fix case sensitive headers (#392)

* fix header

* add test

* more tests

* eh

* eh

* one more test

* format a bit

Author: ruslandoga

.typos.toml

@@ -2,3 +2,4 @@
 "som" = "som" # ./test/ch/ecto_type_test.exs
 "ECT" = "ECT" # ./test/ch/query_test.exs
 "Evn" = "Evn" # ./CHANGELOG.md
+"Fo" = "Fo"   # ./test/ch/query_test.exs

lib/ch.ex

@@ -221,6 +221,7 @@ defmodule Ch do
     headers =
       options
       |> Keyword.get(:headers, [])
+      |> Enum.map(fn {k, v} -> {String.downcase(k), v} end)
       |> put_new_header("user-agent", @user_agent)
       |> put_new_header("x-clickhouse-format", "RowBinaryWithNamesAndTypes")
 

test/ch/query_test.exs

@@ -492,6 +492,63 @@ defmodule Ch.QueryTest do
       assert :proplists.get_keys(headers_continue) == :proplists.get_keys(headers_normal)
     end
 
+    test "mixed-case x-clickhouse-format overrides the default", %{
+      conn: conn,
+      query_options: query_options
+    } do
+      for header_name <- [
+            "x-clickhouse-format",
+            "X-ClickHouse-Format",
+            "x-ClIcKhOuSe-FoRmAt"
+          ] do
+        assert %Ch.Result{data: "1\n", headers: headers, names: nil, rows: nil} =
+                 Ch.query!(
+                   conn,
+                   "SELECT 1",
+                   %{},
+                   Keyword.merge(query_options, headers: [{header_name, "CSV"}])
+                 )
+
+        assert :proplists.get_value("x-clickhouse-format", headers) == "CSV"
+      end
+    end
+
+    test "mixed-case user-agent overrides the default", %{
+      conn: conn,
+      query_options: query_options
+    } do
+      assert %Ch.Result{rows: [["custom-agent/ABC"]]} =
+               Ch.query!(
+                 conn,
+                 "SELECT getClientHTTPHeader('user-agent')",
+                 %{},
+                 Keyword.merge(query_options,
+                   headers: [{"User-Agent", "custom-agent/ABC"}],
+                   settings: [allow_get_client_http_header: 1]
+                 )
+               )
+    end
+
+    test "first x-clickhouse-format header wins regardless of case", %{
+      conn: conn,
+      query_options: query_options
+    } do
+      assert %Ch.Result{data: "1\n", headers: headers} =
+               Ch.query!(
+                 conn,
+                 "SELECT 1",
+                 %{},
+                 Keyword.merge(query_options,
+                   headers: [
+                     {"X-ClickHouse-Format", "CSV"},
+                     {"x-clickhouse-format", "JSONEachRow"}
+                   ]
+                 )
+               )
+
+      assert :proplists.get_value("x-clickhouse-format", headers) == "CSV"
+    end
+
     test "connection works after failure in execute", %{conn: conn, query_options: query_options} do
       assert {:error, %Ch.Error{}} = Ch.query(conn, "wat", [], query_options)
       assert [[42]] = Ch.query!(conn, "SELECT 42", [], query_options).rows