use std::{collections::HashSet, sync::Arc};

use ruma::{EventId, OwnedEventId, OwnedRoomId, RoomId};

use crate::{
    Error, Result,
    database::KeyValueDatabase,
    service::{
        self,
        globals::marker,
        rooms::short::{ShortEventId, ShortStateHash},
    },
    utils::{self, on_demand_hashmap::KeyToken},
};

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

    fn set_room_state(
        &self,
        room_id: &KeyToken<OwnedRoomId, marker::State>,
        new_shortstatehash: ShortStateHash,
    ) -> Result<()> {
        self.roomid_shortstatehash.insert(
            room_id.as_bytes(),
            &new_shortstatehash.get().to_be_bytes(),
        )?;
        Ok(())
    }

    fn set_event_state(
        &self,
        shorteventid: ShortEventId,
        shortstatehash: ShortStateHash,
    ) -> Result<()> {
        self.shorteventid_shortstatehash.insert(
            &shorteventid.get().to_be_bytes(),
            &shortstatehash.get().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(
        &self,
        room_id: &KeyToken<OwnedRoomId, marker::State>,
        event_ids: Vec<OwnedEventId>,
    ) -> 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.clone();
            key.extend_from_slice(event_id.as_bytes());
            self.roomid_pduleaves.insert(&key, event_id.as_bytes())?;
        }

        Ok(())
    }
}