/
fun getBaseURLFromTag(root: Node): URL? {
val walker = NodeWalker(root)
while (walker.hasNext()) {
val currentNode = walker.nextNode()
val nodeName = currentNode.nodeName
val nodeType = currentNode.nodeType
// is this root a BASE tag?
if (nodeType == Node.ELEMENT_NODE) {
if ("body".equals(nodeName, ignoreCase = true)) { // stop after HEAD
return null
}
if ("base".equals(nodeName, ignoreCase = true)) {
val attrs = currentNode.attributes
for (i in 0 until attrs.length) {
val attr = attrs.item(i)
if ("href".equals(attr.nodeName, ignoreCase = true)) {
try {
return URL(attr.nodeValue)
} catch (ignored: MalformedURLException) {
}
}
}
}
}
}
// no.
return null
}
// returns true if abortOnNestedAnchors is true and we find nested
// anchors
private fun getTextHelper(
sb: StringBuilder,
root: Node,
abortOnNestedAnchors: Boolean,
anchorDepth_: Int
): Boolean {
var anchorDepth = anchorDepth_
var abort = false
val walker = NodeWalker(root)
while (walker.hasNext()) {
val currentNode = walker.nextNode()
val nodeName = currentNode.nodeName
val nodeType = currentNode.nodeType
if ("script".equals(nodeName, ignoreCase = true)) {
walker.skipChildren()
}
if ("style".equals(nodeName, ignoreCase = true)) {
walker.skipChildren()
}
if (abortOnNestedAnchors && "a".equals(nodeName, ignoreCase = true)) {
anchorDepth++
if (anchorDepth > 1) {
abort = true
break
}
}
if (nodeType == Node.COMMENT_NODE) {
walker.skipChildren()
}
if (nodeType == Node.TEXT_NODE) { // cleanup and trim the value
var text = currentNode.nodeValue
text = text.replace("\\s+".toRegex(), " ")
text = text.trim { it <= ' ' }
if (text.isNotEmpty()) {
if (sb.isNotEmpty()) {
sb.append(' ')
}
sb.append(text)
}
}
}
return abort
}
private fun hasOnlyWhiteSpace(root: Node): Boolean {
for (element in root.nodeValue) {
if (!Character.isWhitespace(element)) return false
}
return true
}
// this only covers a few cases of empty links that are symptomatic
// of nekohtml's DOM-fixup process...
private fun shouldThrowAwayLink(root: Node, children: NodeList, childLen: Int, params: LinkParams): Boolean {
if (childLen == 0) { // this has no inner structure
return params.childLen != 0
} else if (childLen == 1
&& children.item(0).nodeType == Node.ELEMENT_NODE
&& params.elName.equals(children.item(0).nodeName, ignoreCase = true)
) { // single nested link
return true
} else if (childLen == 2) {
val c0 = children.item(0)
val c1 = children.item(1)
if (c0.nodeType == Node.ELEMENT_NODE
&& params.elName.equals(c0.nodeName, ignoreCase = true)
&& c1.nodeType == Node.TEXT_NODE && hasOnlyWhiteSpace(c1)
) { // single link followed by whitespace root
return true
}
if (c1.nodeType == Node.ELEMENT_NODE
&& params.elName.equals(c1.nodeName, ignoreCase = true)
&& c0.nodeType == Node.TEXT_NODE && hasOnlyWhiteSpace(c0)
) { // whitespace root followed by single link
return true
}
} else if (childLen == 3) {
val c0 = children.item(0)
val c1 = children.item(1)
val c2 = children.item(2)
if (c1.nodeType == Node.ELEMENT_NODE
&& params.elName.equals(c1.nodeName, ignoreCase = true)
&& c0.nodeType == Node.TEXT_NODE
&& c2.nodeType == Node.TEXT_NODE && hasOnlyWhiteSpace(c0)
&& hasOnlyWhiteSpace(c2)
) { // single link surrounded by whitespace nodes
return true
}
}
return false
}
/**
* This method finds all anchors below the supplied DOM `root`, and
* creates appropriate [HyperlinkPersistable] records for each (relative to the
* supplied `base` URL), and adds them to the `outlinks`
* [ArrayList].
*
* Links without inner structure (tags, text, etc) are discarded, as are links
* which contain only single nested links and empty text nodes (this is a
* common DOM-fixup artifact, at least with nekohtml).
*/
fun collectLinks(base: URL, root: Node): MutableSet {
return collectLinks(base, root, null)
}
fun collectLinks(base: URL, root: Node, crawlFilters: CrawlFilters?): MutableSet {
return collectLinks(base, mutableSetOf(), root, crawlFilters)
}
fun collectLinks(
base: URL,
hyperlinks: MutableSet,
root: Node,
crawlFilters: CrawlFilters?
): MutableSet {
val walker = NodeWalker(root)
while (walker.hasNext()) {
val currentNode = walker.nextNode()
if (crawlFilters == null || crawlFilters.isAllowed(currentNode)) {
getLinksStep2(base, hyperlinks, currentNode, crawlFilters)
walker.skipChildren()
} else {
logger.debug("Block disallowed, skip : " + DomUtil.getPrettyName(currentNode))
}
}
return hyperlinks
}
private fun getLinksStep2(
base: URL,
hyperlinks: MutableSet,
root: Node,
crawlFilters: CrawlFilters?
) {
val walker = NodeWalker(root)
// log.debug("Get hypeLinks for " + DomUtil.getPrettyName(root));
while (walker.hasNext()) {
val currentNode = walker.nextNode()
if (crawlFilters != null && crawlFilters.isDisallowed(currentNode)) {
logger.debug("Block disallowed, skip : " + DomUtil.getPrettyName(currentNode))
walker.skipChildren()
continue
}
var nodeName = currentNode.nodeName
val nodeType = currentNode.nodeType
val children = currentNode.childNodes
val childLen = children?.length ?: 0
if (nodeType == Node.ELEMENT_NODE) {
nodeName = nodeName.lowercase(Locale.getDefault())
val params = linkParams[nodeName]
if (params != null) {
if (!shouldThrowAwayLink(currentNode, children, childLen, params)) {
val linkText = StringBuilder()
getPageText(linkText, currentNode, true)
val attrs = currentNode.attributes
var target: String? = null
var noFollow = false
var post = false
var allow = true
for (i in 0 until attrs.length) {
val attr = attrs.item(i)
val attrName = attr.nodeName
if (params.attrName.equals(attrName, ignoreCase = true)) {
target = attr.nodeValue
} else if ("rel".equals(attrName, ignoreCase = true)
&& "nofollow".equals(attr.nodeValue, ignoreCase = true)
) {
noFollow = true
} else if ("rel".equals(attrName, ignoreCase = true)
&& "qi-nofollow".equals(attr.nodeValue, ignoreCase = true)
) {
allow = false
} else if ("method".equals(attrName, ignoreCase = true)
&& "post".equals(attr.nodeValue, ignoreCase = true)
) {
post = true
}
}
if (target != null && !noFollow && !post) try {
val url = resolveURL(base, target)
hyperlinks.add(HyperlinkPersistable(url.toString(), linkText.toString().trim { it <= ' ' }))
} catch (ignored: MalformedURLException) {
}
} // if not should throw away
// this should not have any children, skip them
if (params.childLen == 0) {
}
}
}
}
}
private class LinkParams(var elName: String, var attrName: String, var childLen: Int) {
override fun toString(): String {
return "LP[el=$elName,attr=$attrName,len=$childLen]"
}
}
}
