use std::sync::Arc;

use ruma::{UserId, DeviceId, RoomId};

use crate::{service, database::KeyValueDatabase, Result};

impl service::rooms::lazy_loading::Data for Arc<KeyValueDatabase> {
    fn lazy_load_was_sent_before(
        &self,
        user_id: &UserId,
        device_id: &DeviceId,
        room_id: &RoomId,
        ll_user: &UserId,
    ) -> Result<bool> {
        let mut key = user_id.as_bytes().to_vec();
        key.push(0xff);
        key.extend_from_slice(device_id.as_bytes());
        key.push(0xff);
        key.extend_from_slice(room_id.as_bytes());
        key.push(0xff);
        key.extend_from_slice(ll_user.as_bytes());
        Ok(self.lazyloadedids.get(&key)?.is_some())
    }

    fn lazy_load_confirm_delivery(
        &self,
        user_id: &UserId,
        device_id: &DeviceId,
        room_id: &RoomId,
        confirmed_user_ids: &mut dyn Iterator<Item = &UserId>,
    ) -> Result<()> {
        let mut prefix = user_id.as_bytes().to_vec();
        prefix.push(0xff);
        prefix.extend_from_slice(device_id.as_bytes());
        prefix.push(0xff);
        prefix.extend_from_slice(room_id.as_bytes());
        prefix.push(0xff);

        for ll_id in confirmed_user_ids {
            let mut key = prefix.clone();
            key.extend_from_slice(ll_id.as_bytes());
            self.lazyloadedids.insert(&key, &[])?;
        }

        Ok(())
    }

    fn lazy_load_reset(
        &self,
        user_id: &UserId,
        device_id: &DeviceId,
        room_id: &RoomId,
    ) -> Result<()> {
        let mut prefix = user_id.as_bytes().to_vec();
        prefix.push(0xff);
        prefix.extend_from_slice(device_id.as_bytes());
        prefix.push(0xff);
        prefix.extend_from_slice(room_id.as_bytes());
        prefix.push(0xff);

        for (key, _) in self.lazyloadedids.scan_prefix(prefix) {
            self.lazyloadedids.remove(&key)?;
        }

        Ok(())
    }
}