diff --git a/mass-rebuilder.php b/mass-rebuilder.php
index 86ed1f9..efb63ed 100644
--- a/mass-rebuilder.php
+++ b/mass-rebuilder.php
@@ -100,40 +100,7 @@ function reply_to_issue($repo, $pr, $prev, $current) {
                              ]
     );
 
-    $labels = [];
-    foreach ($output as $line) {
-        if (preg_match('/^\s*(\d+) (.*)$/', $line, $matches)) {
-            var_dump($matches);
-            # TODO: separate out the rebuild ranges from the rebuild platform and
-            # splice the string together, rather than this ugliness
-            if ($matches[1] > 500) {
-                if ($matches[2] == "x86_64-darwin") {
-                    $labels[] = "10.rebuild-darwin: 501+";
-                } else {
-                    $labels[] = "10.rebuild-linux: 501+";
-                }
-            } else if ($matches[1] > 100 && $matches[1] <= 500) {
-                if ($matches[2] == "x86_64-darwin") {
-                    $labels[] = "10.rebuild-darwin: 101-500";
-                } else {
-                    $labels[] = "10.rebuild-linux: 101-500";
-                }
-            } else if ($matches[1] > 10 && $matches[1] <= 100) {
-                if ($matches[2] == "x86_64-darwin") {
-                    $labels[] = "10.rebuild-darwin: 11-100";
-                } else {
-                    $labels[] = "10.rebuild-linux: 11-100";
-                }
-            } else if ($matches[1] <= 10) {
-                if ($matches[2] == "x86_64-darwin") {
-                    $labels[] = "10.rebuild-darwin: 1-10";
-                } else {
-                    $labels[] = "10.rebuild-linux: 1-10";
-                }
-            }
-        }
-    }
-
+    $labels = GHE\RebuildTagClassifier::parseAndLabel($output);
 
     foreach ($labels as $label) {
         if (in_array($label, $already_there)) {
diff --git a/src/RebuildTagClassifier.php b/src/RebuildTagClassifier.php
new file mode 100644
index 0000000..bcaebc4
--- /dev/null
+++ b/src/RebuildTagClassifier.php
@@ -0,0 +1,62 @@
+<?php
+
+namespace GHE;
+
+class RebuildTagClassifier {
+
+    public static function parseAndLabel($text) {
+        $counts = self::parse($text);
+
+        if (!isset($counts['x86_64-darwin'])) {
+            $counts['x86_64-darwin'] = 0;
+        }
+
+        if (!isset($counts['x86_64-linux'])) {
+            $counts['x86_64-linux'] = 0;
+        }
+
+        $labels = [];
+        foreach ($counts as $arch => $count) {
+            $label[] = self::labelForArchCount($arch, $count);
+        }
+
+        return $label;
+    }
+
+    public static function parse($output) {
+        $counts = [];
+        foreach ($output as $line) {
+            if (preg_match('/^\s*(\d+) (.*)$/', $line, $matches)) {
+                $counts[$matches[2]] = (int)$matches[1];
+            }
+        }
+
+        return $counts;
+    }
+
+    public static function labelForArchCount($arch, $count) {
+        if ($arch == "x86_64-linux") {
+            $prefix = "10.rebuild-linux: ";
+        } elseif ($arch == "x86_64-darwin") {
+            $prefix = "10.rebuild-darwin: ";
+        } else {
+            throw new RebuildTagClassifierArchException("Unknown arch $arch");
+        }
+
+        if ($count > 500) {
+            $suffix = "501+";
+        } else if ($count > 100) {
+            $suffix = "101-500";
+        } else if ($count > 10) {
+            $suffix = "11-100";
+        } else if ($count > 1) {
+            $suffix = "1-10";
+        } else {
+            $suffix = "0";
+        }
+
+        return $prefix . $suffix;
+    }
+}
+
+class RebuildTagClassifierArchException extends \Exception {}
\ No newline at end of file
diff --git a/src/TestRebuildTagClassifier.php b/src/TestRebuildTagClassifier.php
new file mode 100644
index 0000000..cc95a93
--- /dev/null
+++ b/src/TestRebuildTagClassifier.php
@@ -0,0 +1,83 @@
+<?php
+
+
+namespace GHE;
+
+class TestRebuildTagClassifier extends \PHPUnit\Framework\TestCase
+{
+    function testExecParseAndLabelGarbage() {
+        $this->assertEquals(
+            ["10.rebuild-darwin: 0", "10.rebuild-linux: 0", ],
+            RebuildTagClassifier::parseAndLabel(["foo", "bar"])
+        );
+    }
+
+    function testExecParseAndLabelLinuxOnly() {
+        $this->assertEquals(
+            ["10.rebuild-linux: 1-10", "10.rebuild-darwin: 0", ],
+            RebuildTagClassifier::parseAndLabel(["  5 x86_64-linux"])
+        );
+    }
+
+    function testExecParseAndLabelDarwinOnly() {
+        $this->assertEquals(
+            ["10.rebuild-darwin: 1-10", "10.rebuild-linux: 0", ],
+            RebuildTagClassifier::parseAndLabel(["  5 x86_64-darwin"])
+        );
+    }
+
+    function testExecParseAndLabelLinuxAndDarwin() {
+        $this->assertEquals(
+            ["10.rebuild-linux: 1-10", "10.rebuild-darwin: 11-100", ],
+            RebuildTagClassifier::parseAndLabel(["  5 x86_64-linux", "    17 x86_64-darwin"])
+        );
+    }
+
+
+
+    function testExecParseNone() {
+        $this->assertEquals(
+            [],
+            RebuildTagClassifier::parse([])
+        );
+    }
+
+    function testExecParseGarbage() {
+        $this->assertEquals(
+            [],
+            RebuildTagClassifier::parse(["foo", "bar"])
+        );
+    }
+
+    function testExecParseLinuxOnly() {
+        $this->assertEquals(
+            ["x86_64-linux" => 5],
+            RebuildTagClassifier::parse(["  5 x86_64-linux"])
+        );
+    }
+
+    function testExecParseDarwinOnly() {
+        $this->assertEquals(
+            ["x86_64-darwin" => 5],
+            RebuildTagClassifier::parse(["  5 x86_64-darwin"])
+        );
+    }
+
+    function testExecParseLinuxAndDarwin() {
+        $this->assertEquals(
+            ["x86_64-linux" => 5, "x86_64-darwin" => 17],
+            RebuildTagClassifier::parse(["  5 x86_64-linux", "    17 x86_64-darwin"])
+        );
+    }
+
+    function testLabelForArchCount() {
+        $this->assertEquals("10.rebuild-linux: 501+", RebuildTagClassifier::labelForArchCount("x86_64-linux", 501));
+        $this->assertEquals("10.rebuild-linux: 101-500", RebuildTagClassifier::labelForArchCount("x86_64-linux", 150));
+        $this->assertEquals("10.rebuild-darwin: 101-500", RebuildTagClassifier::labelForArchCount("x86_64-darwin", 150));
+    }
+
+    function testLabelForUnknownArch() {
+        $this->expectException(RebuildTagClassifierArchException::class);
+        RebuildTagClassifier::labelForArchCount("lmao", 150);
+    }
+}
\ No newline at end of file