use std::io::{BufRead, Write};
use std::convert::TryFrom;

use chrono::{DateTime, Utc};
use clap::ArgMatches;

use crate::database::Database;
use crate::error::{Error, Result};
use crate::timeparse::parse_time;
use crate::old::{time_or_warning, warn_if_needed};
use crate::io::Streams;

use super::{Command, Facts};

#[derive(Default)]
pub struct Args {
    at: Option<DateTime<Utc>>,
}

impl<'a> TryFrom<&'a ArgMatches> for Args {
    type Error = Error;

    fn try_from(matches: &'a ArgMatches) -> Result<Args> {
        Ok(Args {
            at: matches.value_of("at").map(parse_time).transpose()?,
        })
    }
}

pub struct OutCommand{}

impl<'a> Command<'a> for OutCommand {
    type Args = Args;

    fn handle<D, I, O, E>(args: Self::Args, streams: &mut Streams<D, I, O, E>, facts: &Facts) -> Result<()>
    where
        D: Database,
        I: BufRead,
        O: Write,
        E: Write,
    {
        let end = args.at.unwrap_or(facts.now);
        let sheet = streams.db.current_sheet()?;

        let (end, needs_warning) = time_or_warning(end, &streams.db)?;

        if let Some(entry) = streams.db.running_entry(&sheet)? {
            writeln!(streams.out, "Checked out of sheet \"{}\".", sheet)?;

            streams.db.entry_update(entry.id, entry.start, Some(end), entry.note, &entry.sheet)?;
        } else {
            writeln!(streams.out, "No running entry on sheet \"{}\".", sheet)?;
        }

        warn_if_needed(&mut streams.err, needs_warning, &facts.env)?;

        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use pretty_assertions::assert_eq;
    use chrono::{TimeZone, Local};

    use super::*;

    #[test]
    fn finishes_entry() {
        let args = Default::default();
        let mut streams = Streams::fake(b"");
        let facts = Facts::new();

        streams.db.entry_insert(facts.now, None, None, "default").unwrap();

        OutCommand::handle(args, &mut streams, &facts).unwrap();

        let e = streams.db.entries_full(None, None).unwrap().into_iter().next().unwrap();

        assert_eq!(e.end, Some(facts.now));

        assert_eq!(&String::from_utf8_lossy(&streams.out), "Checked out of sheet \"default\".\n");
        assert_eq!(&String::from_utf8_lossy(&streams.err), "");
    }

    #[test]
    fn tells_if_no_running_entry() {
        let args = Default::default();
        let mut streams = Streams::fake(b"");
        let facts = Facts::new();

        streams.db.entry_insert(facts.now, None, None, "non-default").unwrap();

        OutCommand::handle(args, &mut streams, &facts).unwrap();

        assert_eq!(&String::from_utf8_lossy(&streams.out), "No running entry on sheet \"default\".\n");
        assert_eq!(&String::from_utf8_lossy(&streams.err), "");
    }

    #[test]
    fn warns_if_old_database() {
        let args = Default::default();
        let mut streams = Streams::fake_old(b"");
        let facts = Facts::new();

        streams.db.entry_insert(facts.now, None, None, "default").unwrap();

        OutCommand::handle(args, &mut streams, &facts).unwrap();

        let e = streams.db.entries_full(None, None).unwrap().into_iter().next().unwrap();

        assert_eq!(e.end, Some(Utc.from_utc_datetime(&facts.now.with_timezone(&Local).naive_local())));

        assert_eq!(&String::from_utf8_lossy(&streams.out), "Checked out of sheet \"default\".\n");
        assert_eq!(&String::from_utf8_lossy(&streams.err),
            "[WARNING] You are using the old timetrap format, it is advised that \
            you update your database using t migrate. To supress this warning set TIEMPO_SUPRESS_TIMETRAP_WARNING=1\n");
    }
}