react-native-unistyles/src/types/variants.ts

Level up your React Native StyleSheet

import type { SafeReturnType } from './common'

export type ExtractVariantNames<T> = ExtractVariantKeys<SafeReturnType<T>>

type ExtractVariantKeys<T> = T extends object
    ? ExtractVariant<SafeReturnType<T[keyof T]>>
    : never

type HasBooleanVariants<T> = T extends Record<'true', any>
    ? true
    : T extends Record<'false', any>
        ? true
        : false

type ExtractSubVariantKeys<T> = T extends object
    ? HasBooleanVariants<T> extends true
        ? keyof Omit<T, 'default'> | boolean | undefined
        : keyof Omit<T, 'default'> | undefined
    : never

type ExtractVariant<T> = T extends { variants: infer V }
    ? { [key in keyof V]?: ExtractSubVariantKeys<V[key]> }
    : never

export type UnistylesVariants<ST> = ST extends { useVariants: infer V }
    ? V extends (variants: infer T) => void
        ? T
        : never
    : never