# credo:disable-for-next-line Credo.Check.Refactor.ModuleDependencies
defmodule Mix.Tasks.Enumex.Dynamic.Gen.Enum do
  @shortdoc "Generates an enum module with dynamic values."

  args = [
    %{help: "Specifies an enum module", required: true, value_name: "MODULE"},
    %{help: "Specifies an enum name", required: true, value_name: "ENUM_NAME"},
    %{
      help: "Fields in format 'original:type' or 'original:type:modified'",
      value_name: "FIELD_1 FIELD_2 … FIELD_N"
    }
  ]

  flags = [
    %{help: "Specifies file path for enum", long: "--file", short: "-f", value_name: "FILE_PATH"},
    %{
      help: "Specifies a query prefix",
      long: "--query-prefix",
      short: "-q",
      value_name: "QUERY_PREFIX"
    },
    %{help: "Specifies an ecto repo", long: "--repo", short: "-r", value_name: "ECTO_REPO"},
    %{
      help: "Specifies a table prefix",
      long: "--table-prefix",
      short: "-t",
      value_name: "TABLE_PREFIX"
    }
  ]

  task = Enumex.Generator.Task.new("enumex.dynamic.gen.enum", args, flags)

  if Mix.env() == :test do
    try do
      :meck.new(:io, [:unstick, :passthrough])
    rescue
      _exception -> :ok
    end

    :meck.expect(:io, :columns, fn -> {:ok, 80} end)
  end

  help = Enumex.Generator.Task.help(task, @shortdoc)
  @moduledoc Enumex.Generator.Task.moduledoc(help)

  use Mix.Task

  alias Enumex.Generator.Task
  alias Mix.Generator

  require Generator

  @help help
  @opts [
    aliases: Task.aliases(~w[file table_prefix query_prefix]a),
    strict: Task.options(file: :string, query_prefix: :string, table_prefix: :string)
  ]
  @task_name task.name
  @version Task.version(task)

  @impl Mix.Task
  def run(args) do
    Task.run(@task_name, args, @help, @version, @opts, fn
      [_module], _opts -> Task.missing_args(@task_name, ["ENUM_NAME"])
      [module, name | fields], opts -> generate_enum(module, name, fields, opts)
    end)
  end

  @spec generate_enum(
          String.t(),
          String.t(),
          OptionParser.argv(),
          OptionParser.options()
        ) :: [boolean()]
  defp generate_enum(module, name, fields, opts) do
    ~r/^.+(?<last_dot>\.)[^\.]+$/
    |> Regex.split(module, on: [:last_dot])
    |> then(fn [parent_module, module_part] ->
      generate_enum(parent_module, module_part, name, fields, opts)
    end)
  end

  @spec generate_enum(
          String.t(),
          String.t(),
          String.t(),
          OptionParser.argv(),
          OptionParser.options()
        ) :: [boolean()]
  defp generate_enum(parent_module, module_part, name, fields, opts) do
    Mix.Task.run("loadpaths")
    {file_path, opts} = Keyword.pop(opts, :file, gen_file_path(parent_module))
    {chardata, enum_opts} = Enum.reduce(fields, {[], []}, &prepare_field/2)

    contents =
      enum_template(
        enum_opts: format_enum_opts(enum_opts),
        fields: IO.iodata_to_binary(chardata),
        module: parent_module,
        module_part: module_part,
        # credo:disable-for-next-line Credo.Check.Warning.UnsafeToAtom
        name: String.to_atom(name),
        opts: format_opts(opts)
      )

    file_path
    |> tap(fn path ->
      path
      |> Path.dirname()
      |> Generator.create_directory()
    end)
    |> tap(&Generator.create_file(&1, contents))
    |> List.wrap()
  end

  @spec format_enum_opts(keyword(atom())) :: String.t()
  defp format_enum_opts(enum_opts) do
    enum_opts
    |> List.keysort(0)
    |> Enum.map_join(", ", fn {key, value} -> "#{key}: #{inspect(value)}" end)
  end

  @spec format_opts(keyword(String.t())) :: String.t()
  defp format_opts(opts) do
    Enum.map_join(opts, ",\n  ", fn {key, value} -> "#{key}: #{inspect(value)}" end)
  end

  @spec gen_file_path(String.t()) :: Path.t()
  defp gen_file_path(module) do
    module
    |> Macro.underscore()
    |> then(&Path.join(["lib", &1 <> ".ex"]))
  end

  @spec prepare_field(String.t(), acc) :: acc when acc: {IO.chardata(), keyword(String.t())}
  defp prepare_field(arg, {acc, opts}) do
    arg
    |> String.split(":")
    |> prepare_field(acc, opts)
  end

  @spec prepare_field([String.t()], IO.chardata(), keyword(String.t())) ::
          {IO.chardata(), keyword(String.t())}
  defp prepare_field([original, type], acc, opts) when original in ~w[enum_name id index] do
    # credo:disable-for-next-line Credo.Check.Warning.UnsafeToAtom
    {acc, Keyword.put(opts, :"#{original}_type", String.to_atom(type))}
  end

  defp prepare_field([original, type], acc, opts) do
    # credo:disable-for-next-line Credo.Check.Warning.UnsafeToAtom
    {[acc, "\n    ", field_template(name: String.to_atom(original), type: String.to_atom(type))],
     opts}
  end

  defp prepare_field([original, type, modified], acc, opts)
       when original in ~w[enum_name id index] do
    {acc,
     Keyword.merge(
       opts,
       [
         # credo:disable-for-next-line Credo.Check.Warning.UnsafeToAtom
         {String.to_existing_atom(original), String.to_atom(modified)},
         # credo:disable-for-next-line Credo.Check.Warning.UnsafeToAtom
         {:"#{original}_type", String.to_atom(type)}
       ]
     )}
  end

  defp prepare_field([original, type, source], acc, opts) do
    {[
       acc,
       "\n    ",
       field_with_source_template(
         # credo:disable-for-next-line Credo.Check.Warning.UnsafeToAtom
         name: String.to_atom(original),
         # credo:disable-for-next-line Credo.Check.Warning.UnsafeToAtom
         source: String.to_atom(source),
         # credo:disable-for-next-line Credo.Check.Warning.UnsafeToAtom
         type: String.to_atom(type)
       )
     ], opts}
  end

  @spec enum_template(
          enum_opts: String.t(),
          fields: String.t(),
          module: String.t(),
          module_part: String.t(),
          name: atom(),
          opts: String.t()
        ) :: String.t()
  Generator.embed_template(:enum, """
  defmodule <%= @module %> do
    use Enumex.Dynamic, components: [
      # Enumex.Dynamic.Components.Context,
      # Enumex.Dynamic.Components.Convert,
      # Enumex.Dynamic.Components.EctoChangeset,
      <%= if @opts == "", do: "# Enumex.Dynamic.Components.EctoSchema", else: "# {Enumex.Dynamic.Components.EctoSchema, " <> @opts <> "}" %>,
      # Enumex.Dynamic.Components.Typespecs
    ]

    enum <%= @module_part %>, <%= inspect(@name) %><%= if @enum_opts != "", do: ", " <> @enum_opts %> do<%= if @fields != "", do: @fields %>
    end
  end
  """)

  @spec field_template(name: atom(), type: atom()) :: String.t()
  Generator.embed_template(:field, ~s[field <%= inspect(@name) %>, <%= inspect(@type) %>])

  @spec field_template(name: atom(), source: atom(), type: atom()) :: String.t()
  Generator.embed_template(
    :field_with_source,
    ~s[field <%= inspect(@name) %>, <%= inspect(@type) %>, source: <%= inspect(@source) %>]
  )
end