'use strict';

const attributes = require('./attributes');

/**
 * A `[key, value]` pair of strings describing a text attribute.
 *
 * @typedef {[string, string]} Attribute
 */

/**
 * A concatenated sequence of zero or more attribute identifiers, each one represented by an
 * asterisk followed by a base-36 encoded attribute number.
 *
 * Examples: '', '*0', '*3*j*z*1q'
 *
 * @typedef {string} AttributeString
 */

/**
 * Convenience class to convert an Op's attribute string to/from a Map of key, value pairs.
 */
class AttributeMap extends Map {
  /**
   * Converts an attribute string into an AttributeMap.
   *
   * @param {AttributeString} str - The attribute string to convert into an AttributeMap.
   * @param {AttributePool} pool - Attribute pool.
   * @returns {AttributeMap}
   */
  static fromString(str, pool) {
    return new AttributeMap(pool).updateFromString(str);
  }

  /**
   * @param {AttributePool} pool - Attribute pool.
   */
  constructor(pool) {
    super();
    /** @public */
    this.pool = pool;
  }

  /**
   * @param {string} k - Attribute name.
   * @param {string} v - Attribute value.
   * @returns {AttributeMap} `this` (for chaining).
   */
  set(k, v) {
    k = k == null ? '' : String(k);
    v = v == null ? '' : String(v);
    this.pool.putAttrib([k, v]);
    return super.set(k, v);
  }

  toString() {
    return attributes.attribsToString(attributes.sort([...this]), this.pool);
  }

  /**
   * @param {Iterable<Attribute>} entries - [key, value] pairs to insert into this map.
   * @param {boolean} [emptyValueIsDelete] - If true and an entry's value is the empty string, the
   *     key is removed from this map (if present).
   * @returns {AttributeMap} `this` (for chaining).
   */
  update(entries, emptyValueIsDelete = false) {
    for (let [k, v] of entries) {
      k = k == null ? '' : String(k);
      v = v == null ? '' : String(v);
      if (!v && emptyValueIsDelete) {
        this.delete(k);
      } else {
        this.set(k, v);
      }
    }
    return this;
  }

  /**
   * @param {AttributeString} str - The attribute string identifying the attributes to insert into
   *     this map.
   * @param {boolean} [emptyValueIsDelete] - If true and an entry's value is the empty string, the
   *     key is removed from this map (if present).
   * @returns {AttributeMap} `this` (for chaining).
   */
  updateFromString(str, emptyValueIsDelete = false) {
    return this.update(attributes.attribsFromString(str, this.pool), emptyValueIsDelete);
  }
}

module.exports = AttributeMap;