Parse and publish hashtags in notes when posting

CHANGELOG.md

@@ -11,14 +11,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Release Notes
+- Nos now publishes the hashtags it finds in your note when you post. This means it works the way you’ve always expected it to work. [#44](https://github.com/verse-pbc/issues/issues/44)
 - Fixed galleries expanding past the width of the screen when there are lots of links or images. [#24](https://github.com/verse-pbc/issues/issues/24)
 - Added support for user setting and displaying pronouns.
 - Added display of website urls for user profiles.
 
 ## [1.0.2] - 2024-11-26Z
 
 ### Release Notes
-- Fix typo in minimum age warning
 - Fix crash when tapping Post button on macOS. [#1687](https://github.com/planetary-social/nos/issues/1687)
 - Fix tapping follower notification not opening follower profile. [#11](https://github.com/verse-pbc/issues/issues/11)
 - Adjusted note header UI to make it more readable. [#23](https://github.com/verse-pbc/issues/issues/23)

Nos/Models/NoteParser.swift

@@ -19,9 +19,26 @@ struct NoteParser {
     /// Parses attributed text generated when composing a note and returns
     /// the content and tags.
     func parse(attributedText: AttributedString) -> (String, [[String]]) {
-        cleanLinks(in: attributedText)
+        let (content, tags) = cleanLinks(in: attributedText)
+        let hashtags = hashtags(in: content)
+        return (content, tags + hashtags)
     }
-
+
+    func hashtags(in content: String) -> [[String]] {
+        let pattern = "(?<=^|\\s)#([a-zA-Z0-9]{2,256})(?=\\s|$)"
+        let regex = try! NSRegularExpression(pattern: pattern) // swiftlint:disable:this force_try
+        let matches = regex.matches(in: content, range: NSRange(content.startIndex..., in: content))
+
+        let hashtags = matches.map { match -> [String] in
+            if let range = Range(match.range(at: 1), in: content) {
+                return ["t", String(content[range])]
+            }
+            return []
+        }
+
+        return hashtags
+    }
+
     /// Parses the content and tags stored in a note and returns an attributed text with tagged entities replaced
     /// with readable names.
     func parse(content: String, tags: [[String]], context: NSManagedObjectContext) -> AttributedString {

NosTests/Models/NoteParserTests+Parse.swift

@@ -2,7 +2,7 @@ import Foundation
 import UIKit
 import XCTest
 
-/// Collection of tests that exercise NoteParser.parse() function. This fubction
+/// Collection of tests that exercise NoteParser.parse() function. This function
 /// is the one Nos uses for converting editor generated text to note content
 /// when publishing.
 extension NoteParserTests {
@@ -69,6 +69,23 @@ extension NoteParserTests {
         XCTAssertEqual(content, expected)
     }
 
+    /// Example taken from [NIP-27](https://github.com/nostr-protocol/nips/blob/master/27.md)
+    func testMentionWithNpub() throws {
+        let mention = "@mattn"
+        let npub = "npub1937vv2nf06360qn9y8el6d8sevnndy7tuh5nzre4gj05xc32tnwqauhaj6"
+        let hex = "2c7cc62a697ea3a7826521f3fd34f0cb273693cbe5e9310f35449f43622a5cdc"
+        let link = "nostr:\(npub)"
+        let markdown = "hello [\(mention)](\(link))"
+        let attributedString = try AttributedString(markdown: markdown)
+        let (content, tags) = sut.parse(
+            attributedText: attributedString
+        )
+        let expectedContent = "hello nostr:\(npub)"
+        let expectedTags = [["p", hex]]
+        XCTAssertEqual(content, expectedContent)
+        XCTAssertEqual(tags, expectedTags)
+    }
+
     @MainActor func testTwoMentionsWithEmojiBeforeAndAfter() throws {
         // Arrange
         let name = "🍐 mattn 🍐"
@@ -91,4 +108,56 @@ extension NoteParserTests {
         // Assert
         XCTAssertEqual(content, expected)
     }
+
+    @MainActor func test_parse_returns_hashtag() throws {
+        // Arrange
+        let text = "#photography"
+
+        // Act
+        let expected = [["t", "photography"]]
+        let result = sut.hashtags(in: text)
+
+        // Assert
+        XCTAssertEqual(result, expected)
+    }
+
+    @MainActor func test_parse_returns_multiple_hashtags() throws {
+        // Arrange
+        let text = "#photography #birds #canada"
+
+        // Act
+        let expected = [["t", "photography"], ["t", "birds"], ["t", "canada"]]
+        let result = sut.hashtags(in: text)
+
+        // Assert
+        XCTAssertEqual(result, expected)
+    }
+
+    @MainActor func test_parse_returns_no_hashtags() throws {
+        // Arrange
+        let text = "example.com#photography"
+
+        // Act
+        let expected: [[String]] = []
+        let result = sut.hashtags(in: text)
+
+        // Assert
+        XCTAssertEqual(result, expected)
+    }
+
+    func test_parse_mention_and_hashtag() throws {
+        let mention = "@mattn"
+        let npub = "npub1937vv2nf06360qn9y8el6d8sevnndy7tuh5nzre4gj05xc32tnwqauhaj6"
+        let hex = "2c7cc62a697ea3a7826521f3fd34f0cb273693cbe5e9310f35449f43622a5cdc"
+        let link = "nostr:\(npub)"
+        let markdown = "hello [\(mention)](\(link)) #greetings #hi"
+        let attributedString = try AttributedString(markdown: markdown)
+        let (content, tags) = sut.parse(
+            attributedText: attributedString
+        )
+        let expectedContent = "hello nostr:\(npub) #greetings #hi"
+        let expectedTags = [["p", hex], ["t", "greetings"], ["t", "hi"]]
+        XCTAssertEqual(content, expectedContent)
+        XCTAssertEqual(tags, expectedTags)
+    }
 }

NosTests/Models/NoteParserTests.swift

@@ -93,24 +93,7 @@ final class NoteParserTests: CoreDataTestCase {
         XCTAssertEqual(links[safe: 0]?.key, nip05)
         XCTAssertEqual(links[safe: 0]?.value, URL(string: webLink))
     }
-
-    /// Example taken from [NIP-27](https://github.com/nostr-protocol/nips/blob/master/27.md)
-    func testMentionWithNPub() throws {
-        let mention = "@mattn"
-        let npub = "npub1937vv2nf06360qn9y8el6d8sevnndy7tuh5nzre4gj05xc32tnwqauhaj6"
-        let hex = "2c7cc62a697ea3a7826521f3fd34f0cb273693cbe5e9310f35449f43622a5cdc"
-        let link = "nostr:\(npub)"
-        let markdown = "hello [\(mention)](\(link))"
-        let attributedString = try AttributedString(markdown: markdown)
-        let (content, tags) = sut.parse(
-            attributedText: attributedString
-        )
-        let expectedContent = "hello nostr:\(npub)"
-        let expectedTags = [["p", hex]]
-        XCTAssertEqual(content, expectedContent)
-        XCTAssertEqual(tags, expectedTags)
-    }
-
+
     @MainActor func testContentWithMixedMentions() throws {
         let content = "hello nostr:npub1937vv2nf06360qn9y8el6d8sevnndy7tuh5nzre4gj05xc32tnwqauhaj6 and #[1]"
         let displayName1 = "npub1937vv..."