//! Feeding the chain
use super::*;
#[cfg(any(feature="feed-sentance", feature="split-sentance"))]
use sanitise::Sentance;

pub const DEFAULT_FEED_BOUNDS: std::ops::RangeFrom<usize> = 2..; //TODO: Add to config somehow

/// Feed `what` into `chain`, at least `bounds` tokens.
///
/// # Tokenising
/// How the tokens are split within this function that operates on single buffers is determined largely by the features `split-sentance` and `feed-sentance` determining the use of the sentance API.
///
/// ## Pipeline
/// Since this is called on single buffers, it happens after the `split-newlines` tokenising if it's enabled, and thus the sentance API is only able to operate on each seperate line if that feature is enabled, regardless of `always-aggre`, or `feed-sentance` or `split-sentance`.
/// This is the pipeline for just within this function, after splitting through newlines if enabled.
///
/// * `feed-sentance`
/// ** Feed the buffer through the sentance split tokeniser
/// ** Feed the sentances through the word split tokeniser
/// ** Feed each collection of words into the chain seperately
/// * `split-sentance`
/// ** Feed the buffer through the sentance split tokeniser
/// ** Feed the sentances through the word split tokeniser
/// ** Feed the flattened collection into the chain once, concatenated.
/// * Neither
/// ** Feed the buffer through the word split tokeniser
/// ** Feed the collection into the chain
pub fn feed(chain: &mut Chain<String>, what: impl AsRef<str>, bounds: impl std::ops::RangeBounds<usize>)
{
    cfg_if! {
	if #[cfg(feature="feed-sentance")] { 
	    let map = Sentance::new_iter(&what) //get each sentance in string
		.map(|what| what.words()
		     .map(|s| s.to_owned()).collect::<Vec<_>>());
	    debug_assert!(!bounds.contains(&0), "Cannot allow 0 size feeds");
	    for map in map {// feed each sentance seperately
		if bounds.contains(&map.len()) {
		    debug!("Feeding chain {} items", map.len());
		    chain.feed(map);
		}
		else {
		    debug!("Ignoring feed of invalid length {}: {:?}", map.len(), map);
		}
	    }
	} else {
	    cfg_if!{
		if #[cfg(feature="split-sentance")] {
		    let map = Sentance::new_iter(&what) //get each sentance in string
			.map(|what| what.words())
			.flatten() // add all into one buffer
			.map(|s| s.to_owned()).collect::<Vec<_>>();
		} else {
		    let map: Vec<_> = sanitise::words(what.as_ref()).map(ToOwned::to_owned)
			.collect();
		}
	    }
	    debug_assert!(!bounds.contains(&0), "Cannot allow 0 size feeds");
	    if bounds.contains(&map.len()) {
		debug!("Feeding chain {} items", map.len());
		chain.feed(map);
	    }
	    else {
		debug!("Ignoring feed of invalid length {}: {:?}", map.len(), map);
	    }
	    
	}
    }
}

pub async fn full(who: &IpAddr, state: State, body: impl Unpin + Stream<Item = Result<impl Buf, impl std::error::Error + 'static>>) -> Result<usize, FillBodyError> {

    let mut written = 0usize;
    if_debug! {
	let timer = std::time::Instant::now();
    }
    let bounds = &state.config_cache().feed_bounds;
    macro_rules! feed {
	($chain:expr, $buffer:ident) => {
	    {
		let buffer = $buffer;
		feed($chain, &buffer, bounds)
	    }
	}
    }
    
    cfg_if!{
	if #[cfg(any(not(feature="split-newlines"), feature="always-aggregate"))] {
	    let mut body = body;
	    let mut buffer = Vec::new();
	    while let Some(buf) = body.next().await {
		let mut body = buf.map_err(|_| FillBodyError)?;
		while body.has_remaining() {
		    if body.bytes().len() > 0 {
			buffer.extend_from_slice(body.bytes()); 
			let cnt = body.bytes().len();
			body.advance(cnt);
			written += cnt;
		    }
		}
	    }
	    let buffer = std::str::from_utf8(&buffer[..]).map_err(|_| FillBodyError)?;
	    let buffer = state.inbound_filter().filter_cow(buffer);
	    info!("{} -> {:?}", who, buffer);
	    let mut chain = state.chain().write().await;
	    cfg_if! {
		if #[cfg(feature="split-newlines")] {
		    for buffer in buffer.split('\n').filter(|line| !line.trim().is_empty()) {
			feed!(&mut chain, buffer);
		    }
		} else {
		    feed!(&mut chain, buffer);

		}
	    }
	} else {
	    use tokio::prelude::*;

	    let reader = chunking::StreamReader::new(body.filter_map(|x| x.map(|mut x| x.to_bytes()).ok()));
	    let mut lines = reader.lines();

	    #[cfg(feature="hog-buffer")] 
	    let mut chain = state.chain().write().await;
	    while let Some(line) = lines.next_line().await.map_err(|_| FillBodyError)? {
		let line = state.inbound_filter().filter_cow(&line);
		let line = line.trim();
		if !line.is_empty() {
		    #[cfg(not(feature="hog-buffer"))] 
		    let mut chain = state.chain().write().await; // Acquire mutex once per line? Is this right?
		    
		    feed!(&mut chain, line);
		    info!("{} -> {:?}", who, line);
		}
		written+=line.len();
	    }
	}
    }

    if_debug!{
	trace!("Write took {}ms", timer.elapsed().as_millis());
    }
    state.notify_save();
    Ok(written)
	
}


#[derive(Debug)]
pub struct FillBodyError;

impl error::Error for FillBodyError{}
impl warp::reject::Reject for FillBodyError{}
impl fmt::Display for FillBodyError
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
    {
	write!(f, "failed to feed chain with this data")
    }
}