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

use clap::ArgMatches;
use terminal_size::{Width, terminal_size};
use chrono::{DateTime, Utc, Local, LocalResult, TimeZone};
use ansi_term::Color::Yellow;

use crate::error::{Result, Error};
use crate::database::{Database, DBVersion};
use crate::config::Config;
use crate::models::Entry;
use crate::formatters::Formatter;

pub mod r#in;
pub mod display;
pub mod today;
pub mod sheet;

pub trait Command<'a> {
    type Args: TryFrom<&'a ArgMatches<'a>>;

    fn handle<D: Database, O: Write, E: Write>(args: Self::Args, db: &mut D, out: &mut O, err: &mut E, config: &Config) -> Result<()>;
}

fn local_to_utc(t: DateTime<Utc>) -> Result<DateTime<Utc>> {
    let local_time = match Local.from_local_datetime(&t.naive_utc()) {
        LocalResult::None => return Err(Error::NoneLocalTime(t.naive_utc().to_string())),
        LocalResult::Single(t) => t,
        LocalResult::Ambiguous(t1, t2) => return Err(Error::AmbiguousLocalTime {
            orig: t.naive_utc().to_string(),
            t1: t1.naive_local(),
            t2: t2.naive_local(),
        }),
    };

    Ok(Utc.from_utc_datetime(&local_time.naive_utc()))
}

fn local_to_utc_vec(entries: Vec<Entry>) -> Result<Vec<Entry>> {
    entries
        .into_iter()
        .map(|e| {
            Ok(Entry {
                start: local_to_utc(e.start)?,
                end: e.end.map(|t| local_to_utc(t)).transpose()?,
                ..e
            })
        })
        .collect()
}

fn term_width() -> usize {
    if let Some((Width(w), _)) = terminal_size() {
        w as usize
    } else {
        80
    }
}

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

impl FromStr for Sheet {
    type Err = Error;

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

pub fn entries_for_display<D, O, E>(
    start: Option<DateTime<Utc>>, end: Option<DateTime<Utc>>,
    sheet: Option<Sheet>, db: &mut D, out: &mut O, err: &mut E,
    format: Formatter, ids: bool,
) -> Result<()>
where
    D: Database,
    O: Write,
    E: Write,
{
    let entries = match sheet {
        Some(Sheet::All) => db.entries_all_visible(start, end)?,
        Some(Sheet::Full) => db.entries_full(start, end)?,
        Some(Sheet::Sheet(name)) => db.entries_by_sheet(&name, start, end)?,
        None => {
            let current_sheet = db.current_sheet()?.unwrap_or("default".into());

            db.entries_by_sheet(&current_sheet, start, end)?
        }
    };

    let (entries, needs_warning) = if let DBVersion::Timetrap = db.version()? {
        // this indicates that times in the database are specified in the
        // local time and need to be converted to utc before displaying

        (local_to_utc_vec(entries)?, true)
    } else {
        (entries, false)
    };

    format.print_formatted(
        entries,
        out,
        Utc::now(),
        ids,
        term_width(),
    )?;

    if needs_warning {
        writeln!(
            err,
            "{} You are using the old timetrap format, it is advised that \
            you update your database using t migrate",
            Yellow.bold().paint("[WARNING]"),
        )?;
    }

    Ok(())
}