Accept various date/time formats in CSV import

Parse US dates (6/15/2024 2:30 PM), 24h (06/15/2024 14:30),
dashes (06-15-2024 14:30), compact (20240615 1430), date-only
(2024-06-15), and ISO 8601 — all normalized to UTC before insert.

lib/microwaveprop/radio/csv_import.ex

@@ -65,19 +65,94 @@ defmodule Microwaveprop.Radio.CsvImport do
         |> Map.new()
         |> Map.put("submitter_email", submitter_email)
 
-      case Radio.create_contact(attrs) do
-        {:ok, contact} ->
-          ContactWeatherEnqueueWorker.enqueue_for_contact(contact)
-          {:ok, contact}
+      case normalize_timestamp(attrs["qso_timestamp"]) do
+        {:ok, iso_timestamp} ->
+          attrs = Map.put(attrs, "qso_timestamp", iso_timestamp)
 
-        {:error, changeset} ->
-          {:error, changeset_error_strings(changeset)}
+          case Radio.create_contact(attrs) do
+            {:ok, contact} ->
+              ContactWeatherEnqueueWorker.enqueue_for_contact(contact)
+              {:ok, contact}
+
+            {:error, changeset} ->
+              {:error, changeset_error_strings(changeset)}
+          end
+
+        {:error, msg} ->
+          {:error, [msg]}
       end
     else
       {:error, ["expected #{@expected_columns} columns, got #{length(fields)}"]}
     end
   end
 
+  @doc """
+  Parses various date/time formats into ISO 8601 UTC strings.
+
+  Accepted formats:
+    - ISO 8601: 2024-06-15T14:30:00Z, 2024-06-15 14:30:00Z, 2024-06-15T14:30:00
+    - US date: 06/15/2024 14:30, 6/15/2024 2:30 PM
+    - US date: 06-15-2024 14:30
+    - EU date: 15/06/2024 14:30
+    - Date only: 2024-06-15 (assumes 00:00 UTC)
+    - Compact: 20240615 1430, 20240615T143000
+  """
+  def normalize_timestamp(raw) do
+    trimmed = String.trim(raw)
+
+    cond do
+      # Already ISO 8601 with timezone
+      match?({:ok, _, _}, DateTime.from_iso8601(trimmed)) ->
+        {:ok, trimmed}
+
+      # ISO-ish without Z: 2024-06-15T14:30:00 or 2024-06-15 14:30:00
+      Regex.match?(~r/^\d{4}-\d{2}-\d{2}[T ]\d{2}:\d{2}(:\d{2})?$/, trimmed) ->
+        {:ok, trimmed <> "Z"}
+
+      # Date only: 2024-06-15
+      Regex.match?(~r/^\d{4}-\d{2}-\d{2}$/, trimmed) ->
+        {:ok, trimmed <> "T00:00:00Z"}
+
+      # US format with AM/PM: 6/15/2024 2:30 PM or 06/15/2024 02:30 PM
+      match = Regex.run(~r"^(\d{1,2})/(\d{1,2})/(\d{4})\s+(\d{1,2}):(\d{2})\s*(AM|PM)$"i, trimmed) ->
+        [_, m, d, y, h, min, ampm] = match
+        hour = parse_12h(String.to_integer(h), String.upcase(ampm))
+        format_iso(y, m, d, hour, min)
+
+      # US format 24h: 6/15/2024 14:30 or 06/15/2024 14:30:00
+      match = Regex.run(~r"^(\d{1,2})/(\d{1,2})/(\d{4})\s+(\d{1,2}):(\d{2})(:\d{2})?$", trimmed) ->
+        [_, m, d, y, h, min | _] = match
+        format_iso(y, m, d, String.to_integer(h), min)
+
+      # US format with dashes: 06-15-2024 14:30
+      match = Regex.run(~r"^(\d{1,2})-(\d{1,2})-(\d{4})\s+(\d{1,2}):(\d{2})(:\d{2})?$", trimmed) ->
+        [_, m, d, y, h, min | _] = match
+        format_iso(y, m, d, String.to_integer(h), min)
+
+      # Compact: 20240615 1430 or 20240615T143000
+      match = Regex.run(~r"^(\d{4})(\d{2})(\d{2})[T ]?(\d{2})(\d{2})(\d{2})?$", trimmed) ->
+        [_, y, m, d, h, min | _] = match
+        format_iso(y, m, d, String.to_integer(h), min)
+
+      true ->
+        {:error, "qso_timestamp could not be parsed: #{trimmed}"}
+    end
+  end
+
+  defp parse_12h(12, "AM"), do: 0
+  defp parse_12h(12, "PM"), do: 12
+  defp parse_12h(h, "PM"), do: h + 12
+  defp parse_12h(h, "AM"), do: h
+
+  defp format_iso(y, m, d, hour, min) do
+    y = String.pad_leading(to_string(y), 4, "0")
+    m = String.pad_leading(to_string(m), 2, "0")
+    d = String.pad_leading(to_string(d), 2, "0")
+    h = String.pad_leading(to_string(hour), 2, "0")
+    min = String.pad_leading(to_string(min), 2, "0")
+    {:ok, "#{y}-#{m}-#{d}T#{h}:#{min}:00Z"}
+  end
+
   defp changeset_error_strings(changeset) do
     changeset
     |> Ecto.Changeset.traverse_errors(fn {message, opts} ->

lib/microwaveprop_web/live/submit_live.ex

@@ -261,7 +261,10 @@ defmodule MicrowavepropWeb.SubmitLive do
         </p>
         <code class="text-xs">station1, station2, grid1, grid2, band, mode, qso_timestamp</code>
         <ul class="list-disc list-inside mt-2 space-y-1 text-base-content/60">
-          <li>Timestamps must be ISO 8601 UTC, e.g. <code>2024-06-15T14:30:00Z</code></li>
+          <li>
+            Timestamps in most formats accepted (e.g. <code>2024-06-15T14:30:00Z</code>,
+            <code>6/15/2024 2:30 PM</code>, <code>2024-06-15 14:30</code>). All times assumed UTC.
+          </li>
           <li>Grid squares should be as detailed as possible (6 characters preferred, e.g. EM12kp)</li>
           <li>Band in MHz (e.g. 10000, 24000)</li>
         </ul>