/* @flow */

export type TSFontWeight = 'normal' | 'bold' | '100' | '200' | '300' | '400' | '500' | '600' | '700' | '800' | '900'
export type TSFontStyle = 'normal' | 'italic'
export type TSFontVariant = 'small-caps' | 'oldstyle-nums' | 'lining-nums' | 'tabular-nums' | 'proportional-nums'
export type TSTextBreakStrategy = 'simple' | 'highQuality' | 'balanced'

export type TSFontSize = {|
  +default: number,
  +button: number,
  +label: number,
  +smallSystem: number,
  +system: number,
|}

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

export type TSTextStyle =
| 'body'
| 'callout'
| 'caption1'
| 'caption2'
| 'footnote'
| 'headline'
| 'subheadline'
| 'largeTitle'
| 'title1'
| 'title2'
| 'title3'

export type TSFontInfo = {
  fontFamily: string | null,
  fontName: string | null,
  fontWeight: TSFontWeight,
  fontSize: number,
  fontStyle: TSFontStyle,
  fontVariant?: TSFontVariant | null,
  ascender: number,
  descender: number,
  capHeight?: number,
  xHeight?: number,
  top?: number,
  bottom?: number,
  leading: number,
  lineHeight: number,
  _hash: number,
}

export type TSFontSpecs = {
  fontFamily?: string,
  fontSize?: number,
  fontStyle?: TSFontStyle,
  fontWeight?: TSFontWeight,
  /** @platform ios */
  fontVariant?: Array<TSFontVariant>,
  /** iOS all, Android SDK 21+ with RN 0.55+ */
  letterSpacing?: number,
  /** @platform android */
  includeFontPadding?: boolean,
  /** @platform android (SDK 23+) */
  textBreakStrategy?: TSTextBreakStrategy,
}

export type TSFontForStyle = {
  fontFamily: string,
  fontSize: number,
  /** fontStyle is omitted if it is "normal" */
  fontStyle?: TSFontStyle,
  /** fontWeight is omitted if it is "normal" */
  fontWeight?: TSFontWeight,
  /** @platform ios */
  fontVariant?: Array<TSFontVariant> | null,
  /** iOS all, Android SDK 21+ with RN 0.55+ */
  letterSpacing?: number,
}

export type TSHeightsParams = TSFontSpecs & {
  /** The required text to measure. */
  text: Array<string>,
  /** Maximum width of the area to display the text. @default MAX_INT */
  width?: number,
  /** @default true */
  allowFontScaling?: boolean,
}

export type TSMeasureParams = TSFontSpecs & {
  /**
   * This is the only required parameter and may include _emojis_ or be empty,
   * but it **must not be** `null`.
   *
   * If this is an empty string the resulting `width` will be zero.
   */
  text: string,
  /**
   * To respect the user' setting of large fonts (i.e. use SP units).
   * @default true
   */
  allowFontScaling?: boolean,
  /**
   * Restrict the width. The resulting height will vary depending on the
   * automatic flow of the text.
   * @default MAX_INT
   */
  width?: number,
  /**
   * If `true`, the result will include an exact `width` and the
   * `lastLineWidth` property.
   * @default false
   */
  usePreciseWidth?: boolean,
  /**
   * If `>=0`, the result will include a `lineInfo` property with information
   * for the required line number.
   */
  lineInfoForLine?: number,
}

export interface TSMeasureResult {
  /**
   * Total used width. It may be less or equal to the `width` option.
   *
   * On Android, this value may vary depending on the `usePreciseWidth` flag.
   */
  width: number;
  /**
   * Total height, including top and bottom padding if `includingFontPadding`
   * was set (the default).
   */
  height: number;
  /**
   * Width of the last line, without trailing blanks.
   *
   * If `usePreciseWidth` is `false` (the default), this field is undefined.
   */
  lastLineWidth?: number;
  /**
   * Number of lines, taking into account hard and automatic line breaks.
   */
  lineCount: number;
  /**
   * Line information, if the `lineInfoForLine` option is given.
   */
  lineInfo?: {
    /** Line number of this info, base 0.
     *
     * It can be less than the requested line number if `lineInfoForLine` is out of range.
     */
    line: number;
    /** Text offset of the beginning of this line. */
    start: number;
    /** Text offset after the last _visible_ character (so whitespace is not counted) on this line. */
    end: number;
    /** The vertical position of the bottom of this line, including padding. */
    bottom: number;
    /** Horizontal extent of this line, including leading margin indent, but excluding trailing whitespace. */
    width: number;
  }
}

declare interface TextSizeStatic {
  measure(params: TSMeasureParams): Promise<TSMeasureResult>;
  flatHeights(params: TSHeightsParams): Promise<number[]>;
  specsForTextStyles(): Promise<{ [string]: TSFontForStyle }>;
  fontFromSpecs(specs: TSFontSpecs): Promise<TSFontInfo>;
  fontFamilyNames(): Promise<string[]>;
}

declare var TextSize: TextSizeStatic;
export default TextSize;