Generic Type that recursively flattens a Type by merging property names with dots

TypeFlatten.ts

type DeepKeys<M> = {
  [J in keyof M as `${J & string}${
      M[J] extends Record<string, any> ?
        M[J] extends {constructor: M[J]} ? '' :
          M[J] extends Array<any> ? '' :
            `.${keyof DeepKeys<M[J]> & string}` : ''
  }`]:
  M[J] extends Record<string, any> ? M : M[J]
}

type DeepType<M, K> = K extends `${infer X}.${infer Y}` ?
                      DeepType<M[X & keyof M], Y> :
                      M[K & keyof M]

type Flatten<M, Keys=DeepKeys<M>> = {
  [K in keyof Keys]:
    Keys[K] extends Record<string, any> ?
      DeepType<Keys[K], K> :
      Keys[K]
}

// ---

type A = {
    name: string,
    age: number,
    company: {
        name: string,
        is_admin: boolean,
        address: {
            city: 'pindamomnhangaba' | 'itu',
            street: string,
        }
    }
}

type B = Flatten<A>

// type B = {
//     name: string;
//     age: number;
//     "company.name": string;
//     "company.is_admin": boolean;
//     "company.address.city": "pindamomnhangaba" | "itu";
//     "company.address.street": string;
// }