Add helpers for rendering a Gemini document back to source

GeminiFormat/Document.swift

@@ -15,6 +15,12 @@ public struct Document {
         self.url = url
         self.lines = lines
     }
+    
+    /// Renders this Document to Gemini formatted text. This is not guaranteed to be the original input text.
+    public func toGeminiText() -> String {
+        // todo: should this be \r\n
+        return lines.map { $0.geminiText() }.joined(separator: "\n")
+    }
 }
 
 public extension Document {
@@ -26,11 +32,49 @@ public extension Document {
         case heading(String, level: HeadingLevel)
         case unorderedListItem(String)
         case quote(String)
+        
+        func geminiText() -> String {
+            switch self {
+            case let .text(text):
+                return text
+            case let .link(url, text: text):
+                if let text = text {
+                    return "=> \(url.absoluteString) \(text)"
+                } else {
+                    return "=> \(url.absoluteString)"
+                }
+            case let .preformattedToggle(alt: alt):
+                if let alt = alt {
+                    return "```\(alt)"
+                } else {
+                    return "```"
+                }
+            case let .preformattedText(text):
+                return text
+            case let .heading(text, level: level):
+                return "\(level.geminiText) \(text)"
+            case let .unorderedListItem(text):
+                return "* \(text)"
+            case let .quote(text):
+                return "> \(text)"
+            }
+        }
     }
 }
 
 public extension Document {
     enum HeadingLevel: Int {
         case h1 = 1, h2 = 2, h3 = 3
+        
+        var geminiText: String {
+            switch self {
+            case .h1:
+                return "#"
+            case .h2:
+                return "##"
+            case .h3:
+                return "###"
+            }
+        }
     }
 }

GeminiFormatTests/DocumentTests.swift

@@ -0,0 +1,56 @@
+//
+//  DocumentTests.swift
+//  GeminiFormatTests
+//
+//  Created by Shadowfacts on 7/12/20.
+//
+
+import XCTest
+@testable import GeminiFormat
+
+class DocumentTests: XCTestCase {
+
+    func testLineText() {
+        XCTAssertEqual(Document.Line.text("some text").geminiText(), "some text")
+        XCTAssertEqual(Document.Line.link(URL(string: "gemini://example.com/foo?bar")!, text: "some link").geminiText(), "=> gemini://example.com/foo?bar some link")
+        XCTAssertEqual(Document.Line.link(URL(string: "gemini://example.com/foo?bar")!, text: nil).geminiText(), "=> gemini://example.com/foo?bar")
+        XCTAssertEqual(Document.Line.preformattedToggle(alt: "blah").geminiText(), "```blah")
+        XCTAssertEqual(Document.Line.preformattedToggle(alt: nil).geminiText(), "```")
+        XCTAssertEqual(Document.Line.preformattedText("test").geminiText(), "test")
+        XCTAssertEqual(Document.Line.heading("one", level: .h1).geminiText(), "# one")
+        XCTAssertEqual(Document.Line.heading("two", level: .h2).geminiText(), "## two")
+        XCTAssertEqual(Document.Line.heading("three", level: .h3).geminiText(), "### three")
+        XCTAssertEqual(Document.Line.unorderedListItem("list item").geminiText(), "* list item")
+        XCTAssertEqual(Document.Line.quote("quoted").geminiText(), "> quoted")
+    }
+    
+    func testDocumentText() {
+        let doc = Document(url: URL(string: "gemini://example.com")!, lines: [
+            .text("text"),
+            .link(URL(string: "gemini://example.com/")!, text: "a link"),
+            .link(URL(string: "gemini://example.com/foo?bar")!, text: nil),
+            .preformattedToggle(alt: "blah"),
+            .preformattedText("test"),
+            .preformattedToggle(alt: nil),
+            .heading("one", level: .h1),
+            .heading("two", level: .h2),
+            .heading("three", level: .h3),
+            .unorderedListItem("list item"),
+            .quote("quoted"),
+        ])
+        XCTAssertEqual(doc.toGeminiText(), """
+text
+=> gemini://example.com/ a link
+=> gemini://example.com/foo?bar
+```blah
+test
+```
+# one
+## two
+### three
+* list item
+> quoted
+""")
+    }
+
+}