Space prior to onebox stops onebox resolution

app/assets/javascripts/markdown-it-bundle.js

@@ -10,3 +10,5 @@
 //= require ./pretty-text/engines/markdown-it/category-hashtag
 //= require ./pretty-text/engines/markdown-it/censored
 //= require ./pretty-text/engines/markdown-it/table
+//= require ./pretty-text/engines/markdown-it/paragraph
+//= require ./pretty-text/engines/markdown-it/newline

app/assets/javascripts/pretty-text/engines/markdown-it/newline.js.es6

@@ -0,0 +1,53 @@
+// see: https://github.com/markdown-it/markdown-it/issues/375
+//
+// we use a custom paragraph rule cause we have to signal when a
+// link starts with a space, so we can bypass a onebox
+// this is a freedom patch, so careful, may break on updates
+
+
+function newline(state, silent) {
+  var token, pmax, max, pos = state.pos;
+
+  if (state.src.charCodeAt(pos) !== 0x0A/* \n */) { return false; }
+
+  pmax = state.pending.length - 1;
+  max = state.posMax;
+
+  // '  \n' -> hardbreak
+  // Lookup in pending chars is bad practice! Don't copy to other rules!
+  // Pending string is stored in concat mode, indexed lookups will cause
+  // convertion to flat mode.
+  if (!silent) {
+    if (pmax >= 0 && state.pending.charCodeAt(pmax) === 0x20) {
+      if (pmax >= 1 && state.pending.charCodeAt(pmax - 1) === 0x20) {
+        state.pending = state.pending.replace(/ +$/, '');
+        token = state.push('hardbreak', 'br', 0);
+      } else {
+        state.pending = state.pending.slice(0, -1);
+        token = state.push('softbreak', 'br', 0);
+      }
+
+    } else {
+      token = state.push('softbreak', 'br', 0);
+    }
+  }
+
+  pos++;
+
+  // skip heading spaces for next line
+  while (pos < max && state.md.utils.isSpace(state.src.charCodeAt(pos))) {
+    if (token) {
+      token.leading_space = true;
+    }
+    pos++;
+  }
+
+  state.pos = pos;
+  return true;
+};
+
+export function setup(helper) {
+  helper.registerPlugin(md => {
+    md.inline.ruler.at('newline', newline);
+  });
+}

app/assets/javascripts/pretty-text/engines/markdown-it/onebox.js.es6

@@ -19,9 +19,14 @@ function applyOnebox(state, silent) {
 
         if (child.type === "link_open" && child.markup === 'linkify' && child.info === 'auto') {
 
-          // look behind for soft or hard break
-          if (j > 0 && token.children[j-1].tag !== 'br') {
+          if (j === 0 && token.leading_space) {
             continue;
+          } else if (j > 0) {
+            let prevSibling = token.children[j-1];
+
+            if (prevSibling.tag !== 'br' || prevSibling.leading_space) {
+              continue;
+            }
           }
 
           // look ahead for soft or hard break

app/assets/javascripts/pretty-text/engines/markdown-it/paragraph.js.es6

@@ -0,0 +1,80 @@
+// see: https://github.com/markdown-it/markdown-it/issues/375
+//
+// we use a custom paragraph rule cause we have to signal when a
+// link starts with a space, so we can bypass a onebox
+// this is a freedom patch, so careful, may break on updates
+function paragraph(state, startLine/*, endLine*/) {
+  var content, terminate, i, l, token, oldParentType,
+      nextLine = startLine + 1,
+      terminatorRules = state.md.block.ruler.getRules('paragraph'),
+      endLine = state.lineMax,
+      hasLeadingSpace = false;
+
+  oldParentType = state.parentType;
+  state.parentType = 'paragraph';
+
+  // jump line-by-line until empty one or EOF
+  for (; nextLine < endLine && !state.isEmpty(nextLine); nextLine++) {
+    // this would be a code block normally, but after paragraph
+    // it's considered a lazy continuation regardless of what's there
+    if (state.sCount[nextLine] - state.blkIndent > 3) { continue; }
+
+    // quirk for blockquotes, this line should already be checked by that rule
+    if (state.sCount[nextLine] < 0) { continue; }
+
+    // Some tags can terminate paragraph without empty line.
+    terminate = false;
+    for (i = 0, l = terminatorRules.length; i < l; i++) {
+      if (terminatorRules[i](state, nextLine, endLine, true)) {
+        terminate = true;
+        break;
+      }
+    }
+    if (terminate) { break; }
+  }
+
+  // START CUSTOM CODE
+  content = state.getLines(startLine, nextLine, state.blkIndent, false);
+
+  i=0;
+  let contentLength = content.length;
+  while (i < contentLength) {
+    let chr = content.charCodeAt(i);
+    if (chr === 0x0A) {
+      hasLeadingSpace = false;
+    } else if (state.md.utils.isWhiteSpace(chr)) {
+      hasLeadingSpace = true;
+    } else {
+      break;
+    }
+    i++;
+  }
+
+  content = content.trim();
+  // END CUSTOM CODE
+
+  state.line = nextLine;
+
+  token               = state.push('paragraph_open', 'p', 1);
+  token.map           = [ startLine, state.line ];
+  // CUSTOM
+  token.leading_space = hasLeadingSpace;
+
+  token               = state.push('inline', '', 0);
+  token.content       = content;
+  token.map           = [ startLine, state.line ];
+  token.children      = [];
+  // CUSTOM
+  token.leading_space = hasLeadingSpace;
+
+  token          = state.push('paragraph_close', 'p', -1);
+
+  state.parentType = oldParentType;
+  return true;
+};
+
+export function setup(helper) {
+  helper.registerPlugin(md => {
+    md.block.ruler.at('paragraph', paragraph);
+  });
+}

spec/components/pretty_text_spec.rb

@@ -619,7 +619,6 @@ HTML
       # we expect 2 oneboxes
       expect(PrettyText.cook("http://a.com\nhttp://b.com").split("onebox").length).to eq(3)
       expect(PrettyText.cook("http://a.com\n\nhttp://b.com").split("onebox").length).to eq(3)
-
       expect(PrettyText.cook("a\nhttp://a.com")).to include('onebox')
       expect(PrettyText.cook("> http://a.com")).not_to include('onebox')
       expect(PrettyText.cook("a\nhttp://a.com a")).not_to include('onebox')
@@ -630,6 +629,8 @@ HTML
       expect(PrettyText.cook("http://a.com a")).not_to include('onebox')
       expect(PrettyText.cook("- http://a.com")).not_to include('onebox')
       expect(PrettyText.cook("<http://a.com>")).not_to include('onebox')
+      expect(PrettyText.cook(" http://a.com")).not_to include('onebox')
+      expect(PrettyText.cook("a\n http://a.com")).not_to include('onebox')
     end
 
     it "can handle bbcode" do