[
  {
    "id": 1,
    "title": "Reactを触ってみた",
    "contents": "Reactすごい",
    "author": {
      "id": 1,
      "name": "Linus Torvalds",
      "dob": "1969/12/28"
    }
  },
  {
    "id": 2,
    "title": "Reduxとre-ducks",
    "contents": "Reduxむずい",
    "author": {
      "id": 1,
      "name": "Linus Torvalds",
      "dob": "1969/12/28"
    }
  },
  {
    "id": 3,
    "title": "Vueに入門した",
    "contents": "Vueやばい",
    "author": {
      "id": 2,
      "name": "Jeff Dean",
      "dob": "1968/7/23"
    }
  }
]

{
  articles: {
    1: {
      id: 1,
      title: "Reactを触ってみた",
      contents: "Reactすごい",
      author: 1,
    },
    2: {
      id: 2,
      title: "Reduxとre-ducks",
      contents: "Reduxむずい",
      author: 1,
    },
    3: {
      id: 3,
      title: "Vueに入門した",
      contents: "Vueやばい",
      author: 2,
    },
  },
  users: {
    1: {
      id: 1,
      name: "Linus Torvalds",
      dob: "1969/12/28",
    },
    2: {
      id: 2,
      name: "Jeff Dean",
      dob: "1968/7/23",
    },
  },
}

import { schema, normalize, denormalize } from 'normalizr';
import joi from '@hapi/joi';
import {
  User,
  userJoiSchema,
  userNormalizrSchema,
  userNormalizrSchemaKey,
  NormalizedUsers,
} from '~/state/ducks/user/models';

// Userが埋め込まれたArticleの型。
export type Article = {
  id: string;
  title: string;
  content: string;
  author: User;
};

// 正規化されたArticle単体の型。
// つまり、ArticleのauthorがUserのidになった型。
export type NormalizedArticle = Omit<Article, 'author'> & {
  author: User['id'];
};

// 正規化されたArticleの集合の型。
// つまり、idとArticleオブジェクトのMap形式の型。
export type NormalizedArticles = {
  [id: number]: NormalizedArticle;
};

// normalizrのスキーマ定義。
export const articleNormalizrSchemaKey = 'articles';
export const articleNormalizrSchema = new schema.Entity<Article>(
  articleNormalizrSchemaKey,
  { author: userNormalizrSchema },
  {
    idAttribute: 'id',
  },
);

// 正規化関数。
// Userを埋め込んだArticleのリストを渡すと正規化して返してくれる。
export const normalizeArticles = (articles: Article[]) =>
  normalize<
    Article,
    {
      [articleNormalizrSchemaKey]: NormalizedArticles;
      [userNormalizrSchemaKey]: NormalizedUsers;
    },
    Article['id'][]
  >(articles, [articleNormalizrSchema]);

// 非正規化関数。
// normalizeArticles()の戻り値(i.e. 正規化したArticleの集合)を渡すと非正規化して返してくれる。
// Userを埋め込んだArticleのリストを返してくれる。
export const denormalizeArticles = (articles: ReturnType<typeof normalizeArticles>): Article[] =>
  denormalize(articles.result, [articleNormalizrSchema], articles.entities);

// Articleのサンプルオブジェクト。
// ユニットテストに使えるのと、モデルの理解の助けにもなる。
export const articleSamples: Article[] = [
  {
    id: 1,
    title: "Reactを触ってみた",
    contents: "Reactすごい",
    author: {
      id: 1,
      name: "Linus Torvalds",
      dob: "1969/12/28",
    },
  },
  {
    id: 2,
    title: "Reduxとre-ducks",
    contents: "Reduxむずい",
    author: {
      id: 1,
      name: "Linus Torvalds",
      dob: "1969/12/28",
    },
  },
  {
    id: 3,
    title: "Vueに入門した",
    contents: "Vueやばい",
    author: {
      id: 2,
      name: "Jeff Dean",
      dob: "1968/7/23",
    },
  },
];

// ここ以下はREST APIで取得したArticleオブジェクトのバリデーション関数の定義。詳細は割愛する。
// joi (https://github.com/sideway/joi)を使ってるけど、
// Yup (https://github.com/jquense/yup)とかAjv (https://github.com/ajv-validator/ajv)もよさそう。
export const articleJoiSchema = joi.object({
  id: joi.number().integer(),
  title: joi.string().required(),
  content: joi.string().required(),
  author: userJoiSchema.required(),
});

export const validateArticle = (obj: any) => {
  joi.assert(obj, articleJoiSchema.required());
  return obj as Article;
};

export const validateArticleList = (obj: any) => {
  joi.assert(obj, joi.array().items(articleJoiSchema).required());
  return obj as Article[];
};

{
  result: [1, 2, 3],
  entities: {
    articles: {
      1: {
        id: 1,
        title: "Reactを触ってみた",
        contents: "Reactすごい",
        author: 1,
      },
      2: {
        id: 2,
        title: "Reduxとre-ducks",
        contents: "Reduxむずい",
        author: 1,
      },
      3: {
        id: 3,
        title: "Vueに入門した",
        contents: "Vueやばい",
        author: 2,
      },
    },
    users: {
      1: {
        id: 1,
        name: "Linus Torvalds",
        dob: "1969/12/28",
      },
      2: {
        id: 2,
        name: "Jeff Dean",
        dob: "1968/7/23",
      },
    },
  },
}