// Copyright 2023 System76 <info@system76.com>
// SPDX-License-Identifier: GPL-3.0-only

use cctk::sctk::reexports::{calloop::channel::SyncSender, client::backend::ObjectId};
use cosmic::{
    applet::cosmic_panel_config::PanelAnchor,
    iced::{
        alignment::{Horizontal, Vertical},
        event,
        mouse::{self, ScrollDelta},
        widget::{button, column, row},
        Event::Mouse,
        Length, Limits, Subscription,
    },
    iced_core::{Background, Border},
    widget::{autosize, container, horizontal_space, vertical_space, Id},
    Element, Task, Theme,
};

use cosmic_protocols::workspace::v1::client::zcosmic_workspace_handle_v1;
use once_cell::sync::Lazy;
use std::cmp::Ordering;

use crate::{
    config,
    wayland::{WorkspaceEvent, WorkspaceList},
    wayland_subscription::{workspaces, WorkspacesUpdate},
};

use std::process::Command as ShellCommand;

static AUTOSIZE_MAIN_ID: Lazy<Id> = Lazy::new(|| Id::new("autosize-main"));

pub fn run() -> cosmic::iced::Result {
    cosmic::applet::run::<IcedWorkspacesApplet>(())
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Layout {
    Row,
    Column,
}

struct IcedWorkspacesApplet {
    core: cosmic::app::Core,
    workspaces: WorkspaceList,
    workspace_tx: Option<SyncSender<WorkspaceEvent>>,
    layout: Layout,
}

impl IcedWorkspacesApplet {
    /// returns the index of the workspace button after which which must be moved to a popup
    /// if it exists.
    fn popup_index(&self) -> Option<usize> {
        let mut index = None;
        let Some(max_major_axis_len) = self.core.applet.suggested_bounds.as_ref().map(|c| {
            // if we have a configure for width and height, we're in a overflow popup
            match self.core.applet.anchor {
                PanelAnchor::Top | PanelAnchor::Bottom => c.width as u32,
                PanelAnchor::Left | PanelAnchor::Right => c.height as u32,
            }
        }) else {
            return index;
        };
        let button_total_size = self.core.applet.suggested_size(true).0
            + self.core.applet.suggested_padding(true) * 2
            + 4;
        let btn_count = max_major_axis_len / button_total_size as u32;
        if btn_count >= self.workspaces.len() as u32 {
            index = None;
        } else {
            index = Some((btn_count as usize).min(self.workspaces.len()));
        }
        index
    }
}

#[derive(Debug, Clone)]
enum Message {
    WorkspaceUpdate(WorkspacesUpdate),
    WorkspacePressed(ObjectId),
    WheelScrolled(ScrollDelta),
    WorkspaceOverview,
}

impl cosmic::Application for IcedWorkspacesApplet {
    type Message = Message;
    type Executor = cosmic::SingleThreadExecutor;
    type Flags = ();
    const APP_ID: &'static str = config::APP_ID;

    fn init(
        core: cosmic::app::Core,
        _flags: Self::Flags,
    ) -> (
        Self,
        cosmic::iced::Task<cosmic::app::Message<Self::Message>>,
    ) {
        (
            Self {
                layout: match &core.applet.anchor {
                    PanelAnchor::Left | PanelAnchor::Right => Layout::Column,
                    PanelAnchor::Top | PanelAnchor::Bottom => Layout::Row,
                },
                core,
                workspaces: Vec::new(),
                workspace_tx: Default::default(),
            },
            Task::none(),
        )
    }

    fn core(&self) -> &cosmic::app::Core {
        &self.core
    }

    fn core_mut(&mut self) -> &mut cosmic::app::Core {
        &mut self.core
    }

    fn update(
        &mut self,
        message: Self::Message,
    ) -> cosmic::iced::Task<cosmic::app::Message<Self::Message>> {
        match message {
            Message::WorkspaceUpdate(msg) => match msg {
                WorkspacesUpdate::Workspaces(mut list) => {
                    list.retain(|w| {
                        !matches!(w.1, Some(zcosmic_workspace_handle_v1::State::Hidden))
                    });
                    list.sort_by(|a, b| match a.0.len().cmp(&b.0.len()) {
                        Ordering::Equal => a.0.cmp(&b.0),
                        Ordering::Less => Ordering::Less,
                        Ordering::Greater => Ordering::Greater,
                    });
                    self.workspaces = list;
                }
                WorkspacesUpdate::Started(tx) => {
                    self.workspace_tx.replace(tx);
                }
                WorkspacesUpdate::Errored => {
                    // TODO
                }
            },
            Message::WorkspacePressed(id) => {
                if let Some(tx) = self.workspace_tx.as_mut() {
                    let _ = tx.try_send(WorkspaceEvent::Activate(id));
                }
            }
            Message::WheelScrolled(delta) => {
                let (delta, debounce) = match delta {
                    ScrollDelta::Lines { x, y } => ((x + y) as f64, false),
                    ScrollDelta::Pixels { x, y } => ((x + y) as f64, true),
                };
                if let Some(tx) = self.workspace_tx.as_mut() {
                    let _ = tx.try_send(WorkspaceEvent::Scroll(delta, debounce));
                }
            }
            Message::WorkspaceOverview => {
                let _ = ShellCommand::new("cosmic-workspaces").spawn();
            }
        }
        Task::none()
    }

    fn view(&self) -> Element<Message> {
        if self.workspaces.is_empty() {
            return row![].padding(8).into();
        }
        let horizontal = matches!(
            self.core.applet.anchor,
            PanelAnchor::Top | PanelAnchor::Bottom
        );
        let suggested_total =
            self.core.applet.suggested_size(true).0 + self.core.applet.suggested_padding(true) * 2;
        let suggested_window_size = self.core.applet.suggested_window_size();
        let popup_index = self.popup_index().unwrap_or(self.workspaces.len());

        let buttons = self.workspaces[..popup_index].iter().filter_map(|w| {
            let content = self
                .core
                .applet
                .text(w.0.clone())
                .font(cosmic::font::bold());

            let (width, height) = if self.core.applet.is_horizontal() {
                (suggested_total as f32, suggested_window_size.1.get() as f32)
            } else {
                (suggested_window_size.0.get() as f32, suggested_total as f32)
            };

            let content = row!(content, vertical_space().height(Length::Fixed(height)))
                .align_y(cosmic::iced::Alignment::Center);

            let content = column!(content, horizontal_space().width(Length::Fixed(width)))
                .align_x(cosmic::iced::Alignment::Center);

            let btn = button(
                container(content)
                    .align_x(Horizontal::Center)
                    .align_y(Vertical::Center),
            )
            .padding(if horizontal {
                [0, self.core.applet.suggested_padding(true)]
            } else {
                [self.core.applet.suggested_padding(true), 0]
            })
            .on_press(match w.1 {
                Some(zcosmic_workspace_handle_v1::State::Active) => Message::WorkspaceOverview,
                _ => Message::WorkspacePressed(w.2.clone()),
            })
            .padding(0);

            Some(
                btn.class(match w.1 {
                    Some(zcosmic_workspace_handle_v1::State::Active) => {
                        cosmic::theme::iced::Button::Primary
                    }
                    Some(zcosmic_workspace_handle_v1::State::Urgent) => {
                        let appearance = |theme: &Theme| {
                            let cosmic = theme.cosmic();
                            button::Style {
                                background: Some(Background::Color(
                                    cosmic.palette.neutral_3.into(),
                                )),
                                border: Border {
                                    radius: cosmic.radius_xl().into(),
                                    ..Default::default()
                                },
                                border_radius: theme.cosmic().radius_xl().into(),
                                text_color: theme.cosmic().destructive_button.base.into(),
                                ..button::Style::default()
                            }
                        };
                        cosmic::theme::iced::Button::Custom(Box::new(move |theme, status| {
                            match status {
                                button::Status::Active => appearance(theme),
                                button::Status::Hovered => button::Style {
                                    background: Some(Background::Color(
                                        theme.current_container().component.hover.into(),
                                    )),
                                    border: Border {
                                        radius: theme.cosmic().radius_xl().into(),
                                        ..Default::default()
                                    },
                                    ..appearance(theme)
                                },
                                button::Status::Pressed => appearance(theme),
                                button::Status::Disabled => appearance(theme),
                            }
                        }))
                    }
                    None => {
                        let appearance = |theme: &Theme| {
                            let cosmic = theme.cosmic();
                            button::Style {
                                background: None,
                                border: Border {
                                    radius: cosmic.radius_xl().into(),
                                    ..Default::default()
                                },
                                border_radius: cosmic.radius_xl().into(),
                                text_color: theme.current_container().component.on.into(),
                                ..button::Style::default()
                            }
                        };
                        cosmic::theme::iced::Button::Custom(Box::new(move |theme, status| {
                            match status {
                                button::Status::Active => appearance(theme),
                                button::Status::Hovered => button::Style {
                                    background: Some(Background::Color(
                                        theme.current_container().component.hover.into(),
                                    )),
                                    border: Border {
                                        radius: theme.cosmic().radius_xl().into(),
                                        ..Default::default()
                                    },
                                    ..appearance(theme)
                                },
                                button::Status::Pressed | button::Status::Disabled => {
                                    appearance(theme)
                                }
                            }
                        }))
                    }
                    _ => return None,
                })
                .into(),
            )
        });
        // TODO if there is a popup_index, create a button with a popup for the remaining workspaces
        // Should it appear on hover or on click?
        let layout_section: Element<_> = match self.layout {
            Layout::Row => row(buttons).spacing(4).into(),
            Layout::Column => column(buttons).spacing(4).into(),
        };
        let mut limits = Limits::NONE.min_width(1.).min_height(1.);
        if let Some(b) = self.core.applet.suggested_bounds {
            if b.width as i32 > 0 {
                limits = limits.max_width(b.width);
            }
            if b.height as i32 > 0 {
                limits = limits.max_height(b.height);
            }
        }

        autosize::autosize(
            container(layout_section).padding(0),
            AUTOSIZE_MAIN_ID.clone(),
        )
        .limits(limits)
        .into()
    }

    fn subscription(&self) -> Subscription<Message> {
        Subscription::batch(vec![
            workspaces().map(Message::WorkspaceUpdate),
            event::listen_with(|e, _, _| match e {
                Mouse(mouse::Event::WheelScrolled { delta }) => Some(Message::WheelScrolled(delta)),
                _ => None,
            }),
        ])
    }

    fn style(&self) -> Option<cosmic::iced_runtime::Appearance> {
        Some(cosmic::applet::style())
    }
}