defmodule GitSync.Knot do
  @moduledoc """
  The host keys pinned for one knot a connection pushes to.

  A Tangled account's repositories can be spread over several knots, and a
  host key belongs to the host rather than the account, so there is nowhere on
  the connection itself for one to live.

  `host` is the knot a repo record names, which is an identifier the appview
  routes on rather than something that necessarily answers SSH: Tangled runs
  its own knots behind a proxy that speaks only HTTP and takes pushes for them
  on the appview instead. `ssh_host` is where the push actually goes.
  """

  use Ecto.Schema

  import Ecto.Changeset

  alias GitSync.Connection

  schema "knots" do
    field :host, :string
    field :ssh_host, :string
    field :host_key, :string

    belongs_to :connection, Connection

    timestamps(type: :utc_datetime)
  end

  def changeset(knot, attrs) do
    knot
    |> cast(attrs, [:connection_id, :host, :ssh_host, :host_key])
    |> validate_required([:connection_id, :host, :ssh_host, :host_key])
    |> assoc_constraint(:connection)
    |> unique_constraint([:connection_id, :host])
  end
end