fix up selecting after url case

Signal/test/util/ProtoParsingTest.m

@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //
 
 #import "SignalBaseTest.h"
@@ -63,6 +63,10 @@ NS_ASSUME_NONNULL_BEGIN
     return nil;
 }
 
+- (nonnull NSString *)displayNameForPhoneIdentifier:(NSString * _Nullable)recipientId transaction:(nonnull YapDatabaseReadTransaction *)transaction {
+    return nil;
+}
+
 @end
 
 #pragma mark -

SignalServiceKit/src/Messages/Interactions/OWSLinkPreview.swift

@@ -469,8 +469,9 @@ public class OWSLinkPreview: MTLModel {
 
         if let selectedRange = selectedRange {
             Logger.verbose("match: urlString: \(urlMatch.urlString) range: \(urlMatch.matchRange) selectedRange: \(selectedRange)")
+            let cursorAtEndOfMatch = urlMatch.matchRange.location + urlMatch.matchRange.length == selectedRange.location
             if selectedRange.location != body.count,
-                urlMatch.matchRange.intersection(selectedRange) != nil {
+                (urlMatch.matchRange.intersection(selectedRange) != nil || cursorAtEndOfMatch) {
                 Logger.debug("ignoring URL, since the user is currently editing it.")
                 // we don't want to cache the result here, as we want to fetch the link preview
                 // if the user moves the cursor.

SignalServiceKit/tests/Messages/OWSLinkPreviewTest.swift

@@ -169,19 +169,20 @@ class OWSLinkPreviewTest: SSKBaseTestSwift {
     }
 
     func testPreviewUrlForMessageBodyText() {
-        XCTAssertNil(OWSLinkPreview.previewUrl(forMessageBodyText: ""))
-        XCTAssertNil(OWSLinkPreview.previewUrl(forMessageBodyText: "alice bob jim"))
-        XCTAssertNil(OWSLinkPreview.previewUrl(forMessageBodyText: "alice bob jim http://"))
-        XCTAssertNil(OWSLinkPreview.previewUrl(forMessageBodyText: "alice bob jim http://a.com"))
+        Assert(bodyText: "", extractsLink: nil)
+        Assert(bodyText: "alice bob jim", extractsLink: nil)
+        Assert(bodyText: "alice bob jim http://", extractsLink: nil)
+        Assert(bodyText: "alice bob jim http://a.com", extractsLink: nil)
 
-        XCTAssertEqual(OWSLinkPreview.previewUrl(forMessageBodyText: "https://www.youtube.com/watch?v=tP-Ipsat90c"),
-                       "https://www.youtube.com/watch?v=tP-Ipsat90c")
-        XCTAssertEqual(OWSLinkPreview.previewUrl(forMessageBodyText: "alice bob https://www.youtube.com/watch?v=tP-Ipsat90c jim"),
-                       "https://www.youtube.com/watch?v=tP-Ipsat90c")
+        Assert(bodyText: "https://www.youtube.com/watch?v=tP-Ipsat90c",
+               extractsLink: "https://www.youtube.com/watch?v=tP-Ipsat90c")
+
+        Assert(bodyText: "alice bob https://www.youtube.com/watch?v=tP-Ipsat90c jim",
+               extractsLink: "https://www.youtube.com/watch?v=tP-Ipsat90c")
 
         // If there are more than one, take the first.
-        XCTAssertEqual(OWSLinkPreview.previewUrl(forMessageBodyText: "alice bob https://www.youtube.com/watch?v=tP-Ipsat90c jim https://www.youtube.com/watch?v=other-url carol"),
-                       "https://www.youtube.com/watch?v=tP-Ipsat90c")
+        Assert(bodyText: "alice bob https://www.youtube.com/watch?v=tP-Ipsat90c jim https://www.youtube.com/watch?v=other-url carol",
+               extractsLink: "https://www.youtube.com/watch?v=tP-Ipsat90c")
     }
 
     func testUtils() {
@@ -454,4 +455,87 @@ class OWSLinkPreviewTest: SSKBaseTestSwift {
                                          options: [],
                                          range: NSRange(location: 0, length: text.utf16.count)))
     }
+
+    func testCursorPositions() {
+        // sanity check
+        Assert(bodyText: "https://www.youtube.com/watch?v=testCursorPositionsa",
+               extractsLink: "https://www.youtube.com/watch?v=testCursorPositionsa",
+               selectedRange: nil)
+
+        // Don't extract link if cursor is touching text
+        let text2 = "https://www.youtube.com/watch?v=testCursorPositionsb"
+        XCTAssertEqual(text2.count, 52)
+        Assert(bodyText: text2,
+               extractsLink: nil,
+               selectedRange: NSRange(location: 51, length: 0))
+
+        Assert(bodyText: text2,
+               extractsLink: nil,
+               selectedRange: NSRange(location: 51, length: 10))
+
+        Assert(bodyText: text2,
+               extractsLink: nil,
+               selectedRange: NSRange(location: 0, length: 0))
+
+        // Unless the cursor is at the end of the text
+        Assert(bodyText: text2,
+               extractsLink: "https://www.youtube.com/watch?v=testCursorPositionsb",
+               selectedRange: NSRange(location: 52, length: 0))
+
+        // Once extracted, keep the existing link preview, even if the cursor moves back.
+        Assert(bodyText: text2,
+               extractsLink: "https://www.youtube.com/watch?v=testCursorPositionsb",
+               selectedRange: NSRange(location: 51, length: 0))
+
+        let text3 = "foo https://www.youtube.com/watch?v=testCursorPositionsc bar"
+        XCTAssertEqual(text3.count, 60)
+
+        // front edge
+        Assert(bodyText: text3,
+               extractsLink: nil,
+               selectedRange: NSRange(location: 4, length: 0))
+
+        // middle
+        Assert(bodyText: text3,
+               extractsLink: nil,
+               selectedRange: NSRange(location: 4, length: 0))
+
+        // rear edge
+        Assert(bodyText: text3,
+               extractsLink: nil,
+               selectedRange: NSRange(location: 56, length: 0))
+
+        // extract link if selecting after link
+        Assert(bodyText: text3,
+               extractsLink: "https://www.youtube.com/watch?v=testCursorPositionsc",
+               selectedRange: NSRange(location: 57, length: 0))
+
+        let text4 = "bar https://www.youtube.com/watch?v=testCursorPositionsd foo"
+        XCTAssertEqual(text4.count, 60)
+
+        // front edge
+        Assert(bodyText: text4,
+               extractsLink: nil,
+               selectedRange: NSRange(location: 4, length: 0))
+
+        // middle
+        Assert(bodyText: text4,
+               extractsLink: nil,
+               selectedRange: NSRange(location: 20, length: 0))
+
+        // rear edge
+        Assert(bodyText: text4,
+               extractsLink: nil,
+               selectedRange: NSRange(location: 56, length: 0))
+
+        // extract link if selecting before link
+        Assert(bodyText: text4,
+               extractsLink: "https://www.youtube.com/watch?v=testCursorPositionsd",
+               selectedRange: NSRange(location: 3, length: 0))
+    }
+
+    private func Assert(bodyText: String, extractsLink link: String?, selectedRange: NSRange? = nil, file: StaticString = #file, line: UInt = #line) {
+        let actual = OWSLinkPreview.previewUrl(forMessageBodyText: bodyText, selectedRange: selectedRange)
+        XCTAssertEqual(actual, link, file: file, line: line)
+    }
 }