/**
 * Copyright 2015 CANAL+ Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import noop from "../../../../../utils/noop";

/** Type of the function called when a Node opening is encountered. */
export type IChildrenParser = (node: number) => void;

/** Type of the function called when an attribute is encountered. */
export type IAttributeParser = (attr: number, ptr: number, len: number) => void;

/**
 * Maintains a stack of children and attributes parsers, to easily parse
 * the very hierarchical MPDs.
 *
 * This class allows to easily push and pop such parsers once nodes are
 * respectively opened and closed.
 *
 * @class ParsersStack
 */
export default class ParsersStack {
  private _currentNodeId: number | null;
  public childrenParser: IChildrenParser;
  public attributeParser: IAttributeParser;

  private _stack: Array<{
    nodeId: number | null;
    attribute: IAttributeParser;
    children: IChildrenParser;
  }>;
  constructor() {
    this._currentNodeId = null;
    this.childrenParser = noop;
    this.attributeParser = noop;
    this._stack = [{ nodeId: null, children: noop, attribute: noop }];
  }

  public pushParsers(
    nodeId: number | null,
    childrenParser: IChildrenParser,
    attrParser: IAttributeParser,
  ): void {
    this._currentNodeId = nodeId;
    this.childrenParser = childrenParser;
    this.attributeParser = attrParser;
    this._stack.push({
      nodeId,
      attribute: attrParser,
      children: childrenParser,
    });
  }

  public popIfCurrent(idToPop: number): void {
    if (this._currentNodeId !== idToPop) {
      return;
    }
    this._stack.pop();
    const { nodeId, children, attribute } = this._stack[this._stack.length - 1];
    this._currentNodeId = nodeId;
    this.attributeParser = attribute;
    this.childrenParser = children;
  }

  public reset(): void {
    this.childrenParser = noop;
    this.attributeParser = noop;
    this._stack = [{ nodeId: null, children: noop, attribute: noop }];
  }
}