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

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

use crate::error::{Error, Result};
use crate::timeparse::parse_time;
use crate::database::Database;
use crate::models::Entry;
use crate::io::Streams;

use super::{Command, Facts, r#in, sheet};

#[derive(Default)]
pub struct Args {
    id: Option<u64>,
    at: Option<DateTime<Utc>>,
}

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

    fn try_from(matches: &'a ArgMatches) -> Result<Self> {
        Ok(Args {
            at: matches.value_of("at").map(|s| parse_time(s)).transpose()?,
            id: matches.value_of("id").map(|i| i.parse().unwrap()),
        })
    }
}

fn resume<D, I, O, E>(args: Args, streams: &mut Streams<D, I, O, E>, facts: &Facts, entry: Entry) -> Result<()>
where
    D: Database,
    I: BufRead,
    O: Write,
    E: Write,
{
    writeln!(
        streams.out,
        "Resuming \"{}\" from entry #{}",
        entry.note.clone().unwrap_or_else(|| "".to_owned()), entry.id
    )?;

    r#in::InCommand::handle(r#in::Args {
        at: args.at,
        note: entry.note,
    }, streams, facts)
}

pub struct ResumeCommand;

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

    fn handle<D, I, O, E>(args: Args, streams: &mut Streams<D, I, O, E>, facts: &Facts) -> Result<()>
    where
        D: Database,
        I: BufRead,
        O: Write,
        E: Write,
    {
        let current_sheet = streams.db.current_sheet()?.unwrap_or_else(|| "default".to_owned());

        // First try to process using the given id
        if let Some(entry_id) = args.id {
            if let Some(entry) = streams.db.entry_by_id(entry_id)? {
                if entry.sheet != current_sheet {
                    // first swith to the sheet
                    sheet::SheetCommand::handle(sheet::Args {
                        sheet: Some(entry.sheet.clone()),
                    }, streams, facts)?;
                }

                return resume(args, streams, facts, entry);
            } else {
                writeln!(streams.out, "The entry with id '{}' could not be found to be resumed. Perhaps it was deleted?", entry_id)?;

                return Ok(());
            }
        }

        // No id specified, try to find something suitable to switch to in the
        // database
        if let Some(entry) = streams.db.last_checkout_of_sheet(&current_sheet)? {
            resume(args, streams, facts, entry)
        } else {
            writeln!(streams.out, "No entry to resume in the sheet '{}'. Perhaps start a new one?
Hint: use t in", current_sheet)?;

            Ok(())
        }
    }
}

#[cfg(test)]
mod tests {
    use chrono::Duration;
    use pretty_assertions::assert_eq;

    use crate::test_utils::Ps;

    use super::*;

    #[test]
    fn resume_an_entry() {
        let args = Default::default();
        let mut streams = Streams::fake(b"");
        let facts = Facts::new();
        let one_hour_ago = facts.now - Duration::hours(1);
        let two_hours_ago = facts.now - Duration::hours(2);

        streams.db.entry_insert(two_hours_ago, Some(one_hour_ago), Some("fake note".into()), "default").unwrap();

        assert_eq!(streams.db.entries_full(None, None).unwrap().len(), 1);

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

        let all_entries = streams.db.entries_full(None, None).unwrap();

        assert_eq!(all_entries.len(), 2);

        assert_eq!(all_entries[1].id, 2);
        assert_eq!(all_entries[1].start, facts.now);
        assert_eq!(all_entries[1].end, None);
        assert_eq!(all_entries[1].note, Some("fake note".into()));
        assert_eq!(all_entries[1].sheet, "default");

        assert_eq!(Ps(&String::from_utf8_lossy(&streams.out)), Ps("Resuming \"fake note\" from entry #1
Checked into sheet \"default\".\n"));
        assert_eq!(Ps(&String::from_utf8_lossy(&streams.err)), Ps(""));
    }

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

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

        assert_eq!(Ps(&String::from_utf8_lossy(&streams.out)), Ps("\
No entry to resume in the sheet 'default'. Perhaps start a new one?
Hint: use t in
"));
    }
}