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// Copyright 2019-2021 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

use crate::{
  command::{CommandArg, CommandItem},
  InvokeError, Runtime,
};
use state::Container;

/// A guard for a state value.
pub struct State<'r, T: Send + Sync + 'static>(&'r T);

impl<'r, T: Send + Sync + 'static> State<'r, T> {
  /// Retrieve a borrow to the underlying value with a lifetime of `'r`.
  /// Using this method is typically unnecessary as `State` implements
  /// [`std::ops::Deref`] with a [`std::ops::Deref::Target`] of `T`.
  #[inline(always)]
  pub fn inner(&self) -> &'r T {
    self.0
  }
}

impl<T: Send + Sync + 'static> std::ops::Deref for State<'_, T> {
  type Target = T;

  #[inline(always)]
  fn deref(&self) -> &T {
    self.0
  }
}

impl<T: Send + Sync + 'static> Clone for State<'_, T> {
  fn clone(&self) -> Self {
    State(self.0)
  }
}

impl<'r, T: Send + Sync + std::fmt::Debug> std::fmt::Debug for State<'r, T> {
  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
    f.debug_tuple("State").field(&self.0).finish()
  }
}

impl<'r, 'de: 'r, T: Send + Sync + 'static, R: Runtime> CommandArg<'de, R> for State<'r, T> {
  /// Grabs the [`State`] from the [`CommandItem`]. This will never fail.
  fn from_command(command: CommandItem<'de, R>) -> Result<Self, InvokeError> {
    Ok(command.message.state_ref().try_get().unwrap_or_else(|| {
      panic!(
        "state not managed for field `{}` on command `{}`. You muse call `.manage()` before using this command",
        command.key, command.name
      )
    }))
  }
}

/// The Tauri state manager.
#[derive(Debug)]
pub struct StateManager(pub(crate) Container![Send + Sync]);

impl StateManager {
  pub(crate) fn new() -> Self {
    Self(<Container![Send + Sync]>::new())
  }

  pub(crate) fn set<T: Send + Sync + 'static>(&self, state: T) -> bool {
    self.0.set(state)
  }

  /// Gets the state associated with the specified type.
  pub fn get<T: Send + Sync + 'static>(&self) -> State<'_, T> {
    self.0.get::<T>();
    State(
      self
        .0
        .try_get()
        .expect("state: get() called before set() for given type"),
    )
  }

  /// Gets the state associated with the specified type.
  pub fn try_get<T: Send + Sync + 'static>(&self) -> Option<State<'_, T>> {
    self.0.try_get().map(State)
  }
}