use std::collections::BTreeMap;

use ruma::{
	api::{
		client::{error::ErrorKind, to_device::send_event_to_device},
		federation::{self, transactions::edu::DirectDeviceContent},
	},
	to_device::DeviceIdOrAllDevices,
};

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

/// # `PUT /_matrix/client/r0/sendToDevice/{eventType}/{txnId}`
///
/// Send a to-device event to a set of client devices.
pub(crate) async fn send_event_to_device_route(
	body: Ruma<send_event_to_device::v3::Request>,
) -> Result<send_event_to_device::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");
	let sender_device = body.sender_device.as_deref();

	// Check if this is a new transaction id
	if services()
		.transaction_ids
		.existing_txnid(sender_user, sender_device, &body.txn_id)?
		.is_some()
	{
		return Ok(send_event_to_device::v3::Response {});
	}

	for (target_user_id, map) in &body.messages {
		for (target_device_id_maybe, event) in map {
			if target_user_id.server_name() != services().globals.server_name() {
				let mut map = BTreeMap::new();
				map.insert(target_device_id_maybe.clone(), event.clone());
				let mut messages = BTreeMap::new();
				messages.insert(target_user_id.clone(), map);
				let count = services().globals.next_count()?;

				services().sending.send_edu_server(
					target_user_id.server_name(),
					serde_json::to_vec(&federation::transactions::edu::Edu::DirectToDevice(DirectDeviceContent {
						sender: sender_user.clone(),
						ev_type: body.event_type.clone(),
						message_id: count.to_string().into(),
						messages,
					}))
					.expect("DirectToDevice EDU can be serialized"),
				)?;

				continue;
			}

			match target_device_id_maybe {
				DeviceIdOrAllDevices::DeviceId(target_device_id) => {
					services().users.add_to_device_event(
						sender_user,
						target_user_id,
						target_device_id,
						&body.event_type.to_string(),
						event
							.deserialize_as()
							.map_err(|_| Error::BadRequest(ErrorKind::InvalidParam, "Event is invalid"))?,
					)?;
				},

				DeviceIdOrAllDevices::AllDevices => {
					for target_device_id in services().users.all_device_ids(target_user_id) {
						services().users.add_to_device_event(
							sender_user,
							target_user_id,
							&target_device_id?,
							&body.event_type.to_string(),
							event
								.deserialize_as()
								.map_err(|_| Error::BadRequest(ErrorKind::InvalidParam, "Event is invalid"))?,
						)?;
					}
				},
			}
		}
	}

	// Save transaction id with empty data
	services()
		.transaction_ids
		.add_txnid(sender_user, sender_device, &body.txn_id, &[])?;

	Ok(send_event_to_device::v3::Response {})
}
