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use std::cell::RefCell;
use std::iter::{IntoIterator, Iterator};
use std::rc::Rc;
use std::vec::IntoIter;
use serde::de::DeserializeOwned;
use tokio_core::reactor::Core;
use rincon_client::cursor::methods::*;
use rincon_client::cursor::types::{Cursor, CursorStatistics, Warning};
use rincon_core::api::connector::{Connector, Execute};
use rincon_core::api::method::{Method, Prepare};
use rincon_core::api::types::{Empty, EMPTY};
use super::Result;
/// A session for operating with a specific `Cursor`.
#[derive(Debug)]
pub struct CursorSession<T, C> {
cursor: Cursor<T>,
database_name: String,
connector: Rc<C>,
core: Rc<RefCell<Core>>,
}
impl<T, C> CursorSession<T, C>
where T: 'static + DeserializeOwned, C: 'static + Connector
{
/// Instantiates a new `CursorSession` for the given cursor.
pub(crate) fn new(
cursor: Cursor<T>,
database_name: String,
connector: Rc<C>,
core: Rc<RefCell<Core>>,
) -> Self {
CursorSession {
cursor,
database_name,
connector,
core,
}
}
/// Executes an API method applied to the database of this session.
fn execute<M>(&self, method: M) -> Result<<M as Method>::Result>
where M: 'static + Method + Prepare
{
self.core.borrow_mut().run(
self.connector.connection(&self.database_name)
.execute(method)
)
}
/// Returns the name of the database the query has been executed for.
pub fn database_name(&self) -> &str {
&self.database_name
}
/// Returns the `Cursor` entity of this session.
pub fn entity(&self) -> &Cursor<T> {
&self.cursor
}
/// Unwraps the `Cursor` entity out of this session.
pub fn unwrap(self) -> Cursor<T> {
self.cursor
}
/// Returns the id of this cursor.
pub fn id(&self) -> Option<&String> {
self.cursor.id()
}
/// Returns the slice of result documents retrieved with this cursor.
///
/// The query may have more results. Whether a query has more results can
/// be checked by the `has_more()` attribute function. To fetch the next
/// batch of results use the `next_cursor()` function or iterate over all
/// results by using the `Iterator` returned by the `into_iter()` function.
pub fn result(&self) -> &[T] {
self.cursor.result()
}
/// Returns whether there are more results available for this cursor on
/// the server.
pub fn has_more(&self) -> bool {
self.cursor.has_more()
}
/// Returns whether the query result was served from the query cache or not.
///
/// If the query result is served from the query cache, the stats attribute
/// will be `None`.
pub fn is_cached(&self) -> bool {
self.cursor.is_cached()
}
/// Returns the total number of result documents available (only available
/// if the query was executed with the count attribute set).
pub fn count(&self) -> Option<u64> {
self.cursor.count()
}
/// Returns the statistics about the execution of data modification queries.
///
/// The stats will be `None` if the query is not a data modification query
/// or the result is served from the query cache.
pub fn stats(&self) -> Option<&CursorStatistics> {
self.cursor.stats()
}
/// Returns warnings that occurred during query execution.
pub fn warnings(&self) -> Option<&Vec<Warning>> {
self.cursor.warnings()
}
/// Checks whether this cursor has more results and if yes fetches a
/// cursor with the next batch of results and returns it as a new
/// `CursorSession`.
///
/// This function returns `None` if there are no more results for this
/// cursor. It returns `Some(Error)` if fetching the next batch of results
/// fails.
pub fn next_cursor(&self) -> Option<Result<CursorSession<T, C>>> {
self.cursor.id().map(|v| v.to_owned()).map(|id|
self.execute(ReadNextBatchFromCursor::with_id(id))
.map(|cursor| CursorSession {
cursor,
database_name: self.database_name.clone(),
connector: self.connector.clone(),
core: self.core.clone(),
})
)
}
/// Deletes the cursor represented by this session on the server if it is
/// still existing otherwise those nothing.
pub fn delete(self) -> Result<Empty> {
if let Some(id) = self.cursor.id() {
self.execute(DeleteCursor::with_id_ref(id))
} else {
Ok(EMPTY)
}
}
}
impl<T, C> IntoIterator for CursorSession<T, C>
where T: 'static + DeserializeOwned, C: 'static + Connector
{
type Item = Result<T>;
type IntoIter = CursorSessionIntoIter<T, C>;
fn into_iter(self) -> Self::IntoIter {
let has_more = self.cursor.has_more();
let (cursor_id, count, result) = self.cursor.unwrap();
CursorSessionIntoIter {
batch: result.into_iter(),
count,
has_more,
cursor_id,
database_name: self.database_name,
connector: self.connector,
core: self.core,
}
}
}
/// An `Iterator` over all results for a specific cursor.
#[derive(Debug)]
pub struct CursorSessionIntoIter<T, C> {
batch: IntoIter<T>,
count: Option<u64>,
has_more: bool,
cursor_id: Option<String>,
database_name: String,
connector: Rc<C>,
core: Rc<RefCell<Core>>,
}
impl<T, C> CursorSessionIntoIter<T, C>
where T: 'static + DeserializeOwned, C: 'static + Connector
{
/// Executes an API method applied to the database of this session.
fn execute<M>(&self, method: M) -> Result<<M as Method>::Result>
where M: 'static + Method + Prepare
{
self.core.borrow_mut().run(
self.connector.connection(&self.database_name)
.execute(method)
)
}
}
impl<T, C> Iterator for CursorSessionIntoIter<T, C>
where T: 'static + DeserializeOwned, C: 'static + Connector
{
type Item = Result<T>;
fn next(&mut self) -> Option<Self::Item> {
if let Some(next) = self.batch.next() {
Some(Ok(next))
} else if self.has_more {
self.cursor_id.clone().and_then(|id| {
let cursor = self.execute(ReadNextBatchFromCursor::new(id));
match cursor {
Ok(cursor) => {
self.has_more = cursor.has_more();
let (id, count, result) = cursor.unwrap();
self.cursor_id = id;
self.count = count;
self.batch = result.into_iter();
self.batch.next().map(Ok)
},
Err(error) => Some(Err(error)),
}
})
} else {
None
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.batch.len(), self.count.map(|c| c as usize))
}
fn count(self) -> usize where Self: Sized {
self.count.map(|c| c as usize)
.unwrap_or_else(|| self.fold(0, |cnt, _| cnt + 1))
}
}