// See LICENSE file for copyright and license details.

use x11::xlib;
use x11::xlib::{
    Display,
    XErrorEvent,
    Atom,
    XChangeProperty,
};

use safe_x11::{
    open_display,
    close_display,
    atom,
    screen_size,
};

use safe_x11::window::XWindow;

use std::ptr;
use std::process::exit;
use std::mem::uninitialized;
use std::collections::HashMap;
use libc::c_int;

#[allow(unused_variables)]
unsafe extern "C" fn error_handler(d: *mut Display, evptr: *mut XErrorEvent) -> c_int {
    println!("ERRORR");
    let ev = ptr::read(evptr);
    if ev.error_code == xlib::BadAccess {
        println!("Another widnow manager is running :C");
        exit(1);
    }

    0
}

#[derive(Hash,Eq,PartialEq)]
pub enum WmAtom {
    Protocols,
    DeleteWindow,
}

#[derive(Hash,Eq,PartialEq)]
pub enum NetAtom {
    NetSupported,
    NetFullscreen,
    NetWmState,
    NetActive,
}

/// State of the window manager.
pub struct DotWM {
    /// Reference to the X display.
    pub display: *mut Display,
    /// References to all the windows.
    pub window_list: Vec<XWindow>,
    /// Check if the window manager needs to end.
    pub finish: bool,
    /// Vec holding atoms for ICCCM support
    pub wmatoms: HashMap<WmAtom, Atom>,
    /// Vec holding atoms for EWHM support
    pub netatoms: HashMap<NetAtom, Atom>,
    /// Number of the active desctop
    current_desktop: usize,
    cw_idx: usize,
}

/// DotWM state.
impl DotWM {
    /// Create a state of the Dot Window Manager
    pub fn new() -> DotWM {
        let d = open_display("").unwrap();
        unsafe { xlib::XSetErrorHandler(Some(error_handler)) };

        // Add substructure notify mask
        let root = unsafe { xlib::XDefaultRootWindow(d) };

        unsafe {
            let mut attrs: xlib::XSetWindowAttributes = uninitialized();
            attrs.event_mask = xlib::SubstructureNotifyMask;
            xlib::XChangeWindowAttributes(d, root, xlib::CWEventMask, &mut attrs);
        }

        // Get the wmatoms
        let mut wmatoms = HashMap::new();
        wmatoms.insert(WmAtom::Protocols, atom(d, "WM_PROTOCOLS"));
        wmatoms.insert(WmAtom::DeleteWindow, atom(d, "WM_DELETE_WINDOW"));

        // Get the netatoms
        let mut netatoms = HashMap::new();
        netatoms.insert(NetAtom::NetSupported, atom(d, "_NET_SUPPORTED"));
        netatoms.insert(NetAtom::NetFullscreen, atom(d, "_NET_WM_STATE_FULLSCREEN"));
        netatoms.insert(NetAtom::NetWmState, atom(d, "_NET_ACTIVE_WINDOW"));
        netatoms.insert(NetAtom::NetActive, atom(d, "_NET_WM_STATE"));

        // Propagate EWHM support
        unsafe {
            let atomvec: Vec<&Atom> = netatoms.values().collect();
            let len: i32 = netatoms.len() as i32;
            let atomptr = atomvec.as_ptr();

            XChangeProperty(d, root, netatoms[&NetAtom::NetSupported], xlib::XA_ATOM,
                            32, xlib::PropModeReplace, atomptr as *const u8, len);
        }

        DotWM {
            display: d,
            cw_idx: 0,
            finish: false,
            wmatoms: wmatoms,
            netatoms: netatoms,
            current_desktop: 0,
            window_list: vec![],
        }
    }

    pub fn add_window(&mut self, w: xlib::Window) {
        self.unfocus_current_window();
        if let Some(w) = XWindow::new(self.display, w) {
            w.select_input(xlib::EnterWindowMask);
            self.window_list.push(w);
            // Last windows get focus.
            self.cw_idx = self.window_list.len() - 1;
            self.focus_current_window();
        }
    }

    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
        }
    }

    pub fn remove_window(&mut self, w: xlib::Window) {
        let pos = self.window_list.iter().position(|xw| xw.inner == w);
        
        match pos {
            Some(idx) => { 
                let new_idx = if idx == 0 { usize::max_value() } else { idx - 1 };
                self.window_list.remove(idx);
                self.cw_idx = new_idx;
                self.focus_current_window();
            },
            None => (),
        }
    }

    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.window_list.len() > 0 {
            // 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.iter() {
            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()
    }
}

impl Drop for DotWM {
    fn drop(&mut self) {
        println!("Closing display");
        close_display(self.display);
    }
}