defmodule Microwaveprop.Weather.MapLayers do
  @moduledoc false

  @layers [
    %{
      id: "temperature",
      label: "Temperature",
      unit: "°C",
      group: "Surface",
      desc: "2m air temperature. Warm, humid air increases refractivity and ducting potential at lower frequencies."
    },
    %{
      id: "dewpoint_depression",
      label: "Td Depression",
      unit: "°C",
      group: "Surface",
      desc:
        "Temperature minus dewpoint. Small values (< 5°C) mean moist boundary layer — favorable for ducting at 10 GHz, but increases absorption above 24 GHz."
    },
    %{
      id: "surface_rh",
      label: "Humidity",
      unit: "%",
      group: "Surface",
      desc:
        "Relative humidity from surface T and Td. High RH supports refractivity gradients that bend microwave signals."
    },
    %{
      id: "pwat",
      label: "PWAT",
      unit: "mm",
      group: "Surface",
      desc:
        "Precipitable water — total moisture in the atmospheric column. High values signal rain fade risk for 24 GHz and above."
    },
    %{
      id: "surface_refractivity",
      label: "Refractivity",
      unit: "N",
      group: "Surface",
      desc:
        "Radio refractivity (N-units) at the surface. Typical values 280–380. Higher N means the atmosphere bends signals more toward the ground."
    },
    %{
      id: "refractivity_gradient",
      label: "N-Gradient",
      unit: "N/km",
      group: "Surface",
      desc:
        "Minimum refractivity gradient in the profile. Standard is −40 N/km. Below −157 N/km signals are trapped in a duct. More negative = stronger ducting."
    },
    %{
      id: "bl_height",
      label: "BL Height",
      unit: "m",
      group: "Surface",
      desc:
        "Planetary boundary layer height. Shallow BL (< 500m) concentrates moisture and heat near the surface, favoring temperature inversions and ducting."
    },
    %{
      id: "temp_850mb",
      label: "T @ 850mb",
      unit: "°C",
      group: "Upper Air",
      desc:
        "Temperature at 850 mb (~1500m altitude). Warm 850mb air over cool surface air indicates a capping inversion — a classic ducting setup."
    },
    %{
      id: "dewpoint_850mb",
      label: "Td @ 850mb",
      unit: "°C",
      group: "Upper Air",
      desc:
        "Dewpoint at 850 mb. A sharp moisture drop between the surface and 850mb creates an elevated refractivity gradient that can form ducts."
    },
    %{
      id: "temp_700mb",
      label: "T @ 700mb",
      unit: "°C",
      group: "Upper Air",
      desc:
        "Temperature at 700 mb (~3000m altitude). The classic capping diagnostic over the southern Plains: ≥10°C indicates a moderate cap, ≥12°C strong. Combined with warm 850 mb, signals a 'loaded gun' setup that suppresses convection until forcing arrives."
    },
    %{
      id: "dewpoint_700mb",
      label: "Td @ 700mb",
      unit: "°C",
      group: "Upper Air",
      desc:
        "Dewpoint at 700 mb. Wide depressions (T-Td > 10°C) signal the elevated mixed layer (EML) plume — a hallmark cap mechanism off the Mexican plateau."
    },
    %{
      id: "lapse_rate",
      label: "Lapse Rate",
      unit: "°C/km",
      group: "Upper Air",
      desc:
        "Temperature decrease per km from surface to 700mb. Low rates (< 5 °C/km) mean stable air that preserves inversions. High rates (> 8) mean convective mixing that destroys them."
    },
    %{
      id: "mid_lapse_rate",
      label: "Mid Lapse 850-700",
      unit: "°C/km",
      group: "Upper Air",
      desc:
        "Lapse rate across the 850→700 mb layer. Steep values (≥7 °C/km) above a warm moist boundary layer indicate an elevated mixed layer — the textbook cap structure that holds back convection until the inversion is broken."
    },
    %{
      id: "inversion_strength",
      label: "Inversion",
      unit: "°C",
      group: "Upper Air",
      desc:
        "Strongest temperature increase between adjacent levels. Inversions trap microwave signals. > 3°C is significant, > 5°C is strong."
    },
    %{
      id: "inversion_base_m",
      label: "Inv. Base",
      unit: "m",
      group: "Upper Air",
      desc:
        "Height (m AGL) where the strongest inversion begins. Surface-based inversions (< 200m) create surface ducts. Elevated inversions create elevated ducts."
    },
    %{
      id: "ducting",
      label: "Ducting",
      unit: "",
      group: "Ducting",
      desc:
        "Whether a trapping layer (modified refractivity decreasing with height) was detected in the profile. Green = duct present, signals can travel far beyond line of sight."
    },
    %{
      id: "duct_base_m",
      label: "Duct Base",
      unit: "m",
      group: "Ducting",
      desc:
        "Height of the lowest duct base. Surface ducts (< 100m) are most effective for ground-based stations. Elevated ducts require antennas near the duct height."
    },
    %{
      id: "duct_strength",
      label: "Duct Strength",
      unit: "M",
      group: "Ducting",
      desc:
        "Duct trapping strength in modified refractivity (M) units. > 10 M is moderate, > 20 M is strong. Stronger ducts trap a wider range of frequencies."
    }
  ]

  @default_layer "temperature"
  @valid_ids MapSet.new(Enum.map(@layers, & &1.id))

  @spec all() :: [map()]
  def all, do: @layers

  @spec default_id() :: String.t()
  def default_id, do: @default_layer

  @spec valid_id?(term()) :: boolean()
  def valid_id?(id) when is_binary(id), do: MapSet.member?(@valid_ids, id)
  def valid_id?(_id), do: false
end
