use ruma::{ServerName, UserId};

use crate::{
    database::KeyValueDatabase,
    service::{
        self,
        sending::{OutgoingKind, SendingEventType},
    },
    services, utils, Error, Result,
};

impl service::sending::Data for KeyValueDatabase {
    fn active_requests<'a>(
        &'a self,
    ) -> Box<
        dyn Iterator<Item = Result<(Vec<u8>, OutgoingKind, SendingEventType)>>
            + 'a,
    > {
        Box::new(self.servercurrentevent_data.iter().map(|(key, v)| {
            parse_servercurrentevent(&key, v).map(|(k, e)| (key, k, e))
        }))
    }

    fn active_requests_for<'a>(
        &'a self,
        outgoing_kind: &OutgoingKind,
    ) -> Box<dyn Iterator<Item = Result<(Vec<u8>, SendingEventType)>> + 'a>
    {
        let prefix = outgoing_kind.get_prefix();
        Box::new(self.servercurrentevent_data.scan_prefix(prefix).map(
            |(key, v)| parse_servercurrentevent(&key, v).map(|(_, e)| (key, e)),
        ))
    }

    fn delete_active_request(&self, key: Vec<u8>) -> Result<()> {
        self.servercurrentevent_data.remove(&key)
    }

    fn delete_all_active_requests_for(
        &self,
        outgoing_kind: &OutgoingKind,
    ) -> Result<()> {
        let prefix = outgoing_kind.get_prefix();
        for (key, _) in self.servercurrentevent_data.scan_prefix(prefix) {
            self.servercurrentevent_data.remove(&key)?;
        }

        Ok(())
    }

    fn queue_requests(
        &self,
        requests: &[(&OutgoingKind, SendingEventType)],
    ) -> Result<Vec<Vec<u8>>> {
        let mut batch = Vec::new();
        let mut keys = Vec::new();
        for (outgoing_kind, event) in requests {
            let mut key = outgoing_kind.get_prefix();
            if let SendingEventType::Pdu(value) = &event {
                key.extend_from_slice(value);
            } else {
                key.extend_from_slice(
                    &services().globals.next_count()?.to_be_bytes(),
                );
            }
            let value = if let SendingEventType::Edu(value) = &event {
                &**value
            } else {
                &[]
            };
            batch.push((key.clone(), value.to_owned()));
            keys.push(key);
        }
        self.servernameevent_data.insert_batch(&mut batch.into_iter())?;
        Ok(keys)
    }

    fn queued_requests<'a>(
        &'a self,
        outgoing_kind: &OutgoingKind,
    ) -> Box<dyn Iterator<Item = Result<(SendingEventType, Vec<u8>)>> + 'a>
    {
        let prefix = outgoing_kind.get_prefix();
        return Box::new(self.servernameevent_data.scan_prefix(prefix).map(
            |(k, v)| parse_servercurrentevent(&k, v).map(|(_, ev)| (ev, k)),
        ));
    }

    fn mark_as_active(
        &self,
        events: &[(SendingEventType, Vec<u8>)],
    ) -> Result<()> {
        for (e, key) in events {
            let value = if let SendingEventType::Edu(value) = &e {
                &**value
            } else {
                &[]
            };
            self.servercurrentevent_data.insert(key, value)?;
            self.servernameevent_data.remove(key)?;
        }

        Ok(())
    }

    fn set_latest_educount(
        &self,
        server_name: &ServerName,
        last_count: u64,
    ) -> Result<()> {
        self.servername_educount
            .insert(server_name.as_bytes(), &last_count.to_be_bytes())
    }

    fn get_latest_educount(&self, server_name: &ServerName) -> Result<u64> {
        self.servername_educount.get(server_name.as_bytes())?.map_or(
            Ok(0),
            |bytes| {
                utils::u64_from_bytes(&bytes).map_err(|_| {
                    Error::bad_database("Invalid u64 in servername_educount.")
                })
            },
        )
    }
}

#[tracing::instrument(skip(key))]
fn parse_servercurrentevent(
    key: &[u8],
    value: Vec<u8>,
) -> Result<(OutgoingKind, SendingEventType)> {
    // Appservices start with a plus
    Ok::<_, Error>(if key.starts_with(b"+") {
        let mut parts = key[1..].splitn(2, |&b| b == 0xFF);

        let server = parts.next().expect("splitn always returns one element");
        let event = parts.next().ok_or_else(|| {
            Error::bad_database("Invalid bytes in servercurrentpdus.")
        })?;

        let server = utils::string_from_bytes(server).map_err(|_| {
            Error::bad_database(
                "Invalid server bytes in server_currenttransaction",
            )
        })?;

        (
            OutgoingKind::Appservice(server),
            if value.is_empty() {
                SendingEventType::Pdu(event.to_vec())
            } else {
                SendingEventType::Edu(value)
            },
        )
    } else if key.starts_with(b"$") {
        let mut parts = key[1..].splitn(3, |&b| b == 0xFF);

        let user = parts.next().expect("splitn always returns one element");
        let user_string = utils::string_from_bytes(user).map_err(|_| {
            Error::bad_database("Invalid user string in servercurrentevent")
        })?;
        let user_id = UserId::parse(user_string).map_err(|_| {
            Error::bad_database("Invalid user id in servercurrentevent")
        })?;

        let pushkey = parts.next().ok_or_else(|| {
            Error::bad_database("Invalid bytes in servercurrentpdus.")
        })?;
        let pushkey_string =
            utils::string_from_bytes(pushkey).map_err(|_| {
                Error::bad_database("Invalid pushkey in servercurrentevent")
            })?;

        let event = parts.next().ok_or_else(|| {
            Error::bad_database("Invalid bytes in servercurrentpdus.")
        })?;

        (
            OutgoingKind::Push(user_id, pushkey_string),
            if value.is_empty() {
                SendingEventType::Pdu(event.to_vec())
            } else {
                // I'm pretty sure this should never be called
                SendingEventType::Edu(value)
            },
        )
    } else {
        let mut parts = key.splitn(2, |&b| b == 0xFF);

        let server = parts.next().expect("splitn always returns one element");
        let event = parts.next().ok_or_else(|| {
            Error::bad_database("Invalid bytes in servercurrentpdus.")
        })?;

        let server = utils::string_from_bytes(server).map_err(|_| {
            Error::bad_database(
                "Invalid server bytes in server_currenttransaction",
            )
        })?;

        (
            OutgoingKind::Normal(ServerName::parse(server).map_err(|_| {
                Error::bad_database(
                    "Invalid server string in server_currenttransaction",
                )
            })?),
            if value.is_empty() {
                SendingEventType::Pdu(event.to_vec())
            } else {
                SendingEventType::Edu(value)
            },
        )
    })
}