src/theme/typography.ts

/**
 * Typography helpers & reference mappings for the Antaram design system.
 *
 * We rely on React Native Paper's built-in MD3 type scale for most text
 * rendering, but this module re-exports the variants so that custom
 * components can reference a single source of truth.
 */

// ─── Paper text variant → description mapping ───────────────────────────────────
// These correspond to the `variant` prop accepted by `<Text>` from
// react-native-paper.  They are listed here for documentation and
// for use in custom components that need programmatic access.

export interface PaperTextVariant {
  variant: string;
  description: string;
}

export const paperTextVariants: readonly PaperTextVariant[] = [
  { variant: 'displayLarge', description: '57px / –1.25 tracking' },
  { variant: 'displayMedium', description: '45px / –1.25 tracking' },
  { variant: 'displaySmall', description: '36px / 0 tracking' },
  { variant: 'headlineLarge', description: '32px / 0 tracking' },
  { variant: 'headlineMedium', description: '28px / 0 tracking' },
  { variant: 'headlineSmall', description: '24px / 0 tracking' },
  { variant: 'titleLarge', description: '22px / 0 tracking' },
  { variant: 'titleMedium', description: '16px / 0.15 tracking, medium weight' },
  { variant: 'titleSmall', description: '14px / 0.1 tracking, medium weight' },
  { variant: 'bodyLarge', description: '16px / 0.5 tracking' },
  { variant: 'bodyMedium', description: '14px / 0.25 tracking' },
  { variant: 'bodySmall', description: '12px / 0.4 tracking' },
  { variant: 'labelLarge', description: '14px / 0.1 tracking, medium weight' },
  { variant: 'labelMedium', description: '12px / 0.5 tracking, medium weight' },
  { variant: 'labelSmall', description: '11px / 0.5 tracking, medium weight' },
] as const;

/** Convenience type – union of all supported Paper text variant strings */
export type PaperVariant = (typeof paperTextVariants)[number]['variant'];

// ─── App-specific font family ───────────────────────────────────────────────────
// Override at the application level if a custom font is bundled.

export const fontFamily = {
  regular: 'System',
  medium: 'System',
  bold: 'System',
  light: 'System',
  thin: 'System',
} as const;

/**
 * Default font size overrides keyed by Paper variant name.
 * These values extend / override what Paper provides out-of-the-box.
 */
export const fontSizes: Record<PaperVariant, number> = {
  displayLarge: 57,
  displayMedium: 45,
  displaySmall: 36,
  headlineLarge: 32,
  headlineMedium: 28,
  headlineSmall: 24,
  titleLarge: 22,
  titleMedium: 16,
  titleSmall: 14,
  bodyLarge: 16,
  bodyMedium: 14,
  bodySmall: 12,
  labelLarge: 14,
  labelMedium: 12,
  labelSmall: 11,
};