export function getThemedContext(context: ICustomizerContext, scheme?: ISchemeNames, theme?: ITheme): ICustomizerContext {
  let newContext: ICustomizerContext = context;
  let newSettings;

  // Only fall back to context and customizations when theme arg is not provided.
  let schemeSource = theme || Customizations.getSettings(['theme'], undefined, context.customizations).theme;

  if (theme) {
    newSettings = { theme };
  }

  const schemeTheme: ITheme | undefined = scheme && schemeSource && schemeSource.schemes && schemeSource.schemes[scheme];

  // These first two checks are logically redundant but TS doesn't infer schemeSource.schemes is defined when schemeTheme is defined.
  if (schemeSource && schemeTheme && schemeSource !== schemeTheme) {
    newSettings = { theme: schemeTheme };
    newSettings.theme.schemes = schemeSource.schemes;
  }

  if (newSettings) {
    newContext = {
      customizations: {
        settings: mergeSettings(context.customizations.settings, newSettings),
        scopedSettings: context.customizations.scopedSettings
      }
    };
  }

  return newContext;
}

export function loadTheme(theme: IPartialTheme, depComments: boolean = false): ITheme {
  _theme = createTheme(theme, depComments);

  // Invoke the legacy method of theming the page as well.
  legacyLoadTheme({ ..._theme.palette, ..._theme.semanticColors, ..._loadFonts(_theme) });

  Customizations.applySettings({ [ThemeSettingName]: _theme });

  _onThemeChangeCallbacks.forEach((callback: (theme: ITheme) => void) => {
    try {
      callback(_theme);
    } catch (e) {
      // don't let a bad callback break everything else
    }
  });

  return _theme;
}

import { DefaultSpacing } from './DefaultSpacing';
import { loadTheme as legacyLoadTheme } from '@microsoft/load-themed-styles';
import { DefaultEffects } from './DefaultEffects';

let _theme: ITheme = createTheme({
  palette: DefaultPalette,
  semanticColors: _makeSemanticColorsFromPalette(DefaultPalette, false, false),
  fonts: DefaultFontStyles,
  isInverted: false,
  disableGlobalClassNames: false
});
let _onThemeChangeCallbacks: Array<(theme: ITheme) => void> = [];

export const ThemeSettingName = 'theme';

if (!Customizations.getSettings([ThemeSettingName]).theme) {
  let win = typeof window !== 'undefined' ? window : undefined;

  // tslint:disable:no-string-literal no-any
  if (win && (win as any)['FabricConfig'] && (win as any)['FabricConfig'].theme) {
    _theme = createTheme((win as any)['FabricConfig'].theme);
  }
  // tslint:enable:no-string-literal no-any

  // Set the default theme.
  Customizations.applySettings({ [ThemeSettingName]: _theme });
}

/**
 * Gets the theme object
 * @param depComments - Whether to include deprecated tags as comments for deprecated slots.