defmodule Credo.Check.Consistency.ParameterPatternMatching do
  @moduledoc false

  @checkdoc """
  When capturing a parameter using pattern matching you can either put the name before or after the value
  i.e.

    def parse({:ok, values} = pair)

  or

    def parse(pair = {:ok, values})

  While this is not necessarily a concern for the correctness of your code,
  you should use a consistent style throughout your codebase.
  """
  @explanation [check: @checkdoc]
  @collector Credo.Check.Consistency.ParameterPatternMatching.Collector

  use Credo.Check, run_on_all: true, base_priority: :high

  @doc false
  def run(source_files, exec, params \\ []) when is_list(source_files) do
    @collector.find_and_append_issues(source_files, exec, params, &issues_for/3)
  end

  defp issues_for(expected, source_file, params) do
    issue_meta = IssueMeta.for(source_file, params)

    issue_locations = @collector.find_locations_not_matching(expected, source_file)

    Enum.map(issue_locations, fn location ->
      format_issue(issue_meta, [{:message, message_for(expected)} | location])
    end)
  end

  defp message_for(expected) do
    actual = @collector.actual_for(expected)

    "File has #{message_for_kind(actual)} while most of the files " <>
      "have #{message_for_kind(expected)} when naming parameter pattern matches"
  end

  defp message_for_kind(:after), do: "the variable name after the pattern"
  defp message_for_kind(:before), do: "the variable name before the pattern"
end