use std::convert::TryFrom;
use std::io::Write;
use std::str::FromStr;

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

use crate::error;
use crate::database::Database;
use crate::formatters::Formatter;
use crate::config::Config;

use super::Command;

enum Sheet {
    All,
    Full,
    Sheet(String),
}

impl FromStr for Sheet {
    type Err = error::Error;

    fn from_str(name: &str) -> error::Result<Sheet> {
        Ok(match name {
            "all" => Sheet::All,
            "full" => Sheet::Full,
            name => Sheet::Sheet(name.into()),
        })
    }
}

pub struct Args {
    ids: bool,
    start: Option<DateTime<Utc>>,
    end: Option<DateTime<Utc>>,
    format: Formatter,
    grep: Option<String>,
    sheet: Option<Sheet>,
}

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

    fn try_from(matches: &'a ArgMatches) -> error::Result<Args> {
        Ok(Args {
            ids: matches.is_present("ids"),
            start: matches.value_of("at").map(|s| s.parse()).transpose()?,
            end: matches.value_of("at").map(|s| s.parse()).transpose()?,
            format: matches.value_of("format").unwrap().parse()?,
            grep: matches.value_of("grep").map(|s| s.into()),
            sheet: matches.value_of("sheet").map(|s| s.parse()).transpose()?,
        })
    }
}

pub struct DisplayCommand {
}

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

    fn handle<D, W>(args: Self::Args, db: &mut D, out: &mut W, config: &Config) -> error::Result<()>
    where
        D: Database,
        W: Write,
    {
        let sheets_to_display = match args.sheet {
            Some(Sheet::All) => db.entries_all_visible()?,
            Some(Sheet::Full) => db.entries_full()?,
            Some(Sheet::Sheet(name)) => db.entries_by_sheet(&name)?,
            None => {
                let current_sheet = db.current_sheet()?.unwrap_or("default".into());

                db.entries_by_sheet(&current_sheet)?
            }
        };

        args.format.print_formatted(sheets_to_display, out, Utc::now(), Local.offset_from_utc_datetime(&Utc::now().naive_utc()), args.ids)
    }
}