defmodule Bylaw.Credo.Check.Elixir.NoEndOfDayTime do
  @moduledoc """
  Avoid `~T[23:59:59]` as an end-of-day bound.

  ## Examples

  Avoid:

        occurred_at >= day_start and occurred_at <= ~T[23:59:59]

  Prefer:

        occurred_at >= day_start and occurred_at < next_day_start

  ## Notes

  An inclusive `23:59:59` bound misses values with fractional seconds, such
  as `23:59:59.500000`. That creates edge-case bugs for timestamp and time
  comparisons.

  Use the next day's midnight as an exclusive upper bound. Half-open ranges
  include every representable time in the day without guessing precision.

  Path exclusions are matched against the source filename and are intended for generated files or temporary migration areas.

  The check uses static AST analysis, so dynamic code generation and macro-expanded code may fall outside its signal.

  ## Options

  Configure options in `.credo.exs` with the check tuple:

  ```elixir
  %{
    configs: [
      %{
        name: "default",
        checks: [
          {Bylaw.Credo.Check.Elixir.NoEndOfDayTime,
           [
             excluded_paths: ["test/support/"]
           ]}
        ]
      }
    ]
  }
  ```

  - `:excluded_paths` - Paths containing any configured string are skipped. Defaults to `test/` so fixtures and assertions can still describe boundary values directly.

  ## Usage

  Add this check to Credo's `checks:` list in `.credo.exs`:

  ```elixir
  %{
    configs: [
      %{
        name: "default",
        checks: [
          {Bylaw.Credo.Check.Elixir.NoEndOfDayTime, []}
        ]
      }
    ]
  }
  ```
  """

  use Credo.Check,
    base_priority: :higher,
    category: :warning,
    param_defaults: [excluded_paths: ["test/"]],
    explanations: [
      check: @moduledoc,
      params: [
        excluded_paths: """
        Paths containing any configured string are skipped. Defaults to `test/`
        so fixtures and assertions can still describe boundary values directly.
        """
      ]
    ]

  @doc false
  @impl Credo.Check
  def run(%Credo.SourceFile{} = source_file, params \\ []) do
    excluded_paths = Params.get(params, :excluded_paths, __MODULE__)

    if path_excluded?(source_file.filename, excluded_paths) do
      []
    else
      issue_meta = IssueMeta.for(source_file, params)
      Credo.Code.prewalk(source_file, &traverse(&1, &2, issue_meta))
    end
  end

  defp path_excluded?(filename, excluded_paths) do
    Enum.any?(excluded_paths, &String.contains?(filename, &1))
  end

  defp traverse(
         {:sigil_T, meta, [{:<<>>, _str_meta, [time_string]}, _modifiers]} = ast,
         issues,
         issue_meta
       )
       when is_binary(time_string) do
    if String.starts_with?(time_string, "23:59:59") do
      {ast, [issue_for(issue_meta, meta[:line] || 0, time_string) | issues]}
    else
      {ast, issues}
    end
  end

  defp traverse(ast, issues, _issue_meta), do: {ast, issues}

  defp issue_for(issue_meta, line_no, time_string) do
    format_issue(
      issue_meta,
      message:
        "Avoid using `~T[#{time_string}]` as end of day. Use `~T[00:00:00]` of the next day as an exclusive bound instead.",
      trigger: "~T[#{time_string}]",
      line_no: line_no
    )
  end
end