mirror of https://github.com/oxen-io/session-ios
Niels Andriesse
2 years ago
9 changed files with 275 additions and 168 deletions
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import Foundation |
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public struct HTMLMetadata: Equatable { |
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/// Parsed from <title> |
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var titleTag: String? |
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/// Parsed from <link rel="icon"...> |
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var faviconUrlString: String? |
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/// Parsed from <meta name="description"...> |
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var description: String? |
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/// Parsed from the og:title meta property |
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var ogTitle: String? |
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/// Parsed from the og:description meta property |
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var ogDescription: String? |
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/// Parsed from the og:image or og:image:url meta property |
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var ogImageUrlString: String? |
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/// Parsed from the og:published_time meta property |
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var ogPublishDateString: String? |
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/// Parsed from article:published_time meta property |
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var articlePublishDateString: String? |
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/// Parsed from the og:modified_time meta property |
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var ogModifiedDateString: String? |
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/// Parsed from the article:modified_time meta property |
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var articleModifiedDateString: String? |
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static func construct(parsing rawHTML: String) -> HTMLMetadata { |
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let metaPropertyTags = Self.parseMetaProperties(in: rawHTML) |
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return HTMLMetadata( |
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titleTag: Self.parseTitleTag(in: rawHTML), |
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faviconUrlString: Self.parseFaviconUrlString(in: rawHTML), |
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description: Self.parseDescriptionTag(in: rawHTML), |
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ogTitle: metaPropertyTags["og:title"], |
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ogDescription: metaPropertyTags["og:description"], |
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ogImageUrlString: (metaPropertyTags["og:image"] ?? metaPropertyTags["og:image:url"]), |
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ogPublishDateString: metaPropertyTags["og:published_time"], |
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articlePublishDateString: metaPropertyTags["article:published_time"], |
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ogModifiedDateString: metaPropertyTags["og:modified_time"], |
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articleModifiedDateString: metaPropertyTags["article:modified_time"] |
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) |
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} |
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} |
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// MARK: - Parsing |
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extension HTMLMetadata { |
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private static func parseTitleTag(in rawHTML: String) -> String? { |
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titleRegex |
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.firstMatchSet(in: rawHTML)? |
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.group(idx: 0) |
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.flatMap { decodeHTMLEntities(in: String($0)) } |
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} |
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private static func parseFaviconUrlString(in rawHTML: String) -> String? { |
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guard let matchedTag = faviconRegex |
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.firstMatchSet(in: rawHTML) |
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.map({ String($0.fullString) }) else { return nil } |
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return faviconUrlRegex |
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.parseFirstMatch(inText: matchedTag) |
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.flatMap { decodeHTMLEntities(in: String($0)) } |
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} |
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private static func parseDescriptionTag(in rawHTML: String) -> String? { |
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guard let matchedTag = metaDescriptionRegex |
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.firstMatchSet(in: rawHTML) |
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.map({ String($0.fullString) }) else { return nil } |
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return metaContentRegex |
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.parseFirstMatch(inText: matchedTag) |
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.flatMap { decodeHTMLEntities(in: String($0)) } |
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} |
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private static func parseMetaProperties(in rawHTML: String) -> [String: String] { |
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metaPropertyRegex |
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.allMatchSets(in: rawHTML) |
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.reduce(into: [:]) { (builder, matchSet) in |
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guard let ogTypeSubstring = matchSet.group(idx: 0) else { return } |
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let ogType = String(ogTypeSubstring) |
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let fullTag = String(matchSet.fullString) |
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// Exit early if we've already found a tag of this type |
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guard builder[ogType] == nil else { return } |
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guard let content = metaContentRegex.parseFirstMatch(inText: fullTag) else { return } |
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builder[ogType] = decodeHTMLEntities(in: content) |
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} |
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} |
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private static func decodeHTMLEntities(in string: String) -> String? { |
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guard let data = string.data(using: .utf8) else { |
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return nil |
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} |
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let options: [NSAttributedString.DocumentReadingOptionKey: Any] = [ |
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.documentType: NSAttributedString.DocumentType.html, |
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.characterEncoding: String.Encoding.utf8.rawValue |
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] |
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guard let attributedString = try? NSAttributedString(data: data, options: options, documentAttributes: nil) else { |
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return nil |
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} |
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return attributedString.string |
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} |
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} |
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// MARK: - Regular Expressions |
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extension HTMLMetadata { |
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static let titleRegex = regex(pattern: "<\\s*title[^>]*>(.*?)<\\s*/title[^>]*>") |
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static let faviconRegex = regex(pattern: "<\\s*link[^>]*rel\\s*=\\s*\"\\s*(shortcut\\s+)?icon\\s*\"[^>]*>") |
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static let faviconUrlRegex = regex(pattern: "href\\s*=\\s*\"([^\"]*)\"") |
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static let metaDescriptionRegex = regex(pattern: "<\\s*meta[^>]*name\\s*=\\s*\"\\s*description[^\"]*\"[^>]*>") |
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static let metaPropertyRegex = regex(pattern: "<\\s*meta[^>]*property\\s*=\\s*\"\\s*([^\"]+?)\"[^>]*>") |
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static let metaContentRegex = regex(pattern: "content\\s*=\\s*\"([^\"]*?)\"") |
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static private func regex(pattern: String) -> NSRegularExpression { |
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try! NSRegularExpression( |
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pattern: pattern, |
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options: [.dotMatchesLineSeparators, .caseInsensitive]) |
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} |
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} |
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