use std::borrow::Cow;
use std::ffi::OsStr;
use std::fs;
use std::ops::Deref;
use std::path::{Path, PathBuf};

use tokio;

use matrix_sdk::{
    attachment::AttachmentConfig,
    media::{MediaFormat, MediaRequest},
    room::{Joined, Room as MatrixRoom},
    ruma::{
        events::reaction::{ReactionEventContent, Relation as Reaction},
        events::room::message::{
            MessageType,
            OriginalRoomMessageEvent,
            Relation,
            Replacement,
            RoomMessageEventContent,
            TextMessageEventContent,
        },
        EventId,
        OwnedRoomId,
        RoomId,
    },
};

use modalkit::{
    input::dialog::PromptYesNo,
    tui::{
        buffer::Buffer,
        layout::Rect,
        text::{Span, Spans},
        widgets::{Paragraph, StatefulWidget, Widget},
    },
    widgets::textbox::{TextBox, TextBoxState},
    widgets::TerminalCursor,
    widgets::{PromptActions, WindowOps},
};

use modalkit::editing::{
    action::{
        Action,
        EditError,
        EditInfo,
        EditResult,
        Editable,
        EditorAction,
        InfoMessage,
        Jumpable,
        PromptAction,
        Promptable,
        Scrollable,
        UIError,
    },
    base::{CloseFlags, Count, MoveDir1D, PositionList, ScrollStyle, WordStyle, WriteFlags},
    completion::CompletionList,
    context::Resolve,
    history::{self, HistoryList},
    rope::EditRope,
};

use crate::base::{
    DownloadFlags,
    IambAction,
    IambBufferId,
    IambError,
    IambInfo,
    IambResult,
    MessageAction,
    ProgramAction,
    ProgramContext,
    ProgramStore,
    RoomFocus,
    RoomInfo,
    SendAction,
};

use crate::message::{text_to_message, Message, MessageEvent, MessageKey, MessageTimeStamp};
use crate::worker::Requester;

use super::scrollback::{Scrollback, ScrollbackState};

pub struct ChatState {
    room_id: OwnedRoomId,
    room: MatrixRoom,

    tbox: TextBoxState<IambInfo>,
    sent: HistoryList<EditRope>,
    sent_scrollback: history::ScrollbackState,

    scrollback: ScrollbackState,
    focus: RoomFocus,

    reply_to: Option<MessageKey>,
    editing: Option<MessageKey>,
}

impl ChatState {
    pub fn new(room: MatrixRoom, store: &mut ProgramStore) -> Self {
        let room_id = room.room_id().to_owned();
        let scrollback = ScrollbackState::new(room_id.clone());
        let id = IambBufferId::Room(room_id.clone(), RoomFocus::MessageBar);
        let ebuf = store.load_buffer(id);
        let tbox = TextBoxState::new(ebuf);

        ChatState {
            room_id,
            room,

            tbox,
            sent: HistoryList::new(EditRope::from(""), 100),
            sent_scrollback: history::ScrollbackState::Pending,

            scrollback,
            focus: RoomFocus::MessageBar,

            reply_to: None,
            editing: None,
        }
    }

    fn get_joined(&self, worker: &Requester) -> Result<Joined, IambError> {
        worker.client.get_joined_room(self.id()).ok_or(IambError::NotJoined)
    }

    fn get_reply_to<'a>(&self, info: &'a RoomInfo) -> Option<&'a OriginalRoomMessageEvent> {
        let key = self.reply_to.as_ref()?;
        let msg = info.messages.get(key)?;

        if let MessageEvent::Original(ev) = &msg.event {
            Some(ev)
        } else {
            None
        }
    }

    fn reset(&mut self) -> EditRope {
        self.reply_to = None;
        self.editing = None;
        self.tbox.reset()
    }

    pub fn refresh_room(&mut self, store: &mut ProgramStore) {
        if let Some(room) = store.application.worker.client.get_room(self.id()) {
            self.room = room;
        }
    }

    pub async fn message_command(
        &mut self,
        act: MessageAction,
        _: ProgramContext,
        store: &mut ProgramStore,
    ) -> IambResult<EditInfo> {
        let client = &store.application.worker.client;

        let settings = &store.application.settings;
        let info = store.application.rooms.get_or_default(self.room_id.clone());

        let msg = self
            .scrollback
            .get_mut(&mut info.messages)
            .ok_or(IambError::NoSelectedMessage)?;

        match act {
            MessageAction::Cancel(skip_confirm) => {
                self.reply_to = None;
                self.editing = None;

                if skip_confirm {
                    return Ok(None);
                }

                let msg = "Would you like to clear the message bar?";
                let act = PromptAction::Abort(false);
                let prompt = PromptYesNo::new(msg, vec![Action::from(act)]);
                let prompt = Box::new(prompt);

                Err(UIError::NeedConfirm(prompt))
            },
            MessageAction::Download(filename, flags) => {
                if let MessageEvent::Original(ev) = &msg.event {
                    let media = client.media();

                    let mut filename = match filename {
                        Some(f) => PathBuf::from(f),
                        None => settings.dirs.downloads.clone(),
                    };

                    let (source, msg_filename) = match &ev.content.msgtype {
                        MessageType::Audio(c) => (c.source.clone(), c.body.as_str()),
                        MessageType::File(c) => {
                            (c.source.clone(), c.filename.as_deref().unwrap_or(c.body.as_str()))
                        },
                        MessageType::Image(c) => (c.source.clone(), c.body.as_str()),
                        MessageType::Video(c) => (c.source.clone(), c.body.as_str()),
                        _ => {
                            return Err(IambError::NoAttachment.into());
                        },
                    };

                    if filename.is_dir() {
                        filename.push(msg_filename);
                    }

                    if filename.exists() && !flags.contains(DownloadFlags::FORCE) {
                        // Find an incrementally suffixed filename, e.g. image-2.jpg -> image-3.jpg
                        if let Some(stem) = filename.file_stem().and_then(OsStr::to_str) {
                            let ext = filename.extension();
                            let mut filename_incr = filename.clone();
                            for n in 1..=1000 {
                                if let Some(ext) = ext.and_then(OsStr::to_str) {
                                    filename_incr.set_file_name(format!("{}-{}.{}", stem, n, ext));
                                } else {
                                    filename_incr.set_file_name(format!("{}-{}", stem, n));
                                }

                                if !filename_incr.exists() {
                                    filename = filename_incr;
                                    break;
                                }
                            }
                        }
                    }

                    if !filename.exists() || flags.contains(DownloadFlags::FORCE) {
                        let req = MediaRequest { source, format: MediaFormat::File };

                        let bytes =
                            media.get_media_content(&req, true).await.map_err(IambError::from)?;

                        fs::write(filename.as_path(), bytes.as_slice())?;

                        msg.downloaded = true;
                    } else if !flags.contains(DownloadFlags::OPEN) {
                        let msg = format!(
                            "The file {} already exists; add ! to end of command to overwrite it.",
                            filename.display()
                        );
                        let err = UIError::Failure(msg);

                        return Err(err);
                    }

                    let info = if flags.contains(DownloadFlags::OPEN) {
                        // open::that may not return until the spawned program closes.
                        let target = filename.clone().into_os_string();
                        tokio::task::spawn_blocking(move || open::that(target));

                        InfoMessage::from(format!(
                            "Attachment downloaded to {} and opened",
                            filename.display()
                        ))
                    } else {
                        InfoMessage::from(format!(
                            "Attachment downloaded to {}",
                            filename.display()
                        ))
                    };

                    return Ok(info.into());
                }

                Err(IambError::NoAttachment.into())
            },
            MessageAction::Edit => {
                if msg.sender != settings.profile.user_id {
                    let msg = "Cannot edit messages sent by someone else";
                    let err = UIError::Failure(msg.into());

                    return Err(err);
                }

                let ev = match &msg.event {
                    MessageEvent::Original(ev) => &ev.content,
                    MessageEvent::Local(_, ev) => ev.deref(),
                    _ => {
                        let msg = "Cannot edit a redacted message";
                        let err = UIError::Failure(msg.into());

                        return Err(err);
                    },
                };

                let text = match &ev.msgtype {
                    MessageType::Text(msg) => msg.body.as_str(),
                    _ => {
                        let msg = "Cannot edit a non-text message";
                        let err = UIError::Failure(msg.into());

                        return Err(err);
                    },
                };

                self.tbox.set_text(text);
                self.reply_to = msg.reply_to().and_then(|id| info.get_message_key(&id)).cloned();
                self.editing = self.scrollback.get_key(info);
                self.focus = RoomFocus::MessageBar;

                Ok(None)
            },
            MessageAction::React(emoji) => {
                let room = self.get_joined(&store.application.worker)?;
                let event_id = match &msg.event {
                    MessageEvent::EncryptedOriginal(ev) => ev.event_id.clone(),
                    MessageEvent::EncryptedRedacted(ev) => ev.event_id.clone(),
                    MessageEvent::Original(ev) => ev.event_id.clone(),
                    MessageEvent::Local(event_id, _) => event_id.clone(),
                    MessageEvent::Redacted(_) => {
                        let msg = "Cannot react to a redacted message";
                        let err = UIError::Failure(msg.into());

                        return Err(err);
                    },
                };

                let reaction = Reaction::new(event_id, emoji);
                let msg = ReactionEventContent::new(reaction);
                let _ = room.send(msg, None).await.map_err(IambError::from)?;

                Ok(None)
            },
            MessageAction::Redact(reason, skip_confirm) => {
                if !skip_confirm {
                    let msg = "Are you sure you want to redact this message?";
                    let act = IambAction::Message(MessageAction::Redact(reason, true));
                    let prompt = PromptYesNo::new(msg, vec![Action::from(act)]);
                    let prompt = Box::new(prompt);

                    return Err(UIError::NeedConfirm(prompt));
                }

                let room = self.get_joined(&store.application.worker)?;
                let event_id = match &msg.event {
                    MessageEvent::EncryptedOriginal(ev) => ev.event_id.clone(),
                    MessageEvent::EncryptedRedacted(ev) => ev.event_id.clone(),
                    MessageEvent::Original(ev) => ev.event_id.clone(),
                    MessageEvent::Local(event_id, _) => event_id.clone(),
                    MessageEvent::Redacted(_) => {
                        let msg = "Cannot redact already redacted message";
                        let err = UIError::Failure(msg.into());

                        return Err(err);
                    },
                };

                let event_id = event_id.as_ref();
                let reason = reason.as_deref();
                let _ = room.redact(event_id, reason, None).await.map_err(IambError::from)?;

                Ok(None)
            },
            MessageAction::Reply => {
                self.reply_to = self.scrollback.get_key(info);
                self.focus = RoomFocus::MessageBar;

                Ok(None)
            },
            MessageAction::Unreact(emoji) => {
                let room = self.get_joined(&store.application.worker)?;
                let event_id: &EventId = match &msg.event {
                    MessageEvent::EncryptedOriginal(ev) => ev.event_id.as_ref(),
                    MessageEvent::EncryptedRedacted(ev) => ev.event_id.as_ref(),
                    MessageEvent::Original(ev) => ev.event_id.as_ref(),
                    MessageEvent::Local(event_id, _) => event_id.as_ref(),
                    MessageEvent::Redacted(_) => {
                        let msg = "Cannot unreact to a redacted message";
                        let err = UIError::Failure(msg.into());

                        return Err(err);
                    },
                };

                let reactions = match info.reactions.get(event_id) {
                    Some(r) => r,
                    None => return Ok(None),
                };

                let reactions = reactions.iter().filter_map(|(event_id, (reaction, user_id))| {
                    if user_id != &settings.profile.user_id {
                        return None;
                    }

                    if let Some(emoji) = &emoji {
                        if emoji == reaction {
                            return Some(event_id);
                        } else {
                            return None;
                        }
                    } else {
                        return Some(event_id);
                    }
                });

                for reaction in reactions {
                    let _ = room.redact(reaction, None, None).await.map_err(IambError::from)?;
                }

                Ok(None)
            },
        }
    }

    pub async fn send_command(
        &mut self,
        act: SendAction,
        _: ProgramContext,
        store: &mut ProgramStore,
    ) -> IambResult<EditInfo> {
        let room = store
            .application
            .worker
            .client
            .get_joined_room(self.id())
            .ok_or(IambError::NotJoined)?;
        let info = store.application.rooms.get_or_default(self.id().to_owned());
        let mut show_echo = true;

        let (event_id, msg) = match act {
            SendAction::Submit => {
                let msg = self.tbox.get();

                if msg.is_blank() {
                    return Ok(None);
                }

                let mut msg = text_to_message(msg.to_string());

                if let Some((_, event_id)) = &self.editing {
                    msg.relates_to = Some(Relation::Replacement(Replacement::new(
                        event_id.clone(),
                        Box::new(msg.clone()),
                    )));

                    show_echo = false;
                } else if let Some(m) = self.get_reply_to(info) {
                    // XXX: Switch to RoomMessageEventContent::reply() once it's stable?
                    msg = msg.make_reply_to(m);
                }

                // XXX: second parameter can be a locally unique transaction id.
                // Useful for doing retries.
                let resp = room.send(msg.clone(), None).await.map_err(IambError::from)?;
                let event_id = resp.event_id;

                // Reset message bar state now that it's been sent.
                self.reset();

                (event_id, msg)
            },
            SendAction::Upload(file) => {
                let path = Path::new(file.as_str());
                let mime = mime_guess::from_path(path).first_or(mime::APPLICATION_OCTET_STREAM);

                let bytes = fs::read(path)?;
                let name = path
                    .file_name()
                    .map(OsStr::to_string_lossy)
                    .unwrap_or_else(|| Cow::from("Attachment"));
                let config = AttachmentConfig::new();

                let resp = room
                    .send_attachment(name.as_ref(), &mime, bytes.as_ref(), config)
                    .await
                    .map_err(IambError::from)?;

                // Mock up the local echo message for the scrollback.
                let msg = TextMessageEventContent::plain(format!("[Attached File: {name}]"));
                let msg = MessageType::Text(msg);
                let msg = RoomMessageEventContent::new(msg);

                (resp.event_id, msg)
            },
        };

        if show_echo {
            let user = store.application.settings.profile.user_id.clone();
            let key = (MessageTimeStamp::LocalEcho, event_id.clone());
            let msg = MessageEvent::Local(event_id, msg.into());
            let msg = Message::new(msg, user, MessageTimeStamp::LocalEcho);
            info.messages.insert(key, msg);
        }

        // Jump to the end of the scrollback to show the message.
        self.scrollback.goto_latest();

        Ok(None)
    }

    pub fn focus_toggle(&mut self) {
        self.focus = match self.focus {
            RoomFocus::Scrollback => RoomFocus::MessageBar,
            RoomFocus::MessageBar => RoomFocus::Scrollback,
        };
    }

    pub fn room(&self) -> &MatrixRoom {
        &self.room
    }

    pub fn id(&self) -> &RoomId {
        &self.room_id
    }

    pub fn typing_notice(
        &self,
        act: &EditorAction,
        ctx: &ProgramContext,
        store: &mut ProgramStore,
    ) {
        if !self.focus.is_msgbar() || act.is_readonly(ctx) {
            return;
        }

        if !store.application.settings.tunables.typing_notice_send {
            return;
        }

        store.application.worker.typing_notice(self.room_id.clone());
    }
}

macro_rules! delegate {
    ($s: expr, $id: ident => $e: expr) => {
        match $s.focus {
            RoomFocus::Scrollback => {
                match $s {
                    ChatState { scrollback: $id, .. } => $e,
                }
            },
            RoomFocus::MessageBar => {
                match $s {
                    ChatState { tbox: $id, .. } => $e,
                }
            },
        }
    };
}

impl WindowOps<IambInfo> for ChatState {
    fn draw(&mut self, area: Rect, buf: &mut Buffer, focused: bool, store: &mut ProgramStore) {
        Chat::new(store).focus(focused).render(area, buf, self)
    }

    fn dup(&self, store: &mut ProgramStore) -> Self {
        // XXX: I want each WindowSlot to have its own shared buffer, instead of each Room; need to
        // find a good way to pass that info here so that it can be part of the content id.
        let id = IambBufferId::Room(self.room_id.clone(), RoomFocus::MessageBar);
        let ebuf = store.load_buffer(id);
        let tbox = TextBoxState::new(ebuf);

        ChatState {
            room_id: self.room_id.clone(),
            room: self.room.clone(),

            tbox,
            sent: self.sent.clone(),
            sent_scrollback: history::ScrollbackState::Pending,

            scrollback: self.scrollback.dup(store),
            focus: self.focus,

            reply_to: None,
            editing: None,
        }
    }

    fn close(&mut self, _: CloseFlags, _: &mut ProgramStore) -> bool {
        // XXX: what's the right closing behaviour for a room?
        // Should write send a message?
        true
    }

    fn write(
        &mut self,
        _: Option<&str>,
        _: WriteFlags,
        _: &mut ProgramStore,
    ) -> IambResult<EditInfo> {
        // XXX: what's the right writing behaviour for a room?
        // Should write send a message?
        Ok(None)
    }

    fn get_completions(&self) -> Option<CompletionList> {
        delegate!(self, w => w.get_completions())
    }

    fn get_cursor_word(&self, style: &WordStyle) -> Option<String> {
        delegate!(self, w => w.get_cursor_word(style))
    }

    fn get_selected_word(&self) -> Option<String> {
        delegate!(self, w => w.get_selected_word())
    }
}

impl Editable<ProgramContext, ProgramStore, IambInfo> for ChatState {
    fn editor_command(
        &mut self,
        act: &EditorAction,
        ctx: &ProgramContext,
        store: &mut ProgramStore,
    ) -> EditResult<EditInfo, IambInfo> {
        self.typing_notice(act, ctx, store);

        match delegate!(self, w => w.editor_command(act, ctx, store)) {
            res @ Ok(_) => res,
            Err(EditError::WrongBuffer(IambBufferId::Room(room_id, focus)))
                if room_id == self.room_id && act.is_switchable(ctx) =>
            {
                // Switch focus.
                self.focus = focus;

                // Run command again.
                delegate!(self, w => w.editor_command(act, ctx, store))
            },
            res @ Err(_) => res,
        }
    }
}

impl TerminalCursor for ChatState {
    fn get_term_cursor(&self) -> Option<(u16, u16)> {
        delegate!(self, w => w.get_term_cursor())
    }
}

impl Jumpable<ProgramContext, IambInfo> for ChatState {
    fn jump(
        &mut self,
        list: PositionList,
        dir: MoveDir1D,
        count: usize,
        ctx: &ProgramContext,
    ) -> IambResult<usize> {
        delegate!(self, w => w.jump(list, dir, count, ctx))
    }
}

impl Scrollable<ProgramContext, ProgramStore, IambInfo> for ChatState {
    fn scroll(
        &mut self,
        style: &ScrollStyle,
        ctx: &ProgramContext,
        store: &mut ProgramStore,
    ) -> EditResult<EditInfo, IambInfo> {
        // Send all scroll commands to the scrollback.
        //
        // If there's enough message text for scrolling to be necessary,
        // navigating with movement keys should be enough to do the job.
        self.scrollback.scroll(style, ctx, store)
    }
}

impl PromptActions<ProgramContext, ProgramStore, IambInfo> for ChatState {
    fn submit(
        &mut self,
        ctx: &ProgramContext,
        _: &mut ProgramStore,
    ) -> EditResult<Vec<(ProgramAction, ProgramContext)>, IambInfo> {
        let act = SendAction::Submit;

        Ok(vec![(IambAction::from(act).into(), ctx.clone())])
    }

    fn abort(
        &mut self,
        empty: bool,
        _: &ProgramContext,
        _: &mut ProgramStore,
    ) -> EditResult<Vec<(ProgramAction, ProgramContext)>, IambInfo> {
        let text = self.tbox.get();

        if empty && text.is_blank() {
            return Ok(vec![]);
        }

        let text = self.reset().trim();

        if text.is_empty() {
            let _ = self.sent.end();
        } else {
            self.sent.select(text);
        }

        return Ok(vec![]);
    }

    fn recall(
        &mut self,
        dir: &MoveDir1D,
        count: &Count,
        prefixed: bool,
        ctx: &ProgramContext,
        _: &mut ProgramStore,
    ) -> EditResult<Vec<(ProgramAction, ProgramContext)>, IambInfo> {
        let count = ctx.resolve(count);
        let rope = self.tbox.get();

        let text = self.sent.recall(&rope, &mut self.sent_scrollback, *dir, prefixed, count);

        if let Some(text) = text {
            self.tbox.set_text(text);
        }

        Ok(vec![])
    }
}

impl Promptable<ProgramContext, ProgramStore, IambInfo> for ChatState {
    fn prompt(
        &mut self,
        act: &PromptAction,
        ctx: &ProgramContext,
        store: &mut ProgramStore,
    ) -> EditResult<Vec<(ProgramAction, ProgramContext)>, IambInfo> {
        if let RoomFocus::Scrollback = self.focus {
            return Ok(vec![]);
        }

        match act {
            PromptAction::Submit => self.submit(ctx, store),
            PromptAction::Abort(empty) => self.abort(*empty, ctx, store),
            PromptAction::Recall(dir, count, prefixed) => {
                self.recall(dir, count, *prefixed, ctx, store)
            },
            _ => Err(EditError::Unimplemented("unknown prompt action".to_string())),
        }
    }
}

pub struct Chat<'a> {
    store: &'a mut ProgramStore,
    focused: bool,
}

impl<'a> Chat<'a> {
    pub fn new(store: &'a mut ProgramStore) -> Chat<'a> {
        Chat { store, focused: false }
    }

    pub fn focus(mut self, focused: bool) -> Self {
        self.focused = focused;
        self
    }
}

impl<'a> StatefulWidget for Chat<'a> {
    type State = ChatState;

    fn render(self, area: Rect, buf: &mut Buffer, state: &mut Self::State) {
        // Determine whether we have a description to show for the message bar.
        let desc_spans = match (&state.editing, &state.reply_to) {
            (None, None) => None,
            (Some(_), None) => Some(Spans::from("Editing message")),
            (editing, Some(_)) => {
                state.reply_to.as_ref().and_then(|k| {
                    let room = self.store.application.rooms.get(state.id())?;
                    let msg = room.messages.get(k)?;
                    let user = self.store.application.settings.get_user_span(msg.sender.as_ref());
                    let prefix = if editing.is_some() {
                        Span::from("Editing reply to ")
                    } else {
                        Span::from("Replying to ")
                    };
                    let spans = Spans(vec![prefix, user]);

                    spans.into()
                })
            },
        };

        // Determine the region to show each UI element.
        let lines = state.tbox.has_lines(5).max(1) as u16;
        let drawh = area.height;
        let texth = lines.min(drawh).clamp(1, 5);
        let desch = if desc_spans.is_some() {
            drawh.saturating_sub(texth).min(1)
        } else {
            0
        };
        let scrollh = drawh.saturating_sub(texth).saturating_sub(desch);

        let scrollarea = Rect::new(area.x, area.y, area.width, scrollh);
        let descarea = Rect::new(area.x, scrollarea.y + scrollh, area.width, desch);
        let textarea = Rect::new(area.x, descarea.y + desch, area.width, texth);

        // Render the message bar and any description for it.
        if let Some(desc_spans) = desc_spans {
            Paragraph::new(desc_spans).render(descarea, buf);
        }

        let prompt = if self.focused { "> " } else { "  " };

        let tbox = TextBox::new().prompt(prompt);
        tbox.render(textarea, buf, &mut state.tbox);

        // Render the message scrollback.
        let scrollback_focused = state.focus.is_scrollback() && self.focused;
        let scrollback = Scrollback::new(self.store).focus(scrollback_focused);
        scrollback.render(scrollarea, buf, &mut state.scrollback);
    }
}