I’ve got a bit of a real world problem that I’m trying to teach myself through and am straight stuck. I’ve tried a handful of things to get to where I want to be…but just don’t have enough base knowledge to work through it. Obviously I could put this away and come back to it, but figure asking for a little help/tutoring is better. I’ve started with enumerating over a ‘categories’ list, then piping it into a Map.update, accumulating things but bah, didn’t get close.

Here’s the module:

defmodule Categories do
  def categorize!(directory, categories) do
    result = %{}
    cat1 = find_types_for_cat(directory, categories[:cat1])

    result =
      if Kernel.length(cat1[:cat1]) > 0 do
        Map.merge(result, cat1)
      else
        result
      end

    cat2 = find_types_for_cat(directory, categories[:cat2])

    result =
      if Kernel.length(cat2[:cat2]) > 0 do
        Map.merge(result, cat2)
      else
        result
      end

    cat3 = find_types_for_cat(directory, categories[:cat3])

    result =
      if Kernel.length(cat3[:cat3]) > 0 do
        Map.merge(result, cat3)
      else
        result
      end

    result
  end

  def find_types_for_cat(directory, category) do
    %{category.name => Path.wildcard("#{directory}/**/#{Category.types_to_string(category)}")}
  end
end

The struct:

defmodule Category do
  alias __MODULE__

  defstruct name: nil, types: []

  def types_to_string(category) do
    types = Enum.join(category.types, ",")
    "{" <> types <> "}"
  end
end

And here’s the tests:

defmodule CategoriesTest do
  use ExUnit.Case, async: true
  doctest Categories

  setup_all do
    category_one = %Category{name: :cat1, types: ["type1", "type1.1"]}
    category_two = %Category{name: :cat2, types: ["type2", "type2.1"]}
    category_three = %Category{name: :cat3, types: ["type3"]}

    ## TODO: Make this an extensible list of categories, no keys
    cat_map = %{:cat1 => category_one, :cat2 => category_two, :cat3 => category_three}
    [categories: cat_map]
  end

  describe "greets the world with bad Elixir" do
    test "dir1", %{categories: categories} do
      expected = %{
        cat1: ["test/dirs/dir1/type1"]
      }

      assert Categories.categorize!("test/dirs/dir1", categories) == expected
    end

    test "dir2", %{categories: categories} do
      expected = %{
        cat1: ["test/dirs/dir2/subdir1/type1", "test/dirs/dir2/type1"],
        cat2: ["test/dirs/dir2/subdir2/type2", "test/dirs/dir2/type2.1"]
      }

      assert Categories.categorize!("test/dirs/dir2", categories) == expected
    end

    test "dir3", %{categories: categories} do
      expected = %{
        cat1: ["test/dirs/dir3/subdir2/type1", "test/dirs/dir3/type1", "test/dirs/dir3/type1.1"],
        cat2: ["test/dirs/dir3/subdir3/type2", "test/dirs/dir3/type2"],
        cat3: ["test/dirs/dir3/subdir1/type3", "test/dirs/dir3/type3"]
      }

      assert Categories.categorize!("test/dirs/dir3", categories) == expected
    end
  end
end

I’ve also created a simple project to work on the problem if that’s easier to look at than pasted code blocks here.

Appreciate any help/guidance I can get. TIA.

Kit