use std::sync::Weak;
use std::{collections::HashMap, sync::Arc};

use appflowy_integrate::collab_builder::AppFlowyCollabBuilder;
use appflowy_integrate::{CollabType, RocksCollabDB};
use collab::core::collab::MutexCollab;
use collab_document::blocks::DocumentData;
use collab_document::document::Document;
use collab_document::document_data::default_document_data;
use collab_document::YrsDocAction;
use parking_lot::RwLock;

use crate::document::MutexDocument;
use flowy_document_deps::cloud::DocumentCloudService;
use flowy_error::{internal_error, FlowyError, FlowyResult};

use crate::entities::DocumentSnapshotPB;

pub trait DocumentUser: Send + Sync {
  fn user_id(&self) -> Result<i64, FlowyError>;
  fn token(&self) -> Result<Option<String>, FlowyError>; // unused now.
  fn collab_db(&self, uid: i64) -> Result<Weak<RocksCollabDB>, FlowyError>;
}

pub struct DocumentManager {
  user: Arc<dyn DocumentUser>,
  collab_builder: Arc<AppFlowyCollabBuilder>,
  documents: Arc<RwLock<HashMap<String, Arc<MutexDocument>>>>,
  #[allow(dead_code)]
  cloud_service: Arc<dyn DocumentCloudService>,
}

impl DocumentManager {
  pub fn new(
    user: Arc<dyn DocumentUser>,
    collab_builder: Arc<AppFlowyCollabBuilder>,
    cloud_service: Arc<dyn DocumentCloudService>,
  ) -> Self {
    Self {
      user,
      collab_builder,
      documents: Default::default(),
      cloud_service,
    }
  }

  pub async fn initialize(&self, _uid: i64, _workspace_id: String) -> FlowyResult<()> {
    self.documents.write().clear();
    Ok(())
  }

  pub async fn initialize_with_new_user(&self, uid: i64, workspace_id: String) -> FlowyResult<()> {
    self.initialize(uid, workspace_id).await?;
    Ok(())
  }
  /// Create a new document.
  ///
  /// if the document already exists, return the existing document.
  /// if the data is None, will create a document with default data.
  pub fn create_document(
    &self,
    doc_id: &str,
    data: Option<DocumentData>,
  ) -> FlowyResult<Arc<MutexDocument>> {
    tracing::trace!("create a document: {:?}", doc_id);
    let collab = self.collab_for_document(doc_id, vec![])?;
    let data = data.unwrap_or_else(default_document_data);
    let document = Arc::new(MutexDocument::create_with_data(collab, data)?);
    Ok(document)
  }

  /// Return the document
  pub async fn get_document(&self, doc_id: &str) -> FlowyResult<Arc<MutexDocument>> {
    if let Some(doc) = self.documents.read().get(doc_id) {
      return Ok(doc.clone());
    }
    let mut updates = vec![];
    if !self.is_doc_exist(doc_id)? {
      // Try to get the document from the cloud service
      if let Ok(document_updates) = self.cloud_service.get_document_updates(doc_id).await {
        updates = document_updates;
      } else {
        return Err(
          FlowyError::record_not_found().context(format!("document: {} is not exist", doc_id)),
        );
      };
    }

    tracing::debug!("open_document: {:?}", doc_id);
    let uid = self.user.user_id()?;
    let db = self.user.collab_db(uid)?;
    let collab = self
      .collab_builder
      .build(uid, doc_id, CollabType::Document, updates, db)?;
    let document = Arc::new(MutexDocument::open(doc_id, collab)?);

    // save the document to the memory and read it from the memory if we open the same document again.
    // and we don't want to subscribe to the document changes if we open the same document again.
    self
      .documents
      .write()
      .insert(doc_id.to_string(), document.clone());
    Ok(document)
  }

  pub async fn get_document_data(&self, doc_id: &str) -> FlowyResult<DocumentData> {
    let mut updates = vec![];
    if !self.is_doc_exist(doc_id)? {
      if let Ok(document_updates) = self.cloud_service.get_document_updates(doc_id).await {
        updates = document_updates;
      } else {
        return Err(
          FlowyError::record_not_found().context(format!("document: {} is not exist", doc_id)),
        );
      }
    }

    let collab = self.collab_for_document(doc_id, updates)?;
    Document::open(collab)?
      .get_document_data()
      .map_err(internal_error)
  }

  pub fn close_document(&self, doc_id: &str) -> FlowyResult<()> {
    self.documents.write().remove(doc_id);
    Ok(())
  }

  pub fn delete_document(&self, doc_id: &str) -> FlowyResult<()> {
    let uid = self.user.user_id()?;
    if let Some(db) = self.user.collab_db(uid)?.upgrade() {
      let _ = db.with_write_txn(|txn| {
        txn.delete_doc(uid, &doc_id)?;
        Ok(())
      });
      self.documents.write().remove(doc_id);
    }
    Ok(())
  }

  /// Return the list of snapshots of the document.
  pub async fn get_document_snapshots(
    &self,
    document_id: &str,
  ) -> FlowyResult<Vec<DocumentSnapshotPB>> {
    let mut snapshots = vec![];
    if let Some(snapshot) = self
      .cloud_service
      .get_document_latest_snapshot(document_id)
      .await?
      .map(|snapshot| DocumentSnapshotPB {
        snapshot_id: snapshot.snapshot_id,
        snapshot_desc: "".to_string(),
        created_at: snapshot.created_at,
        data: snapshot.data,
      })
    {
      snapshots.push(snapshot);
    }

    Ok(snapshots)
  }

  fn collab_for_document(
    &self,
    doc_id: &str,
    updates: Vec<Vec<u8>>,
  ) -> FlowyResult<Arc<MutexCollab>> {
    let uid = self.user.user_id()?;
    let db = self.user.collab_db(uid)?;
    let collab = self
      .collab_builder
      .build(uid, doc_id, CollabType::Document, updates, db)?;
    Ok(collab)
  }

  fn is_doc_exist(&self, doc_id: &str) -> FlowyResult<bool> {
    let uid = self.user.user_id()?;
    if let Some(collab_db) = self.user.collab_db(uid)?.upgrade() {
      let read_txn = collab_db.read_txn();
      Ok(read_txn.is_exist(uid, doc_id))
    } else {
      Ok(false)
    }
  }

  /// Only expose this method for testing
  #[cfg(debug_assertions)]
  pub fn get_cloud_service(&self) -> &Arc<dyn DocumentCloudService> {
    &self.cloud_service
  }
}