neiam /gitgud

defmodule GitGud.Repo.Migrations.CreateCacheEntries do
  use Ecto.Migration

  def change do
    create table(:cache_entries) do
      add :repository_id, references(:repositories, on_delete: :delete_all), null: false

      # The opaque cache key set by `actions/cache`. May be a literal or
      # a hash-derived string. Bounded to 512 chars by the action.
      add :key, :string, null: false, size: 600

      # `version` is a hash of the cached *paths*, so two cache actions
      # with the same `key` but different paths don't collide.
      add :version, :string, null: false, size: 128

      # Ref the cache was uploaded for ("refs/heads/main" etc). Lookup
      # honors the current ref first, then falls back to the repo's
      # default branch, matching GitHub's scope-isolation semantics.
      # NULL means "global to the repo" — accepts lookups from any ref.
      add :ref, :string, size: 250

      add :storage_key, :text, null: false

      # Bytes — populated by `finalize`. Pending uploads (reserved but
      # not finalized) have nil here.
      add :size, :bigint

      # When the upload completed. Lookups gate on this being non-null
      # so half-uploaded rows aren't returned as hits.
      add :archived_at, :utc_datetime

      # Used by the eviction worker (next slice).
      add :last_used_at, :utc_datetime

      timestamps(type: :utc_datetime)
    end

    # The same (repo, key, version, ref) re-uploads as a single row —
    # the row's storage_key is replaced + archived_at refreshes.
    # NULL ref is its own scope (PG treats NULL distinctly in unique
    # indexes by default; we accept that).
    create unique_index(:cache_entries, [:repository_id, :key, :version, :ref],
             name: :cache_entries_scope_index
           )

    # Hot path: prefix-key lookups within (repo, version).
    create index(:cache_entries, [:repository_id, :version])
  end
end