Parse history file

lib/mihainator/csv_parser.ex

@@ -3,7 +3,35 @@ defmodule Mihainator.CSVParser do
 
   def start(file) do
     File.stream!(file)
-    |> Stream.map(&String.split(&1, ","))
-    |> Enum.count()
+    |> CSV.decode!(separator: ?,, headers: true, escape_max_lines: 100)
+    |> Stream.chunk_every(2, 1, :discard)
+    |> Stream.filter(&next_day?/1)
+    |> Stream.map(&extract_data/1)
+    |> Enum.to_list()
+  end
+
+  defp next_day?([%{"posted_at" => current}, %{"posted_at" => next}]) do
+    current =
+      current
+      |> String.to_integer()
+      |> DateTime.from_unix!(:millisecond)
+
+    next =
+      next
+      |> String.to_integer()
+      |> DateTime.from_unix!(:millisecond)
+
+    Date.diff(next, current) == 1
+  end
+
+  defp extract_data([_, %{"isoutbox" => is_out, "posted_at" => posted_at}]) do
+    is_out = is_out == "1"
+
+    posted_at =
+      posted_at
+      |> String.to_integer()
+      |> DateTime.from_unix!(:millisecond)
+
+    [is_out, posted_at]
   end
 end