//
// Copyright 2021 Google LLC
// SPDX-License-Identifier: Apache-2.0
//

@use 'sass:list';
@use 'sass:map';
@use 'sass:meta';
@use './var';

/// Resolves one or more shape tokens and expands them into 4 separate logical
/// tokens for each corner.
///
/// @example - scss
///   $theme: (container-shape: (4px 4px 0 0));
///   $theme: resolve-theme(
///     $theme,
///     map.get($resolvers, shape),
///     container-shape,
///   );
///   // (
///   //   container-shape-start-start: 4px,
///   //   container-shape-start-end: 4px,
///   //   container-shape-end-end: 0,
///   //   container-shape-end-start: 0,
///   // )
///
/// @param {Map} $theme - The theme to resolve tokens for.
/// @param {Function} $resolver - The shape resolver to use.
/// @param {String...} $shape-tokens - The shape tokens to resolve.
/// @return {Map} The theme with resolved shape tokens.
@function resolve-theme($theme, $resolver, $shape-tokens...) {
  @if $resolver == null {
    @return $theme;
  }

  @each $token in $shape-tokens {
    $shape-theme: meta.call($resolver, $shape: map.get($theme, $token));

    // Add resolved values, but allow $theme to override the results if needed.
    $theme: map.merge(
      (
        '#{$token}-start-start': map.get($shape-theme, start-start),
        '#{$token}-start-end': map.get($shape-theme, start-end),
        '#{$token}-end-end': map.get($shape-theme, end-end),
        '#{$token}-end-start': map.get($shape-theme, end-start),
      ),
      $theme
    );

    $theme: map.remove($theme, $token);
  }

  @return $theme;
}

/// Resolves a shape value by expanding it into logical values for each corner.
///
/// @param {Number|List} $shape - The shape token's value.
/// @return {Map} A map with logical tokens for each corner's value.
@function resolver($args...) {
  $args: meta.keywords($args);
  $shape: map.get($args, shape);
  @if meta.type-of($shape) != 'list' {
    @return (
      start-start: $shape,
      start-end: $shape,
      end-end: $shape,
      end-start: $shape
    );
  }

  @if list.length($shape) == 1 {
    @return (
      start-start: list.nth($shape, 1),
      start-end: list.nth($shape, 1),
      end-end: list.nth($shape, 1),
      end-start: list.nth($shape, 1)
    );
  }

  @if list.length($shape) == 2 {
    @return (
      start-start: list.nth($shape, 1),
      start-end: list.nth($shape, 2),
      end-end: list.nth($shape, 1),
      end-start: list.nth($shape, 2)
    );
  }

  @if list.length($shape) == 3 {
    @return (
      start-start: list.nth($shape, 1),
      start-end: list.nth($shape, 2),
      end-end: list.nth($shape, 3),
      end-start: list.nth($shape, 2)
    );
  }

  @return (
    start-start: list.nth($shape, 1),
    start-end: list.nth($shape, 2),
    end-end: list.nth($shape, 3),
    end-start: list.nth($shape, 4)
  );
}