@use 'sass:list';
@use 'sass:map';
@use 'sass:meta';
@use './theming';
@use '../m2/theming' as m2-theming;
@use '../m2/typography-utils' as m2-typography-utils;
@use '../typography/versioning' as typography-versioning;

/// Key used to access the Angular Material theme internals.
$_internals: _mat-theming-internals-do-not-access;

/// Keys that indicate a config object is a color config.
$_color-keys: (
  primary,
  accent,
  warn,
  foreground,
  background,
  is-dark,
  color, /* included for themes that incorrectly nest the color config: (color: (color: (....))) */
);

/// Keys that indicate a config object is a typography config.
$_typography-keys: (
  headline-1,
  headline-2,
  headline-3,
  headline-4,
  headline-5,
  headline-6,
  subtitle-1,
  font-family,
  subtitle-2,
  body-1,
  body-2,
  button,
  caption,
  overline,
);

/// The CSS typography properties supported by the inspection API.
$_typography-properties: (font, font-family, line-height, font-size, letter-spacing, font-weight);

/// Gets the m2-config from the theme.
@function get-m2-config($theme) {
  // It is possible for a user to pass a "density theme" that is just a number.
  @if meta.type-of($theme) != 'map' {
    @return $theme;
  }
  $internal: map.get($theme, $_internals, m2-config);
  $theme: map.remove($theme, $_internals);
  @if (_is-error-theme($theme)) {
    @return $internal;
  }
  @return $theme;
}

/// Checks whether the given theme contains error values.
/// @param {*} $theme The theme to check.
/// @return {Boolean} true if the theme contains error values, else false.
@function _is-error-theme($theme) {
  @if meta.type-of($theme) != 'map' {
    @return false;
  }
  @if map.get($theme, ERROR) {
    @return true;
  }
  @return _is-error-theme(list.nth(map.values($theme), 1));
}

/// Checks whether the given theme object has any of the given keys.
/// @param {Map} $theme The theme to check
/// @param {List} $keys The keys to check for
/// @return {Boolean} Whether the theme has any of the given keys.
@function _has-any-key($theme, $keys) {
  @each $key in $keys {
    @if map.has-key($theme, $key) {
      @return true;
    }
  }
  @return false;
}

/// Checks whether the given theme is a density scale value.
/// @param {*} $theme The theme to check.
/// @return {Boolean} true if the theme is a density scale value, else false.
@function _is-density-value($theme) {
  @return $theme == minimum or $theme == maximum or meta.type-of($theme) == 'number';
}

/// Gets the type of theme represented by a theme object (light or dark).
/// @param {Map} $theme The theme
/// @return {String} The type of theme (either `light` or `dark`).
@function get-theme-type($theme) {
  $theme: get-m2-config($theme);
  @if not theme-has($theme, color) {
    @error 'Color information is not available on this theme.';
  }
  $colors: m2-theming.get-color-config($theme);
  // Some apps seem to have mistakenly created nested color themes that somehow work with our old
  // theme normalization logic. This check allows those apps to keep working.
  @if theme-has($colors, color) {
    $colors: m2-theming.get-color-config($colors);
  }
  @if (map.get($colors, is-dark)) {
    @return dark;
  }
  @return light;
}

/// Gets a color from a theme object. This function can take between 2 and 4 arguments. The first
/// argument is the theme, the second one is the palette from which to extract the color, the third
/// one is the hue within the palette and the fourth is the opacity of the returned color.
/// @param {Map} $theme The theme
/// @param {String} $palette-name The name of a color palette.
/// @param {Number} $hue The palette hue to get (passing this argument means the second argument is
///   interpreted as a palette name).
/// @param {Number} $opacity The alpha channel value for the color.
/// @return {Color} The requested theme color.
@function get-theme-color($theme, $palette-name, $args...) {
  $theme: get-m2-config($theme);
  @if not theme-has($theme, color) {
    @error 'Color information is not available on this theme.';
  }
  $colors: m2-theming.get-color-config($theme);
  // Some apps seem to have mistakenly created nested color themes that somehow work with our old
  // theme normalization logic. This check allows those apps to keep working.
  @if theme-has($colors, color) {
    $colors: m2-theming.get-color-config($colors);
  }
  $palette: map.get($colors, $palette-name);
  @if not $palette {
    @error $palette-name $args $theme;
    @error #{'Unrecognized palette name:'} $palette-name;
  }
  @return m2-theming.get-color-from-palette($palette, $args...);
}

/// Gets a typography value from a theme object.
/// @param {Map} $theme The theme
/// @param {String} $typescale The typescale name.
/// @param {String} $property The CSS font property to get
///   (font, font-family, font-size, font-weight, line-height, or letter-spacing).
/// @return {*} The value of the requested font property.
@function get-theme-typography($theme, $typescale, $property) {
  $theme: get-m2-config($theme);
  @if not theme-has($theme, typography) {
    @error 'Typography information is not available on this theme.';
  }
  $typography: typography-versioning.private-typography-to-2018-config(
      m2-theming.get-typography-config($theme));
  @if $property == font {
    $font-weight: m2-typography-utils.font-weight($typography, $typescale);
    $font-size: m2-typography-utils.font-size($typography, $typescale);
    $line-height: m2-typography-utils.line-height($typography, $typescale);
    $font-family: m2-typography-utils.font-family($typography, $typescale);
    @return ($font-weight list.slash($font-size, $line-height) $font-family);
  }
  @else if $property == font-family {
    $result: m2-typography-utils.font-family($typography, $typescale);
    @return $result or m2-typography-utils.font-family($typography);
  }
  @else if $property == font-size {
    @return m2-typography-utils.font-size($typography, $typescale);
  }
  @else if $property == font-weight {
    @return m2-typography-utils.font-weight($typography, $typescale);
  }
  @else if $property == line-height {
    @return m2-typography-utils.line-height($typography, $typescale);
  }
  @else if $property == letter-spacing {
    @return m2-typography-utils.letter-spacing($typography, $typescale);
  }
  @else {
    @error #{'Valid typography properties are: #{$_typography-properties}. Got:'} $property;
  }
}

/// Gets the density scale from a theme object.
/// @param {Map} $theme The theme
/// @return {Number} The density scale.
@function get-theme-density($theme) {
  $theme: get-m2-config($theme);
  @if not theme-has($theme, density) {
    @error 'Density information is not available on this theme.';
  }
  $scale: m2-theming.get-density-config($theme);
  @return theming.clamp-density($scale, -5);
}

/// Checks whether the theme has information about given theming system.
/// @param {Map} $theme The theme
/// @param {String} $system The system to check
/// @param {Boolean} Whether the theme has information about the system.
@function theme-has($theme, $system) {
  $theme: get-m2-config($theme);
  @if $system == base {
    @return true;
  }
  @if $system == color {
    $color: m2-theming.get-color-config($theme);
    @return $color != null and _has-any-key($color, $_color-keys);
  }
  @if $system == typography {
    $typography: m2-theming.get-typography-config($theme);
    @return $typography != null and _has-any-key($typography, $_typography-keys);
  }
  @if $system == density {
    // Backwards compatibility for the case where an explicit, but invalid density is given
    // (this was previously treated as density 0).
    @if meta.type-of($theme) == 'map' and map.get($theme, density) {
      @return true;
    }
    $density: m2-theming.get-density-config($theme);
    @return $density != null and _is-density-value($density);
  }
  @error 'Valid systems are: base, color, typography, density. Got:' $system;
}

/// Removes the information about the given theming system(s) from the given theme.
/// @param {Map} $theme The theme to remove information from
/// @param {String...} $systems The systems to remove
/// @return {Map} A version of the theme without the removed theming systems.
@function theme-remove($theme, $systems...) {
  $internal: map.get($theme, $_internals, m2-config);
  @each $system in $systems {
    @if $system == color {
      $theme: map.set($theme, color, null);
    }
    @else if $system == typography {
      $theme: map.set($theme, typography, null);
    }
    @else if $system == density {
      $theme: map.set($theme, density, null);
    }
  }
  @if $internal {
    $internal: theme-remove($internal, $systems...);
    $theme: map.set($theme, $_internals, m2-config, $internal);
  }
  @return $theme;
}