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

use clap::ArgMatches;

use crate::error::{Error, Result};
use crate::database::Database;
use crate::interactive::{ask, confirm_deletion};
use crate::io::Streams;

use super::{Command, Facts};

#[derive(Debug)]
pub enum Args {
    Id(u64),
    Sheet(String),
    Last,
}

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

    fn try_from(args: &'a ArgMatches) -> Result<Args> {
        Ok(if let Some(id) = args.value_of("id") {
            Args::Id(id.parse().unwrap())
        } else if args.is_present("last") {
            Args::Last
        } else if let Some(sheet) = args.value_of("sheet") {
            Args::Sheet(sheet.to_owned())
        } else {
            unreachable!()
        })
    }
}

pub struct KillCommand;

impl<'a> Command<'a> for KillCommand {
    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,
    {
        match args {
            Args::Id(id) => {
                if let Some(entry) = streams.db.entry_by_id(id)? {
                    confirm_deletion(streams, entry, facts.now)?;
                } else {
                    writeln!(streams.out, "There's no entry with id {}. Someone found it before we did.", id)?;
                }
            }
            Args::Last => {
                let current_sheet = streams.db.current_sheet()?;
                if let Some(entry) = streams.db.last_entry_of_sheet(&current_sheet)? {
                    confirm_deletion(streams, entry, facts.now)?;
                } else {
                    writeln!(streams.out, "Nothing to delete")?;
                }
            }
            Args::Sheet(sheet) => {
                let n = streams.db.entries_by_sheet(&sheet, None, None)?.len();

                if ask(streams, &format!("are you sure you want to delete {} entries on sheet \"{}\"?", n, sheet))? {
                    streams.db.delete_entries_in_sheet(&sheet)?;
                    writeln!(streams.out, "They're gone")?;
                } else {
                    writeln!(streams.out, "Don't worry, they're still there")?;
                }
            }
        }

        Ok(())
    }
}