use x11::xlib;
use x11::xlib::{
    Display,
};

use safe_x11::window::XWindow;
use safe_x11::{
    screen_size,
};

pub struct Desktop {
    #[allow(dead_code)]
    display: *mut Display,
    #[allow(dead_code)]
    tag: String,
    window_list: Vec<XWindow>,
    cw_idx: usize,
}

impl Desktop {
    pub fn new(display: *mut Display, tag: &'static str) -> Desktop {
        Desktop {
            display: display,
            tag: String::from(tag),
            window_list: vec![],
            cw_idx: 0,
        }
    }

    /// Tells if the current index is valid for indexing the window list.
    /// 
    /// This is a precondition that must be valid wherever one index that
    /// list.
    fn valid_idx(&self) -> bool {
        self.cw_idx != usize::max_value()
    }

    pub fn current_window(&self) -> Option<&XWindow> {
        if self.cw_idx < self.window_list.len() {
            self.window_list.get(self.cw_idx)
        } else {
            None
        }
    }

    pub fn current_window_mut(&mut self) -> Option<&mut XWindow> {
        if self.cw_idx < self.window_list.len() {
            self.window_list.get_mut(self.cw_idx)
        } else {
            None
        }
    }

    /// Add a window to the current desktop
    pub fn add_window(&mut self, w: xlib::Window) {
        if self.find_window(w).is_some() {
            return;
        }
        self.unfocus_current_window();
        if let Some(w) = XWindow::new(self.display, w) {
            w.select_input(xlib::EnterWindowMask | xlib::ExposureMask);
            self.window_list.push(w);
            // Last windows get focus.
            self.focus_current_window();
        }
    }

    /// Remove a window.
    pub fn remove_window(&mut self, w: xlib::Window) {
        let pos = self.window_list.iter().position(|xw| xw.inner == w);
        
        if let Some(idx) = pos {
            let new_idx = if idx == 0 {
                if self.window_list.len() == 1 { usize::max_value() } else { 0 }
            } else {
                idx - 1
            };
            self.window_list.remove(idx);
            self.cw_idx = new_idx;
            self.focus_current_window();
        }
    }

    /// Changes the focus from the current window to the window on the idx
    /// postition on the window_list.
    pub fn change_focus_of(&mut self, idx: usize) {
        let w = &self.window_list[idx];
        self.unfocus_current_window();
        self.cw_idx = idx;
        w.set_border_width(1);
        w.set_border_color("red");
        w.raise();
    }

    /// Find a given window and returns it's position on the window_list.
    pub fn find_window(&self, w: xlib::Window) -> Option<usize> {
        self.window_list.iter().position(|xw| xw.inner == w)
    }

    /// Focus the next window.
    ///
    /// There're 3 posibilities. There's no window, there's one window or there
    /// are more windows.
    pub fn focus_next(&mut self) {
        if self.valid_idx() {
            // Unfocus the current window.
            let prev_win = &self.window_list[self.cw_idx];
            prev_win.unfocus();

            // And give focus to the next one.
            let next_win_idx = if self.cw_idx < self.window_list.len() - 1 {
                self.cw_idx + 1
            } else {
                0
            };

            let curr_win = &self.window_list[next_win_idx];
            curr_win.focus();
            self.cw_idx = next_win_idx;
        }
    }

    fn focus_current_window(&self) {
        self.current_window().map(|x| x.focus());
    }

    fn unfocus_current_window(&self) {
        self.current_window().map(|x| x.unfocus());
    }

    /// Get a list of the geometries for every window in the screen (including
    /// the screen borders. The form is (x, y).
    ///
    /// # Example
    ///
    /// Having a screen of 800x600, and a window on 10(x), 10(y) with dimensions 
    /// 400(width) and 300(height):
    ///
    /// ```
    /// for (x, y) in dotwm.geometries() {
    ///     println!("x: {} - y: {}", x, y);
    /// }
    /// ```
    ///
    /// The output will be:
    ///
    /// ```
    /// (0,0)
    /// (800, 600)
    /// (10, 10)
    /// (410, 310)
    /// ```
    pub fn geometries(&self) -> Vec<(i32,i32)> {
        let (screen_width, screen_height) = screen_size(self.display);
        let mut result: Vec<(i32,i32)> = vec![
            (0, 0),
            (screen_width as i32, screen_height as i32),
        ];

        for w in &self.window_list {
            let attrs = w.attributes();
            result.push((attrs.x, attrs.y));
            result.push((attrs.x + attrs.width, attrs.y + attrs.height));
        }

        result
    }

    pub fn x_geometries(&self) -> Vec<i32> {
        self.geometries().iter().map(|x| x.0).collect()
    }

    pub fn y_geometries(&self) -> Vec<i32> {
        self.geometries().iter().map(|x| x.1).collect()
    }


    pub fn show_windows(&self) {
        for win in &self.window_list {
            win.map();
        }
    }

    pub fn hide_windows(&self) {
        for win in &self.window_list {
            win.unmap();
        }
    }
}