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

Level up your React Native StyleSheet

import type { ColorValue, OpaqueColorValue } from 'react-native'
import type { SafeReturnType, UnionToIntersection } from './common'
import type { TransformStyles } from './core'
import type { BreakpointsOrMediaQueries, ToDeepUnistyles } from './stylesheet'

type ExtractTransformArray<T> = T extends object
    ? { [K in keyof T]: ExtractBreakpoints<T[K]> }
    : never

type ExtractBreakpoints<T> = T extends object
    ? keyof T extends BreakpointsOrMediaQueries
        ? T[keyof T]
        : T extends Array<ToDeepUnistyles<TransformStyles>>
            ? Array<ExtractTransformArray<T[number]>>
            : T extends Array<infer _U>
                ? T
                : {
                    [K in keyof T]: ExtractBreakpoints<T[K]>
                }
    : T

// Helper type to check if the base styles (without variants) are truly empty or just {}
type IsEmptyObject<T> = T extends Record<string, never> ? true : keyof T extends never ? true : false

type ParseNestedObject<T, ShouldFlatten> = T extends (...args: infer A) => infer R
    ? (...args: A) => ParseNestedObject<R, false>
    : T extends object
        ? T extends { variants: infer R, compoundVariants: infer C }
            ? (ParseVariants<FlattenVariants<R, false>> & FlattenCompoundVariants<C, false> & ParseNestedObject<Omit<T, 'variants' | 'compoundVariants'>, false>) extends never
                ? ParseVariants<FlattenVariants<R, true>> & FlattenCompoundVariants<C, true> & ParseNestedObject<Omit<T, 'variants' | 'compoundVariants'>, false>
                : ParseVariants<FlattenVariants<R, false>> & FlattenCompoundVariants<C, false> & ParseNestedObject<Omit<T, 'variants' | 'compoundVariants'>, false>
            : T extends { variants: infer R }
                ? IsEmptyObject<ParseNestedObject<Omit<T, 'variants'>, false>> extends true
                    ? ParseVariants<FlattenVariants<R, false>>
                    : (ParseVariants<FlattenVariants<R, false>> & ParseNestedObject<Omit<T, 'variants'>, false>) extends never
                        ? ParseVariants<FlattenVariants<R, true>> & ParseNestedObject<Omit<T, 'variants'>, false>
                        : ParseVariants<FlattenVariants<R, false>> & ParseNestedObject<Omit<T, 'variants'>, false>
                : T extends { compoundVariants: object }
                    ? ParseNestedObject<Omit<T, 'compoundVariants'>, false>
                    : {
                        [K in keyof T as K extends '_web' ? never : K]: T[K] extends object
                            ? T[K] extends OpaqueColorValue
                                ? ColorValue
                                : ExtractBreakpoints<T[K]>
                            : T[K] extends string
                                ? ShouldFlatten extends true
                                    ? string
                                    : T[K]
                                : T[K]
                    }
        : T

type FlattenVariants<T, ShouldFlatten> = T extends object
    ? {
        [K in keyof T]: T[K] extends object
            ? {
                [key in keyof T[K]]: T[K][key] extends object
                    ? ParseNestedObject<T[K][key], ShouldFlatten>
                    : never
            }
            : never
    }
    : never

type FlattenCompoundVariants<T, ShouldFlatten> = T extends Array<infer _>
    ? FlattenCompoundVariants<T[number], ShouldFlatten>
    : T extends { styles: infer S }
        ? ParseNestedObject<S, ShouldFlatten>
        : never

type IsNonEmpty<T> = T extends object ? (keyof T extends never ? false : true) : false

type IntersectCategoryValues<T> = T extends object
    ? T extends Array<any>
        ? T
        : UnionToIntersection<T[keyof T]> extends infer R
            ? R extends never
                ? T[keyof T]
                : R
            : never
    : never

type MergeVariantCategories<T> = T extends object
    ? UnionToIntersection<
        {
            [K in keyof T]: IsNonEmpty<T[K]> extends true ? T[K] : never
        }[keyof T]
    > extends infer R
        ? R extends never
            ? NonNullable<T[keyof T]>
            : R
        : never
    : never

type ParseVariants<T> = T extends object
    ? T[keyof T] extends object
        ? T[keyof T] extends Array<any>
            ? T
            : MergeVariantCategories<{
                [K in keyof T]: T[K] extends object ? IntersectCategoryValues<T[K]> : never
            }>
        : T
    : T

type ParseStyleKeys<T> = T extends object
    ? { [K in keyof T]: ParseNestedObject<T[K], false> }
    : never

export type ReactNativeStyleSheet<T> = ParseStyleKeys<SafeReturnType<T>>