use anyhow::anyhow;
use async_utility::task::spawn;
use chats::{registry::ChatRegistry, room::Room};
use common::{
    constants::IMAGE_SERVICE,
    last_seen::LastSeen,
    profile::NostrProfile,
    utils::{compare, nip96_upload},
};
use gpui::{
    div, img, list, prelude::FluentBuilder, px, relative, svg, white, AnyElement, App, AppContext,
    Context, Element, Entity, EventEmitter, Flatten, FocusHandle, Focusable, InteractiveElement,
    IntoElement, ListAlignment, ListState, ObjectFit, ParentElement, PathPromptOptions, Render,
    SharedString, StatefulInteractiveElement, Styled, StyledImage, Subscription, WeakEntity,
    Window,
};
use itertools::Itertools;
use nostr_sdk::prelude::*;
use smol::fs;
use state::get_client;
use std::sync::Arc;
use ui::{
    button::{Button, ButtonRounded, ButtonVariants},
    dock_area::panel::{Panel, PanelEvent},
    input::{InputEvent, TextInput},
    notification::Notification,
    popup_menu::PopupMenu,
    theme::{scale::ColorScaleStep, ActiveTheme},
    v_flex, ContextModal, Icon, IconName, Sizable, StyledExt,
};

const ALERT: &str =
    "This conversation is private. Only members of this chat can see each other's messages.";

pub fn init(
    id: &u64,
    window: &mut Window,
    cx: &mut App,
) -> Result<Arc<Entity<Chat>>, anyhow::Error> {
    if let Some(chats) = ChatRegistry::global(cx) {
        if let Some(room) = chats.read(cx).get(id, cx) {
            Ok(Arc::new(Chat::new(id, room, window, cx)))
        } else {
            Err(anyhow!("Chat room is not exist"))
        }
    } else {
        Err(anyhow!("Chat Registry is not initialized"))
    }
}

#[derive(PartialEq, Eq)]
struct ParsedMessage {
    avatar: SharedString,
    display_name: SharedString,
    created_at: SharedString,
    content: SharedString,
}

impl ParsedMessage {
    pub fn new(profile: &NostrProfile, content: &str, created_at: Timestamp) -> Self {
        let avatar = profile.avatar().into();
        let display_name = profile.name().into();
        let content = SharedString::new(content);
        let created_at = LastSeen(created_at).human_readable();

        Self {
            avatar,
            display_name,
            created_at,
            content,
        }
    }
}

#[derive(PartialEq, Eq)]
enum Message {
    User(Box<ParsedMessage>),
    System(SharedString),
    Placeholder,
}

impl Message {
    pub fn new(message: ParsedMessage) -> Self {
        Self::User(Box::new(message))
    }

    pub fn system(content: SharedString) -> Self {
        Self::System(content)
    }

    pub fn placeholder() -> Self {
        Self::Placeholder
    }
}

pub struct Chat {
    // Panel
    id: SharedString,
    closable: bool,
    zoomable: bool,
    focus_handle: FocusHandle,
    // Chat Room
    room: WeakEntity<Room>,
    messages: Entity<Vec<Message>>,
    new_messages: Option<WeakEntity<Vec<Event>>>,
    list_state: ListState,
    subscriptions: Vec<Subscription>,
    // New Message
    input: Entity<TextInput>,
    // Media
    attaches: Entity<Option<Vec<Url>>>,
    is_uploading: bool,
}

impl Chat {
    pub fn new(
        id: &u64,
        room: WeakEntity<Room>,
        window: &mut Window,
        cx: &mut App,
    ) -> Entity<Self> {
        let new_messages = room
            .read_with(cx, |this, _| this.new_messages.downgrade())
            .ok();

        cx.new(|cx| {
            let messages = cx.new(|_| vec![Message::placeholder()]);
            let attaches = cx.new(|_| None);

            let input = cx.new(|cx| {
                TextInput::new(window, cx)
                    .appearance(false)
                    .text_size(ui::Size::Small)
                    .placeholder("Message...")
            });

            let subscriptions = vec![cx.subscribe_in(
                &input,
                window,
                move |this: &mut Chat, _, input_event, window, cx| {
                    if let InputEvent::PressEnter = input_event {
                        this.send_message(window, cx);
                    }
                },
            )];

            // Initialize list state
            // [item_count] always equal to 1 at the beginning
            let list_state = ListState::new(1, ListAlignment::Bottom, px(1024.), {
                let this = cx.entity().downgrade();
                move |ix, window, cx| {
                    this.update(cx, |this, cx| {
                        this.render_message(ix, window, cx).into_any_element()
                    })
                    .unwrap()
                }
            });

            let mut this = Self {
                closable: true,
                zoomable: true,
                focus_handle: cx.focus_handle(),
                is_uploading: false,
                id: id.to_string().into(),
                room,
                new_messages,
                messages,
                list_state,
                input,
                attaches,
                subscriptions,
            };

            // Verify messaging relays of all members
            this.verify_messaging_relays(cx);

            // Load all messages from database
            this.load_messages(cx);

            // Subscribe and load new messages
            this.load_new_messages(cx);

            this
        })
    }

    fn verify_messaging_relays(&self, cx: &mut Context<Self>) {
        let Some(model) = self.room.upgrade() else {
            return;
        };

        let room = model.read(cx);
        let pubkeys: Vec<PublicKey> = room.members.iter().map(|m| m.public_key()).collect();
        let client = get_client();
        let (tx, rx) = oneshot::channel::<Vec<(PublicKey, bool)>>();

        cx.background_spawn(async move {
            let mut result = Vec::new();

            for pubkey in pubkeys.into_iter() {
                let filter = Filter::new()
                    .kind(Kind::InboxRelays)
                    .author(pubkey)
                    .limit(1);

                let is_ready = if let Ok(events) = client.database().query(filter).await {
                    events.first_owned().is_some()
                } else {
                    false
                };

                result.push((pubkey, is_ready));
            }

            _ = tx.send(result);
        })
        .detach();

        cx.spawn(|this, cx| async move {
            if let Ok(result) = rx.await {
                _ = cx.update(|cx| {
                    _ = this.update(cx, |this, cx| {
                        for item in result.into_iter() {
                            if !item.1 {
                                let name = this
                                    .room
                                    .read_with(cx, |this, _| this.name())
                                    .unwrap_or("Unnamed".into());

                                this.push_system_message(
                                    format!("{} has not set up Messaging (DM) Relays, so they will NOT receive your messages.", name),
                                    cx,
                                );
                            }
                        }
                    });
                });
            }
        })
        .detach();
    }

    fn load_messages(&self, cx: &mut Context<Self>) {
        let Some(model) = self.room.upgrade() else {
            return;
        };

        let client = get_client();
        let (tx, rx) = oneshot::channel::<Events>();

        let room = model.read(cx);
        let pubkeys = room
            .members
            .iter()
            .map(|m| m.public_key())
            .collect::<Vec<_>>();

        let recv = Filter::new()
            .kind(Kind::PrivateDirectMessage)
            .author(room.owner.public_key())
            .pubkeys(pubkeys.iter().copied());

        let send = Filter::new()
            .kind(Kind::PrivateDirectMessage)
            .authors(pubkeys)
            .pubkey(room.owner.public_key());

        cx.background_spawn(async move {
            let Ok(recv_events) = client.database().query(recv).await else {
                return;
            };
            let Ok(send_events) = client.database().query(send).await else {
                return;
            };
            let events = recv_events.merge(send_events);

            _ = tx.send(events);
        })
        .detach();

        cx.spawn(|this, cx| async move {
            if let Ok(events) = rx.await {
                _ = cx.update(|cx| {
                    _ = this.update(cx, |this, cx| {
                        this.push_messages(events, cx);
                    });
                })
            }
        })
        .detach();
    }

    fn push_system_message(&self, content: String, cx: &mut Context<Self>) {
        let old_len = self.messages.read(cx).len();
        let message = Message::system(content.into());

        cx.update_entity(&self.messages, |this, cx| {
            this.extend(vec![message]);
            cx.notify();
        });

        self.list_state.splice(old_len..old_len, 1);
    }

    fn push_message(&self, content: String, window: &mut Window, cx: &mut Context<Self>) {
        let Some(model) = self.room.upgrade() else {
            return;
        };

        let old_len = self.messages.read(cx).len();
        let room = model.read(cx);
        let message = Message::new(ParsedMessage::new(&room.owner, &content, Timestamp::now()));

        // Update message list
        cx.update_entity(&self.messages, |this, cx| {
            this.extend(vec![message]);
            cx.notify();
        });

        // Reset message input
        cx.update_entity(&self.input, |this, cx| {
            this.set_loading(false, window, cx);
            this.set_disabled(false, window, cx);
            this.set_text("", window, cx);
            cx.notify();
        });

        self.list_state.splice(old_len..old_len, 1);
    }

    fn push_messages(&self, events: Events, cx: &mut Context<Self>) {
        let Some(model) = self.room.upgrade() else {
            return;
        };

        let old_len = self.messages.read(cx).len();
        let room = model.read(cx);
        let pubkeys = room.pubkeys();

        let (messages, total) = {
            let items: Vec<Message> = events
                .into_iter()
                .sorted_by_key(|ev| ev.created_at)
                .filter_map(|ev| {
                    let mut other_pubkeys: Vec<_> = ev.tags.public_keys().copied().collect();
                    other_pubkeys.push(ev.pubkey);

                    if compare(&other_pubkeys, &pubkeys) {
                        let member = if let Some(member) =
                            room.members.iter().find(|&m| m.public_key() == ev.pubkey)
                        {
                            member.to_owned()
                        } else {
                            room.owner.to_owned()
                        };

                        let message =
                            Message::new(ParsedMessage::new(&member, &ev.content, ev.created_at));

                        Some(message)
                    } else {
                        None
                    }
                })
                .collect();
            let total = items.len();

            (items, total)
        };

        cx.update_entity(&self.messages, |this, cx| {
            this.extend(messages);
            cx.notify();
        });

        self.list_state.splice(old_len..old_len, total);
    }

    fn load_new_messages(&mut self, cx: &mut Context<Self>) {
        let Some(Some(model)) = self.new_messages.as_ref().map(|state| state.upgrade()) else {
            return;
        };

        let subscription = cx.observe(&model, |view, this, cx| {
            let Some(model) = view.room.upgrade() else {
                return;
            };

            let room = model.read(cx);
            let old_messages = view.messages.read(cx);
            let old_len = old_messages.len();

            let items: Vec<Message> = this
                .read(cx)
                .iter()
                .filter_map(|event| {
                    if let Some(profile) = room.member(&event.pubkey) {
                        let message = Message::new(ParsedMessage::new(
                            &profile,
                            &event.content,
                            event.created_at,
                        ));

                        if !old_messages.iter().any(|old| old == &message) {
                            Some(message)
                        } else {
                            None
                        }
                    } else {
                        None
                    }
                })
                .collect();

            let total = items.len();

            cx.update_entity(&view.messages, |this, cx| {
                let messages: Vec<Message> = items
                    .into_iter()
                    .filter_map(|new| {
                        if !this.iter().any(|old| old == &new) {
                            Some(new)
                        } else {
                            None
                        }
                    })
                    .collect();

                this.extend(messages);
                cx.notify();
            });

            view.list_state.splice(old_len..old_len, total);
        });

        self.subscriptions.push(subscription);
    }

    fn send_message(&mut self, window: &mut Window, cx: &mut Context<Self>) {
        let Some(model) = self.room.upgrade() else {
            return;
        };

        // Get message
        let mut content = self.input.read(cx).text();

        // Get all attaches and merge its with message
        if let Some(attaches) = self.attaches.read(cx).as_ref() {
            let merged = attaches
                .iter()
                .map(|url| url.to_string())
                .collect::<Vec<_>>()
                .join("\n");

            content = format!("{}\n{}", content, merged).into()
        }

        if content.is_empty() {
            window.push_notification("Cannot send an empty message", cx);
            return;
        }

        // Disable input when sending message
        self.input.update(cx, |this, cx| {
            this.set_loading(true, window, cx);
            this.set_disabled(true, window, cx);
        });

        let client = get_client();
        let window_handle = window.window_handle();
        let (tx, rx) = oneshot::channel::<Vec<Error>>();

        let room = model.read(cx);
        let pubkeys = room.pubkeys();
        let async_content = content.clone().to_string();
        let tags: Vec<Tag> = room
            .pubkeys()
            .iter()
            .filter_map(|pubkey| {
                if pubkey != &room.owner.public_key() {
                    Some(Tag::public_key(*pubkey))
                } else {
                    None
                }
            })
            .collect();

        // Send message to all pubkeys
        cx.background_spawn(async move {
            let mut errors = Vec::new();

            for pubkey in pubkeys.iter() {
                if let Err(e) = client
                    .send_private_msg(*pubkey, &async_content, tags.clone())
                    .await
                {
                    errors.push(e);
                }
            }

            _ = tx.send(errors);
        })
        .detach();

        cx.spawn(|this, mut cx| async move {
            _ = cx.update_window(window_handle, |_, window, cx| {
                _ = this.update(cx, |this, cx| {
                    this.push_message(content.to_string(), window, cx);
                });
            });

            if let Ok(errors) = rx.await {
                _ = cx.update_window(window_handle, |_, window, cx| {
                    for error in errors.into_iter() {
                        window.push_notification(
                            Notification::error(error.to_string()).title("Message Failed to Send"),
                            cx,
                        );
                    }
                });
            }
        })
        .detach();
    }

    fn upload_media(&mut self, window: &mut Window, cx: &mut Context<Self>) {
        let window_handle = window.window_handle();

        let paths = cx.prompt_for_paths(PathPromptOptions {
            files: true,
            directories: false,
            multiple: false,
        });

        // Show loading spinner
        self.set_loading(true, cx);

        // TODO: support multiple upload
        cx.spawn(move |this, mut cx| async move {
            match Flatten::flatten(paths.await.map_err(|e| e.into())) {
                Ok(Some(mut paths)) => {
                    let path = paths.pop().unwrap();

                    if let Ok(file_data) = fs::read(path).await {
                        let (tx, rx) = oneshot::channel::<Url>();

                        spawn(async move {
                            let client = get_client();
                            if let Ok(url) = nip96_upload(client, file_data).await {
                                _ = tx.send(url);
                            }
                        });

                        if let Ok(url) = rx.await {
                            _ = cx.update_window(window_handle, |_, _, cx| {
                                _ = this.update(cx, |this, cx| {
                                    // Stop loading spinner
                                    this.set_loading(false, cx);

                                    this.attaches.update(cx, |this, cx| {
                                        if let Some(model) = this.as_mut() {
                                            model.push(url);
                                        } else {
                                            *this = Some(vec![url]);
                                        }
                                        cx.notify();
                                    });
                                });
                            });
                        }
                    }
                }
                Ok(None) => {
                    // Stop loading spinner
                    if let Some(view) = this.upgrade() {
                        cx.update_entity(&view, |this, cx| {
                            this.set_loading(false, cx);
                        })
                        .unwrap();
                    }
                }
                Err(_) => {}
            }
        })
        .detach();
    }

    fn remove_media(&mut self, url: &Url, _window: &mut Window, cx: &mut Context<Self>) {
        self.attaches.update(cx, |model, cx| {
            if let Some(urls) = model.as_mut() {
                let ix = urls.iter().position(|x| x == url).unwrap();
                urls.remove(ix);
                cx.notify();
            }
        });
    }

    fn set_loading(&mut self, status: bool, cx: &mut Context<Self>) {
        self.is_uploading = status;
        cx.notify();
    }

    fn render_message(
        &self,
        ix: usize,
        _window: &mut Window,
        cx: &mut Context<Self>,
    ) -> impl IntoElement {
        if let Some(message) = self.messages.read(cx).get(ix) {
            div()
                .group("")
                .relative()
                .flex()
                .gap_3()
                .w_full()
                .p_2()
                .map(|this| match message {
                    Message::User(item) => this
                        .hover(|this| this.bg(cx.theme().accent.step(cx, ColorScaleStep::ONE)))
                        .child(
                            div()
                                .absolute()
                                .left_0()
                                .top_0()
                                .w(px(2.))
                                .h_full()
                                .bg(cx.theme().transparent)
                                .group_hover("", |this| {
                                    this.bg(cx.theme().accent.step(cx, ColorScaleStep::NINE))
                                }),
                        )
                        .child(
                            img(item.avatar.clone())
                                .size_8()
                                .rounded_full()
                                .flex_shrink_0(),
                        )
                        .child(
                            div()
                                .flex()
                                .flex_col()
                                .flex_initial()
                                .overflow_hidden()
                                .child(
                                    div()
                                        .flex()
                                        .items_baseline()
                                        .gap_2()
                                        .text_xs()
                                        .child(
                                            div().font_semibold().child(item.display_name.clone()),
                                        )
                                        .child(div().child(item.created_at.clone()).text_color(
                                            cx.theme().base.step(cx, ColorScaleStep::ELEVEN),
                                        )),
                                )
                                .child(div().text_sm().child(item.content.clone())),
                        ),
                    Message::System(content) => this
                        .items_center()
                        .child(
                            div()
                                .absolute()
                                .left_0()
                                .top_0()
                                .w(px(2.))
                                .h_full()
                                .bg(cx.theme().transparent)
                                .group_hover("", |this| this.bg(cx.theme().danger)),
                        )
                        .child(
                            img("brand/avatar.png")
                                .size_8()
                                .rounded_full()
                                .flex_shrink_0(),
                        )
                        .text_xs()
                        .text_color(cx.theme().danger)
                        .child(content.clone()),
                    Message::Placeholder => this
                        .w_full()
                        .h_32()
                        .flex()
                        .flex_col()
                        .items_center()
                        .justify_center()
                        .text_center()
                        .text_xs()
                        .text_color(cx.theme().base.step(cx, ColorScaleStep::ELEVEN))
                        .line_height(relative(1.2))
                        .child(
                            svg()
                                .path("brand/coop.svg")
                                .size_8()
                                .text_color(cx.theme().base.step(cx, ColorScaleStep::THREE)),
                        )
                        .child(ALERT),
                })
        } else {
            div()
        }
    }
}

impl Panel for Chat {
    fn panel_id(&self) -> SharedString {
        self.id.clone()
    }

    fn title(&self, cx: &App) -> AnyElement {
        self.room
            .read_with(cx, |this, _cx| {
                let name = this.name();
                let facepill: Vec<String> =
                    this.members.iter().map(|member| member.avatar()).collect();

                div()
                    .flex()
                    .items_center()
                    .gap_1()
                    .child(
                        div()
                            .flex()
                            .flex_row_reverse()
                            .items_center()
                            .justify_start()
                            .children(facepill.into_iter().enumerate().rev().map(|(ix, face)| {
                                div().when(ix > 0, |div| div.ml_neg_1()).child(
                                    img(face)
                                        .size_4()
                                        .rounded_full()
                                        .object_fit(ObjectFit::Cover),
                                )
                            })),
                    )
                    .child(name)
                    .into_any()
            })
            .unwrap_or("Unnamed".into_any())
    }

    fn closable(&self, _cx: &App) -> bool {
        self.closable
    }

    fn zoomable(&self, _cx: &App) -> bool {
        self.zoomable
    }

    fn popup_menu(&self, menu: PopupMenu, _cx: &App) -> PopupMenu {
        menu.track_focus(&self.focus_handle)
    }

    fn toolbar_buttons(&self, _window: &Window, _cx: &App) -> Vec<Button> {
        vec![]
    }
}

impl EventEmitter<PanelEvent> for Chat {}

impl Focusable for Chat {
    fn focus_handle(&self, _: &App) -> FocusHandle {
        self.focus_handle.clone()
    }
}

impl Render for Chat {
    fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        v_flex()
            .size_full()
            .child(list(self.list_state.clone()).flex_1())
            .child(
                div().flex_shrink_0().p_2().child(
                    div()
                        .flex()
                        .flex_col()
                        .when_some(self.attaches.read(cx).as_ref(), |this, attaches| {
                            this.gap_1p5().children(attaches.iter().map(|url| {
                                let url = url.clone();
                                let path: SharedString = url.to_string().into();

                                div()
                                    .id(path.clone())
                                    .relative()
                                    .w_16()
                                    .child(
                                        img(format!(
                                            "{}/?url={}&w=128&h=128&fit=cover&n=-1",
                                            IMAGE_SERVICE, path
                                        ))
                                        .size_16()
                                        .shadow_lg()
                                        .rounded(px(cx.theme().radius))
                                        .object_fit(ObjectFit::ScaleDown),
                                    )
                                    .child(
                                        div()
                                            .absolute()
                                            .top_neg_2()
                                            .right_neg_2()
                                            .size_4()
                                            .flex()
                                            .items_center()
                                            .justify_center()
                                            .rounded_full()
                                            .bg(cx.theme().danger)
                                            .child(
                                                Icon::new(IconName::Close)
                                                    .size_2()
                                                    .text_color(white()),
                                            ),
                                    )
                                    .on_click(cx.listener(move |this, _, window, cx| {
                                        this.remove_media(&url, window, cx);
                                    }))
                            }))
                        })
                        .child(
                            div()
                                .w_full()
                                .h_9()
                                .flex()
                                .items_center()
                                .gap_2()
                                .child(
                                    Button::new("upload")
                                        .icon(Icon::new(IconName::Upload))
                                        .ghost()
                                        .on_click(cx.listener(move |this, _, window, cx| {
                                            this.upload_media(window, cx);
                                        }))
                                        .loading(self.is_uploading),
                                )
                                .child(
                                    div()
                                        .flex_1()
                                        .flex()
                                        .items_center()
                                        .bg(cx.theme().base.step(cx, ColorScaleStep::THREE))
                                        .rounded(px(cx.theme().radius))
                                        .pl_2()
                                        .pr_1()
                                        .child(self.input.clone())
                                        .child(
                                            Button::new("send")
                                                .ghost()
                                                .xsmall()
                                                .bold()
                                                .rounded(ButtonRounded::Medium)
                                                .label("SEND")
                                                .on_click(cx.listener(|this, _, window, cx| {
                                                    this.send_message(window, cx)
                                                })),
                                        ),
                                ),
                        ),
                ),
            )
    }
}