use std::sync::Arc;

use bytes::Bytes;

use tokio::time::{interval, Duration};

use flowy_database::{ConnectionPool, SqliteConnection};
use flowy_infra::future::{wrap_future, FnFuture, ResultFuture};

use crate::{
    entities::doc::{CreateDocParams, Doc, DocDelta, QueryDocParams},
    errors::{internal_error, DocError},
    module::DocumentUser,
    services::{
        cache::DocCache,
        doc::{
            edit::{ClientEditDoc, EditDocWsHandler},
            revision::{DocRevision, RevisionServer},
        },
        server::Server,
        ws::WsDocumentManager,
    },
    sql_tables::doc::{DocTable, DocTableSql},
};
use flowy_ot::core::Delta;

pub(crate) struct DocController {
    server: Server,
    doc_sql: Arc<DocTableSql>,
    ws_manager: Arc<WsDocumentManager>,
    cache: Arc<DocCache>,
    user: Arc<dyn DocumentUser>,
}

impl DocController {
    pub(crate) fn new(server: Server, user: Arc<dyn DocumentUser>, ws: Arc<WsDocumentManager>) -> Self {
        let doc_sql = Arc::new(DocTableSql {});
        let cache = Arc::new(DocCache::new());
        let controller = Self {
            server,
            doc_sql,
            user,
            ws_manager: ws,
            cache: cache.clone(),
        };
        controller
    }

    #[tracing::instrument(skip(self, conn), err)]
    pub(crate) fn create(&self, params: CreateDocParams, conn: &SqliteConnection) -> Result<(), DocError> {
        let doc = Doc {
            id: params.id,
            data: params.data,
            rev_id: 0,
        };
        let _ = self.doc_sql.create_doc_table(DocTable::new(doc), conn)?;
        Ok(())
    }

    #[tracing::instrument(level = "debug", skip(self, pool), err)]
    pub(crate) async fn open(
        &self,
        params: QueryDocParams,
        pool: Arc<ConnectionPool>,
    ) -> Result<Arc<ClientEditDoc>, DocError> {
        if self.cache.is_opened(&params.doc_id) == false {
            let edit_ctx = self.make_edit_context(&params.doc_id, pool.clone()).await?;
            return Ok(edit_ctx);
        }

        let edit_doc_ctx = self.cache.get(&params.doc_id)?;
        Ok(edit_doc_ctx)
    }

    pub(crate) fn close(&self, doc_id: &str) -> Result<(), DocError> {
        self.cache.remove(doc_id);
        self.ws_manager.remove_handler(doc_id);
        Ok(())
    }

    #[tracing::instrument(level = "debug", skip(self, conn), err)]
    pub(crate) fn delete(&self, params: QueryDocParams, conn: &SqliteConnection) -> Result<(), DocError> {
        let doc_id = &params.doc_id;
        let _ = self.doc_sql.delete_doc(doc_id, &*conn)?;

        self.cache.remove(doc_id);
        self.ws_manager.remove_handler(doc_id);
        let _ = self.delete_doc_on_server(params)?;
        Ok(())
    }

    #[tracing::instrument(level = "debug", skip(self, delta), err)]
    pub(crate) async fn edit_doc(&self, delta: DocDelta) -> Result<Doc, DocError> {
        let edit_doc_ctx = self.cache.get(&delta.doc_id)?;
        let _ = edit_doc_ctx.compose_local_delta(Bytes::from(delta.data)).await?;
        Ok(edit_doc_ctx.doc().await?)
    }
}

impl DocController {
    #[tracing::instrument(level = "debug", skip(self), err)]
    fn delete_doc_on_server(&self, params: QueryDocParams) -> Result<(), DocError> {
        let token = self.user.token()?;
        let server = self.server.clone();
        tokio::spawn(async move {
            match server.delete_doc(&token, params).await {
                Ok(_) => {},
                Err(e) => {
                    // TODO: retry?
                    log::error!("Delete doc failed: {:?}", e);
                },
            }
        });
        Ok(())
    }

    async fn make_edit_context(&self, doc_id: &str, pool: Arc<ConnectionPool>) -> Result<Arc<ClientEditDoc>, DocError> {
        // Opti: require upgradable_read lock and then upgrade to write lock using
        // RwLockUpgradableReadGuard::upgrade(xx) of ws
        // let doc = self.read_doc(doc_id, pool.clone()).await?;
        let ws = self.ws_manager.ws();
        let token = self.user.token()?;
        let user = self.user.clone();
        let server = Arc::new(RevisionServerImpl {
            token,
            server: self.server.clone(),
        });

        let edit_ctx = Arc::new(ClientEditDoc::new(doc_id, pool, ws, server, user).await?);
        let ws_handler = Arc::new(EditDocWsHandler(edit_ctx.clone()));
        self.ws_manager.register_handler(doc_id, ws_handler);
        self.cache.set(edit_ctx.clone());
        Ok(edit_ctx)
    }

    #[allow(dead_code)]
    #[tracing::instrument(level = "debug", skip(self, pool), err)]
    async fn read_doc(&self, doc_id: &str, pool: Arc<ConnectionPool>) -> Result<Doc, DocError> {
        match self.doc_sql.read_doc_table(doc_id, pool.clone()) {
            Ok(doc_table) => Ok(doc_table.into()),
            Err(error) => {
                if error.is_record_not_found() {
                    let token = self.user.token()?;
                    let params = QueryDocParams {
                        doc_id: doc_id.to_string(),
                    };
                    match self.server.read_doc(&token, params).await? {
                        None => Err(DocError::not_found()),
                        Some(doc) => {
                            let conn = &*pool.get().map_err(internal_error)?;
                            let _ = self.doc_sql.create_doc_table(doc.clone().into(), conn)?;
                            Ok(doc)
                        },
                    }
                } else {
                    return Err(error);
                }
            },
        }
    }
}

struct RevisionServerImpl {
    token: String,
    server: Server,
}

impl RevisionServer for RevisionServerImpl {
    fn fetch_document_from_remote(&self, doc_id: &str) -> ResultFuture<DocRevision, DocError> {
        let params = QueryDocParams {
            doc_id: doc_id.to_string(),
        };
        let server = self.server.clone();
        let token = self.token.clone();

        ResultFuture::new(async move {
            match server.read_doc(&token, params).await? {
                None => Err(DocError::not_found()),
                Some(doc) => {
                    let delta = Delta::from_bytes(doc.data)?;
                    Ok(DocRevision {
                        rev_id: doc.rev_id.into(),
                        delta,
                    })
                },
            }
        })
    }
}

#[allow(dead_code)]
fn event_loop(_cache: Arc<DocCache>) -> FnFuture<()> {
    let mut i = interval(Duration::from_secs(3));
    wrap_future(async move {
        loop {
            // cache.all_docs().iter().for_each(|doc| doc.tick());
            i.tick().await;
        }
    })
}