use std::collections::HashMap;
use std::path::Path;
use std::path::PathBuf;

use crate::config;
use crate::config::AppListConfig;
use crate::fl;
use crate::toplevel_subscription::toplevel_subscription;
use crate::toplevel_subscription::ToplevelRequest;
use crate::toplevel_subscription::ToplevelUpdate;
use calloop::channel::Sender;
use cctk::toplevel_info::ToplevelInfo;
use cctk::wayland_client::protocol::wl_data_device_manager::DndAction;
use cctk::wayland_client::protocol::wl_seat::WlSeat;
use cosmic::applet::cosmic_panel_config::PanelAnchor;
use cosmic::applet::CosmicAppletHelper;
use cosmic::iced;
use cosmic::iced::wayland::actions::data_device::DataFromMimeType;
use cosmic::iced::wayland::actions::data_device::DndIcon;
use cosmic::iced::wayland::actions::window::SctkWindowSettings;
use cosmic::iced::wayland::popup::destroy_popup;
use cosmic::iced::wayland::popup::get_popup;
use cosmic::iced::widget::dnd_source;
use cosmic::iced::widget::mouse_listener;
use cosmic::iced::widget::{column, row};
use cosmic::iced::Settings;
use cosmic::iced::{window, Application, Command, Subscription};
use cosmic::iced_native::alignment::Horizontal;
use cosmic::iced_native::subscription::events_with;
use cosmic::iced_native::widget::vertical_space;
use cosmic::iced_sctk::commands::data_device::start_drag;
use cosmic::iced_sctk::layout::Limits;
use cosmic::iced_sctk::settings::InitialSurface;
use cosmic::iced_sctk::widget::vertical_rule;
use cosmic::iced_style::application::{self, Appearance};
use cosmic::iced_style::Color;
use cosmic::theme::Button;
use cosmic::widget::divider;
use cosmic::widget::rectangle_tracker::rectangle_tracker_subscription;
use cosmic::widget::rectangle_tracker::RectangleTracker;
use cosmic::widget::rectangle_tracker::RectangleUpdate;
use cosmic::{Element, Theme};
use cosmic_protocols::toplevel_info::v1::client::zcosmic_toplevel_handle_v1::ZcosmicToplevelHandleV1;
use freedesktop_desktop_entry::DesktopEntry;
use iced::widget::container;
use iced::Alignment;
use iced::Background;
use iced::Length;
use itertools::Itertools;
use url::Url;

static MIME_TYPE: &str = "text/uri-list";

pub fn run() -> cosmic::iced::Result {
    let helper = CosmicAppletHelper::default();
    let pixel_size = helper.suggested_size().0;
    let padding = 8;
    let dot_size = 4;
    let spacing = 4;
    let thickness = (pixel_size + 2 * padding + dot_size + spacing) as u32;
    let (w, h) = match helper.anchor {
        PanelAnchor::Top | PanelAnchor::Bottom => (2000, thickness),
        PanelAnchor::Left | PanelAnchor::Right => (thickness, 2000),
    };

    CosmicAppList::run(Settings {
        initial_surface: InitialSurface::XdgWindow(SctkWindowSettings {
            iced_settings: cosmic::iced_native::window::Settings {
                ..Default::default()
            },
            autosize: true,
            size_limits: Limits::NONE
                .min_height(1)
                .min_width(1)
                .max_height(h)
                .max_width(w),
            ..Default::default()
        }),
        ..Default::default()
    })
}

#[derive(Debug, Clone, Default)]
struct DockItem {
    id: usize,
    toplevels: Vec<(ZcosmicToplevelHandleV1, ToplevelInfo)>,
    desktop_info: DesktopInfo,
}

impl DataFromMimeType for DockItem {
    fn from_mime_type(&self, mime_type: &str) -> Option<Vec<u8>> {
        if mime_type == MIME_TYPE {
            Some(
                Url::from_file_path(self.desktop_info.path.clone())
                    .ok()?
                    .to_string()
                    .as_bytes()
                    .to_vec(),
            )
        } else {
            None
        }
    }
}

impl DockItem {
    fn new(
        id: usize,
        toplevel: (ZcosmicToplevelHandleV1, ToplevelInfo),
        desktop_info: DesktopInfo,
    ) -> Self {
        Self {
            id,
            toplevels: vec![toplevel],
            desktop_info,
        }
    }

    fn as_icon(
        &self,
        applet_helper: &CosmicAppletHelper,
        rectangle_tracker: Option<&RectangleTracker<usize>>,
        has_popup: bool,
    ) -> Element<'_, Message> {
        let DockItem {
            toplevels,
            desktop_info,
            id,
            ..
        } = self;

        let cosmic_icon = cosmic::widget::icon(
            Path::new(&desktop_info.icon),
            applet_helper.suggested_size().0,
        );

        let dot_radius = 2;
        let dots = (0..toplevels.len())
            .into_iter()
            .map(|_| {
                container(vertical_space(Length::Units(0)))
                    .padding(dot_radius)
                    .style(<<CosmicAppList as cosmic::iced::Application>::Theme as container::StyleSheet>::Style::Custom(
                        |theme| container::Appearance {
                            text_color: Some(Color::TRANSPARENT),
                            background: Some(Background::Color(
                                theme.cosmic().on_bg_color().into(),
                            )),
                            border_radius: 4.0,
                            border_width: 0.0,
                            border_color: Color::TRANSPARENT,
                        },
                    ))
                    .into()
            })
            .collect_vec();
        let icon_wrapper = match applet_helper.anchor {
            PanelAnchor::Left => row(vec![column(dots).spacing(4).into(), cosmic_icon.into()])
                .align_items(iced::Alignment::Center)
                .spacing(4)
                .into(),
            PanelAnchor::Right => row(vec![cosmic_icon.into(), column(dots).spacing(4).into()])
                .align_items(iced::Alignment::Center)
                .spacing(4)
                .into(),
            PanelAnchor::Top => column(vec![row(dots).spacing(4).into(), cosmic_icon.into()])
                .align_items(iced::Alignment::Center)
                .spacing(4)
                .into(),
            PanelAnchor::Bottom => column(vec![cosmic_icon.into(), row(dots).spacing(4).into()])
                .align_items(iced::Alignment::Center)
                .spacing(4)
                .into(),
        };

        let mut icon_button = cosmic::widget::button(Button::Text)
            .custom(vec![icon_wrapper])
            .padding(8);
        if !has_popup {
            icon_button = icon_button.on_press(
                toplevels
                    .first()
                    .map(|t| Message::Activate(t.0.clone()))
                    .unwrap_or_else(|| Message::Exec(desktop_info.exec.clone())),
            );
        }

        // TODO tooltip on hover
        let icon_button = dnd_source(
            mouse_listener(icon_button.width(Length::Shrink).height(Length::Shrink))
                .on_right_release(Message::Popup(desktop_info.id.clone())),
        )
        .on_drag(Message::StartDrag(*id))
        .on_cancelled(Message::DragFinished)
        .on_finished(Message::DragFinished);
        if let Some(tracker) = rectangle_tracker {
            tracker.container(*id, icon_button).into()
        } else {
            icon_button.into()
        }
    }
}

#[derive(Clone, Default)]
struct CosmicAppList {
    theme: Theme,
    popup: Option<(window::Id, DockItem)>,
    surface_id_ctr: u32,
    subscription_ctr: u32,
    active_list: Vec<DockItem>,
    favorite_list: Vec<DockItem>,
    dnd_source: Option<(window::Id, DockItem, DndAction)>,
    dnd_preview: Option<(bool, DockItem)>, // TODO allow non-toplevels to be dragged
    config: AppListConfig,
    toplevel_sender: Option<Sender<ToplevelRequest>>,
    applet_helper: CosmicAppletHelper,
    seat: Option<WlSeat>,
    rectangle_tracker: Option<RectangleTracker<usize>>,
    rectangles: HashMap<usize, iced::Rectangle>,
}

// TODO DnD after sctk merges DnD
#[derive(Debug, Clone)]
enum Message {
    Toplevel(ToplevelUpdate),
    Favorite(String),
    UnFavorite(String),
    Popup(String),
    ClosePopup,
    Activate(ZcosmicToplevelHandleV1),
    Exec(String),
    Quit(String),
    Ignore,
    NewSeat(WlSeat),
    RemovedSeat(WlSeat),
    Rectangle(RectangleUpdate<usize>),
    StartDrag(usize), // id of the DockItem
    DragFinished
}

#[derive(Debug, Clone, Default)]
struct DesktopInfo {
    id: String,
    icon: PathBuf,
    exec: String,
    name: String,
    path: PathBuf,
}

fn desktop_info_for_app_ids(mut app_ids: Vec<String>) -> Vec<DesktopInfo> {
    let mut ret = freedesktop_desktop_entry::Iter::new(freedesktop_desktop_entry::default_paths())
        .filter_map(|path| {
            std::fs::read_to_string(&path).ok().and_then(|input| {
                DesktopEntry::decode(&path, &input).ok().and_then(|de| {
                    if let Some(i) = app_ids
                        .iter()
                        .position(|s| s == de.appid || s.eq(&de.name(None).unwrap_or_default()))
                    {
                        freedesktop_icons::lookup(de.icon().unwrap_or(de.appid))
                            .with_size(128)
                            .with_cache()
                            .find()
                            .map(|buf| DesktopInfo {
                                id: app_ids.remove(i),
                                icon: buf,
                                exec: de.exec().unwrap_or_default().to_string(),
                                name: de.name(None).unwrap_or_default().to_string(),
                                path: path.clone(),
                            })
                    } else {
                        None
                    }
                })
            })
        })
        .collect_vec();
    ret.append(
        &mut app_ids
            .into_iter()
            .map(|id| DesktopInfo {
                id,
                ..Default::default()
            })
            .collect_vec(),
    );
    ret
}

fn split_toplevel_favorites(
    toplevel_list: Vec<DockItem>,
    existing_favorites: &mut Vec<DockItem>,
) -> Vec<DockItem> {
    let mut active_list = Vec::new();
    for toplevel in toplevel_list {
        if let Some(favorite) = existing_favorites.iter_mut().find(|f| {
            f.desktop_info.name == toplevel.desktop_info.id
                || f.desktop_info.id == toplevel.desktop_info.id
        }) {
            favorite.toplevels = toplevel.toplevels;
        } else {
            active_list.push(toplevel);
        }
    }
    active_list
}

impl Application for CosmicAppList {
    type Message = Message;
    type Theme = Theme;
    type Executor = cosmic::SingleThreadExecutor;
    type Flags = ();

    fn new(_flags: ()) -> (Self, Command<Message>) {
        let config = config::AppListConfig::load().unwrap_or_default();
        let self_ = CosmicAppList {
            favorite_list: desktop_info_for_app_ids(config.favorites.clone())
                .into_iter()
                .enumerate()
                .map(|(i, e)| DockItem {
                    id: i,
                    toplevels: Default::default(),
                    desktop_info: e,
                })
                .collect(),
            config,
            ..Default::default()
        };

        (self_, Command::none())
    }

    fn title(&self) -> String {
        config::APP_ID.to_string()
    }

    fn update(&mut self, message: Message) -> Command<Message> {
        match message {
            Message::Popup(id) => {
                if let Some((popup_id, _toplevel)) = self.popup.take() {
                    return destroy_popup(popup_id);
                }
                if let Some(toplevel_group) = self
                    .active_list
                    .iter()
                    .chain(self.favorite_list.iter())
                    .find(|t| t.desktop_info.id == id)
                {
                    let rectangle = match self.rectangles.get(&toplevel_group.id) {
                        Some(r) => r,
                        None => return Command::none(),
                    };

                    self.surface_id_ctr += 1;
                    let new_id = window::Id::new(self.surface_id_ctr);
                    self.popup = Some((new_id, toplevel_group.clone()));

                    let mut popup_settings = self.applet_helper.get_popup_settings(
                        window::Id::new(0),
                        new_id,
                        None,
                        None,
                        None,
                    );
                    let iced::Rectangle {
                        x,
                        y,
                        width,
                        height,
                    } = *rectangle;
                    popup_settings.positioner.anchor_rect = iced::Rectangle::<i32> {
                        x: x as i32,
                        y: y as i32,
                        width: width as i32,
                        height: height as i32,
                    };
                    return get_popup(popup_settings);
                }
            }
            Message::Favorite(id) => {
                let _ = self.config.add_favorite(id);
            }
            Message::UnFavorite(id) => {
                let _ = self.config.remove_favorite(id.clone());
                if let Some(i) = self
                    .favorite_list
                    .iter()
                    .position(|t| t.desktop_info.id == id)
                {
                    let entry = self.favorite_list.remove(i);
                    self.rectangles.remove(&entry.id);
                    if !entry.toplevels.is_empty() {
                        self.active_list.push(entry);
                    }
                }
            }
            Message::Activate(handle) => {
                if let (Some(tx), Some(seat)) = (self.toplevel_sender.as_ref(), self.seat.as_ref())
                {
                    let _ = tx.send(ToplevelRequest::Activate(handle, seat.clone()));
                }
            }
            Message::Quit(id) => {
                if let Some(toplevel_group) = self
                    .active_list
                    .iter()
                    .chain(self.favorite_list.iter())
                    .find(|t| t.desktop_info.id == id)
                {
                    for (handle, _) in &toplevel_group.toplevels {
                        if let Some(tx) = self.toplevel_sender.as_ref() {
                            let _ = tx.send(ToplevelRequest::Quit(handle.clone()));
                        }
                    }
                }
            }
            Message::StartDrag(id) => {
                if let Some(toplevel_group) = self
                    .active_list
                    .iter()
                    .chain(self.favorite_list.iter())
                    .find(|t| t.id == id)
                {
                    self.surface_id_ctr += 1;
                    let icon_id = window::Id::new(self.surface_id_ctr);
                    self.dnd_source = Some((icon_id, toplevel_group.clone(), DndAction::empty()));
                    return start_drag(
                        vec![MIME_TYPE.to_string()],
                        DndAction::all(),
                        window::Id::new(0),
                        Some(DndIcon::Custom(icon_id)),
                        Box::new(toplevel_group.clone()),
                    );
                }
            }
            Message::DragFinished => {
                self.dnd_source = None;
            }
            Message::Toplevel(event) => {
                match event {
                    ToplevelUpdate::AddToplevel(handle, info) => {
                        if info.app_id.is_empty() {
                            return Command::none();
                        }
                        if let Some(t) = self
                            .active_list
                            .iter_mut()
                            .chain(self.favorite_list.iter_mut())
                            .find(|DockItem { desktop_info, .. }| {
                                desktop_info.id == info.app_id || desktop_info.name == info.app_id
                            })
                        {
                            t.toplevels.push((handle, info));
                        } else {
                            let desktop_info =
                                desktop_info_for_app_ids(vec![info.app_id.clone()]).remove(0);
                            self.active_list.push(DockItem {
                                id: self.active_list.len(),
                                toplevels: vec![(handle, info)],
                                desktop_info,
                            });
                        }
                    }
                    ToplevelUpdate::Init(tx) => {
                        self.toplevel_sender.replace(tx);
                    }
                    ToplevelUpdate::Finished => {
                        self.subscription_ctr += 1;
                        for t in &mut self.favorite_list {
                            t.toplevels.clear();
                        }
                        self.active_list.clear();
                    }
                    ToplevelUpdate::RemoveToplevel(handle) => {
                        for t in self
                            .active_list
                            .iter_mut()
                            .chain(self.favorite_list.iter_mut())
                        {
                            t.toplevels.retain(|(t_handle, _)| t_handle != &handle);
                        }
                        self.active_list.retain(|t| !t.toplevels.is_empty());
                    }
                    ToplevelUpdate::UpdateToplevel(handle, info) => {
                        // TODO probably want to make sure it is removed
                        if info.app_id.is_empty() {
                            return Command::none();
                        }
                        'toplevel_loop: for toplevel_list in self
                            .active_list
                            .iter_mut()
                            .chain(self.favorite_list.iter_mut())
                        {
                            for (t_handle, t_info) in &mut toplevel_list.toplevels {
                                if &handle == t_handle {
                                    *t_info = info;
                                    break 'toplevel_loop;
                                }
                            }
                        }
                    }
                }
            }
            Message::NewSeat(s) => {
                self.seat.replace(s);
            }
            Message::RemovedSeat(_) => {
                self.seat.take();
            }
            Message::Exec(exec_str) => {
                let mut exec = shlex::Shlex::new(&exec_str);
                let mut cmd = match exec.next() {
                    Some(cmd) if !cmd.contains('=') => tokio::process::Command::new(cmd),
                    _ => return Command::none(),
                };
                for arg in exec {
                    // TODO handle "%" args here if necessary?
                    if !arg.starts_with('%') {
                        cmd.arg(arg);
                    }
                }
                let _ = cmd.spawn();
            }
            Message::Rectangle(u) => match u {
                RectangleUpdate::Rectangle(r) => {
                    self.rectangles.insert(r.0, r.1);
                }
                RectangleUpdate::Init(tracker) => {
                    self.rectangle_tracker.replace(tracker);
                }
            },
            Message::Ignore => {}
            Message::ClosePopup => {
                if let Some(p) = self.popup.take() {
                    return destroy_popup(p.0);
                }
            }
        }
        Command::none()
    }

    fn view(&self, id: window::Id) -> Element<Message> {
        if let Some((_, item, _)) = self.dnd_source.as_ref().filter(|s| s.0 == id) {
            return cosmic::widget::icon(
                Path::new(&item.desktop_info.icon),
                self.applet_helper.suggested_size().0,
            )
            .into();
        }
        if let Some((
            _popup_id,
            DockItem {
                toplevels,
                desktop_info,
                ..
            },
        )) = self.popup.as_ref().filter(|p| id == p.0)
        {
            let is_favorite = self.config.favorites.contains(&desktop_info.id)
                || self.config.favorites.contains(&desktop_info.name);

            let mut content = column![
                iced::widget::text(&desktop_info.name).horizontal_alignment(Horizontal::Center),
                cosmic::widget::button(Button::Text)
                    .custom(vec![iced::widget::text(fl!("new-window")).into()])
                    .on_press(Message::Exec(desktop_info.exec.clone())),
            ]
            .padding(8)
            .spacing(4)
            .align_items(Alignment::Center);
            if !toplevels.is_empty() {
                let mut list_col = column![];
                for (handle, info) in toplevels {
                    let title = if info.title.len() > 20 {
                        format!("{:.24}...", &info.title)
                    } else {
                        info.title.clone()
                    };
                    list_col = list_col.push(
                        cosmic::widget::button(Button::Text)
                            .custom(vec![iced::widget::text(title).into()])
                            .on_press(Message::Activate(handle.clone())),
                    );
                }
                content = content.push(divider::horizontal::light());
                content = content.push(list_col);
                content = content.push(divider::horizontal::light());
            }
            content = content.push(if is_favorite {
                cosmic::widget::button(Button::Text)
                    .custom(vec![iced::widget::text(fl!("unfavorite")).into()])
                    .on_press(Message::UnFavorite(desktop_info.id.clone()))
            } else {
                cosmic::widget::button(Button::Text)
                    .custom(vec![iced::widget::text(fl!("favorite")).into()])
                    .on_press(Message::Favorite(desktop_info.id.clone()))
            });

            content = match toplevels.len() {
                0 => content,
                1 => content.push(
                    cosmic::widget::button(Button::Text)
                        .custom(vec![iced::widget::text(fl!("quit")).into()])
                        .on_press(Message::Quit(desktop_info.id.clone())),
                ),
                _ => content.push(
                    cosmic::widget::button(Button::Text)
                        .custom(vec![iced::widget::text(&fl!("quit-all")).into()])
                        .on_press(Message::Quit(desktop_info.id.clone())),
                ),
            };
            return self.applet_helper.popup_container(content).into();
        }

        let favorites = self
            .favorite_list
            .iter()
            .map(|dock_item| {
                dock_item.as_icon(
                    &self.applet_helper,
                    self.rectangle_tracker.as_ref(),
                    self.popup.is_some(),
                )
            })
            .collect();
        let active = self
            .active_list
            .iter()
            .map(|dock_item| {
                dock_item.as_icon(
                    &self.applet_helper,
                    self.rectangle_tracker.as_ref(),
                    self.popup.is_some(),
                )
            })
            .collect();

        let (w, h) = match self.applet_helper.anchor {
            PanelAnchor::Top | PanelAnchor::Bottom => (Length::Shrink, Length::Fill),
            PanelAnchor::Left | PanelAnchor::Right => (Length::Fill, Length::Shrink),
        };

        let content = match &self.applet_helper.anchor {
            PanelAnchor::Left | PanelAnchor::Right => container(
                column![
                    column(favorites),
                    divider::horizontal::light(),
                    column(active)
                ]
                .spacing(4)
                .align_items(Alignment::Center)
                .height(h)
                .width(w),
            ),
            PanelAnchor::Top | PanelAnchor::Bottom => container(
                row![row(favorites), vertical_rule(1), row(active)]
                    .spacing(4)
                    .align_items(Alignment::Center)
                    .height(h)
                    .width(w),
            ),
        };
        if self.popup.is_some() {
            mouse_listener(content)
                .on_right_press(Message::ClosePopup)
                .on_press(Message::ClosePopup)
                .into()
        } else {
            content.into()
        }
    }

    fn subscription(&self) -> Subscription<Message> {
        Subscription::batch(vec![
            toplevel_subscription(self.subscription_ctr).map(|(_, event)| Message::Toplevel(event)),
            events_with(|e, _| match e {
                cosmic::iced_native::Event::PlatformSpecific(
                    cosmic::iced_native::event::PlatformSpecific::Wayland(
                        cosmic::iced_native::event::wayland::Event::Seat(e, seat),
                    ),
                ) => match e {
                    cosmic::iced_native::event::wayland::SeatEvent::Enter => {
                        Some(Message::NewSeat(seat))
                    }
                    cosmic::iced_native::event::wayland::SeatEvent::Leave => {
                        Some(Message::RemovedSeat(seat))
                    }
                },
                _ => None,
            }),
            rectangle_tracker_subscription(0).map(|(_, update)| Message::Rectangle(update)),
        ])
    }

    fn theme(&self) -> Theme {
        self.theme
    }

    fn close_requested(&self, _id: window::Id) -> Self::Message {
        Message::Ignore
    }

    fn style(&self) -> <Self::Theme as application::StyleSheet>::Style {
        <Self::Theme as application::StyleSheet>::Style::Custom(|theme| Appearance {
            background_color: Color::from_rgba(0.0, 0.0, 0.0, 0.0),
            text_color: theme.cosmic().on_bg_color().into(),
        })
    }
}