"use strict";

const parsers = require("../helpers/css-values");

const property = "background-attachment";
const shorthand = "background";

const descriptor = {
  set(v) {
    v = v.trim();
    if (parsers.hasVarFunc(v)) {
      this._setProperty(shorthand, "");
      this._setProperty(property, v);
    } else {
      const val = parse(v);
      if (typeof val === "string") {
        const priority =
          !this._priorities.get(shorthand) && this._priorities.has(property) ? this._priorities.get(property) : "";
        this._setProperty(property, val, priority);
      }
    }
  },
  get() {
    return this.getPropertyValue(property);
  },
  enumerable: true,
  configurable: true
};

/**
 * Parses the background-attachment property value.
 *
 * @param {string} v - The value to parse.
 * @returns {string|undefined} The parsed value or undefined if invalid.
 */
function parse(v) {
  if (v === "") {
    return v;
  }
  const values = parsers.splitValue(v, { delimiter: "," });
  const parsedValues = [];
  for (const val of values) {
    const value = parsers.parsePropertyValue(property, val);
    if (Array.isArray(value) && value.length === 1) {
      const parsedValue = parsers.resolveKeywordValue(value);
      if (!parsedValue) {
        return undefined;
      }
      parsedValues.push(parsedValue);
    } else if (typeof value === "string") {
      parsedValues.push(value);
    }
  }
  if (parsedValues.length) {
    return parsedValues.join(", ");
  }
  return undefined;
}

module.exports = {
  descriptor,
  parse,
  property
};
