use crate::core::*;
pub(crate) use ratatui::prelude::*;
pub(crate) use ratatui::buffer::Cell;
use ratatui::widgets::WidgetRef;

pub fn fill_bg (buf: &mut Buffer, area: Rect, color: Color) {
    let Rect { x, y, width, height } = area;
    for y in y..y+height {
        if y >= buf.area.height {
            break
        }
        for x in x..x+width {
            if x >= buf.area.width {
                break
            }
            buf.get_mut(x, y).set_bg(color);
        }
    }
}

pub trait Blit {
    // Render something to X, Y coordinates in a buffer, ignoring width/height.
    fn blit (&self, buf: &mut Buffer, x: u16, y: u16, style: Option<Style>) -> Usually<Rect>;
}

impl<T: AsRef<str>> Blit for T {
    fn blit (&self, buf: &mut Buffer, x: u16, y: u16, style: Option<Style>) -> Usually<Rect> {
        if x < buf.area.width && y < buf.area.height {
            buf.set_string(x, y, self.as_ref(), style.unwrap_or(Style::default()));
        }
        Ok(Rect { x, y, width: self.as_ref().len() as u16, height: 1 })
    }
}

/// Trait for things that render to the display.
pub trait Render: Send {
    // Render something to an area of the buffer.
    // Returns area used by component.
    // This is insufficient but for the most basic dynamic layout algorithms.
    fn render (&self, _b: &mut Buffer, _a: Rect) -> Usually<Rect> {
        Ok(Rect { x: 0, y: 0, width: 0, height: 0 })
    }
}

/// Implement the `Render` trait.
#[macro_export] macro_rules! render {
    ($T:ty) => {
        impl Render for $T {}
    };
    ($T:ty |$self:ident, $buf:ident, $area:ident|$block:tt) => {
        impl Render for $T {
            fn render (&$self, $buf: &mut Buffer, $area: Rect) -> Usually<Rect> {
                $block
            }
        }
    };
    ($T:ty = $render:path) => {
        impl Render for $T {
            fn render (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
                $render(self, buf, area)
            }
        }
    }
}

impl Render for () {
    fn render (&self, _: &mut Buffer, a: Rect) -> Usually<Rect> {
        Ok(Rect { x: a.x, y: a.y, width: 0, height: 0 })
    }
}

impl<T: Fn(&mut Buffer, Rect) -> Usually<Rect> + Send> Render for T {
    fn render (&self, b: &mut Buffer, a: Rect) -> Usually<Rect> {
        (*self)(b, a)
    }
}

impl Render for Box<dyn Device> {
    fn render (&self, b: &mut Buffer, a: Rect) -> Usually<Rect> {
        (**self).render(b, a)
    }
}

impl<T: Render> Render for Arc<Mutex<T>> {
    fn render (&self, b: &mut Buffer, a: Rect) -> Usually<Rect> {
        self.lock().unwrap().render(b, a)
    }
}

impl<T: Render + Sync> Render for Arc<RwLock<T>> {
    fn render (&self, b: &mut Buffer, a: Rect) -> Usually<Rect> {
        self.read().unwrap().render(b, a)
    }
}

impl WidgetRef for &dyn Render {
    fn render_ref (&self, area: Rect, buf: &mut Buffer) {
        Render::render(*self, buf, area).expect("Failed to render device.");
    }
}

impl WidgetRef for dyn Render {
    fn render_ref (&self, area: Rect, buf: &mut Buffer) {
        Render::render(self, buf, area).expect("Failed to render device.");
    }
}

pub struct LineBuffer {
    width: usize,
    cells: Vec<Cell>,
    style: Option<Style>,
    bg:    Cell,
}

impl LineBuffer {
    pub fn new (bg: Cell, width: usize, height: usize) -> Self {
        Self {
            style: None,
            width: width,
            cells: vec![bg.clone();width*height],
            bg,
        }
    }
    pub fn height (&self) -> usize {
        self.cells.len() / self.width
    }
    pub fn style (&mut self, style: Style) -> &mut Self {
        self.style = Some(style);
        self
    }
    pub fn no_style (&mut self) -> &mut Self {
        self.style = None;
        self
    }
    pub fn put (&mut self, data: &str, x: usize, y: usize) -> &mut Self {
        if x < self.width {
            for (i, c) in data.chars().enumerate() {
                if x + i >= self.width {
                    break;
                }
                let index = y * self.width + x + i;
                while index >= self.cells.len() {
                    self.cells.extend_from_slice(&vec![self.bg.clone();self.width]);
                }
                self.cells[index].set_char(c);
                if let Some(s) = self.style {
                    self.cells[index].set_style(s);
                }
            }
        }
        self
    }
    pub fn show (&self, buf: &mut Buffer, area: Rect, offset: isize) -> Usually<Rect> {
        let Rect { x, mut y, width, height } = area;
        for row in offset..self.height() as isize {
            let length = self.cells.len();
            let start  = ((row.max(0) as usize)*self.width).min(length);
            let end    = (((row + 1).max(0) as usize)*self.width).min(length);
            for (column, cell) in self.cells[start..end].iter().enumerate() {
                if column >= width as usize {
                    break
                }
                *buf.get_mut(x + column as u16, y + row as u16) = cell.clone();
            }
            y = y + 1;
            if y > height {
                break
            }
        }
        Ok(area)
    }
}

#[cfg(test)]
mod test {
    use super::*;
    #[test]
    fn test_line_buffer () {
        let mut buffer = LineBuffer::new(Cell::default(), 12, 0);
        assert_eq!(buffer.cells.len(), 0);
        buffer.put("FOO", 0, 0);
        assert_eq!(buffer.cells.len(), 12);
        buffer.put("FOO", 6, 0);
        assert_eq!(buffer.cells.len(), 12);
        buffer.put("FOO", 11, 0);
        assert_eq!(buffer.cells.len(), 12);
        buffer.put("FOO", 12, 0);
        assert_eq!(buffer.cells.len(), 12);
        buffer.put("FOO", 24, 0);
        assert_eq!(buffer.cells.len(), 12);
        buffer.put("FOO", 0, 1);
        assert_eq!(buffer.cells.len(), 24);

    }
}