aurelia/aurelia

import { type Writable, resolve } from '@aurelia/kernel';
import { type ISubscriber } from '@aurelia/runtime';
import { type IBinding, BindingBehavior, type IOverrideContext, Scope } from '@aurelia/runtime-html';
import { IStore, type IStoreSubscriber } from './interfaces';
import { StateBinding } from './state-binding';
import { createStateBindingScope } from './state-utilities';

const bindingStateSubscriberMap = new WeakMap<IBinding, StateSubscriber>();

export class StateBindingBehavior {

  /** @internal */private readonly _store = resolve(IStore);

  public bind(scope: Scope, binding: IBinding): void {
    const isStateBinding = binding instanceof StateBinding;
    scope = isStateBinding ? scope : createStateBindingScope(this._store.getState(), scope);
    let subscriber: StateSubscriber | undefined;
    if (!isStateBinding) {
      subscriber = bindingStateSubscriberMap.get(binding);
      if (subscriber == null) {
        bindingStateSubscriberMap.set(binding, subscriber = new StateSubscriber(binding, scope));
      } else {
        subscriber._wrappedScope = scope;
      }
      this._store.subscribe(subscriber);
      if (__DEV__ && !binding.useScope) {
        // eslint-disable-next-line no-console
        console.warn(`Binding ${binding.constructor.name} does not support "state" binding behavior`);
      }
      binding.useScope?.(scope);
    }
  }

  public unbind(scope: Scope, binding: IBinding): void {
    const isStateBinding = binding instanceof StateBinding;
    if (!isStateBinding) {
      this._store.unsubscribe(bindingStateSubscriberMap.get(binding)!);
      bindingStateSubscriberMap.delete(binding);
    }
  }
}
BindingBehavior.define('state', StateBindingBehavior);

class StateSubscriber implements IStoreSubscriber<object> {
  public constructor(
    public _binding: IBinding,
    public _wrappedScope: Scope,
  ) {}

  public handleStateChange(state: object): void {
    const scope = this._wrappedScope;
    const overrideContext = scope.overrideContext as Writable<IOverrideContext>;
    scope.bindingContext = overrideContext.bindingContext = state;
    (this._binding as unknown as ISubscriber).handleChange?.(undefined, undefined);
  }
}