jaredsinclair · April 8, 2019 01:02 · Apr 8, 2019
diff --git a/Importer.swift b/Importer.swift
@@ -0,0 +1,110 @@
+import Foundation
+
+/*
+
+ Alls you gotta do is (in Main.swift):
+
+ 1. Initialize an Importer with the file URL to the JSON file (origin) and a URL to the directory that will contain all the Jekyll-formatted posts (destination).
+ 2. Call the `run()` method on the Importer.
+
+ */
+
+struct Post: Codable {
+    static let filenameFormatter: DateFormatter = {
+        let formatter = DateFormatter()
+        formatter.dateFormat = "YYYY-MM-dd"
+        return formatter
+    }()
+
+    static let frontmatterFormatter: DateFormatter = {
+        let formatter = DateFormatter()
+        formatter.dateFormat = "YYYY-MM-dd HH:mm:ss"
+        return formatter
+    }()
+
+    static let disallowedCharacters = NSCharacterSet
+        .alphanumerics
+        .union(CharacterSet(charactersIn: "-"))
+        .inverted
+
+    let title: String
+    let url: String
+    let content: String
+    let published: Date
+
+    var fileName: String {
+        let date = Post.filenameFormatter.string(from: published)
+        let slug = title
+            .lowercased()
+            .replacingOccurrences(of: " ", with: "-")
+            .components(separatedBy: Post.disallowedCharacters)
+            .joined(separator: "")
+            .prefix(32)
+            .trimmingCharacters(in: CharacterSet(charactersIn: "-"))
+        return "\(date)-\(slug).html"
+    }
+
+    var fileContent: String {
+        let dateStamp = Post.frontmatterFormatter.string(from: published)
+        return """
+        ---
+        layout: post
+        title: "\(title)"
+        date: \(dateStamp)
+        categories:
+        navtab: blog
+        ---
+
+        \(content)
+        """
+    }
+}
+
+public final class Importer {
+
+    let origin: URL
+    let destination: URL
+    let formatter: ISO8601DateFormatter
+
+    public init(origin: URL, destination: URL) {
+        print("Will read data from \(origin)")
+        self.origin = origin
+        self.destination = destination
+        self.formatter = ISO8601DateFormatter()
+        // init satisfied
+        formatter.formatOptions = formatter.formatOptions.union(.withFractionalSeconds)
+    }
+
+    public func run() throws {
+        let data = try Data(contentsOf: origin)
+        try decode(data)
+    }
+
+    private func decode(_ data: Data) throws {
+        let decoder = JSONDecoder()
+        decoder.dateDecodingStrategy = .custom(formatter.parseDate)
+        let posts = try decoder.decode([Post].self, from: data)
+        posts.forEach { post in
+            let fileUrl = destination.appendingPathComponent(post.fileName, isDirectory: false)
+            let fileContent = post.fileContent.data(using: .utf8)!
+            try! fileContent.write(to: fileUrl, options: .atomicWrite)
+        }
+    }
+
+}
+
+extension ISO8601DateFormatter {
+
+    enum DateError: Error {
+        case invalidDateFormat
+    }
+
+    func parseDate(using decoder: Decoder) throws -> Date {
+        let string = try decoder.singleValueContainer().decode(String.self)
+        guard let date = date(from: string) else {
+            throw DateError.invalidDateFormat
+        }
+        return date
+    }
+
+}