diff --git a/app/Parser.php b/app/Parser.php
index b74cf7b9f7..6b4440bd61 100644
--- a/app/Parser.php
+++ b/app/Parser.php
@@ -2,12 +2,59 @@
 
 namespace App;
 
-use Exception;
-
 final class Parser
 {
     public function parse(string $inputPath, string $outputPath): void
     {
-        throw new Exception('TODO');
+        \gc_disable();
+
+        $data = $this->parseInput($inputPath);
+        $this->formatOutput($outputPath, $data);
+    }
+
+    private function parseInput(string $inputPath): array
+    {
+        $data = [];
+        $counters = \array_fill(0, 32 * 16 * 6, 0);
+
+        $stream = \fopen($inputPath, 'rb');
+        \stream_set_read_buffer($stream, 16 << 20);
+
+        while (4 === \fscanf($stream, 'https://stitcher.io/blog/%[^,],%d-%d-%d', $path, $y, $m, $d)) {
+            $data[$path] ??= $counters;
+            ++$data[$path][($y - 2021) << 9 | $m << 5 | $d];
+        }
+
+        \fclose($stream);
+
+        return $data;
+    }
+
+    private function formatOutput(string $outputPath, array $data): void
+    {
+        $stream = \fopen($outputPath, 'wb');
+        \stream_set_write_buffer($stream, 16 << 20);
+
+        $path_sep = "{";
+        foreach ($data as $path => $counters) {
+            \fwrite($stream, "{$path_sep}\n    \"\\/blog\\/{$path}\": {\n");
+            $date_sep = '';
+            foreach ($counters as $date => $count) {
+                if ($count !== 0) {
+                    \fprintf(
+                        $stream,
+                        "{$date_sep}        \"%d-%02d-%02d\": {$count}",
+                        ($date >> 9) + 2021,
+                        ($date >> 5) & 0b1111,
+                        $date & 0b11111,
+                    );
+                    $date_sep = ",\n";
+                }
+            }
+            $path_sep = "\n    },";
+        }
+        \fwrite($stream, "\n    }\n}");
+
+        \fsync($stream) and \fclose($stream);
     }
-}
\ No newline at end of file
+}