import {List, ValueObject} from 'immutable';

import {SassBoolean} from './boolean';
import {SassColor} from './color';
import {SassFunction} from './function';
import {ListSeparator} from './list';
import {SassMap} from './map';
import {SassNumber} from './number';
import {SassString} from './string';

export {SassArgumentList} from './argument_list';
export {SassBoolean, sassTrue, sassFalse} from './boolean';
export {SassColor} from './color';
export {SassFunction} from './function';
export {SassList, ListSeparator} from './list';
export {SassMap} from './map';
export {SassNumber} from './number';
export {SassString} from './string';

/**
 * Sass's [`null` value](https://sass-lang.com/documentation/values/null).
 *
 * @category Custom Function
 */
export const sassNull: Value;

/**
 * The abstract base class of Sass's value types.
 *
 * This is passed to and returned by {@link CustomFunction}s, which are passed
 * into the Sass implementation using {@link Options.functions}.
 *
 * @category Custom Function
 */
export abstract class Value implements ValueObject {
  protected constructor();

  /**
   * This value as a list.
   *
   * All SassScript values can be used as lists. Maps count as lists of pairs,
   * and all other values count as single-value lists.
   *
   * @returns An immutable {@link List} from the [`immutable`
   * package](https://immutable-js.com/).
   */
  get asList(): List<Value>;

  /**
   * Whether this value as a list has brackets.
   *
   * All SassScript values can be used as lists. Maps count as lists of pairs,
   * and all other values count as single-value lists.
   */
  get hasBrackets(): boolean;

  /**
   * Whether the value counts as `true` in an `@if` statement and other
   * contexts.
   */
  get isTruthy(): boolean;

  /**
   * Returns JavaScript's `null` value if this is {@link sassNull}, and returns
   * `this` otherwise.
   */
  get realNull(): null | Value;

  /**
   * The separator for this value as a list.
   *
   * All SassScript values can be used as lists. Maps count as lists of pairs,
   * and all other values count as single-value lists.
   */
  get separator(): ListSeparator;

  /**
   * Converts `sassIndex` into a JavaScript-style index into the list returned
   * by {@link asList}.
   *
   * Sass indexes are one-based, while JavaScript indexes are zero-based. Sass
   * indexes may also be negative in order to index from the end of the list.
   *
   * @param sassIndex - The Sass-style index into this as a list.
   * @param name - The name of the function argument `sassIndex` came from
   * (without the `$`) if it came from an argument. Used for error reporting.
   * @throws `Error` If `sassIndex` isn't a number, if that number isn't an
   * integer, or if that integer isn't a valid index for {@link asList}.
   */
  sassIndexToListIndex(sassIndex: Value, name?: string): number;

  /**
   * Returns the value at index `index` in this value as a list, or `undefined`
   * if `index` isn't valid for this list.
   *
   * All SassScript values can be used as lists. Maps count as lists of pairs,
   * and all other values count as single-value lists.
   *
   * This is a shorthand for `this.asList.get(index)`, although it may be more
   * efficient in some cases.
   *
   * **Heads up!** This method uses the same indexing conventions as the
   * `immutable` package: unlike Sass the index of the first element is 0, but
   * like Sass negative numbers index from the end of the list.
   */
  get(index: number): Value | undefined;

  /**
   * Throws if `this` isn't a {@link SassBoolean}.
   *
   * **Heads up!** Functions should generally use {@link isTruthy} rather than
   * requiring a literal boolean.
   *
   * @param name - The name of the function argument `this` came from (without
   * the `$`) if it came from an argument. Used for error reporting.
   */
  assertBoolean(name?: string): SassBoolean;

  /**
   * Throws if `this` isn't a {@link SassColor}.
   *
   * @param name - The name of the function argument `this` came from (without
   * the `$`) if it came from an argument. Used for error reporting.
   */
  assertColor(name?: string): SassColor;

  /**
   * Throws if `this` isn't a {@link SassFunction}.
   *
   * @param name - The name of the function argument `this` came from (without
   * the `$`) if it came from an argument. Used for error reporting.
   */
  assertFunction(name?: string): SassFunction;

  /**
   * Throws if `this` isn't a {@link SassMap}.
   *
   * @param name - The name of the function argument `this` came from (without
   * the `$`) if it came from an argument. Used for error reporting.
   */
  assertMap(name?: string): SassMap;

  /**
   * Throws if `this` isn't a {@link SassNumber}.
   *
   * @param name - The name of the function argument `this` came from (without
   * the `$`) if it came from an argument. Used for error reporting.
   */
  assertNumber(name?: string): SassNumber;

  /**
   * Throws if `this` isn't a {@link SassString}.
   *
   * @param name - The name of the function argument `this` came from (without
   * the `$`) if it came from an argument. Used for error reporting.
   */
  assertString(name?: string): SassString;

  /**
   * Returns `this` as a map if it counts as one (empty lists count as empty
   * maps) or `null` if it doesn't.
   */
  tryMap(): SassMap | null;

  /** Returns whether `this` represents the same value as `other`. */
  equals(other: Value): boolean;

  /** Returns a hash code that can be used to store `this` in a hash map. */
  hashCode(): number;

  /** @hidden */
  toString(): string;
}
