extern crate timer;
extern crate termion;
extern crate systemstat;

use std::thread;
use termion::{cursor, color, clear, terminal_size};
use termion::color::Color;
use termion::raw::{IntoRawMode};
use termion::screen::{AlternateScreen};
use termion::async_stdin;
use std::io::{Read, Write, stdout};
use std::time::{Duration, Instant};
use std::cmp::min;

use systemstat::{System, Platform, Memory};
use systemstat::data::{LoadAverage};

fn update_values<T>(value:T, values:&mut Vec<T>, max_length:usize)
{
    values.push(value);
    if values.len() > max_length
    {
        let number = values.len()-max_length;
        values.drain(0..number);
    }
}
fn print_cpu_load_time<W:Write>(stdout:&mut W, load_time:LoadAverage)
{
    write!(stdout, "{}{}{}{} {}{} {}{}", cursor::Goto(1,3), clear::CurrentLine,
        color::Fg(color::Yellow), load_time.one,
        color::Fg(color::LightYellow), load_time.five,
        color::Fg(color::White), load_time.fifteen
    ).unwrap();
}

fn print_mem_load<W:Write>(stdout:&mut W, memory:Memory)
{
    write!(stdout, "{}{}{}{}/{}{}", cursor::Goto(1,4), clear::CurrentLine,
        color::Fg(color::Yellow), memory.total - memory.free,
        color::Fg(color::White), memory.total
    ).unwrap();
}

fn print_graph<W:Write, C:Color>(stdout:&mut W, values:&[f32], y_pos:u16, color:color::Fg<C>)
{
    const GRAPH:&'static str = "▁▂▃▄▅▆▇█";
    write!(stdout, "{}{}{}", cursor::Goto(1, y_pos), clear::CurrentLine, color).unwrap();
    for value in values {
        if *value <= 1. as f32
        {
            let i:usize = (value * (GRAPH.chars().count() as f32)) as usize;
            match GRAPH.chars().nth(i)
            {
                Some(c) => write!(stdout, "{}", c).unwrap(),
                None => write!(stdout, "#").unwrap()
            }

        }
        else
        {
            write!(stdout, "{}█{}", color::Fg(color::Red), color).unwrap();

        }
    }
}

fn main() {
    let mut screen = AlternateScreen::from(stdout().into_raw_mode().unwrap());
    let mut stdin = async_stdin().bytes();
    let system = System::new();

    let mut cpu_load_graph:Vec<f32> = Vec::new();
    let mut mem_load_graph:Vec<f32> = Vec::new();


    let start_time = Instant::now();
    let mut num_seconds:u64 = 0;
    let mut previous_size:(u16, u16) = (0,0);

    write!(screen, "{}", cursor::Hide).unwrap();

    loop {
        let b = stdin.next();
        match terminal_size()
        {
            Ok(size) => {
                if size != previous_size
                {
                    write!(screen, "{}", clear::All).unwrap();
                    previous_size = size;
                }
                let x:usize = size.0 as usize & 0xFFFF;
                let new_time = start_time.elapsed().as_secs();
                if new_time > num_seconds
                {
                    let cpu = system.load_average();
                    if let Ok(cpu_load) = cpu
                    {
                        update_values(cpu_load.one, &mut cpu_load_graph, x);
                        print_cpu_load_time(&mut screen, cpu_load);
                    }
                    if let Ok(mem_load) = system.memory()
                    {
                        update_values(((mem_load.total.as_usize() - mem_load.free.as_usize()) as f32) / (mem_load.total.as_usize() as f32), &mut mem_load_graph, x);
                        print_mem_load(&mut screen, mem_load);
                    }

                    print_graph(&mut screen, &cpu_load_graph[0..min(x, cpu_load_graph.len())], 1, color::Fg(color::White));
                    print_graph(&mut screen, &mem_load_graph[0..min(x, mem_load_graph.len())], 2, color::Fg(color::Blue));

                    screen.flush().unwrap();
                    num_seconds = new_time;
                }
                if let Some(Ok(b'q')) = b {
                    break;
                }
                thread::sleep(Duration::from_millis(50));

            },
            Err(e) => {
                println!("{}{}Error : {}", clear::All, cursor::Goto(1,1), e);
                break
            }
        }

    }
    write!(screen, "{}", cursor::Show).unwrap();
}