# Compiled only when the user has ecto_sql (Oban-style): fief itself has no
# hard dependency on Ecto — see the optional deps note in mix.exs.
if Code.ensure_loaded?(Ecto.Migration) do
  defmodule Fief.Authority.Postgres.Migrations do
    @moduledoc """
    Table definitions for `Fief.Authority.Postgres` (implementation.md §3.1):
    five tables, every one keyed by namespace — the instance name, stringified.
    One set of migrations covers all instances sharing the database; adding an
    instance is rows, never DDL.

    Lives under the adapter it provisions — it exists solely to set up
    `Fief.Authority.Postgres`'s tables.

    Run from your own Ecto migration:

        defmodule MyApp.Repo.Migrations.AddFief do
          use Ecto.Migration

          def up, do: Fief.Authority.Postgres.Migrations.up()
          def down, do: Fief.Authority.Postgres.Migrations.down()
        end

    The DDL is idempotent (`IF NOT EXISTS`), so re-running `up/0` is safe.
    """

    use Ecto.Migration

    @tables ~w(fief_leases fief_members fief_table fief_meta fief_leader)

    @doc "Create the five fief tables."
    def up do
      execute("""
      CREATE TABLE IF NOT EXISTS fief_leases (
        ns         text        NOT NULL,
        node       text        NOT NULL,
        expires_at timestamptz NOT NULL,
        granted_at timestamptz NOT NULL,
        PRIMARY KEY (ns, node)
      )
      """)

      execute("""
      CREATE TABLE IF NOT EXISTS fief_members (
        ns        text        NOT NULL,
        node      text        NOT NULL,
        status    text        NOT NULL,
        joined_at timestamptz NOT NULL,
        PRIMARY KEY (ns, node)
      )
      """)

      # prev_owner NULL = settled; epoch = the namespace epoch of the last
      # successful CAS on this row (the M4 row-epoch decision).
      execute("""
      CREATE TABLE IF NOT EXISTS fief_table (
        ns         text   NOT NULL,
        vnode      integer NOT NULL,
        owner      text   NOT NULL,
        prev_owner text,
        epoch      bigint NOT NULL,
        PRIMARY KEY (ns, vnode)
      )
      """)

      # The per-namespace epoch/term domain plus the immutable first-writer-wins
      # config: `config` carries the full config term (ETF); partitions and
      # impl_fingerprint are broken out for operator visibility.
      execute("""
      CREATE TABLE IF NOT EXISTS fief_meta (
        ns               text   PRIMARY KEY,
        epoch            bigint NOT NULL DEFAULT 0,
        max_term         bigint NOT NULL DEFAULT 0,
        partitions       integer,
        impl_fingerprint text,
        config           bytea
      )
      """)

      execute("""
      CREATE TABLE IF NOT EXISTS fief_leader (
        ns         text        PRIMARY KEY,
        holder     text        NOT NULL,
        term       bigint      NOT NULL,
        expires_at timestamptz NOT NULL
      )
      """)
    end

    @doc "Drop the five fief tables."
    def down do
      for table <- @tables, do: execute("DROP TABLE IF EXISTS #{table}")
    end
  end
end