//! A window is an abstraction for the UI. Buffers (like [Threads]) draw "to" windows.

use std::io::Write;
use termion::{color, cursor};

#[derive(Clone, Copy)]
pub struct Area {
    pub x: u16,
    pub y: u16,
    pub w: u16,
    pub h: u16,
}

pub enum Line {
    Normal(String),
    Highlight(String),
}

pub struct Window {
    pub lines: Vec<Line>,
    scroll: usize,
}

impl Window {
    pub fn new() -> Self {
        Self {
            lines: Vec::new(),
            scroll: 0,
        }
    }

    pub fn draw<W: Write>(&mut self, out: &mut W, area: Area) -> Result<(), std::io::Error> {
        let mut y = area.y;
        let mut lines = self.lines.iter().skip(self.scroll);
        while y < area.h + 1 {
            match lines.next() {
                Some(line) => {
                    write!(out, "{}", cursor::Goto(area.x, y))?;
                    match line {
                        Line::Normal(s) => write!(out, "{}", s)?,
                        Line::Highlight(s) => write!(
                            out,
                            "{}{}{}",
                            color::Fg(color::Red),
                            s,
                            color::Fg(color::Reset),
                        )?,
                    }
                    y += 1;
                }
                None => break,
            }
        }
        out.flush()?;

        self.lines.clear();
        Ok(())
    }

    pub fn scroll_down(&mut self) {
        //TODO check if we're at bottom
        self.scroll += 1;
    }

    pub fn scroll_up(&mut self) {
        if self.scroll != 0 {
            self.scroll -= 1;
        }
    }
}