Much nicer!!
lgp
drolll
One more cleanup tweak:
defmodule JsonAPI do
@c %{"posts"=>100,"comments"=>500,"albums"=>100,"photos"=>5000,"todos"=>200,"users"=>10}
@b "https://jsonplaceholder.typicode.com/"
def query(c, id \\ 0, keys \\ []), do: chk_input(c, id) |> request({c, id, keys})
defp chk_input(c, id), do: is_cat(c in Map.keys(@c), c, id)
defp is_cat(true, c, id), do: in_range(id <= @c[c], c)
defp is_cat(_, c, _ ), do: {:error, "'#{c}' is invalid"}
defp in_range(true, _ ), do: :ok
defp in_range( _ , c ), do: {:error, "#{c} max id: #{@c[c]}"}
defp request( :ok, {c, id, keys}), do: lookup(c, id) |> reply(keys)
defp request({:error, msg}, _ ), do: msg
defp lookup(c, 0), do: HTTPoison.get("#{@b}#{c}")
defp lookup(c, i), do: HTTPoison.get("#{@b}#{c}/#{to_string(i)}")
defp reply({:error, reason }, _ ), do: {:error, reason}
defp reply({_,%{status_code: 200,body: b}},[]), do: {:ok, parse(b) }
defp reply({_,%{status_code: 200,body: b}},k), do: {:ok, filter(b, k) }
defp reply({_,%{status_code: s, body: b}},_), do: {:error,s,filter(b,["message"])}
defp filter(body, keys), do: parse(body) |> get_in(keys)
defp parse(body), do: Poison.Parser.parse!(body, %{})
end
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