use crate::{
    entities::doc::{Doc, RevId, RevType, Revision, RevisionRange},
    errors::{internal_error, DocError},
    services::{doc::revision::store_actor::RevisionCmd, util::RevIdCounter, ws::DocumentWebSocket},
};
use flowy_infra::future::ResultFuture;
use flowy_ot::core::{Delta, OperationTransformable};
use tokio::sync::{mpsc, oneshot};

pub struct DocRevision {
    pub base_rev_id: RevId,
    pub rev_id: RevId,
    pub delta: Delta,
}

pub trait RevisionServer: Send + Sync {
    fn fetch_document_from_remote(&self, doc_id: &str) -> ResultFuture<Doc, DocError>;
}

pub struct RevisionManager {
    doc_id: String,
    rev_id_counter: RevIdCounter,
    rev_store: mpsc::Sender<RevisionCmd>,
}

impl RevisionManager {
    pub fn new(doc_id: &str, rev_id: RevId, rev_store: mpsc::Sender<RevisionCmd>) -> Self {
        let rev_id_counter = RevIdCounter::new(rev_id.into());
        Self {
            doc_id: doc_id.to_string(),
            rev_id_counter,
            rev_store,
        }
    }

    pub async fn add_revision(&self, revision: &Revision) -> Result<(), DocError> {
        let (ret, rx) = oneshot::channel();
        let cmd = RevisionCmd::Revision {
            revision: revision.clone(),
            ret,
        };
        let _ = self.rev_store.send(cmd).await;
        let result = rx.await.map_err(internal_error)?;
        result
    }

    pub fn ack_rev(&self, rev_id: RevId) -> Result<(), DocError> {
        let sender = self.rev_store.clone();
        tokio::spawn(async move {
            let _ = sender.send(RevisionCmd::AckRevision { rev_id }).await;
        });
        Ok(())
    }

    pub fn rev_id(&self) -> i64 { self.rev_id_counter.value() }

    pub fn next_rev_id(&self) -> (i64, i64) {
        let cur = self.rev_id_counter.value();
        let next = self.rev_id_counter.next();
        (cur, next)
    }

    pub fn set_rev_id(&self, rev_id: i64) { self.rev_id_counter.set(rev_id); }

    pub async fn construct_revisions(&self, range: RevisionRange) -> Result<Revision, DocError> {
        debug_assert!(&range.doc_id == &self.doc_id);
        let (ret, rx) = oneshot::channel();
        let sender = self.rev_store.clone();
        let cmd = RevisionCmd::GetRevisions {
            range: range.clone(),
            ret,
        };
        let _ = sender.send(cmd).await;
        let revisions = rx.await.map_err(internal_error)??;
        let mut new_delta = Delta::new();
        for revision in revisions {
            match Delta::from_bytes(revision.delta_data) {
                Ok(delta) => {
                    new_delta = new_delta.compose(&delta)?;
                },
                Err(_) => {},
            }
        }

        let delta_data = new_delta.to_bytes();
        let revision = Revision::new(
            range.start,
            range.end,
            delta_data.to_vec(),
            &self.doc_id,
            RevType::Remote,
        );

        Ok(revision)
    }
}