Move Paste line range reading code into AphrontRequest

Summary: Ref T13088. This lifts the code for parsing "$x-y" line ranges in URIs into AphrontRequest so Diffusion, Paste, Harbormaster, etc., can share it.

Test Plan: Viewed lines, line ranges, no lines, negative line ranges, line ranges with 0, and extremely long line ranges in Paste.

Maniphest Tasks: T13088

Differential Revision: https://secure.phabricator.com/D19162

src/aphront/AphrontRequest.php

@@ -49,6 +49,54 @@ final class AphrontRequest extends Phobject {
     return idx($this->uriData, $key, $default);
   }
 
+  /**
+   * Read line range parameter data from the request.
+   *
+   * Applications like Paste, Diffusion, and Harbormaster use "$12-14" in the
+   * URI to allow users to link to particular lines.
+   *
+   * @param string URI data key to pull line range information from.
+   * @param int|null Maximum length of the range.
+   * @return null|pair<int, int> Null, or beginning and end of the range.
+   */
+  public function getURILineRange($key, $limit) {
+    $range = $this->getURIData($key);
+    if (!strlen($range)) {
+      return null;
+    }
+
+    $range = explode('-', $range, 2);
+
+    foreach ($range as $key => $value) {
+      $value = (int)$value;
+      if (!$value) {
+        // If either value is "0", discard the range.
+        return null;
+      }
+      $range[$key] = $value;
+    }
+
+    // If the range is like "$10", treat it like "$10-10".
+    if (count($range) == 1) {
+      $range[] = head($range);
+    }
+
+    // If the range is "$7-5", treat it like "$5-7".
+    if ($range[1] < $range[0]) {
+      $range = array_reverse($range);
+    }
+
+    // If the user specified something like "$1-999999999" and we have a limit,
+    // clamp it to a more reasonable range.
+    if ($limit !== null) {
+      if ($range[1] - $range[0] > $limit) {
+        $range[1] = $range[0] + $limit;
+      }
+    }
+
+    return $range;
+  }
+
   public function setApplicationConfiguration(
     $application_configuration) {
     $this->applicationConfiguration = $application_configuration;

src/applications/paste/controller/PhabricatorPasteViewController.php

@@ -2,30 +2,10 @@
 
 final class PhabricatorPasteViewController extends PhabricatorPasteController {
 
-  private $highlightMap;
-
   public function shouldAllowPublic() {
     return true;
   }
 
-  public function willProcessRequest(array $data) {
-    $raw_lines = idx($data, 'lines');
-    $map = array();
-    if ($raw_lines) {
-      $lines = explode('-', $raw_lines);
-      $first = idx($lines, 0, 0);
-      $last = idx($lines, 1);
-      if ($last) {
-        $min = min($first, $last);
-        $max = max($first, $last);
-        $map = array_fuse(range($min, $max));
-      } else {
-        $map[$first] = $first;
-      }
-    }
-    $this->highlightMap = $map;
-  }
-
   public function handleRequest(AphrontRequest $request) {
     $viewer = $request->getViewer();
     $id = $request->getURIData('id');
@@ -40,11 +20,18 @@ final class PhabricatorPasteViewController extends PhabricatorPasteController {
       return new Aphront404Response();
     }
 
+    $lines = $request->getURILineRange('lines', 1000);
+    if ($lines) {
+      $map = range($lines[0], $lines[1]);
+    } else {
+      $map = array();
+    }
+
     $header = $this->buildHeaderView($paste);
     $curtain = $this->buildCurtain($paste);
 
     $subheader = $this->buildSubheaderView($paste);
-    $source_code = $this->buildSourceCodeView($paste, $this->highlightMap);
+    $source_code = $this->buildSourceCodeView($paste, $map);
 
     require_celerity_resource('paste-css');