//! A lightweight X11 window manager, inspired by dwm.

use atoms::Atoms;
use clients::ClientState;
use colours::Colours;
use cursors::Cursors;
use error::*;
use keys::KeyboardInfo;
use xcb::{
    x::{
        self, ChangeProperty, ChangeWindowAttributes, CreateWindow, DeleteProperty,
        PropertyNotifyEvent, Window, WindowClass,
    },
    Connection, Event, Extension,
};

mod atoms;
mod clients;
mod colours;
mod config;
mod cursors;
mod error;
mod focus;
mod keys;

fn main() -> Result<()> {
    cleanup_process_children();

    let (conn, screen_num) =
        Connection::connect_with_extensions(None, &[], &[Extension::Xinerama])?;

    let mut wm = WM::new(&conn, screen_num)?;
    wm.event_loop()?;

    Ok(())
}

/// The window manager's state
struct WM<'a> {
    /// The open connection to an X server
    conn: &'a Connection,

    /// The 'screen' number on the X server
    /// Note this isn't what you think it is on multi-monitor setups
    screen_num: i32,

    /// The root window
    root: Window,

    /// A window used to prove we're actually EWMH compliant.
    /// See [the EWMH spec](https://specifications.freedesktop.org/wm-spec/wm-spec-1.3.html#idm46187912047344)
    check_window: Window,

    /// WM client state
    clients: ClientState,

    /// Cached colours,
    colours: Colours,

    /// Cached cursors
    cursors: Cursors,

    /// Cached atoms
    atoms: Atoms,

    /// Cached keyboard layout information
    keyboard_state: KeyboardInfo,
}

impl WM<'_> {
    /// Prepare the window manager to run on the given connection and screen number.
    /// This will fail if another WM is running.
    fn new(conn: &'_ Connection, screen_num: i32) -> Result<WM<'_>> {
        // Fetch root window
        let setup = conn.get_setup();
        let screen = setup
            .roots()
            .nth(screen_num as usize)
            .ok_or(Error::NoSuchScreen)?;

        // Check no other WM is running
        conn.check_request(conn.send_request_checked(&ChangeWindowAttributes {
            window: screen.root(),
            value_list: &[
                x::Cw::BackPixel(screen.white_pixel()),
                x::Cw::EventMask(x::EventMask::SUBSTRUCTURE_REDIRECT),
            ],
        }))
        .map_err(|_| Error::OtherWMRunning)?;

        Ok(WM {
            colours: Colours::new_with(conn, screen.default_colormap())?,
            atoms: Atoms::intern_all(conn)?,
            cursors: Cursors::new_with(conn)?,
            keyboard_state: KeyboardInfo::new_with(conn)?,
            clients: Default::default(),
            check_window: conn.generate_id(),
            conn,
            screen_num,
            root: screen.root(),
        })
    }

    /// Set the correct properties on the root window
    fn setup_root(&mut self) -> Result<()> {
        // Check window
        self.conn.send_request(&CreateWindow {
            wid: self.check_window,
            parent: self.root,
            depth: 0,
            x: 0,
            y: 0,
            width: 0,
            height: 0,
            border_width: 0,
            class: WindowClass::InputOutput,
            visual: 0,
            value_list: &[],
        });

        self.conn.send_request(&ChangeProperty {
            mode: x::PropMode::Replace,
            window: self.root,
            property: self.atoms.net_wm_check,
            r#type: x::ATOM_WINDOW,
            data: &[self.check_window],
        });

        self.conn.send_request(&ChangeProperty {
            mode: x::PropMode::Replace,
            window: self.check_window,
            property: self.atoms.net_wm_check,
            r#type: x::ATOM_WINDOW,
            data: &[self.check_window],
        });

        self.conn.send_request(&ChangeProperty {
            mode: x::PropMode::Replace,
            window: self.check_window,
            property: self.atoms.net_wm_name,
            r#type: x::ATOM_STRING,
            data: b"blow",
        });

        // Supported flag
        self.conn.send_request(&ChangeProperty {
            mode: x::PropMode::Replace,
            window: self.root,
            property: self.atoms.net_supported,
            r#type: x::ATOM_ATOM,
            data: &[
                self.atoms.net_active_window,
                self.atoms.net_wm_name,
                self.atoms.net_wm_state,
                self.atoms.net_wm_check,
                self.atoms.net_wm_fullscreen,
                self.atoms.net_wm_window_type,
                self.atoms.net_wm_window_type_dialog,
                self.atoms.net_client_list,
            ],
        });

        // Cleanup state
        self.conn.send_request(&DeleteProperty {
            window: self.root,
            property: self.atoms.net_client_list,
        });

        // Get the right events
        self.conn.send_request(&ChangeWindowAttributes {
            window: self.root,
            value_list: &[
                x::Cw::EventMask(
                    x::EventMask::SUBSTRUCTURE_REDIRECT
                        | x::EventMask::SUBSTRUCTURE_NOTIFY
                        | x::EventMask::BUTTON_PRESS
                        | x::EventMask::ENTER_WINDOW
                        | x::EventMask::FOCUS_CHANGE
                        | x::EventMask::STRUCTURE_NOTIFY
                        | x::EventMask::PROPERTY_CHANGE,
                ),
                x::Cw::Cursor(self.cursors.normal()),
            ],
        });

        self.grab_keys()?;

        self.refocus(usize::MAX, usize::MAX);
        self.conn.flush()?;

        Ok(())
    }

    fn event_loop(&mut self) -> Result<()> {
        // Perform setup
        self.update_geometry()?;
        self.setup_root()?;

        loop {
            match self.conn.wait_for_event()? {
                // See keys.rs
                Event::X(x::Event::KeyPress(e)) => self.handle_key_press(e)?,
                Event::X(x::Event::MappingNotify(e)) => self.handle_mapping_notify(e)?,

                // See clients.rs
                Event::X(x::Event::ConfigureRequest(e)) => self.handle_configure_request(e)?,
                Event::X(x::Event::ConfigureNotify(e)) => self.handle_configure_notify(e)?,
                Event::X(x::Event::DestroyNotify(e)) => self.handle_destroy_notify(e)?,
                Event::X(x::Event::MapRequest(e)) => self.handle_map_request(e)?,
                Event::X(x::Event::UnmapNotify(e)) => self.handle_unmap_notify(e)?,

                // See focus.rs
                Event::X(x::Event::EnterNotify(e)) => self.handle_enter_notify(e)?,
                Event::X(x::Event::FocusIn(e)) => self.handle_focus_in(e)?,

                // See below
                Event::X(x::Event::PropertyNotify(e)) => self.handle_property_notify(e)?,
                _ => {}
            };
        }
    }

    /// Handle a property notify event, by doing *todo*
    fn handle_property_notify(&self, _e: PropertyNotifyEvent) -> Result<()> {
        println!("TODO: handle_property_notify");
        Ok(())
    }
}

/// Cleanup this process' children and set some flags.
/// This is necessary when used with `startx`
fn cleanup_process_children() {
    // TODO: dont transform children into zombies when they terminate
    // TODO: cleanup zombies
}

impl<'a> std::fmt::Debug for WM<'a> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("WM")
            .field("screen_num", &self.screen_num)
            .field("root", &self.root)
            .field("clients", &self.clients)
            .field("atoms", &self.atoms)
            .finish()
    }
}