214 lines
5.4 KiB
Swift
214 lines
5.4 KiB
Swift
//
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// FeedFinder.swift
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// FeedFinder
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//
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// Created by Brent Simmons on 8/2/16.
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// Copyright © 2016 Ranchero Software, LLC. All rights reserved.
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//
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import Foundation
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import RSParser
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import RSWeb
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import RSCore
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protocol FeedFinderDelegate: class {
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func feedFinder(_: FeedFinder, didFindFeeds: Set<FeedSpecifier>)
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}
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class FeedFinder {
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private weak var delegate: FeedFinderDelegate?
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private var feedSpecifiers = [String: FeedSpecifier]()
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private var didNotifyDelegate = false
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var initialDownloadError: Error?
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var initialDownloadStatusCode = -1
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init(url: URL, delegate: FeedFinderDelegate) {
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self.delegate = delegate
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DispatchQueue.main.async() { () -> Void in
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self.findFeeds(url)
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}
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}
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deinit {
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notifyDelegateIfNeeded()
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}
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}
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private extension FeedFinder {
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func addFeedSpecifier(_ feedSpecifier: FeedSpecifier) {
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// If there’s an existing feed specifier, merge the two so that we have the best data. If one has a title and one doesn’t, use that non-nil title. Use the better source.
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if let existingFeedSpecifier = feedSpecifiers[feedSpecifier.urlString] {
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let mergedFeedSpecifier = existingFeedSpecifier.feedSpecifierByMerging(feedSpecifier)
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feedSpecifiers[feedSpecifier.urlString] = mergedFeedSpecifier
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}
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else {
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feedSpecifiers[feedSpecifier.urlString] = feedSpecifier
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}
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}
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func findFeedsInHTMLPage(htmlData: Data, urlString: String) {
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// Feeds in the <head> section we automatically assume are feeds.
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// If there are none from the <head> section,
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// then possible feeds in <body> section are downloaded individually
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// and added once we determine they are feeds.
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let possibleFeedSpecifiers = possibleFeedsInHTMLPage(htmlData: htmlData, urlString: urlString)
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var feedSpecifiersToDownload = Set<FeedSpecifier>()
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var didFindFeedInHTMLHead = false
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for oneFeedSpecifier in possibleFeedSpecifiers {
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if oneFeedSpecifier.source == .HTMLHead {
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addFeedSpecifier(oneFeedSpecifier)
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didFindFeedInHTMLHead = true
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}
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else {
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if !feedSpecifiersContainsURLString(oneFeedSpecifier.urlString) {
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feedSpecifiersToDownload.insert(oneFeedSpecifier)
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}
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}
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}
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if didFindFeedInHTMLHead || feedSpecifiersToDownload.isEmpty {
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stopFinding()
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}
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else {
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downloadFeedSpecifiers(feedSpecifiersToDownload)
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}
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}
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func possibleFeedsInHTMLPage(htmlData: Data, urlString: String) -> Set<FeedSpecifier> {
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let parserData = ParserData(url: urlString, data: htmlData)
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var feedSpecifiers = HTMLFeedFinder(parserData: parserData).feedSpecifiers
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if feedSpecifiers.isEmpty {
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// Odds are decent it’s a WordPress site, and just adding /feed/ will work.
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// It’s also fairly common for /index.xml to work.
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if let url = URL(string: urlString) {
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let feedURL = url.appendingPathComponent("feed", isDirectory: true)
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let wordpressFeedSpecifier = FeedSpecifier(title: nil, urlString: feedURL.absoluteString, source: .HTMLLink)
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feedSpecifiers.insert(wordpressFeedSpecifier)
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let indexXMLURL = url.appendingPathComponent("index.xml", isDirectory: false)
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let indexXMLFeedSpecifier = FeedSpecifier(title: nil, urlString: indexXMLURL.absoluteString, source: .HTMLLink)
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feedSpecifiers.insert(indexXMLFeedSpecifier)
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}
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}
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return feedSpecifiers
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}
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func feedSpecifiersContainsURLString(_ urlString: String) -> Bool {
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if let _ = feedSpecifiers[urlString] {
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return true
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}
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return false
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}
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func isHTML(_ data: Data) -> Bool {
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return (data as NSData).rs_dataIsProbablyHTML()
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}
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func findFeeds(_ initialURL: URL) {
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downloadInitialFeed(initialURL)
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}
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func downloadInitialFeed(_ initialURL: URL) {
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downloadUsingCache(initialURL) { (data, response, error) in
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self.initialDownloadStatusCode = response?.forcedStatusCode ?? -1
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if let error = error {
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self.initialDownloadError = error
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self.stopFinding()
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return
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}
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guard let data = data, let response = response else {
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self.stopFinding()
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return
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}
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if !response.statusIsOK || data.isEmpty {
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self.stopFinding()
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return
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}
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if self.isFeed(data, initialURL.absoluteString) {
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let feedSpecifier = FeedSpecifier(title: nil, urlString: initialURL.absoluteString, source: .UserEntered)
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self.addFeedSpecifier(feedSpecifier)
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self.stopFinding()
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return
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}
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if !self.isHTML(data) {
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self.stopFinding()
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return
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}
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self.findFeedsInHTMLPage(htmlData: data, urlString: initialURL.absoluteString)
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}
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}
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func downloadFeedSpecifiers(_ feedSpecifiers: Set<FeedSpecifier>) {
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var pendingDownloads = feedSpecifiers
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for oneFeedSpecifier in feedSpecifiers {
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guard let url = URL(string: oneFeedSpecifier.urlString) else {
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pendingDownloads.remove(oneFeedSpecifier)
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continue
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}
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downloadUsingCache(url) { (data, response, error) in
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pendingDownloads.remove(oneFeedSpecifier)
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if let data = data, let response = response, response.statusIsOK, error == nil {
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if self.isFeed(data, oneFeedSpecifier.urlString) {
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self.addFeedSpecifier(oneFeedSpecifier)
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}
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}
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if pendingDownloads.isEmpty {
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self.stopFinding()
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}
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}
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}
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}
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func stopFinding() {
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notifyDelegateIfNeeded()
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}
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func notifyDelegateIfNeeded() {
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if !didNotifyDelegate {
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delegate?.feedFinder(self, didFindFeeds: Set(feedSpecifiers.values))
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didNotifyDelegate = true
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}
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}
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func isFeed(_ data: Data, _ urlString: String) -> Bool {
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let parserData = ParserData(url: urlString, data: data)
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return FeedParser.canParse(parserData)
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}
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}
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