use ruma::{EventId, OwnedEventId, RoomId};
use std::collections::HashSet;

use std::sync::Arc;
use tokio::sync::MutexGuard;

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

impl service::rooms::state::Data for KeyValueDatabase {
    fn get_room_shortstatehash(&self, room_id: &RoomId) -> Result<Option<u64>> {
        self.roomid_shortstatehash
            .get(room_id.as_bytes())?
            .map_or(Ok(None), |bytes| {
                Ok(Some(utils::u64_from_bytes(&bytes).map_err(|_| {
                    Error::bad_database("Invalid shortstatehash in roomid_shortstatehash")
                })?))
            })
    }

    fn set_room_state(
        &self,
        room_id: &RoomId,
        new_shortstatehash: u64,
        _mutex_lock: &MutexGuard<'_, ()>, // Take mutex guard to make sure users get the room state mutex
    ) -> Result<()> {
        self.roomid_shortstatehash
            .insert(room_id.as_bytes(), &new_shortstatehash.to_be_bytes())?;
        Ok(())
    }

    fn set_event_state(&self, shorteventid: u64, shortstatehash: u64) -> Result<()> {
        self.shorteventid_shortstatehash
            .insert(&shorteventid.to_be_bytes(), &shortstatehash.to_be_bytes())?;
        Ok(())
    }

    fn get_forward_extremities(&self, room_id: &RoomId) -> Result<HashSet<Arc<EventId>>> {
        let mut prefix = room_id.as_bytes().to_vec();
        prefix.push(0xff);

        self.roomid_pduleaves
            .scan_prefix(prefix)
            .map(|(_, bytes)| {
                EventId::parse_arc(utils::string_from_bytes(&bytes).map_err(|_| {
                    Error::bad_database("EventID in roomid_pduleaves is invalid unicode.")
                })?)
                .map_err(|_| Error::bad_database("EventId in roomid_pduleaves is invalid."))
            })
            .collect()
    }

    fn set_forward_extremities<'a>(
        &self,
        room_id: &RoomId,
        event_ids: Vec<OwnedEventId>,
        _mutex_lock: &MutexGuard<'_, ()>, // Take mutex guard to make sure users get the room state mutex
    ) -> Result<()> {
        let mut prefix = room_id.as_bytes().to_vec();
        prefix.push(0xff);

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

        for event_id in event_ids {
            let mut key = prefix.to_owned();
            key.extend_from_slice(event_id.as_bytes());
            self.roomid_pduleaves.insert(&key, event_id.as_bytes())?;
        }

        Ok(())
    }
}