//! Global resources and utilities

use std::fmt::Debug;
use xcb::{
    x::{
        self, Atom, ChangeProperty, ChangeWindowAttributes, ClientMessageData, ClientMessageEvent,
        CreateWindow, DeleteProperty, DestroyWindow, EventMask, GetProperty, SendEvent,
        SendEventDest, Window, WindowClass,
    },
    Connection as RawConnection, VoidCookieChecked, Xid,
};

#[doc(hidden)]
mod atoms;
#[doc(hidden)]
mod colours;
#[doc(hidden)]
mod cursors;
#[doc(hidden)]
mod keys;

pub use self::{
    atoms::Atoms,
    colours::{Colour, Colours},
    cursors::Cursors,
    keys::KeyboardInfo,
};
use crate::{
    debug_req,
    error::{Error, Result},
};

/// The connection, along with some cached resources required for WM operations.
pub struct Connection<'a> {
    /// The open connection to an X server
    conn: &'a RawConnection,

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

    /// 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,

    /// Cached colours,
    pub colours: Colours,

    /// Cached cursors
    pub cursors: Cursors,

    /// Cached atoms
    pub atoms: Atoms,

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

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

        // Create check window
        let check_window = conn.generate_id();
        let root = screen.root();
        let atoms = Atoms::intern_all(conn)?;
        conn.send_request(&CreateWindow {
            wid: check_window,
            parent: root,
            depth: 0,
            x: 0,
            y: 0,
            width: 1,
            height: 1,
            border_width: 0,
            class: WindowClass::InputOnly,
            visual: 0,
            value_list: &[],
        });

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

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

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

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

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

        // Get the right events
        let cursors = Cursors::new_with(conn)?;
        conn.send_request(&ChangeWindowAttributes {
            window: 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::PROPERTY_CHANGE,
                ),
                x::Cw::Cursor(cursors.normal()),
            ],
        });

        conn.flush()?;

        Ok(Self {
            colours: Colours::new_with(conn, screen.default_colormap())?,
            atoms,
            cursors,
            keyboard_state: KeyboardInfo::new_with(conn)?,
            check_window,
            conn,
            screen_num,
            root: screen.root(),
        })
    }

    /// Refresh cached info about keyboard layout
    pub fn refresh_keyboard_info(&mut self) -> Result<()> {
        self.keyboard_state = KeyboardInfo::new_with(self.conn)?;
        Ok(())
    }

    /// Send event to window `w`, if the event is supported.
    pub fn send_event(&self, window: Window, event: Atom) {
        let Ok(protocols) = self.wait_for_reply(self.send_request(&GetProperty {
            delete: false,
            window,
            property: self.atoms.wm_protocols,
            r#type: x::ATOM_ATOM,
            long_offset: 0,
            long_length: 100_000,
        })) else {
            return;
        };

        if protocols.r#type() != x::ATOM_ATOM || protocols.format() != 32 {
            return;
        }

        let supported = protocols
            .value::<u32>()
            .iter()
            .any(|a| *a == event.resource_id());

        if supported {
            self.send_request(&SendEvent {
                propagate: false,
                destination: SendEventDest::Window(window),
                event_mask: EventMask::NO_EVENT,
                event: &ClientMessageEvent::new(
                    window,
                    self.atoms.wm_protocols,
                    ClientMessageData::Data32([event.resource_id(), x::CURRENT_TIME, 0, 0, 0]),
                ),
            });
        }
    }

    /// Delegate for [`RawConnection::send_request`]
    pub fn send_request<R>(&self, req: &R) -> R::Cookie
    where
        R: xcb::Request + Debug,
    {
        let cookie = self.conn.send_request(req);
        debug_req!(req, cookie);
        cookie
    }

    /// Delegate for [`RawConnection::send_request_checked`]
    #[must_use]
    pub fn send_request_checked<R>(&self, req: &R) -> VoidCookieChecked
    where
        R: xcb::RequestWithoutReply + Debug,
    {
        let cookie = self.conn.send_request_checked(req);
        debug_req!(req, cookie);
        cookie
    }

    /// Delegate for [`RawConnection::send_and_check_request`]
    pub fn send_and_check_request<R>(&self, req: &R) -> Result<()>
    where
        R: xcb::RequestWithoutReply + Debug,
    {
        debug_req!(req);
        self.conn.send_and_check_request(req).map_err(Into::into)
    }

    /// Delegate for [`RawConnection::check_request`]
    pub fn check_request(&self, c: VoidCookieChecked) -> Result<()> {
        self.conn.check_request(c).map_err(Into::into)
    }

    /// Delegate for [`RawConnection::flush`]
    pub fn flush(&self) -> Result<()> {
        self.conn.flush().map_err(Into::into)
    }

    /// Delegate for [`RawConnection::wait_for_event`]
    pub fn wait_for_event(&self) -> Result<xcb::Event> {
        self.conn.wait_for_event().map_err(Into::into)
    }

    /// Delegate for [`RawConnection::active_extensions`]
    pub fn active_extensions(&self) -> impl Iterator<Item = xcb::Extension> + '_ {
        self.conn.active_extensions()
    }

    /// Delegate for [`RawConnection::wait_for_reply`]
    pub fn wait_for_reply<C>(&self, cookie: C) -> xcb::Result<C::Reply>
    where
        C: xcb::CookieWithReplyChecked,
    {
        self.conn.wait_for_reply(cookie)
    }

    /// Delegate for [`RawConnection::get_setup`]
    pub fn get_setup(&self) -> &x::Setup {
        self.conn.get_setup()
    }

    /// The root window
    pub const fn root(&self) -> Window {
        self.root
    }

    /// The 'screen' number on the X server. Note this isn’t what you think it is on multi-monitor setups
    pub const fn screen_num(&self) -> usize {
        self.screen_num
    }
}

impl Drop for Connection<'_> {
    fn drop(&mut self) {
        self.conn.send_request(&DestroyWindow {
            window: self.check_window,
        });

        // Unset attributes of root window
        self.conn.send_request(&DeleteProperty {
            window: self.root,
            property: self.atoms.net_wm_check,
        });
        self.conn.send_request(&DeleteProperty {
            window: self.root,
            property: self.atoms.net_client_list,
        });
        self.conn.send_request(&DeleteProperty {
            window: self.root,
            property: self.atoms.net_supported,
        });
        self.conn.send_request(&ChangeWindowAttributes {
            window: self.root,
            value_list: &[x::Cw::EventMask(x::EventMask::NO_EVENT)],
        });

        // Safety: These methods only require that the object is not used again, which will be true since we're in the destructor.
        unsafe {
            self.cursors.free(self.conn);
            self.colours.free(self.conn);
        }
    }
}