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 "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 "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
end