import * as React from 'react';
import * as CSS from 'csstype';
import { Palette } from './createPalette';

export type Variant =
  | 'h1'
  | 'h2'
  | 'h3'
  | 'h4'
  | 'h5'
  | 'h6'
  | 'subtitle1'
  | 'subtitle2'
  | 'body1'
  | 'body2'
  | 'caption'
  | 'button'
  | 'overline';

export interface FontStyle
  extends Required<{
    fontFamily: React.CSSProperties['fontFamily'];
    fontSize: number;
    fontWeightLight: React.CSSProperties['fontWeight'];
    fontWeightRegular: React.CSSProperties['fontWeight'];
    fontWeightMedium: React.CSSProperties['fontWeight'];
    fontWeightBold: React.CSSProperties['fontWeight'];
    htmlFontSize: number;
  }> {}

export type NormalCssProperties = CSS.Properties<number | string>;
export type Fontface = CSS.AtRule.FontFace & { fallbacks?: CSS.AtRule.FontFace[] };

/**
 * Allows the user to augment the properties available
 */
export interface BaseCSSProperties extends NormalCssProperties {
  '@font-face'?: Fontface | Fontface[];
}

export interface CSSProperties extends BaseCSSProperties {
  // Allow pseudo selectors and media queries
  // `unknown` is used since TS does not allow assigning an interface without
  // an index signature to one with an index signature. This is to allow type safe
  // module augmentation.
  // Technically we want any key not typed in `BaseCSSProperties` to be of type
  // `CSSProperties` but this doesn't work. The index signature needs to cover
  // BaseCSSProperties as well. Usually you would use `BaseCSSProperties[keyof BaseCSSProperties]`
  // but this would not allow assigning React.CSSProperties to CSSProperties
  [k: string]: unknown | CSSProperties;
}

export interface FontStyleOptions extends Partial<FontStyle> {
  allVariants?: React.CSSProperties;
}

// TODO: which one should actually be allowed to be subject to module augmentation?
// current type vs interface decision is kept for historical reasons until we
// made a decision
export type TypographyStyle = CSSProperties;
export interface TypographyStyleOptions extends TypographyStyle {}

export interface TypographyUtils {
  pxToRem: (px: number) => string;
}

export interface Typography extends Record<Variant, TypographyStyle>, FontStyle, TypographyUtils {}

export interface TypographyOptions
  extends Partial<Record<Variant, TypographyStyleOptions> & FontStyleOptions> {}

export default function createTypography(
  palette: Palette,
  typography: TypographyOptions | ((palette: Palette) => TypographyOptions),
): Typography;