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use cxmr_candles::CandleCollector;
use cxmr_feeds::EventData;
use cxmr_orderbook::OrderBook;

use super::{Snapshot, State};

/// Snapshot collector.
#[derive(Default)]
pub struct SnapshotCollector {
    collector: CandleCollector,
    orderbook: OrderBook,
}

impl SnapshotCollector {
    /// Creates snapshot collector with `interval`.
    pub fn new(interval: u64) -> Self {
        SnapshotCollector {
            collector: CandleCollector::new(interval),
            ..SnapshotCollector::default()
        }
    }

    /// Returns last state.
    pub fn finish(self) -> Option<State> {
        let orderbook = self.orderbook;
        self.collector
            .finish()
            .map(move |candle| State::new_close(candle, orderbook))
    }

    /// Pops state from collector if timestamp can close the candle.
    pub fn try_pop(&mut self, ts: u64) -> Option<State> {
        self.collector
            .try_pop(ts)
            .map(|candle| State::new_close(candle, self.orderbook.clone()))
    }

    /// Collects data into a snapshot and returns if state is filled.
    pub fn update(&mut self, event: &EventData) -> Option<State> {
        self.orderbook.update_from_row(event);
        if event.is_trade {
            let update = self.collector.update(event)?;
            Some(State::new(update, self.orderbook.clone()))
        } else {
            self.try_pop(event.ts)
        }
    }

    /// Creates a snapshot from data rows.
    /// Returns `None` if input is empty vector.
    pub fn consume(mut self, events: &Vec<EventData>) -> Option<Snapshot> {
        let mut states: Vec<_> = events
            .iter()
            .filter_map(|event| self.update(event))
            .collect();
        let interval = self.collector.interval;
        if let Some(state) = self.finish() {
            states.push(state);
        }
        Some(Snapshot {
            market: None,
            start_time: events.first().map(|ev| ev.ts),
            interval,
            states,
        })
    }

    /// Creates a snapshot from data rows. Filters close state only.
    /// Returns `None` if input is empty vector.
    pub fn consume_close(mut self, events: &Vec<EventData>) -> Option<Snapshot> {
        self.collector.close_only = true;
        self.consume(events)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    use cxmr_tectonic::read_dtf;

    static TEST_FILE: &'static str = "../../tests/data-002/bnc_ETH_PAX.dtf";
    #[test]
    fn dtf_snapshots() {
        let interval = 4 * 60 * 60 * 1000;
        let mut events = read_dtf(TEST_FILE).unwrap().events.unwrap();
        events.iter_mut().for_each(|event| {
            assert!(event.amount >= 0.0);
            event.amount = event.amount.round();
        });
        let mut snapshot: Vec<State> = SnapshotCollector::new(interval)
            .consume(&events)
            .unwrap()
            .states
            .into_iter()
            .filter_map(|state| state.into_close())
            .collect();
        let events = <Vec<EventData>>::from(&Snapshot {
            market: None,
            start_time: None,
            interval,
            states: snapshot.clone(),
        });
        let mut snapshot_squashed: Vec<State> = SnapshotCollector::new(interval)
            .consume(&events)
            .unwrap()
            .states
            .into_iter()
            .filter_map(|state| state.into_close())
            .collect();
        snapshot.iter_mut().for_each(|state| {
            state.candle.volume = state.candle.volume.round();
            state.orderbook.last_update = 0;
        });
        snapshot_squashed.iter_mut().for_each(|state| {
            state.candle.volume = state.candle.volume.round();
            state.orderbook.last_update = 0;
        });
        assert_eq!(snapshot.len(), 7);
        for (index, a) in snapshot.iter().enumerate() {
            let sq = snapshot_squashed.get(index).unwrap();
            assert_eq!(a.candle, sq.candle, "Index: {}", index);
            assert_eq!(a.orderbook, sq.orderbook, "Index: {}", index);
        }
    }

    #[test]
    fn downscale() {
        let interval = 60 * 60 * 1000;
        let longer_interval = 4 * interval;
        let events = read_dtf(TEST_FILE).unwrap().events.unwrap();
        let snapshot = SnapshotCollector::new(interval)
            .consume(&events)
            .unwrap()
            .into_close();
        assert_eq!(snapshot.states.len(), 23);
        let snapshot_bin = Snapshot::open(TEST_FILE, longer_interval).unwrap();
        let snapshot_longerned = snapshot.downscale(longer_interval).unwrap();
        assert_eq!(snapshot_longerned.states.len(), snapshot_bin.states.len());
        for (index, a) in snapshot_bin.states.iter().enumerate() {
            let sq = snapshot_longerned.states.get(index).unwrap();
            assert_eq!(a.candle, sq.candle, "Index: {}", index);
            assert_eq!(a.orderbook, sq.orderbook, "Index: {}", index);
        }
    }
}