prop/test/microwaveprop/weather/era5_client_test.exs

defmodule Microwaveprop.Weather.Era5ClientTest do
  # async: false — tests mutate the global ERA5_CDS_API_KEY env var to match
  # production's lookup path. Running concurrently with Era5BatchClientTest
  # (which *deletes* the env var to exercise the missing-key error path)
  # leaks state in both directions.
  use ExUnit.Case, async: false

  alias Microwaveprop.Weather.Era5Client

  setup do
    # A real key — stubs don't care about value, only presence.
    System.put_env("ERA5_CDS_API_KEY", "test-key")
    on_exit(fn -> System.delete_env("ERA5_CDS_API_KEY") end)
    :ok
  end

  describe "submit_job/2" do
    test "returns {:ok, job_id} when CDS accepts the request" do
      Req.Test.stub(Era5Client, fn conn ->
        assert conn.method == "POST"
        assert String.ends_with?(conn.request_path, "/reanalysis-era5-single-levels/execution")
        Req.Test.json(conn, %{"jobID" => "cds-job-123", "status" => "accepted"})
      end)

      assert {:ok, "cds-job-123"} =
               Era5Client.submit_job("reanalysis-era5-single-levels", %{"foo" => "bar"})
    end

    test "returns {:error, _} when CDS returns 400" do
      Req.Test.stub(Era5Client, fn conn ->
        conn
        |> Plug.Conn.put_resp_content_type("application/json")
        |> Plug.Conn.resp(400, ~s({"detail":"bad request"}))
      end)

      assert {:error, reason} = Era5Client.submit_job("reanalysis-era5-single-levels", %{})
      assert reason =~ "HTTP 400"
    end

    test "returns {:error, _} when API key is missing" do
      System.delete_env("ERA5_CDS_API_KEY")
      assert {:error, reason} = Era5Client.submit_job("reanalysis-era5-single-levels", %{})
      assert reason =~ "ERA5_CDS_API_KEY"
    end
  end

  describe "check_status/1" do
    test "returns :running while CDS job is accepted" do
      Req.Test.stub(Era5Client, fn conn ->
        assert conn.method == "GET"
        assert String.ends_with?(conn.request_path, "/jobs/cds-job-123")
        Req.Test.json(conn, %{"status" => "accepted"})
      end)

      assert :running = Era5Client.check_status("cds-job-123")
    end

    test "returns :running while CDS job is running" do
      Req.Test.stub(Era5Client, fn conn ->
        Req.Test.json(conn, %{"status" => "running"})
      end)

      assert :running = Era5Client.check_status("cds-job-123")
    end

    test "returns {:done, {:url, href}} when CDS job completes with an asset href" do
      Req.Test.stub(Era5Client, fn conn ->
        case conn.request_path do
          "/api/retrieve/v1/jobs/cds-job-123" ->
            Req.Test.json(conn, %{"status" => "successful"})

          "/api/retrieve/v1/jobs/cds-job-123/results" ->
            Req.Test.json(conn, %{
              "asset" => %{"value" => %{"href" => "https://example.com/file.grib"}}
            })
        end
      end)

      assert {:done, {:url, "https://example.com/file.grib"}} =
               Era5Client.check_status("cds-job-123")
    end

    test "returns {:failed, _} when CDS reports the job failed" do
      Req.Test.stub(Era5Client, fn conn ->
        assert conn.request_path == "/api/retrieve/v1/jobs/cds-job-123"
        Req.Test.json(conn, %{"status" => "failed", "message" => "input out of range"})
      end)

      assert {:failed, reason} = Era5Client.check_status("cds-job-123")
      assert reason =~ "input out of range"
    end

    test "returns :not_found when CDS returns 404 for the job" do
      # 404 means the CDS job was deleted or never existed. This is terminal —
      # retrying will always 404 — so callers should treat it as a distinct
      # state from the generic {:error, _} retryable bucket.
      Req.Test.stub(Era5Client, fn conn ->
        conn
        |> Plug.Conn.put_resp_content_type("application/json")
        |> Plug.Conn.resp(
          404,
          ~s({"detail":"job cds-job-123 deleted","status":404,"title":"job not found"})
        )
      end)

      assert :not_found = Era5Client.check_status("cds-job-123")
    end

    test "returns {:rejected, reason} when CDS marks the job as rejected" do
      # CDS rejects submits when the user's in-flight queue is over the cap
      # (150 jobs). The rejected job still gets a jobID and a GET /jobs/:id
      # returns a body with status=rejected. This is terminal — re-polling
      # will never transition to successful — so callers should treat it
      # like {:failed, _} and re-submit the tile-month.
      Req.Test.stub(Era5Client, fn conn ->
        Req.Test.json(conn, %{
          "jobID" => "cds-job-123",
          "status" => "rejected",
          "metadata" => %{"origin" => "api"}
        })
      end)

      assert {:rejected, reason} = Era5Client.check_status("cds-job-123")
      assert is_binary(reason)
    end
  end

  describe "delete_job/1" do
    test "sends DELETE to the CDS jobs endpoint and returns :ok on 204" do
      test_pid = self()

      Req.Test.stub(Era5Client, fn conn ->
        send(test_pid, {:delete_request, conn.method, conn.request_path})
        Plug.Conn.resp(conn, 204, "")
      end)

      assert :ok = Era5Client.delete_job("cds-job-123")
      assert_received {:delete_request, "DELETE", "/api/retrieve/v1/jobs/cds-job-123"}
    end

    test "also treats 200/202/404 as success (CDS sometimes returns 200 or the job may already be gone)" do
      for status <- [200, 202, 404] do
        Req.Test.stub(Era5Client, fn conn -> Plug.Conn.resp(conn, status, "") end)
        assert :ok = Era5Client.delete_job("cds-job-#{status}")
      end
    end

    test "returns {:error, _} for unexpected statuses" do
      Req.Test.stub(Era5Client, fn conn -> Plug.Conn.resp(conn, 500, "server error") end)
      assert {:error, reason} = Era5Client.delete_job("cds-job-500")
      assert reason =~ "HTTP 500"
    end
  end

  describe "download_source_to_file/3" do
    test "writes a {:body, binary} source directly to the target path" do
      path = Path.join(System.tmp_dir!(), "era5_test_#{System.unique_integer([:positive])}.grib")

      try do
        assert :ok = Era5Client.download_source_to_file({:body, "grib-payload"}, nil, path)
        assert File.read!(path) == "grib-payload"
      after
        File.rm(path)
      end
    end

    test "streams a {:url, href} source through Req into the target path" do
      Req.Test.stub(Era5Client, fn conn ->
        assert conn.method == "GET"

        conn
        |> Plug.Conn.put_resp_content_type("application/octet-stream")
        |> Plug.Conn.resp(200, "streamed-grib-data")
      end)

      path = Path.join(System.tmp_dir!(), "era5_test_#{System.unique_integer([:positive])}.grib")

      try do
        assert :ok =
                 Era5Client.download_source_to_file(
                   {:url, "https://example.com/file.grib"},
                   "test-key",
                   path
                 )

        assert File.read!(path) == "streamed-grib-data"
      after
        File.rm(path)
      end
    end

    test "removes partial file and returns {:error, _} on HTTP error" do
      Req.Test.stub(Era5Client, fn conn ->
        Plug.Conn.resp(conn, 503, "")
      end)

      path = Path.join(System.tmp_dir!(), "era5_test_#{System.unique_integer([:positive])}.grib")

      assert {:error, reason} =
               Era5Client.download_source_to_file(
                 {:url, "https://example.com/file.grib"},
                 "test-key",
                 path
               )

      assert reason =~ "HTTP 503"
      refute File.exists?(path)
    end
  end

  describe "pressure_levels/0" do
    test "covers upper troposphere and lower stratosphere for the skew-T plot" do
      levels = Enum.map(Era5Client.pressure_levels(), &String.to_integer/1)

      # Boundary-layer resolution near the surface stays intact.
      assert 1000 in levels
      assert 700 in levels

      # Upper-air levels needed to fill out the skew-T above 700 mb.
      for level <- [500, 300, 200, 100] do
        assert level in levels, "expected #{level} mb in Era5Client.pressure_levels/0"
      end
    end
  end
end