use crate::ChannelId;
use anyhow::Result;
use client::Client;
use gpui::{AppContext, AsyncAppContext, Entity, ModelContext, ModelHandle, Task};
use rpc::{proto, TypedEnvelope};
use std::sync::Arc;
use util::ResultExt;

pub(crate) fn init(client: &Arc<Client>) {
    client.add_model_message_handler(ChannelBuffer::handle_update_channel_buffer);
    client.add_model_message_handler(ChannelBuffer::handle_add_channel_buffer_collaborator);
    client.add_model_message_handler(ChannelBuffer::handle_remove_channel_buffer_collaborator);
}

pub struct ChannelBuffer {
    channel_id: ChannelId,
    collaborators: Vec<proto::Collaborator>,
    buffer: ModelHandle<language::Buffer>,
    client: Arc<Client>,
    _subscription: client::Subscription,
}

impl Entity for ChannelBuffer {
    type Event = ();

    fn release(&mut self, _: &mut AppContext) {
        self.client
            .send(proto::LeaveChannelBuffer {
                channel_id: self.channel_id,
            })
            .log_err();
    }
}

impl ChannelBuffer {
    pub fn join_channel(
        channel_id: ChannelId,
        client: Arc<Client>,
        cx: &mut AppContext,
    ) -> Task<Result<ModelHandle<Self>>> {
        cx.spawn(|mut cx| async move {
            let response = client
                .request(proto::JoinChannelBuffer { channel_id })
                .await?;

            let base_text = response.base_text;
            let operations = response
                .operations
                .into_iter()
                .map(language::proto::deserialize_operation)
                .collect::<Result<Vec<_>, _>>()?;

            let collaborators = response.collaborators;

            let buffer =
                cx.add_model(|cx| language::Buffer::new(response.replica_id as u16, base_text, cx));
            buffer.update(&mut cx, |buffer, cx| buffer.apply_ops(operations, cx))?;

            let subscription = client.subscribe_to_entity(channel_id)?;

            anyhow::Ok(cx.add_model(|cx| {
                cx.subscribe(&buffer, Self::on_buffer_update).detach();

                Self {
                    buffer,
                    client,
                    channel_id,
                    collaborators,
                    _subscription: subscription.set_model(&cx.handle(), &mut cx.to_async()),
                }
            }))
        })
    }

    async fn handle_update_channel_buffer(
        this: ModelHandle<Self>,
        update_channel_buffer: TypedEnvelope<proto::UpdateChannelBuffer>,
        _: Arc<Client>,
        mut cx: AsyncAppContext,
    ) -> Result<()> {
        let ops = update_channel_buffer
            .payload
            .operations
            .into_iter()
            .map(language::proto::deserialize_operation)
            .collect::<Result<Vec<_>, _>>()?;

        this.update(&mut cx, |this, cx| {
            cx.notify();
            this.buffer
                .update(cx, |buffer, cx| buffer.apply_ops(ops, cx))
        })?;

        Ok(())
    }

    async fn handle_add_channel_buffer_collaborator(
        this: ModelHandle<Self>,
        envelope: TypedEnvelope<proto::AddChannelBufferCollaborator>,
        _: Arc<Client>,
        mut cx: AsyncAppContext,
    ) -> Result<()> {
        let collaborator = envelope.payload.collaborator.ok_or_else(|| {
            anyhow::anyhow!(
                "Should have gotten a collaborator in the AddChannelBufferCollaborator message"
            )
        })?;

        this.update(&mut cx, |this, cx| {
            this.collaborators.push(collaborator);
            cx.notify();
        });

        Ok(())
    }

    async fn handle_remove_channel_buffer_collaborator(
        this: ModelHandle<Self>,
        message: TypedEnvelope<proto::RemoveChannelBufferCollaborator>,
        _: Arc<Client>,
        mut cx: AsyncAppContext,
    ) -> Result<()> {
        this.update(&mut cx, |this, cx| {
            this.collaborators.retain(|collaborator| {
                if collaborator.peer_id == message.payload.peer_id {
                    this.buffer.update(cx, |buffer, cx| {
                        buffer.remove_peer(collaborator.replica_id as u16, cx)
                    });
                    false
                } else {
                    true
                }
            });
            cx.notify();
        });

        Ok(())
    }

    fn on_buffer_update(
        &mut self,
        _: ModelHandle<language::Buffer>,
        event: &language::Event,
        _: &mut ModelContext<Self>,
    ) {
        if let language::Event::Operation(operation) = event {
            let operation = language::proto::serialize_operation(operation);
            self.client
                .send(proto::UpdateChannelBuffer {
                    channel_id: self.channel_id,
                    operations: vec![operation],
                })
                .log_err();
        }
    }

    pub fn buffer(&self) -> ModelHandle<language::Buffer> {
        self.buffer.clone()
    }

    pub fn collaborators(&self) -> &[proto::Collaborator] {
        &self.collaborators
    }
}