use log::{debug, info, trace};
use xcb::{x, xfixes, Xid};

use crate::*;

pub struct Embedder<'a> {
    conn: &'a xcb::Connection,
    embedder: x::Window,
    client: x::Window,
    flags: XEmbedFlags,
}

struct XEmbedInfo {
    version: u32,
    flags: XEmbedFlags,
}

impl<'a> Embedder<'a> {
    pub fn start(conn: &'a xcb::Connection, embedder: x::Window, client: x::Window) -> Result<Embedder<'a>, Error> {
        debug!("Reparenting {} to be a child of {}", client.resource_id(), embedder.resource_id());
        conn.send_and_check_request(&x::ReparentWindow {
            window: client,
            parent: embedder,
            x: 0,
            y: 0,
        })?;

        let event_mask = x::EventMask::PROPERTY_CHANGE | x::EventMask::STRUCTURE_NOTIFY;
        let cookie = conn.send_request(&x::GetWindowAttributes {
            window: client,
        });
        let reply = conn.wait_for_reply(cookie)?;
        if reply.your_event_mask().intersection(event_mask) != event_mask {
            conn.send_and_check_request(&x::ChangeWindowAttributes {
                window: client,
                value_list: &[
                    x::Cw::EventMask(reply.your_event_mask() | event_mask),
                ],
            })?;
        }

        let info = fetch_xembed_info(conn, client)?;
        let supported_version = std::cmp::min(info.version, XEMBED_VERSION);

        if let Err(err) = conn.send_and_check_request(&xfixes::ChangeSaveSet {
            mode: xfixes::SaveSetMode::Insert,
            target: xfixes::SaveSetTarget::Root,
            map: xfixes::SaveSetMapping::Unmap,
            window: client,
        }) {
            info!("Failed to send XFIXES ChangeSaveSet request: {}", err);
        }

        debug!("sending EMBEDDED_NOTIFY to client with embedder wid {} and version {}", embedder.resource_id(), supported_version);
        send_xembed_message(conn, client, x::CURRENT_TIME, XEmbedMessage::EmbeddedNotify, None, Some(embedder.resource_id()), Some(supported_version))?;

        let cookie = conn.send_request(&x::GetInputFocus {});
        let reply = conn.wait_for_reply(cookie)?;
        let focus_window = reply.focus();

        let mut cur_window = embedder;
        let activated_message = if focus_window == embedder {
            XEmbedMessage::WindowActivate
        } else {
            loop {
                let cookie = conn.send_request(&x::QueryTree {
                    window: cur_window,
                });
                let reply = conn.wait_for_reply(cookie)?;
                if reply.root() == reply.parent() {
                    break XEmbedMessage::WindowDeactivate;
                } else if reply.parent() == focus_window {
                    break XEmbedMessage::WindowActivate;
                } else {
                    cur_window = reply.parent();
                }
            }
        };
        send_xembed_message(conn, client, x::CURRENT_TIME, activated_message, None, None, None)?;

        let (focus_message, focus_detail) = if focus_window == embedder {
            (XEmbedMessage::FocusIn, Some(XEmbedFocus::Current))
        } else {
            (XEmbedMessage::FocusOut, None)
        };
        send_xembed_message(conn, client, x::CURRENT_TIME, focus_message, focus_detail.map(|fd| fd as u32), None, None)?;

        // XXX: how do we know if there's something modal active?
        send_xembed_message(conn, client, x::CURRENT_TIME, XEmbedMessage::ModalityOff, None, None, None)?;

        Ok(Embedder {
            conn,
            embedder,
            client,
            flags: info.flags,
        })
    }
    
    pub fn end(mut self) -> Result<(), Error> {
        self.end_internal()
    }

    fn end_internal(&mut self) -> Result<(), Error> {
        if self.client == x::WINDOW_NONE {
            return Err(Error::ClientDestroyed);
        }

        debug!("Ending XEMBED");
        let cookie = self.conn.send_request(&x::QueryTree {
            window: self.client,
        });
        let reply = self.conn.wait_for_reply(cookie)?;
        self.conn.send_and_check_request(&x::UnmapWindow {
            window: self.client,
        })?;
        self.conn.send_and_check_request(&x::ReparentWindow {
            window: self.client,
            parent: reply.root(),
            x: 0,
            y: 0,
        })?;
        Ok(())
    }

    pub fn event(&mut self, event: &xcb::Event) -> Result<bool, Error> {
        if self.client == x::WINDOW_NONE {
            return Err(Error::ClientDestroyed);
        }

        match event {
            xcb::Event::X(x::Event::PropertyNotify(ev)) if ev.window() == self.client && ev.atom() == intern_atom(self.conn, XEMBED_INFO_ATOM_NAME)? => {
                let info = fetch_xembed_info(self.conn, self.client)?;
                if (self.flags & XEmbedFlags::MAPPED) != (info.flags & XEmbedFlags::MAPPED) {
                    if info.flags.contains(XEmbedFlags::MAPPED) {
                        debug!("Mapping client window");
                        self.conn.send_and_check_request(&x::MapWindow {
                            window: self.client,
                        })?;
                    } else {
                        debug!("Unmapping client window");
                        self.conn.send_and_check_request(&x::UnmapWindow {
                            window: self.client,
                        })?;
                    }
                    self.flags = info.flags;
                }
                Ok(true)
            },
            xcb::Event::X(x::Event::ConfigureNotify(ev)) if ev.window() == self.client => {
                let mut cookies = Vec::new();
                if ev.x() != 0 || ev.y() != 0 {
                    cookies.push(self.conn.send_request_checked(&x::ConfigureWindow {
                        window: self.client,
                        value_list: &[
                            x::ConfigWindow::X(0),
                            x::ConfigWindow::Y(0),
                        ],
                    }));
                }
                cookies.push(self.conn.send_request_checked(&x::ConfigureWindow {
                    window: self.embedder,
                    value_list: &[
                        x::ConfigWindow::Width(ev.width() as u32),
                        x::ConfigWindow::Height(ev.height() as u32),
                    ],
                }));
                for cookie in cookies {
                    self.conn.check_request(cookie)?;
                }
                Ok(true)
            },
            xcb::Event::X(x::Event::ClientMessage(ev)) if ev.window() == self.embedder && ev.r#type() == intern_atom(self.conn, XEMBED_MESSAGE_ATOM_NAME)? => {
                match ev.data() {
                    x::ClientMessageData::Data32(data) if data[1] == XEmbedMessage::RequestFocus as u32 => {
                        debug!("Client requests focus");
                        self.conn.send_and_check_request(&x::SetInputFocus {
                            revert_to: x::InputFocus::Parent,
                            focus: self.client,
                            time: x::CURRENT_TIME,
                        })?;
                        send_xembed_message(self.conn, self.client, x::CURRENT_TIME, XEmbedMessage::FocusIn, Some(XEmbedFocus::Current as u32), None, None)?;
                        Ok(true)
                    },
                    // TODO: XEMBED_FOCUS_NEXT
                    // TODO: XEMBED_FOCUS_PREV
                    // TODO: XEMBED_REGISTER_ACCELERATOR
                    // TODO: XEMBED_UNREGISTER_ACCELERATOR
                    _ => Ok(false),
                }
            },
            xcb::Event::X(x::Event::KeyPress(ev)) if ev.event() == self.embedder && self.flags.contains(XEmbedFlags::MAPPED) => {
                trace!("Forwarding key press to client ({:?} + {})", ev.state(), ev.detail());
                self.conn.send_and_check_request(&x::SendEvent {
                    propagate: false,
                    destination: x::SendEventDest::Window(self.client),
                    event_mask: x::EventMask::NO_EVENT,
                    event: &x::KeyPressEvent::new(ev.detail(), ev.time(), ev.root(), self.client, ev.child(), ev.root_x(), ev.root_y(), ev.event_x(), ev.event_y(), ev.state(), ev.same_screen()),
                })?;
                Ok(true)
            },
            /*
            xcb::Event::X(x::Event::KeyRelease(ev)) if ev.event() == self.embedder && self.flags.contains(XEmbedFlags::MAPPED) => {
                trace!("Forwarding key release to client ({:?} + {})", ev.state(), ev.detail());
                self.conn.send_and_check_request(&x::SendEvent {
                    propagate: false,
                    destination: x::SendEventDest::Window(self.client),
                    event_mask: x::EventMask::NO_EVENT,
                    event: &x::KeyReleaseEvent::new(ev.detail(), ev.time(), ev.root(), self.client, ev.child(), ev.root_x(), ev.root_y(), ev.event_x(), ev.event_y(), ev.state(), ev.same_screen()),
                })?;
                Ok(true)
            },
            */
            xcb::Event::X(x::Event::MotionNotify(ev)) if ev.event() == self.embedder && self.flags.contains(XEmbedFlags::MAPPED) => {
                trace!("Forwarding pointer motion to client ({}, {})", ev.event_x(), ev.event_y());
                self.conn.send_and_check_request(&x::SendEvent {
                    propagate: false,
                    destination: x::SendEventDest::Window(self.client),
                    event_mask: x::EventMask::NO_EVENT,
                    event: &x::MotionNotifyEvent::new(ev.detail(), ev.time(), ev.root(), self.client, ev.child(), ev.root_x(), ev.root_y(), ev.event_x(), ev.event_y(), ev.state(), ev.same_screen()),
                })?;
                Ok(true)
            },
            xcb::Event::X(x::Event::ButtonPress(ev)) if ev.event() == self.embedder && self.flags.contains(XEmbedFlags::MAPPED) => {
                trace!("Forwarding button press to client ({:?} + {}: {}, {})", ev.state(), ev.detail(), ev.event_x(), ev.event_y());
                self.conn.send_and_check_request(&x::SendEvent {
                    propagate: false,
                    destination: x::SendEventDest::Window(self.client),
                    event_mask: x::EventMask::NO_EVENT,
                    event: &x::ButtonPressEvent::new(ev.detail(), ev.time(), ev.root(), self.client, ev.child(), ev.root_x(), ev.root_y(), ev.event_x(), ev.event_y(), ev.state(), ev.same_screen()),
                })?;
                Ok(true)
            },
            xcb::Event::X(x::Event::ButtonRelease(ev)) if ev.event() == self.embedder && self.flags.contains(XEmbedFlags::MAPPED) => {
                trace!("Forwarding button release to client ({:?} + {}: {}, {})", ev.state(), ev.detail(), ev.event_x(), ev.event_y());
                self.conn.send_and_check_request(&x::SendEvent {
                    propagate: false,
                    destination: x::SendEventDest::Window(self.client),
                    event_mask: x::EventMask::NO_EVENT,
                    event: &x::ButtonReleaseEvent::new(ev.detail(), ev.time(), ev.root(), self.client, ev.child(), ev.root_x(), ev.root_y(), ev.event_x(), ev.event_y(), ev.state(), ev.same_screen()),
                })?;
                Ok(true)
            },
            xcb::Event::X(x::Event::UnmapNotify(ev)) if ev.window() == self.client => {
                debug!("Client was unmapped");
                self.flags -= XEmbedFlags::MAPPED;
                Ok(true)
            },
            xcb::Event::X(x::Event::DestroyNotify(ev)) if ev.window() == self.client => {
                debug!("Client was destroyed");
                self.flags -= XEmbedFlags::MAPPED;
                self.client = x::WINDOW_NONE;
                Ok(true)
            },
            event => {
                trace!("Not handling event {:#?}", event);
                Ok(false)
            },
        }
    }

    pub fn activate_client(&self) -> Result<(), Error> {
        if self.client != x::WINDOW_NONE {
            send_xembed_message(&self.conn, self.client, x::CURRENT_TIME, XEmbedMessage::WindowActivate, None, None, None)?;
            Ok(())
        } else {
            Err(Error::ClientDestroyed)
        }
    }

    pub fn focus_client(&self, mode: super::XEmbedFocus) -> Result<(), Error> {
        if self.client != x::WINDOW_NONE {
            self.conn.send_and_check_request(&x::SetInputFocus {
                revert_to: x::InputFocus::Parent,
                focus: self.client,
                time: x::CURRENT_TIME,
            })?;
            send_xembed_message(&self.conn, self.client, x::CURRENT_TIME, XEmbedMessage::FocusIn, Some(mode as u32), None, None)?;
            Ok(())
        } else {
            Err(Error::ClientDestroyed)
        }
    }

    pub fn embedder_window(&self) -> x::Window {
        self.embedder
    }

    pub fn client_window(&self) -> x::Window {
        self.client
    }

    pub fn is_client_mapped(&self) -> bool {
        self.flags.contains(XEmbedFlags::MAPPED)
    }
}

impl<'a> Drop for Embedder<'a> {
    fn drop(&mut self) {
        let _ = self.end_internal();
    }
}

fn fetch_xembed_info(conn: &xcb::Connection, client: x::Window) -> Result<XEmbedInfo, Error> {
    let xembed_info_atom = intern_atom(conn, XEMBED_INFO_ATOM_NAME)?;
    let cookie = conn.send_request(&x::GetProperty {
        delete: false,
        window: client,
        property: xembed_info_atom,
        r#type: xembed_info_atom,
        long_offset: 0,
        long_length: 8,
    });
    let reply = conn.wait_for_reply(cookie)?;
    if reply.value::<u32>().len() < 2 {
        Err(Error::ProtocolError("Invalid format of _XEMBED_INFO property".to_string()))
    } else {
        debug!("_XEMBED_INFO -> ({}, 0x{:x})", reply.value::<u32>()[0], reply.value::<u32>()[1]);
        Ok(XEmbedInfo {
            version: reply.value()[0],
            flags: XEmbedFlags::from_bits_truncate(reply.value()[1]),
        })
    }
}

fn intern_atom(conn: &xcb::Connection, name: &str) -> xcb::Result<x::Atom> {
    let cookie = conn.send_request(&x::InternAtom {
        only_if_exists: false,
        name: name.as_bytes(),
    });
    conn.wait_for_reply(cookie).map(|reply| reply.atom())
}

fn send_xembed_message(conn: &xcb::Connection, window: x::Window, time: u32, message: XEmbedMessage, detail: Option<u32>, data1: Option<u32>, data2: Option<u32>) -> xcb::Result<()> {
    conn.send_and_check_request(&x::SendEvent {
        propagate: false,
        destination: x::SendEventDest::Window(window),
        event_mask: x::EventMask::NO_EVENT,
        event: &x::ClientMessageEvent::new(
            window,
            intern_atom(conn, XEMBED_MESSAGE_ATOM_NAME)?,
            x::ClientMessageData::Data32([
                time,
                message as u32,
                detail.unwrap_or(0),
                data1.unwrap_or(0),
                data2.unwrap_or(0),
            ]),
        ),
    })?;
    Ok(())
}