use event::{Event, EventResult};
use vec::Vec2;
use view::{Margins, View, ViewWrapper};
use Printer;

/// Adds padding to another view.
///
/// This view wraps another view and adds some padding.
///
/// The wrapped view will see a reduced space available.
///
/// # Examples
///
/// ```rust
/// # use cursive::views::{TextView, PaddedView};
/// // Adds 2 columns of padding to the left and to the right.
/// let view = PaddedView::new(
///     ((2,2), (0,0)), // ((left, right), (top, bottom))
///     TextView::new("Padded text")
/// );
/// ```
pub struct PaddedView<V> {
    view: V,
    margins: Margins,
}

impl<V: View> PaddedView<V> {
    /// Wraps `view` in a new `PaddedView` with the given margins.
    pub fn new<M: Into<Margins>>(margins: M, view: V) -> Self {
        let margins = margins.into();
        PaddedView { view, margins }
    }

    /// Sets the margins for this view.
    pub fn set_margins<M: Into<Margins>>(&mut self, margins: M) {
        // TODO: invalidate?
        self.margins = margins.into();
    }
}

impl<V: View> ViewWrapper for PaddedView<V> {
    wrap_impl!(self.view: V);

    fn wrap_required_size(&mut self, req: Vec2) -> Vec2 {
        let margins = self.margins.combined();
        self.view.required_size(req.saturating_sub(margins)) + margins
    }

    fn wrap_layout(&mut self, size: Vec2) {
        let margins = self.margins.combined();
        self.view.layout(size.saturating_sub(margins));
    }

    fn wrap_on_event(&mut self, event: Event) -> EventResult {
        let padding = self.margins.top_left();
        self.view.on_event(event.relativized(padding))
    }

    fn wrap_draw(&self, printer: &Printer) {
        let top_left = self.margins.top_left();
        let bot_right = self.margins.bot_right();
        let printer = &printer.offset(top_left).shrinked(bot_right);
        self.view.draw(printer);
    }
}