#![allow(unused_imports)]
#![allow(unused_labels)]

use std::str::FromStr;
use std::time::{Instant, Duration};
use std::{fs, io};
use std::io::prelude::*;
use std::str::from_utf8;
use std::error::Error;
use std::f64::NAN;
use serde::{Serialize, Deserialize};
use itertools_num::linspace;
use std::collections::HashMap as Map;

const N: usize = 128;
const LOGSPACE: [i64; 128] =
    [-2134300000000, -1854700000000, -1611800000000, -1400600000000,
     -1217200000000, -1057700000000,  -919200000000,  -798800000000,
      -694100000000,  -603200000000,  -524200000000,  -455500000000,
      -395800000000,  -344000000000,  -298900000000,  -259700000000,
      -225700000000,  -196100000000,  -170400000000,  -148100000000,
      -128700000000,  -111800000000,   -97200000000,   -84400000000,
       -73400000000,   -63800000000,   -55400000000,   -48100000000,
       -41800000000,   -36300000000,   -31600000000,   -27400000000,
       -23800000000,   -20700000000,   -18000000000,   -15600000000,
       -13600000000,   -11800000000,   -10200000000,    -8900000000,
        -7700000000,    -6700000000,    -5800000000,    -5000000000,
        -4400000000,    -3800000000,    -3300000000,    -2900000000,
        -2500000000,    -2100000000,    -1900000000,    -1600000000,
        -1400000000,    -1200000000,    -1000000000,     -900000000,
         -800000000,     -700000000,     -600000000,     -500000000,
         -400000000,     -300000000,     -200000000,     -100000000,
          100000000,      200000000,      300000000,      400000000,
          500000000,      600000000,      700000000,      800000000,
          900000000,     1000000000,     1200000000,     1400000000,
         1600000000,     1900000000,     2100000000,     2500000000,
         2900000000,     3300000000,     3800000000,     4400000000,
         5000000000,     5800000000,     6700000000,     7700000000,
         8900000000,    10200000000,    11800000000,    13600000000,
        15600000000,    18000000000,    20700000000,    23800000000,
        27400000000,    31600000000,    36300000000,    41800000000,
        48100000000,    55400000000,    63800000000,    73400000000,
        84400000000,    97200000000,   111800000000,   128700000000,
       148100000000,   170400000000,   196100000000,   225700000000,
       259700000000,   298900000000,   344000000000,   395800000000,
       455500000000,   524200000000,   603200000000,   694100000000,
       798800000000,   919200000000,  1057700000000,  1217200000000,
      1400600000000,  1611800000000,  1854700000000,  2134300000000];


#[derive(Deserialize)]
struct Trade {
    pub time: i64,
    pub price: f64,
    pub amount: f64,
}

/// Use this to deserialize just the time column on the first pass through
/// the events file.
#[derive(Deserialize)]
struct EventTime {
    pub time: i64,
}

struct Event {
    pub time: i64,
    pub data: Vec<f64>,
}

pub fn seconds(d: Duration) -> f64 {
    d.as_secs() as f64 + (d.subsec_nanos() as f64 / 1_000_000_000_f64)
}

fn main() -> Result<(), Box<dyn Error>> {
    let start = Instant::now();
    let args: clap::ArgMatches = clap::App::new("time-explorer")
        .version("0.1")
        .arg(clap::Arg::with_name("trades")
             .long("trades-csv")
             .short("t")
             .help("Path of csv with time (integer nanoseconds timestamp), \
                    price (f64), and amount (f64) columns.")
             .takes_value(true)
             .required(true))
        .arg(clap::Arg::with_name("events")
             .long("events-csv")
             .short("e")
             .help("Path of csv file with a time (integer nanoseconds timestamp) as column 0, \
                    along with any other metadata columns that will be included in results")
             .takes_value(true)
             .required(true))
        .arg(clap::Arg::with_name("output")
             .long("output-file")
             .short("o")
             .help("Path to save results csv to")
             .takes_value(true)
             .required(true))
        .arg(clap::Arg::with_name("verbose")
             .long("verbose")
             .short("v"))
        .arg(clap::Arg::with_name("n-periods")
             .long("n-periods")
             .short("n")
             .help("Controls how many time buckets are evaluated")
             .takes_value(true)
             .default_value("50"))
        .get_matches();

    let verbose = args.is_present("verbose");

    if verbose { println!("{:>8.2}s reading...", seconds(Instant::now() - start)); }

    let trades_csv = args.value_of("trades").unwrap();
    let events_csv = args.value_of("events").unwrap();
    let output = args.value_of("output").unwrap();
    let n: &str = args.value_of("n-periods").unwrap();
    let n: usize = usize::from_str(n)?;

    let trades_csv =
        fs::OpenOptions::new()
            .read(true)
            .open(trades_csv)?;

    let mut times: Vec<i64> = Vec::with_capacity(8192);
    let mut amounts: Vec<f64> = Vec::with_capacity(8192);
    let mut totals: Vec<f64> = Vec::with_capacity(8192);

    #[cfg(feature = "super-fast-csv-parsing")]
    {
        // lookout below! MANY unwraps in here

        // note: this code NOT part of original time-explorer. this code is what
        // I was referring to in the "fine print" note where it says "With 10
        // minutes work (knowing what I know today), I was able to get CSV parsing
        // down to 3.46sec"

        let mut rdr = csv::Reader::from_reader(io::BufReader::new(rdr));
        let headers = rdr.byte_headers().unwrap().clone();
        let mut row = csv::ByteRecord::new();
        let mut col_index: [usize; 3] = [
            headers.iter().position(|x| x == b"time").unwrap(),
            headers.iter().position(|x| x == b"amount").unwrap(),
            headers.iter().position(|x| x == b"price").unwrap(),
        ];

        while rdr.read_byte_record(&mut row).unwrap() {
            times.push(atoi::atoi(row.get(col_index[0]).unwrap()).unwrap());

            let amount: f64 = lexical::parse(row.get(col_index[1]).unwrap()).unwrap();
            let price: f64 = lexical::parse(row.get(col_index[2]).unwrap()).unwrap();

            totals.push(price * amount);
            amounts.push(amount);
        }
    }

    #[cfg(not(feature = "super-fast-csv-parsing"))]
    {
        // this is what was originally in time-explorer

        let mut trades: Vec<Trade> =
            csv::Reader::from_reader(trades_csv)
                .deserialize()
                .map(|x| x.unwrap())
                .collect();

        trades.sort_by_key(|k| k.time);

        for Trade { time, price, amount } in trades {
            times.push(time);
            totals.push(price * amount);
            amounts.push(amount);
        }
    }

    if verbose { println!("{:>8.2}s finished parsing trades csv (times.len() = {}) ...", seconds(Instant::now() - start), times.len()); }

    let mut events: Vec<Event> = {
        let events_csv =
            fs::OpenOptions::new()
                .read(true)
                .open(events_csv)?;

        csv::Reader::from_reader(events_csv)
            .deserialize()
            .map(|t: Result<EventTime, _>| {
                let EventTime { time } = t.unwrap();
                //let data = [0.0; N - 1];
                let data = vec![0.0; n - 1];
                Event { time, data }
            }).collect()
    };

    assert!(!events.is_empty());

    events.sort_by_key(|k| k.time);

    let mut cursor: usize = 0;
    let mut truncate_events = None;

    let buckets: Vec<i64> =
        linspace(LOGSPACE[0] as f64, LOGSPACE[N - 1] as f64, n)
            .map(|x| x as i64)
            .collect();
    
    if verbose { println!("{:>8.2}s calculating...", seconds(Instant::now() - start)); }

    let mut n_incomplete_buckets = 0;
    let mut n_skipped_buckets = 0;
    let mut n_time_buckets = 0;

    'a: for (i, event) in events.iter_mut().enumerate() {

        let mut min_time: i64 = event.time + buckets[0];
        let mut max_time: i64 = event.time + buckets[1];

        'oops: while times[cursor] > min_time && cursor > 0 { cursor -= 1; }
        n_incomplete_buckets += (times[cursor] > min_time) as usize;
        n_skipped_buckets += (times[cursor] > max_time) as usize;

        // find the beginning if there are gaps
        'b: while times[cursor] < min_time {
            if cursor >= times.len() - 1 {
                truncate_events = Some(i);
                break 'a
            } else {
                cursor += 1
            }
        }

        let mut j: usize = cursor;

        'c: for k in 0..(n - 2) {
            let mut wsum: f64 = 0.0;
            let mut w: f64 = 0.0;

            'd: while j < times.len() - 1 && times[j] < max_time {
                wsum += totals[j];
                w += amounts[j];
                j += 1;
            }

            event.data[k] = if w > 0.0 { wsum / w } else { NAN };

            min_time = max_time;
            max_time = event.time + buckets[k + 2];
            n_time_buckets += 1;
        }

        if i % 512 == 0 {
            assert!(max_time > min_time);
            if verbose {
                //let n_nan = event.data.iter().filter(|x| !x.is_finite()).count();
                println!("{:>8.2}s     No. {:>5} {:>12.2}, {:>12.2}, {:>12.2} ...", //, {:>12.2}, {:>12.2}, {:>12.2}  ...",
                          //cursor={}, j={}, times[cursor]={}, n_nan={}, max_time-min_time={}",
                          seconds(Instant::now() - start), i,
                         event.data[0], event.data[20], event.data[40]); //, event.data[60], event.data[80], event.data[100]);
                         //min_time, max_time, cursor,
                         //j, times[cursor], n_nan, max_time-min_time);
            }
        }
    }

    assert!(truncate_events.is_none()); // for now

    if verbose { println!("{:>8.2} writing... (n_time_buckets={}, n_incomplete_buckets={}, n_skipped_buckets={})", seconds(Instant::now() - start), n_time_buckets, n_incomplete_buckets, n_skipped_buckets); }

    // we have to read this again because I could not figure out ownership problems
    let events_csv =
        fs::OpenOptions::new()
            .read(true)
            .open(events_csv)?;

    let mut events_csv = csv::Reader::from_reader(events_csv);

    let output_csv =
        fs::OpenOptions::new()
            .write(true)
            .create(true)
            .truncate(true)
            .open(output)?;

    let mut wtr = csv::Writer::from_writer(output_csv);

    let data_cols: Vec<i64> = {
        let mut xs = vec![0; n - 1];
        for i in 0..(n - 1) {
            xs[i] = (buckets[i] + buckets[i + 1]) / 2;
        }
        xs
    };

    {
        let headers = events_csv.byte_headers()?;
        for col in headers.iter() {
            wtr.write_field(col)?;
        }
        for col in data_cols.iter() {
            wtr.write_field(&format!("{}", col))?;
        }
        wtr.write_record(None::<&[u8]>)?;
    }

    let mut record = csv::ByteRecord::new();

    for event in events {
        if !events_csv.read_byte_record(&mut record)? { panic!("failed to read from events csv") }
        for meta in record.iter() {
            wtr.write_field(meta)?;
        }
        for val in event.data.iter() {
            wtr.write_field(&format!("{}", val))?;
        }
        wtr.write_record(None::<&[u8]>)?;
    }


    if verbose { println!("{:>8.2} finished.", seconds(Instant::now() - start)); }

    Ok(())
}

/*
def to_tframe(version, df, trades, start):
    d = {'bid': {}, 'ask': {}}
    cursor = 0
    n = 0
    n_periods = 40
    xs = np.concatenate([periods(n_periods)[:0:-1] * -1, periods(n_periods)]) * 1000000 # mult to convert to nanos
    mask = df['version'] == version
    #my_trades = sorted(list(zip(df.loc[mask].index, df.loc[mask, 'side'], df.loc[mask, 'gid'])))
    my_trades = sorted(list(zip(df.loc[mask].index.values.astype(np.int64), df.loc[mask, 'side'], df.loc[mask, 'gid'])))
    #idx = trades.index
    idx = trades.index.values.astype(np.int64)
    amts = trades['amount']
    totals = trades['total']
    assert len(idx) == len(amts)
    assert len(idx) == len(totals)
    for tm, side, gid in my_trades:
        print '{} to_tfame {} {} (cursor = {})'.format(time.time() - start, version, n, cursor)
        #min_time = tm + timedelta(milliseconds=xs[0])
        #max_time = tm + timedelta(milliseconds=xs[1])
        min_time = tm + xs[0]
        max_time = tm + xs[1]
        if idx[cursor] > min_time:
            print 'warning: idx[cursor] ({}) > min_time ({})'.format(idx[cursor], min_time)
            while idx[cursor] > min_time and cursor > 0:
                cursor -= 1
        else:
            while idx[cursor] < min_time and cursor < len(idx) - 1:
                cursor += 1
        i = 1
        j = cursor
        d[side][gid] = {}
        while i < len(xs) - 1:
            wsum = 0.0
            w = 0.0
            while idx[j] < max_time:
                wsum += totals[j]
                w += amts[j]
                j += 1
            if w > 0.0:
                d[side][gid][xs[i]] = wsum / w
            else:
                d[side][gid][xs[i]] = np.nan
            i += 1
            min_time = max_time
            #max_time = tm + timedelta(milliseconds=xs[i])
            max_time = tm + xs[i]
        n += 1
    d['bid'] = sort_cols(pd.DataFrame.from_dict(d['bid'], orient='index'))
    d['ask'] = sort_cols(pd.DataFrame.from_dict(d['ask'], orient='index'))
    #yield (version, d)
    return d
*/