use ruma::api::client::{error::ErrorKind, threads::get_threads};

use crate::{services, Error, Result, Ruma};

/// # `GET /_matrix/client/r0/rooms/{roomId}/threads`
pub(crate) async fn get_threads_route(body: Ruma<get_threads::v1::Request>) -> Result<get_threads::v1::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	// Use limit or else 10, with maximum 100
	let limit = body
		.limit
		.and_then(|l| l.try_into().ok())
		.unwrap_or(10)
		.min(100);

	let from = if let Some(from) = &body.from {
		from.parse()
			.map_err(|_| Error::BadRequest(ErrorKind::InvalidParam, ""))?
	} else {
		u64::MAX
	};

	let threads = services()
		.rooms
		.threads
		.threads_until(sender_user, &body.room_id, from, &body.include)?
		.take(limit)
		.filter_map(Result::ok)
		.filter(|(_, pdu)| {
			services()
				.rooms
				.state_accessor
				.user_can_see_event(sender_user, &body.room_id, &pdu.event_id)
				.unwrap_or(false)
		})
		.collect::<Vec<_>>();

	let next_batch = threads.last().map(|(count, _)| count.to_string());

	Ok(get_threads::v1::Response {
		chunk: threads
			.into_iter()
			.map(|(_, pdu)| pdu.to_room_event())
			.collect(),
		next_batch,
	})
}
