defmodule Microwaveprop.Weather.HrrrClientTest do
  use ExUnit.Case, async: true

  alias Microwaveprop.Weather.HrrrClient

  describe "nearest_hrrr_hour/1" do
    test "rounds down when within first 30 minutes" do
      assert HrrrClient.nearest_hrrr_hour(~U[2026-03-28 18:15:00Z]) ==
               ~U[2026-03-28 18:00:00Z]
    end

    test "rounds up when past 30 minutes" do
      assert HrrrClient.nearest_hrrr_hour(~U[2026-03-28 18:45:00Z]) ==
               ~U[2026-03-28 19:00:00Z]
    end

    test "stays same when exactly on the hour" do
      assert HrrrClient.nearest_hrrr_hour(~U[2026-03-28 18:00:00Z]) ==
               ~U[2026-03-28 18:00:00Z]
    end

    test "rounds at exactly 30 minutes" do
      result = HrrrClient.nearest_hrrr_hour(~U[2026-03-28 18:30:00Z])
      assert result in [~U[2026-03-28 18:00:00Z], ~U[2026-03-28 19:00:00Z]]
    end
  end

  describe "hrrr_url/3" do
    test "builds surface product URL" do
      url = HrrrClient.hrrr_url(~D[2026-03-28], 18, :surface)

      assert url ==
               "https://noaa-hrrr-bdp-pds.s3.amazonaws.com/hrrr.20260328/conus/hrrr.t18z.wrfsfcf00.grib2"
    end

    test "builds pressure product URL" do
      url = HrrrClient.hrrr_url(~D[2026-03-28], 6, :pressure)

      assert url ==
               "https://noaa-hrrr-bdp-pds.s3.amazonaws.com/hrrr.20260328/conus/hrrr.t06z.wrfprsf00.grib2"
    end

    test "pads single-digit hours" do
      url = HrrrClient.hrrr_url(~D[2026-03-28], 3, :surface)
      assert String.contains?(url, "hrrr.t03z")
    end
  end

  describe "parse_idx/1" do
    @sample_idx """
    1:0:d=2026032818:TMP:2 m above ground:anl:
    2:1234567:d=2026032818:DPT:2 m above ground:anl:
    3:2345678:d=2026032818:PRES:surface:anl:
    4:3456789:d=2026032818:HPBL:surface:anl:
    5:4567890:d=2026032818:PWAT:entire atmosphere (considered as a single layer):anl:
    6:5678901:d=2026032818:TMP:1000 mb:anl:
    """

    test "parses idx into structured list" do
      entries = HrrrClient.parse_idx(@sample_idx)

      assert length(entries) == 6

      first = hd(entries)
      assert first.msg == 1
      assert first.offset == 0
      assert first.var == "TMP"
      assert first.level == "2 m above ground"
    end

    test "correctly extracts offsets" do
      entries = HrrrClient.parse_idx(@sample_idx)
      offsets = Enum.map(entries, & &1.offset)
      assert offsets == [0, 1_234_567, 2_345_678, 3_456_789, 4_567_890, 5_678_901]
    end

    test "handles empty input" do
      assert HrrrClient.parse_idx("") == []
    end
  end

  describe "byte_ranges_for_messages/2" do
    test "computes byte ranges from idx entries" do
      entries = [
        %{msg: 1, offset: 0, var: "TMP", level: "2 m above ground"},
        %{msg: 2, offset: 1000, var: "DPT", level: "2 m above ground"},
        %{msg: 3, offset: 2000, var: "PRES", level: "surface"},
        %{msg: 4, offset: 3000, var: "HPBL", level: "surface"}
      ]

      wanted = [
        %{var: "TMP", level: "2 m above ground"},
        %{var: "PRES", level: "surface"}
      ]

      ranges = HrrrClient.byte_ranges_for_messages(entries, wanted)

      assert length(ranges) == 2
      assert {0, 999} in ranges
      assert {2000, 2999} in ranges
    end

    test "handles last message in file" do
      entries = [
        %{msg: 1, offset: 0, var: "TMP", level: "2 m above ground"},
        %{msg: 2, offset: 1000, var: "DPT", level: "2 m above ground"}
      ]

      wanted = [%{var: "DPT", level: "2 m above ground"}]

      ranges = HrrrClient.byte_ranges_for_messages(entries, wanted)

      # Last message - uses a large end offset
      assert length(ranges) == 1
      [{start, _end}] = ranges
      assert start == 1000
    end
  end

  describe "fetch_profile/3" do
    test "succeeds when ranges are downloaded individually" do
      grib_data = File.read!("test/fixtures/grib2/hrrr_tmp_2m.grib2")

      # Idx with multiple surface variables to trigger multi-range download
      grib_size = byte_size(grib_data)

      idx_text = """
      1:0:d=2026032818:TMP:2 m above ground:anl:
      2:#{grib_size}:d=2026032818:DPT:2 m above ground:anl:
      3:#{grib_size * 2}:d=2026032818:PRES:surface:anl:
      """

      Req.Test.stub(HrrrClient, fn conn ->
        if String.ends_with?(conn.request_path, ".idx") do
          Plug.Conn.send_resp(conn, 200, idx_text)
        else
          [range] = Plug.Conn.get_req_header(conn, "range")

          if String.contains?(range, ",") do
            # Multi-range: S3 ignores Range header, returns full file
            Plug.Conn.send_resp(conn, 200, "full file")
          else
            # Single range: S3 supports this fine
            Plug.Conn.send_resp(conn, 206, grib_data)
          end
        end
      end)

      assert {:ok, profile} = HrrrClient.fetch_profile(32.90, -97.04, ~U[2026-03-28 18:00:00Z])
      assert is_float(profile.surface_temp_c)
      assert is_struct(profile.run_time, DateTime)
    end
  end

  describe "build_profile/1" do
    test "assembles profile from parsed data" do
      parsed = %{
        "TMP:1000 mb" => 298.0,
        "DPT:1000 mb" => 291.0,
        "HGT:1000 mb" => 110.0,
        "TMP:975 mb" => 296.0,
        "DPT:975 mb" => 289.0,
        "HGT:975 mb" => 350.0,
        "TMP:950 mb" => 294.0,
        "DPT:950 mb" => 287.0,
        "HGT:950 mb" => 590.0,
        "TMP:2 m above ground" => 299.0,
        "DPT:2 m above ground" => 292.0,
        "PRES:surface" => 101_350.0,
        "HPBL:surface" => 1500.0,
        "PWAT:entire atmosphere (considered as a single layer)" => 25.0
      }

      result = HrrrClient.build_profile(parsed)

      assert result.surface_temp_c == 299.0 - 273.15
      assert result.surface_dewpoint_c == 292.0 - 273.15
      assert_in_delta result.surface_pressure_mb, 1013.5, 0.1
      assert result.hpbl_m == 1500.0
      assert result.pwat_mm == 25.0
      assert length(result.profile) == 3

      first_level = hd(result.profile)
      assert first_level["pres"] == 1000.0
      assert first_level["tmpc"] == 298.0 - 273.15
      assert first_level["dwpc"] == 291.0 - 273.15
      assert first_level["hght"] == 110.0
    end

    test "includes wind, cloud cover, and precip fields" do
      parsed = %{
        "TMP:2 m above ground" => 299.0,
        "DPT:2 m above ground" => 292.0,
        "PRES:surface" => 101_350.0,
        "HPBL:surface" => 1500.0,
        "PWAT:entire atmosphere (considered as a single layer)" => 25.0,
        "UGRD:10 m above ground" => 3.5,
        "VGRD:10 m above ground" => -2.1,
        "TCDC:entire atmosphere" => 75.0,
        "APCP:surface" => 1.2
      }

      result = HrrrClient.build_profile(parsed)

      assert result.wind_u == 3.5
      assert result.wind_v == -2.1
      assert result.cloud_cover_pct == 75.0
      assert result.precip_mm == 1.2
    end

    test "wind, cloud, and precip fields are nil when missing" do
      parsed = %{
        "TMP:2 m above ground" => 299.0,
        "DPT:2 m above ground" => 292.0,
        "PRES:surface" => 101_350.0,
        "HPBL:surface" => 1500.0,
        "PWAT:entire atmosphere (considered as a single layer)" => 25.0
      }

      result = HrrrClient.build_profile(parsed)

      assert result.wind_u == nil
      assert result.wind_v == nil
      assert result.cloud_cover_pct == nil
      assert result.precip_mm == nil
    end

    test "skips pressure levels with missing data" do
      parsed = %{
        "TMP:1000 mb" => 298.0,
        "DPT:1000 mb" => 291.0,
        "HGT:1000 mb" => 110.0,
        # 975 mb missing HGT
        "TMP:975 mb" => 296.0,
        "DPT:975 mb" => 289.0,
        "TMP:2 m above ground" => 299.0,
        "DPT:2 m above ground" => 292.0,
        "PRES:surface" => 101_350.0,
        "HPBL:surface" => 1500.0,
        "PWAT:entire atmosphere (considered as a single layer)" => 25.0
      }

      result = HrrrClient.build_profile(parsed)
      assert length(result.profile) == 1
    end
  end

  describe "surface_messages/0" do
    test "returns list of surface message descriptors" do
      messages = HrrrClient.surface_messages()

      assert is_list(messages)
      assert length(messages) == 9

      vars = Enum.map(messages, & &1.var)
      assert "TMP" in vars
      assert "DPT" in vars
      assert "PRES" in vars
      assert "HPBL" in vars
      assert "PWAT" in vars
      assert "UGRD" in vars
      assert "VGRD" in vars
      assert "TCDC" in vars
      assert "APCP" in vars
    end

    test "includes wind messages at 10 m above ground" do
      messages = HrrrClient.surface_messages()

      ugrd = Enum.find(messages, &(&1.var == "UGRD"))
      assert ugrd.level == "10 m above ground"

      vgrd = Enum.find(messages, &(&1.var == "VGRD"))
      assert vgrd.level == "10 m above ground"
    end

    test "includes cloud cover for entire atmosphere" do
      messages = HrrrClient.surface_messages()
      tcdc = Enum.find(messages, &(&1.var == "TCDC"))
      assert tcdc.level == "entire atmosphere"
    end

    test "includes precipitation at surface" do
      messages = HrrrClient.surface_messages()
      apcp = Enum.find(messages, &(&1.var == "APCP"))
      assert apcp.level == "surface"
    end
  end

  describe "merge_grid_data/2" do
    test "merges surface and pressure grids by point key" do
      point_a = {32.90, -97.04}
      point_b = {33.10, -96.80}

      sfc_grid = %{
        point_a => %{
          "TMP:2 m above ground" => 299.0,
          "DPT:2 m above ground" => 292.0,
          "PRES:surface" => 101_350.0,
          "HPBL:surface" => 1500.0,
          "PWAT:entire atmosphere (considered as a single layer)" => 25.0,
          "UGRD:10 m above ground" => 3.5,
          "VGRD:10 m above ground" => -2.1,
          "TCDC:entire atmosphere" => 75.0,
          "APCP:surface" => 1.2
        },
        point_b => %{
          "TMP:2 m above ground" => 297.0,
          "DPT:2 m above ground" => 290.0,
          "PRES:surface" => 101_200.0,
          "HPBL:surface" => 1200.0,
          "PWAT:entire atmosphere (considered as a single layer)" => 22.0,
          "UGRD:10 m above ground" => 2.0,
          "VGRD:10 m above ground" => -1.5,
          "TCDC:entire atmosphere" => 50.0,
          "APCP:surface" => 0.0
        }
      }

      prs_grid = %{
        point_a => %{
          "TMP:1000 mb" => 298.0,
          "DPT:1000 mb" => 291.0,
          "HGT:1000 mb" => 110.0
        },
        point_b => %{
          "TMP:1000 mb" => 296.0,
          "DPT:1000 mb" => 289.0,
          "HGT:1000 mb" => 105.0
        }
      }

      merged = HrrrClient.merge_grid_data(sfc_grid, prs_grid)

      assert map_size(merged) == 2
      assert merged[point_a]["TMP:2 m above ground"] == 299.0
      assert merged[point_a]["TMP:1000 mb"] == 298.0
      assert merged[point_b]["TMP:2 m above ground"] == 297.0
      assert merged[point_b]["TMP:1000 mb"] == 296.0
    end

    test "handles empty pressure data" do
      point = {32.90, -97.04}

      sfc_grid = %{
        point => %{"TMP:2 m above ground" => 299.0}
      }

      merged = HrrrClient.merge_grid_data(sfc_grid, %{})

      assert map_size(merged) == 1
      assert merged[point]["TMP:2 m above ground"] == 299.0
    end
  end
end