exports.up = async function(knex) {
	// restore avatars in table in case of rollback and rerun
	const avatars = await knex('actors_avatars')
		.select('actors_avatars.*', 'actors_profiles.actor_id')
		.leftJoin('actors_profiles', 'actors_profiles.id', 'actors_avatars.profile_id');

	await knex('actors_avatars').delete();

	await knex.schema.alterTable('actors_avatars', (table) => {
		table.integer('profile_id')
			.nullable()
			.alter();

		table.integer('actor_id')
			.notNullable()
			.references('id')
			.inTable('actors');

		table.datetime('created_at')
			.notNullable()
			.defaultTo(knex.fn.now());

		table.dropUnique('profile_id');
		table.unique(['profile_id', 'media_id']);
	});

	await knex.schema.alterTable('media', (table) => {
		// actor avatars often retain the same URL when updated, handle URL-deduping in app code
		table.dropUnique('source');
		table.string('source_version'); // usually etag
	});

	await knex.raw('CREATE UNIQUE INDEX unique_main_avatars ON actors_avatars (actor_id) WHERE (profile_id IS NULL);');

	if (avatars.length > 0) {
		await knex('actors_avatars').insert(avatars);
	}

	const profiles = await knex('actors_profiles')
		.select('id', 'actor_id', 'avatar_media_id')
		.whereNotNull('avatar_media_id');

	await knex('actors_avatars')
		.insert(profiles.map((profile) => ({
			actor_id: profile.actor_id,
			profile_id: profile.id,
			media_id: profile.avatar_media_id,
		})))
		.onConflict()
		.ignore();
};

exports.down = async function(knex) {
	// no need to delete all entries, only the ones incompatible with the old scheme
	await knex('actors_avatars')
		.whereNull('profile_id')
		.delete();

	await knex.schema.alterTable('actors_avatars', (table) => {
		table.integer('profile_id')
			.notNullable()
			.alter();

		table.dropColumn('actor_id');
		table.dropColumn('created_at');

		table.unique('profile_id');
		table.dropUnique(['profile_id', 'media_id']);
	});

	await knex.schema.alterTable('media', (table) => {
		table.dropColumn('source_version');
		table.unique('source');
	});
};