Start RSS-in-JSON parser.

Frameworks/RSParser/Feeds/JSON/RSSInJSONParser.swift

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+//
+//  RSSInJSONParser.swift
+//  RSParser
+//
+//  Created by Brent Simmons on 6/24/17.
+//  Copyright © 2017 Ranchero Software, LLC. All rights reserved.
+//
+
+import Foundation
+
+// See https://github.com/scripting/Scripting-News/blob/master/rss-in-json/README.md
+// Also: http://cyber.harvard.edu/rss/rss.html
+
+public struct RSSInJSONParser {
+
+	public static func parse(parserData: ParserData) throws -> ParsedFeed? {
+
+		do {
+			let parsedObject = try JSONSerialization.jsonObject(with: parserData.data)
+
+			guard let channelObject = parsedObject["channel"] as? JSONDictionary else {
+				throw FeedParserError(.rssChannelNotFound)
+			}
+
+			// I’d bet money that in practice the items array won’t always appear correctly inside the channel object.
+			// I’d also bet that sometimes it gets called "items" instead of "item".
+			var itemsObject = channelObject["item"] as? JSONArray
+			if itemsObject == nil {
+				itemsObject = parsedObject["item"] as? JSONArray
+			}
+			if itemsObject == nil {
+				itemsObject = channelObject["items"] as? JSONArray
+			}
+			if itemsObject == nil {
+				itemsObject == parsedObject["items"] as? JSONArray
+			}
+			if itemsObject == nil {
+				throw FeedParserError(.rssItemsNotFound)
+			}
+
+			let title = channelObject["title"] as? String
+			let homePageURL = channelObject["link"] as? String
+			let feedURL = parserData.url
+			let feedDescription = channelObject["description"] as? String
+
+			let items = parseItems(itemsObject)
+
+			return ParsedFeed(type: .rssInJSON, title: title, homePageURL: homePageURL, feedURL: feedURL, feedDescription: feedDescription, nextURL: nil, iconURL: nil, faviconURL: nil, authors: nil, expired: false, hubs: nil, items: items)
+
+		}
+		catch { throw error }
+	}
+
+}
+
+private extension RSSInJSONParser {
+
+	static func parseItems(_ itemsObject: JSONArray) -> [ParsedItem] {
+
+		return itemsObject.flatMap{ (oneItemDictionary) -> ParsedItem in
+
+			return parsedItemWithDictionary(oneItemDictionary)
+		}
+	}
+
+	static func parsedItemWithDictionary(_ JSONDictionary: itemDictionary) -> ParsedItem? {
+
+		let externalURL = itemDictionary["link"] as? String
+		let title = itemDictionary["title"] as? String
+
+		var contentHTML = itemDictionary["description"] as? String
+		var contentText = nil
+		if contentHTML != nil && !(contentHTML!.contains("<")) {
+			contentText = contentHTML
+			contentHTML = nil
+		}
+		if contentHTML == nil && contentText == nil && title == nil {
+			return nil
+		}
+
+		var datePublished: Date = nil
+		if let datePublishedString = itemDictionary["pubDate"] as? String {
+			datePublished = RSDateWithString(datePublishedString as NSString)
+		}
+
+		let authorEmailAddress = itemDictionary["author"] as? String
+		var authors: [ParsedAuthor] = nil
+		if authorEmailAddress != nil {
+			let parsedAuthor = ParsedAuthor(name: nil, url: nil, avatarURL: nil, emailAddress: authorEmailAddress)
+			authors = [parsedAuthor]
+		}
+
+		var tags: [String]? = nil
+		if let categoryObject = itemDictionary["category"] as? JSONDictionary {
+			if let oneTag = categoryObject["#value"] {
+				tags = [oneTag]
+			}
+		}
+		else if let categoryArray = itemDictionary["category"] as? JSONArray {
+			tags = categoryArray.flatMap{ (oneCategoryDictionary) in
+				return oneCategoryDictionary["#value"]
+			}
+		}
+
+		var attachments: [ParsedAttachment]? = nil
+		if let enclosureObject = itemDictionary["enclosure"] as? JSONDictionary {
+			if let attachmentURL = enclosureObject["url"] as? String {
+				var attachmentSize = enclosureObject["length"] as? Int
+				if attachmentSize == nil {
+					if let attachmentSizeString = enclosureObject["length"] as? String {
+						attachmentSize = (attachmentSizeString as NSString).integerValue
+					}
+				}
+				let type = enclosureObject["type"] as? String
+				let oneAttachment = ParsedAttachment(url: attachmentURL, mimeType: type, title: nil, sizeInBytes: attachmentSize, durationInSeconds: nil)
+				attachments = [oneAttachment]
+			}
+		}
+
+		var uniqueID: String? = itemDictionary["guid"] as? String
+		if uniqueID == nil {
+
+			// Calculate a uniqueID based on a combination of non-empty elements. Then hash the result.
+			// Items should have guids. When they don't, re-runs are very likely
+			// because there's no other 100% reliable way to determine identity.
+			// This calculated uniqueID is valid only for this particular feed. (Just like ids in JSON Feed.)
+
+			var s = ""
+			if let datePublished = datePublished {
+				s += "\(datePublished.timeIntervalSince1970)"
+			}
+			if let title = title {
+				s += title
+			}
+			if let externalURL = externalURL {
+				s += externalURL
+			}
+			if let authorEmailAddress = authorEmailAddress {
+				s += authorEmailAddress
+			}
+			if let oneAttachmentURL = attachments?.first?.url {
+				s += oneAttachmentURL
+			}
+			if s.isEmpty {
+				// Sheesh. Tough case.
+				if contentHTML != nil {
+					s = contentHTML
+				}
+				if contentText != nil {
+					s = contentText
+				}
+			}
+			uniqueID = (s as NSString).rsxml_md5HashString()
+		}
+
+		return ParsedItem(uniqueID: uniqueID, url: nil, externalURL: externalURL, title: title, contentHTML: contentHTML, contentText: contentText, summary: nil, imageURL: nil, bannerImageURL: nil, datePublished: datePublished, dateModified: nil, authors: authors, tags: tags, attachments: attachments)
+	}
+}