120 lines
4.9 KiB
Swift
120 lines
4.9 KiB
Swift
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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