66 lines
1.6 KiB
Swift
66 lines
1.6 KiB
Swift
//
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// HTMLMetadataDownloader.swift
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// Evergreen
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//
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// Created by Brent Simmons on 11/26/17.
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// Copyright © 2017 Ranchero Software. All rights reserved.
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//
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import Foundation
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import RSWeb
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import RSParser
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struct HTMLMetadataDownloader {
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static var metadataCache = [String: RSHTMLMetadata]()
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static let serialDispatchQueue = DispatchQueue(label: "HTMLMetadataDownloader")
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static func downloadMetadata(for url: String, _ callback: @escaping (RSHTMLMetadata?) -> Void) {
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guard let actualURL = URL(string: url) else {
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callback(nil)
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return
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}
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downloadUsingCache(actualURL) { (data, response, error) in
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if let data = data, !data.isEmpty, let response = response, response.statusIsOK, error == nil {
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let urlToUse = response.url ?? actualURL
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let parserData = ParserData(url: urlToUse.absoluteString, data: data)
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parseMetadata(with: parserData, callback)
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return
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}
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if let error = error {
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appDelegate.logMessage("Error downloading metadata at \(url): \(error)", type: .warning)
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}
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callback(nil)
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}
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}
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private static func parseMetadata(with parserData: ParserData, _ callback: @escaping (RSHTMLMetadata?) -> Void) {
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serialDispatchQueue.async {
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let md5String = (parserData.data as NSData).rs_md5HashString()
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if let md5String = md5String, let cachedMetadata = metadataCache[md5String] {
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DispatchQueue.main.async {
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callback(cachedMetadata)
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}
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return
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}
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let htmlMetadata = RSHTMLMetadataParser.htmlMetadata(with: parserData)
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if let md5String = md5String {
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metadataCache[md5String] = htmlMetadata
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}
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DispatchQueue.main.async {
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callback(htmlMetadata)
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}
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}
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}
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}
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