use chrono::prelude::*;
use chrono::Duration;
use std::io::{stdout, Result, StdoutLock, Write};
use std::process::{Command, Output};
use std::thread::sleep;

const TIME_FORMAT: &'static str = "%H:%M:%S";

fn main() {
    run().unwrap();
}

/// Runs the application
///
/// Default time settings are 25 minutes for a working block and 5 minutes for a break.
fn run() -> Result<()> {
    let work_duration = Duration::seconds(if cfg!(debug_assertions) { 75 } else { 25 * 60 });
    let break_duration = Duration::seconds(if cfg!(debug_assertions) { 5 } else { 5 * 60 });

    loop {
        timer(
            "Work",
            "The working time is over, have a break now!",
            &work_duration,
        )?;

        timer(
            "Break",
            "The break is over, get back to work!",
            &break_duration,
        )?;
    }
}

/// Handles a timer block
///
/// # Arguments
///
/// * name - The name for this block, e.g. 'Work' or 'Break'
/// * after_msg - The message to be displayed by the Dialog window at the end of the time
/// * duration - How long this block shall be
fn timer(name: &str, after_msg: &str, duration: &Duration) -> Result<()> {
    let out = stdout();
    let mut out = out.lock();
    let start = Local::now();
    writeln!(out, "{} start {}", name, start.format(TIME_FORMAT))?;

    loop {
        reset_line(&mut out)?;
        let elapsed: Duration = Local::now().signed_duration_since(start);

        if elapsed >= *duration {
            break;
        }

        let elapsed_time: NaiveTime = NaiveTime::from_hms(
            (elapsed.num_hours() % 24) as u32,
            (elapsed.num_minutes() % 60) as u32,
            (elapsed.num_seconds() % 60) as u32,
        );
        write!(out, "Time elapsed: {}", elapsed_time.format(TIME_FORMAT))?;
        out.flush().unwrap();

        sleep(Duration::seconds(1).to_std().unwrap());
    }

    let now = Local::now();
    writeln!(out, "{} end {}", name, now.format(TIME_FORMAT))?;
    dialog(after_msg).unwrap();
    Ok(())
}

/// Shows a dialog
///
/// Currently only supports KDE dialogs via command line program `kdialgo`.
///
/// # Arguments
///
/// * text - The text to be shown in the Dialog
fn dialog(text: &str) -> Result<Output> {
    Command::new("sh")
        .arg("-c")
        .arg(format!(
            "kdialog --title 'Pomodoro Timer' --msgbox '{}'",
            text
        ))
        .output()
}

/// Resets the current line on stdout
///
/// Works for me® but is probably unportable as hell.
///
/// # Arguments
///
/// * w - A reference to the locked stdout handle
pub fn reset_line(w: &mut StdoutLock) -> Result<()> {
    write!(w, "\r[2K")
}