Graham McIntire
7d0978f7d5
Maidenhead grid module converts grid squares to lat/lon coordinates. Submission form validates grids, bands, modes, and email, computes positions and distance, then triggers the weather/HRRR/terrain processing pipeline via Oban.
41 lines
982 B
Elixir
41 lines
982 B
Elixir
defmodule Microwaveprop.Radio.Maidenhead do
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@moduledoc false
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@spec valid?(any()) :: boolean()
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def valid?(nil), do: false
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def valid?(grid) when is_binary(grid) do
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String.match?(grid, ~r/^[A-Ra-r]{2}[0-9]{2}$/) or
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String.match?(grid, ~r/^[A-Ra-r]{2}[0-9]{2}[A-Xa-x]{2}$/)
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end
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def valid?(_), do: false
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@spec to_latlon(any()) :: {:ok, {float(), float()}} | :error
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def to_latlon(nil), do: :error
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def to_latlon(grid) when is_binary(grid) do
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grid = String.upcase(grid)
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if valid?(grid) do
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<<f1, f2, s1, s2>> <> rest = grid
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lon = (f1 - ?A) * 20 + (s1 - ?0) * 2 - 180
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lat = (f2 - ?A) * 10 + (s2 - ?0) * 1 - 90
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case rest do
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<<ss1, ss2>> ->
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lon = lon + (ss1 - ?A) * (5 / 60) + 5 / 120
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lat = lat + (ss2 - ?A) * (2.5 / 60) + 2.5 / 120
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{:ok, {lat, lon}}
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"" ->
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{:ok, {lat + 0.5, lon + 1.0}}
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end
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else
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:error
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end
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end
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def to_latlon(_), do: :error
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end
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