import * as React from 'react'

type DefaultTheme = object | null

type WithThemeFactory<Theme> = <
  InnerProps extends {theme: NonNullable<Theme>},
  InnerComponent extends React.ComponentType<InnerProps>,
  OuterProps extends InnerProps & {theme?: NonNullable<Theme>}
>(
  comp: InnerComponent
) => React.ComponentType<OuterProps>

interface ThemeProviderProps<Theme> {
  theme: NonNullable<Theme> | ((outerTheme: Theme) => NonNullable<Theme>)
  children: React.ReactNode
}

type ThemeProviderFactory<Theme> = React.ComponentType<ThemeProviderProps<Theme>>

type UseThemeFactory<Theme> = <CustomTheme = Theme>() => CustomTheme

interface Theming<Theme> {
  context: React.Context<Theme>
  withTheme: WithThemeFactory<Theme>
  ThemeProvider: ThemeProviderFactory<Theme>
  useTheme: UseThemeFactory<Theme>
}

declare function createTheming<Theme>(context: React.Context<Theme>): Theming<Theme>

declare const withTheme: WithThemeFactory<DefaultTheme>
declare const ThemeProvider: ThemeProviderFactory<DefaultTheme>
declare const ThemeContext: React.Context<DefaultTheme>
declare const useTheme: UseThemeFactory<DefaultTheme>

export {
  ThemeContext,
  createTheming,
  withTheme,
  useTheme,
  ThemeProvider,
  ThemeProviderProps,
  Theming
}