AppFlowy/frontend/rust-lib/flowy-client-sync/src/client_document/history.rs

use lib_ot::text_delta::DeltaTextOperations;

const MAX_UNDOES: usize = 20;

#[derive(Debug, Clone)]
pub struct UndoResult {
  pub operations: DeltaTextOperations,
}

#[derive(Debug, Clone)]
pub struct History {
  #[allow(dead_code)]
  cur_undo: usize,
  undoes: Vec<DeltaTextOperations>,
  redoes: Vec<DeltaTextOperations>,
  capacity: usize,
}

impl std::default::Default for History {
  fn default() -> Self {
    History {
      cur_undo: 1,
      undoes: Vec::new(),
      redoes: Vec::new(),
      capacity: MAX_UNDOES,
    }
  }
}

impl History {
  pub fn new() -> Self {
    History::default()
  }

  pub fn can_undo(&self) -> bool {
    !self.undoes.is_empty()
  }

  pub fn can_redo(&self) -> bool {
    !self.redoes.is_empty()
  }

  pub fn add_undo(&mut self, delta: DeltaTextOperations) {
    self.undoes.push(delta);
  }

  pub fn add_redo(&mut self, delta: DeltaTextOperations) {
    self.redoes.push(delta);
  }

  pub fn record(&mut self, delta: DeltaTextOperations) {
    if delta.ops.is_empty() {
      return;
    }

    self.redoes.clear();
    self.add_undo(delta);

    if self.undoes.len() > self.capacity {
      self.undoes.remove(0);
    }
  }

  pub fn undo(&mut self) -> Option<DeltaTextOperations> {
    if !self.can_undo() {
      return None;
    }
    let delta = self.undoes.pop().unwrap();
    Some(delta)
  }

  pub fn redo(&mut self) -> Option<DeltaTextOperations> {
    if !self.can_redo() {
      return None;
    }

    let delta = self.redoes.pop().unwrap();
    Some(delta)
  }
}