initial, copy postgres stuff for migrations, main.go test

migrations/004-Privacy.sql

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+-- Deletion paths.
+--
+-- Discord's developer policy requires deleting user data on request, and API
+-- registrants are an international user base whose data protection expectations
+-- apply regardless. Build this before you need it: retrofitting a deletion path
+-- across three stores is miserable, and being asked for one you do not have is
+-- worse.
+--
+-- These functions cover Postgres. The caller must ALSO clear Redis - cached
+-- callsign lookups, rate-limit counters keyed by hashed Discord ID, and any
+-- verification challenge in flight. Postgres is not the whole story.
+
+-- ---------------------------------------------------------------------------
+
+-- Removes a Discord user and everything referencing them. The ON DELETE CASCADE
+-- chain reaches verifications, subscriptions, imports and qsos, so this is one
+-- statement rather than a list that can fall out of date as tables are added.
+--
+-- Returns the number of QSOs removed, purely so the caller can tell the user
+-- what was deleted.
+CREATE FUNCTION core.forget_user(p_discord_id bigint)
+RETURNS TABLE (deleted_user boolean, deleted_qsos bigint)
+LANGUAGE plpgsql
+-- Pinned: the body qualifies its tables, but now(), count() and friends resolve
+-- through search_path. Matters more if this ever becomes SECURITY DEFINER.
+SET search_path = pg_catalog, core, logbook
+AS $$
+DECLARE
+    v_user_id bigint;
+    v_qsos    bigint := 0;
+BEGIN
+    SELECT id INTO v_user_id FROM core.users WHERE discord_id = p_discord_id;
+
+    IF v_user_id IS NULL THEN
+        RETURN QUERY SELECT false, 0::bigint;
+        RETURN;
+    END IF;
+
+    SELECT count(*) INTO v_qsos FROM logbook.qsos WHERE user_id = v_user_id;
+
+    -- Cascades do the rest.
+    DELETE FROM core.users WHERE id = v_user_id;
+
+    RETURN QUERY SELECT true, v_qsos;
+END;
+$$;
+
+COMMENT ON FUNCTION core.forget_user(bigint) IS 'Hard-deletes a Discord user and all dependent rows. Caller must also purge Redis keys for this user.';
+
+-- ---------------------------------------------------------------------------
+
+-- The API-side equivalent. Keys and usage rows cascade from the owner.
+CREATE FUNCTION api.forget_owner(p_email core.email)
+RETURNS TABLE (deleted_owner boolean, deleted_keys bigint)
+LANGUAGE plpgsql
+SET search_path = pg_catalog, core, api
+AS $$
+DECLARE
+    v_owner_id bigint;
+    v_keys     bigint := 0;
+BEGIN
+    SELECT id INTO v_owner_id FROM api.owners WHERE email = p_email;
+
+    IF v_owner_id IS NULL THEN
+        RETURN QUERY SELECT false, 0::bigint;
+        RETURN;
+    END IF;
+
+    SELECT count(*) INTO v_keys FROM api.keys WHERE owner_id = v_owner_id;
+
+    DELETE FROM api.owners WHERE id = v_owner_id;
+
+    RETURN QUERY SELECT true, v_keys;
+END;
+$$;
+
+-- ---------------------------------------------------------------------------
+
+-- Retention. Verification records carry a hashed challenge and a timestamp, and
+-- are useful for a short while when investigating a failed verification. They
+-- are not useful a year later. Run this from cron.
+CREATE FUNCTION core.prune_verifications(p_keep_days integer DEFAULT 90)
+RETURNS bigint
+LANGUAGE plpgsql
+SET search_path = pg_catalog, core
+AS $$
+DECLARE
+    v_removed bigint;
+BEGIN
+    DELETE FROM core.verifications
+     WHERE created_at < now() - make_interval(days => p_keep_days)
+       AND status <> 'succeeded';
+
+    GET DIAGNOSTICS v_removed = ROW_COUNT;
+
+    RETURN v_removed;
+END;
+$$;
+
+GRANT EXECUTE ON FUNCTION core.forget_user(bigint) TO hammy_app;
+GRANT EXECUTE ON FUNCTION api.forget_owner(core.email) TO hammy_app;
+GRANT EXECUTE ON FUNCTION core.prune_verifications(integer) TO hammy_app;