@use 'sass:color';
@use 'sass:meta';
@use 'sass:math';
@use '../core/tokens/m2-utils';
@use '../core/theming/inspection';
@use '../core/style/elevation';
@use '../core/style/sass-utils';

$_selected-fade-amount: 0.6;
$_today-fade-amount: 0.2;

// Utility that produces a range background color from a specific color.
@function private-get-range-background-color($color) {
  @return rgba($color, 0.2);
}

// Utility that produces the overlap selected color from an overlap color.
@function private-get-default-overlap-selected-color($overlap-color) {
  @return color.adjust($overlap-color, $lightness: -30%);
}

// Default range comparison color.
$private-default-comparison-color: private-get-range-background-color(#f9ab00);

// Default range overlap color.
$private-default-overlap-color: #a8dab5;

// Tokens that can't be configured through Angular Material's current theming API,
// but may be in a future version of the theming API.
@function get-unthemable-tokens() {
  @return (
    datepicker-calendar-container-shape: 4px,
    datepicker-calendar-container-touch-shape: 4px,
    datepicker-calendar-container-elevation-shadow: elevation.get-box-shadow(4),
    datepicker-calendar-container-touch-elevation-shadow: elevation.get-box-shadow(24),
  );
}

// Tokens that can be configured through Angular Material's color theming API.
@function get-color-tokens($theme) {
  $inactive-icon-color: inspection.get-theme-color($theme, foreground, icon);
  $text-color: inspection.get-theme-color($theme, foreground, text);
  $secondary-text-color: inspection.get-theme-color($theme, foreground, secondary-text);
  $disabled-text-color: inspection.get-theme-color($theme, foreground, disabled-text);
  $divider-color: inspection.get-theme-color($theme, foreground, divider);
  $hint-text-color: inspection.get-theme-color($theme, foreground, hint-text);
  $preview-outline-color: $divider-color;
  $today-disabled-outline-color: null;
  $is-dark: inspection.get-theme-type($theme) == dark;

  $primary-color: inspection.get-theme-color($theme, primary);
  $range-tokens: get-range-color-tokens(private-get-range-background-color($primary-color));
  $calendar-tokens: private-get-calendar-color-palette-color-tokens($theme, primary);
  $toggle-tokens: private-get-toggle-color-palette-color-tokens($theme, primary);

  // The divider color is set under the assumption that it'll be used
  // for a solid border, but because we're using a dashed border for the
  // preview range, we need to bump its opacity to ensure that it's visible.
  @if meta.type-of($preview-outline-color) == color {
    $preview-outline-opacity: math.min(color.opacity($preview-outline-color) * 2, 1);
    $preview-outline-color: rgba($preview-outline-color, $preview-outline-opacity);
  }

  @if (meta.type-of($hint-text-color) == color) {
    $today-disabled-outline-color: color.adjust($hint-text-color, $alpha: -$_today-fade-amount);
  }
  @else {
    $today-disabled-outline-color: $disabled-text-color;
  }

  @return sass-utils.merge-all($calendar-tokens, $toggle-tokens, $range-tokens, (
    datepicker-toggle-icon-color: $inactive-icon-color,
    datepicker-calendar-body-label-text-color: $secondary-text-color,
    datepicker-calendar-period-button-text-color:
        inspection.get-theme-color($theme, foreground, text, 1),
    datepicker-calendar-period-button-icon-color: $inactive-icon-color,
    datepicker-calendar-navigation-button-icon-color: $inactive-icon-color,
    datepicker-calendar-header-divider-color: $divider-color,
    datepicker-calendar-header-text-color: $secondary-text-color,

    // Note: though it's not text, the border is a hint about the fact
    // that this is today's date, so we use the hint color.
    datepicker-calendar-date-today-outline-color: $hint-text-color,
    datepicker-calendar-date-today-disabled-state-outline-color: $today-disabled-outline-color,
    datepicker-calendar-date-text-color: $text-color,
    datepicker-calendar-date-outline-color: transparent,
    datepicker-calendar-date-disabled-state-text-color: $disabled-text-color,
    datepicker-calendar-date-preview-state-outline-color: $preview-outline-color,

    datepicker-range-input-separator-color: $text-color,
    datepicker-range-input-disabled-state-separator-color: $disabled-text-color,
    datepicker-range-input-disabled-state-text-color: $disabled-text-color,

    datepicker-calendar-container-background-color:
        inspection.get-theme-color($theme, background, card),
    datepicker-calendar-container-text-color: $text-color,
  ));
}

// Tokens that can be configured through Angular Material's typography theming API.
@function get-typography-tokens($theme) {
  @return (
    // TODO(crisbeto): the typography tokens for other components set every typography dimension of
    // an element (e.g. size, weight, line height, letter spacing). These tokens only set the values
    // that were set in the previous theming API to reduce the amount of subtle screenshot
    // differences. We should look into introducing the other tokens in a follow-up.
    datepicker-calendar-text-font: inspection.get-theme-typography($theme, body-1, font-family),
    datepicker-calendar-text-size: 13px,

    datepicker-calendar-body-label-text-size:
        inspection.get-theme-typography($theme, button, font-size),
    datepicker-calendar-body-label-text-weight:
        inspection.get-theme-typography($theme, button, font-weight),

    datepicker-calendar-period-button-text-size:
        inspection.get-theme-typography($theme, button, font-size),
    datepicker-calendar-period-button-text-weight:
        inspection.get-theme-typography($theme, button, font-weight),

    datepicker-calendar-header-text-size: 11px,
    datepicker-calendar-header-text-weight:
        inspection.get-theme-typography($theme, body-1, font-weight),
  );
}

// Gets the tokens map that can be used to override the range colors.
@function get-range-color-tokens(
  $range-color,
  $comparison-color: $private-default-comparison-color,
  $overlap-color: $private-default-overlap-color,
  $overlap-selected-color: private-get-default-overlap-selected-color($overlap-color)) {

  @return (
    datepicker-calendar-date-in-range-state-background-color: $range-color,
    datepicker-calendar-date-in-comparison-range-state-background-color: $comparison-color,
    datepicker-calendar-date-in-overlap-range-state-background-color: $overlap-color,
    datepicker-calendar-date-in-overlap-range-selected-state-background-color:
        $overlap-selected-color,
  );
}

@function private-get-calendar-color-palette-color-tokens($theme, $palette-name) {
  $palette-color: inspection.get-theme-color($theme, $palette-name);
  $default-contrast: inspection.get-theme-color($theme, $palette-name, default-contrast);
  $active-background-color: sass-utils.safe-color-change($palette-color, $alpha: 0.3);
  $active-disabled-color: null;

  @if (meta.type-of($palette-color) == color) {
    $active-disabled-color: color.adjust($palette-color, $alpha: -$_selected-fade-amount);
  }
  @else {
    $active-disabled-color: inspection.get-theme-color($theme, foreground, disabled-button);
  }

  @return (
    datepicker-calendar-date-selected-state-text-color: $default-contrast,
    datepicker-calendar-date-selected-state-background-color: $palette-color,
    datepicker-calendar-date-selected-disabled-state-background-color: $active-disabled-color,
    datepicker-calendar-date-today-selected-state-outline-color: $default-contrast,
    datepicker-calendar-date-focus-state-background-color: $active-background-color,
    datepicker-calendar-date-hover-state-background-color: $active-background-color,
  );
}

@function private-get-toggle-color-palette-color-tokens($theme, $palette-name) {
  @return (
    datepicker-toggle-active-state-icon-color:
        inspection.get-theme-color($theme, $palette-name, text),
  );
}


// Tokens that can be configured through Angular Material's density theming API.
@function get-density-tokens($theme) {
  @return ();
}

// Combines the tokens generated by the above functions into a single map with placeholder values.
// This is used to create token slots.
@function get-token-slots() {
  @return sass-utils.deep-merge-all(
      get-unthemable-tokens(),
      get-color-tokens(m2-utils.$placeholder-color-config),
      get-typography-tokens(m2-utils.$placeholder-typography-config),
      get-density-tokens(m2-utils.$placeholder-density-config)
  );
}