use antidote::Mutex;
use futures::sync::mpsc;
use futures::{AsyncSink, Sink, Stream};
use postgres_protocol;
use postgres_protocol::message::backend::Message;
use postgres_protocol::message::frontend;
use std::collections::HashMap;
use std::error::Error as StdError;
use std::sync::{Arc, Weak};

use proto::bind::BindFuture;
use proto::connection::{Request, RequestMessages};
use proto::copy_in::{CopyInFuture, CopyInReceiver, CopyMessage};
use proto::copy_out::CopyOutStream;
use proto::execute::ExecuteFuture;
use proto::portal::Portal;
use proto::prepare::PrepareFuture;
use proto::query::QueryStream;
use proto::simple_query::SimpleQueryFuture;
use proto::statement::Statement;
use types::{IsNull, Oid, ToSql, Type};
use Error;

pub struct PendingRequest(Result<RequestMessages, Error>);

pub struct WeakClient(Weak<Inner>);

impl WeakClient {
    pub fn upgrade(&self) -> Option<Client> {
        self.0.upgrade().map(Client)
    }
}

struct State {
    types: HashMap<Oid, Type>,
    typeinfo_query: Option<Statement>,
    typeinfo_enum_query: Option<Statement>,
    typeinfo_composite_query: Option<Statement>,
}

struct Inner {
    state: Mutex<State>,
    sender: mpsc::UnboundedSender<Request>,
}

#[derive(Clone)]
pub struct Client(Arc<Inner>);

impl Client {
    pub fn new(sender: mpsc::UnboundedSender<Request>) -> Client {
        Client(Arc::new(Inner {
            state: Mutex::new(State {
                types: HashMap::new(),
                typeinfo_query: None,
                typeinfo_enum_query: None,
                typeinfo_composite_query: None,
            }),
            sender,
        }))
    }

    pub fn downgrade(&self) -> WeakClient {
        WeakClient(Arc::downgrade(&self.0))
    }

    pub fn cached_type(&self, oid: Oid) -> Option<Type> {
        self.0.state.lock().types.get(&oid).cloned()
    }

    pub fn cache_type(&self, ty: &Type) {
        self.0.state.lock().types.insert(ty.oid(), ty.clone());
    }

    pub fn typeinfo_query(&self) -> Option<Statement> {
        self.0.state.lock().typeinfo_query.clone()
    }

    pub fn set_typeinfo_query(&self, statement: &Statement) {
        self.0.state.lock().typeinfo_query = Some(statement.clone());
    }

    pub fn typeinfo_enum_query(&self) -> Option<Statement> {
        self.0.state.lock().typeinfo_enum_query.clone()
    }

    pub fn set_typeinfo_enum_query(&self, statement: &Statement) {
        self.0.state.lock().typeinfo_enum_query = Some(statement.clone());
    }

    pub fn typeinfo_composite_query(&self) -> Option<Statement> {
        self.0.state.lock().typeinfo_composite_query.clone()
    }

    pub fn set_typeinfo_composite_query(&self, statement: &Statement) {
        self.0.state.lock().typeinfo_composite_query = Some(statement.clone());
    }

    pub fn send(&self, request: PendingRequest) -> Result<mpsc::Receiver<Message>, Error> {
        let messages = request.0?;
        let (sender, receiver) = mpsc::channel(0);
        self.0
            .sender
            .unbounded_send(Request { messages, sender })
            .map(|_| receiver)
            .map_err(|_| Error::closed())
    }

    pub fn batch_execute(&self, query: &str) -> SimpleQueryFuture {
        let pending = self.pending(|buf| {
            frontend::query(query, buf).map_err(Error::parse)?;
            Ok(())
        });

        SimpleQueryFuture::new(self.clone(), pending)
    }

    pub fn prepare(&self, name: String, query: &str, param_types: &[Type]) -> PrepareFuture {
        let pending = self.pending(|buf| {
            frontend::parse(&name, query, param_types.iter().map(|t| t.oid()), buf)
                .map_err(Error::parse)?;
            frontend::describe(b'S', &name, buf).map_err(Error::parse)?;
            frontend::sync(buf);
            Ok(())
        });

        PrepareFuture::new(self.clone(), pending, name)
    }

    pub fn execute(&self, statement: &Statement, params: &[&ToSql]) -> ExecuteFuture {
        let pending = PendingRequest(
            self.excecute_message(statement, params)
                .map(RequestMessages::Single),
        );
        ExecuteFuture::new(self.clone(), pending, statement.clone())
    }

    pub fn query(&self, statement: &Statement, params: &[&ToSql]) -> QueryStream<Statement> {
        let pending = PendingRequest(
            self.excecute_message(statement, params)
                .map(RequestMessages::Single),
        );
        QueryStream::new(self.clone(), pending, statement.clone())
    }

    pub fn bind(&self, statement: &Statement, name: String, params: &[&ToSql]) -> BindFuture {
        let mut buf = self.bind_message(statement, &name, params);
        if let Ok(ref mut buf) = buf {
            frontend::sync(buf);
        }
        let pending = PendingRequest(buf.map(RequestMessages::Single));
        BindFuture::new(self.clone(), pending, name, statement.clone())
    }

    pub fn query_portal(&self, portal: &Portal, rows: i32) -> QueryStream<Portal> {
        let pending = self.pending(|buf| {
            frontend::execute(portal.name(), rows, buf).map_err(Error::parse)?;
            frontend::sync(buf);
            Ok(())
        });
        QueryStream::new(self.clone(), pending, portal.clone())
    }

    pub fn copy_in<S>(&self, statement: &Statement, params: &[&ToSql], stream: S) -> CopyInFuture<S>
    where
        S: Stream,
        S::Item: AsRef<[u8]>,
        S::Error: Into<Box<StdError + Sync + Send>>,
    {
        let (mut sender, receiver) = mpsc::channel(0);
        let pending = PendingRequest(self.excecute_message(statement, params).map(|buf| {
            match sender.start_send(CopyMessage::Data(buf)) {
                Ok(AsyncSink::Ready) => {}
                _ => unreachable!("channel should have capacity"),
            }
            RequestMessages::CopyIn {
                receiver: CopyInReceiver::new(receiver),
                pending_message: None,
            }
        }));
        CopyInFuture::new(self.clone(), pending, statement.clone(), stream, sender)
    }

    pub fn copy_out(&self, statement: &Statement, params: &[&ToSql]) -> CopyOutStream {
        let pending = PendingRequest(
            self.excecute_message(statement, params)
                .map(RequestMessages::Single),
        );
        CopyOutStream::new(self.clone(), pending, statement.clone())
    }

    pub fn close_statement(&self, name: &str) {
        self.close(b'S', name)
    }

    pub fn close_portal(&self, name: &str) {
        self.close(b'P', name)
    }

    fn close(&self, ty: u8, name: &str) {
        let mut buf = vec![];
        frontend::close(ty, name, &mut buf).expect("statement name not valid");
        frontend::sync(&mut buf);
        let (sender, _) = mpsc::channel(0);
        let _ = self.0.sender.unbounded_send(Request {
            messages: RequestMessages::Single(buf),
            sender,
        });
    }

    fn bind_message(
        &self,
        statement: &Statement,
        name: &str,
        params: &[&ToSql],
    ) -> Result<Vec<u8>, Error> {
        let mut buf = vec![];
        let r = frontend::bind(
            name,
            statement.name(),
            Some(1),
            params.iter().zip(statement.params()),
            |(param, ty), buf| match param.to_sql_checked(ty, buf) {
                Ok(IsNull::No) => Ok(postgres_protocol::IsNull::No),
                Ok(IsNull::Yes) => Ok(postgres_protocol::IsNull::Yes),
                Err(e) => Err(e),
            },
            Some(1),
            &mut buf,
        );
        match r {
            Ok(()) => Ok(buf),
            Err(frontend::BindError::Conversion(e)) => return Err(Error::to_sql(e)),
            Err(frontend::BindError::Serialization(e)) => return Err(Error::encode(e)),
        }
    }

    fn excecute_message(&self, statement: &Statement, params: &[&ToSql]) -> Result<Vec<u8>, Error> {
        let mut buf = self.bind_message(statement, "", params)?;
        frontend::execute("", 0, &mut buf).map_err(Error::parse)?;
        frontend::sync(&mut buf);
        Ok(buf)
    }

    fn pending<F>(&self, messages: F) -> PendingRequest
    where
        F: FnOnce(&mut Vec<u8>) -> Result<(), Error>,
    {
        let mut buf = vec![];
        PendingRequest(messages(&mut buf).map(|()| RequestMessages::Single(buf)))
    }
}