saleor-dashboard/src/components/Theme/ThemeProvider.tsx

import { MuiThemeProvider } from "@material-ui/core/styles";
import React from "react";

import Baseline from "../../Baseline";
import createTheme from "../../theme";
import { dark, light } from "./themes";

interface IThemeContext {
  isDark: boolean;
  toggleTheme: () => void;
}
export const ThemeContext = React.createContext<IThemeContext>({
  isDark: false,
  toggleTheme: () => undefined
});

interface ThemeProviderProps {
  isDefaultDark?: boolean;
}
const ThemeProvider: React.FC<ThemeProviderProps> = ({
  children,
  isDefaultDark
}) => {
  const [isDark, setDark] = React.useState(isDefaultDark);
  const toggleTheme = () => {
    setDark(!isDark);
    localStorage.setItem("theme", (!isDark).toString());
  };

  return (
    <ThemeContext.Provider
      value={{
        isDark,
        toggleTheme
      }}
    >
      <MuiThemeProvider theme={createTheme(isDark ? dark : light)}>
        <Baseline />
        {children}
      </MuiThemeProvider>
    </ThemeContext.Provider>
  );
};
ThemeProvider.defaultProps = {
  isDefaultDark: false
};
export default ThemeProvider;