neiam /gitgud

defmodule GitGud.Repositories.Workers.LanguageStats do
  @moduledoc """
  Computes per-language byte/file breakdown for a commit and stores it
  in `git_commit_language_stats`.

  Enqueued from:
    * `CommitBackfill` — when a new HEAD lands on a branch.
    * `RepoLive.Show` — lazily when a viewer hits a commit that's never
      been computed (e.g., legacy commits from before this slice).

  Idempotent — `unique` on `(repository_id, sha)` so duplicate enqueues
  collapse, and the writer uses `on_conflict: :replace` so a re-run
  overwrites stale numbers if the underlying caches changed.
  """

  use Oban.Worker,
    queue: :git_cache,
    max_attempts: 3,
    unique: [
      fields: [:worker, :args],
      keys: [:repository_id, :sha_hex],
      period: :infinity,
      states: [:available, :scheduled, :executing]
    ]

  alias GitGud.Git
  alias GitGud.Repositories

  @impl Oban.Worker
  def perform(%Oban.Job{args: %{"repository_id" => rid, "sha_hex" => hex}}) do
    repo = Repositories.get_repository!(rid)

    with {:ok, sha} <- Git.from_hex(hex),
         {:ok, _} <- Repositories.compute_and_store_language_stats(repo, sha) do
      :ok
    end
  end

  @doc "Build a job for `(repo, sha_binary)`."
  def new_job(%{repository_id: rid, sha: sha}) when is_binary(sha) do
    __MODULE__.new(%{
      "repository_id" => rid,
      "sha_hex" => Git.to_hex(sha)
    })
  end
end