source: node_modules/@reduxjs/toolkit/src/mapBuilders.ts@ a762898

import type { Action } from 'redux'
import type {
  CaseReducer,
  CaseReducers,
  ActionMatcherDescriptionCollection,
} from './createReducer'
import type { TypeGuard } from './tsHelpers'
import type { AsyncThunk, AsyncThunkConfig } from './createAsyncThunk'

export type AsyncThunkReducers<
  State,
  ThunkArg extends any,
  Returned = unknown,
  ThunkApiConfig extends AsyncThunkConfig = {},
> = {
  pending?: CaseReducer<
    State,
    ReturnType<AsyncThunk<Returned, ThunkArg, ThunkApiConfig>['pending']>
  >
  rejected?: CaseReducer<
    State,
    ReturnType<AsyncThunk<Returned, ThunkArg, ThunkApiConfig>['rejected']>
  >
  fulfilled?: CaseReducer<
    State,
    ReturnType<AsyncThunk<Returned, ThunkArg, ThunkApiConfig>['fulfilled']>
  >
  settled?: CaseReducer<
    State,
    ReturnType<
      AsyncThunk<Returned, ThunkArg, ThunkApiConfig>['rejected' | 'fulfilled']
    >
  >
}

export type TypedActionCreator<Type extends string> = {
  (...args: any[]): Action<Type>
  type: Type
}

/**
 * A builder for an action <-> reducer map.
 *
 * @public
 */
export interface ActionReducerMapBuilder<State> {
  /**
   * Adds a case reducer to handle a single exact action type.
   * @remarks
   * All calls to `builder.addCase` must come before any calls to `builder.addMatcher` or `builder.addDefaultCase`.
   * @param actionCreator - Either a plain action type string, or an action creator generated by [`createAction`](./createAction) that can be used to determine the action type.
   * @param reducer - The actual case reducer function.
   */
  addCase<ActionCreator extends TypedActionCreator<string>>(
    actionCreator: ActionCreator,
    reducer: CaseReducer<State, ReturnType<ActionCreator>>,
  ): ActionReducerMapBuilder<State>
  /**
   * Adds a case reducer to handle a single exact action type.
   * @remarks
   * All calls to `builder.addCase` must come before any calls to `builder.addAsyncThunk`, `builder.addMatcher` or `builder.addDefaultCase`.
   * @param actionCreator - Either a plain action type string, or an action creator generated by [`createAction`](./createAction) that can be used to determine the action type.
   * @param reducer - The actual case reducer function.
   */
  addCase<Type extends string, A extends Action<Type>>(
    type: Type,
    reducer: CaseReducer<State, A>,
  ): ActionReducerMapBuilder<State>

  /**
   * Adds case reducers to handle actions based on a `AsyncThunk` action creator.
   * @remarks
   * All calls to `builder.addAsyncThunk` must come before after any calls to `builder.addCase` and before any calls to `builder.addMatcher` or `builder.addDefaultCase`.
   * @param asyncThunk - The async thunk action creator itself.
   * @param reducers - A mapping from each of the `AsyncThunk` action types to the case reducer that should handle those actions.
   * @example
```ts no-transpile
import { createAsyncThunk, createReducer } from '@reduxjs/toolkit'

const fetchUserById = createAsyncThunk('users/fetchUser', async (id) => {
  const response = await fetch(`https://reqres.in/api/users/${id}`)
  return (await response.json()).data
})

const reducer = createReducer(initialState, (builder) => {
  builder.addAsyncThunk(fetchUserById, {
    pending: (state, action) => {
      state.fetchUserById.loading = 'pending'
    },
    fulfilled: (state, action) => {
      state.fetchUserById.data = action.payload
    },
    rejected: (state, action) => {
      state.fetchUserById.error = action.error
    },
    settled: (state, action) => {
      state.fetchUserById.loading = action.meta.requestStatus
    },
  })
})
   */
  addAsyncThunk<
    Returned,
    ThunkArg,
    ThunkApiConfig extends AsyncThunkConfig = {},
  >(
    asyncThunk: AsyncThunk<Returned, ThunkArg, ThunkApiConfig>,
    reducers: AsyncThunkReducers<State, ThunkArg, Returned, ThunkApiConfig>,
  ): Omit<ActionReducerMapBuilder<State>, 'addCase'>

  /**
   * Allows you to match your incoming actions against your own filter function instead of only the `action.type` property.
   * @remarks
   * If multiple matcher reducers match, all of them will be executed in the order
   * they were defined in - even if a case reducer already matched.
   * All calls to `builder.addMatcher` must come after any calls to `builder.addCase` and `builder.addAsyncThunk` and before any calls to `builder.addDefaultCase`.
   * @param matcher - A matcher function. In TypeScript, this should be a [type predicate](https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-predicates)
   *   function
   * @param reducer - The actual case reducer function.
   *
   * @example
```ts
import {
  createAction,
  createReducer,
  AsyncThunk,
  UnknownAction,
} from "@reduxjs/toolkit";

type GenericAsyncThunk = AsyncThunk<unknown, unknown, any>;

type PendingAction = ReturnType<GenericAsyncThunk["pending"]>;
type RejectedAction = ReturnType<GenericAsyncThunk["rejected"]>;
type FulfilledAction = ReturnType<GenericAsyncThunk["fulfilled"]>;

const initialState: Record<string, string> = {};
const resetAction = createAction("reset-tracked-loading-state");

function isPendingAction(action: UnknownAction): action is PendingAction {
  return typeof action.type === "string" && action.type.endsWith("/pending");
}

const reducer = createReducer(initialState, (builder) => {
  builder
    .addCase(resetAction, () => initialState)
    // matcher can be defined outside as a type predicate function
    .addMatcher(isPendingAction, (state, action) => {
      state[action.meta.requestId] = "pending";
    })
    .addMatcher(
      // matcher can be defined inline as a type predicate function
      (action): action is RejectedAction => action.type.endsWith("/rejected"),
      (state, action) => {
        state[action.meta.requestId] = "rejected";
      }
    )
    // matcher can just return boolean and the matcher can receive a generic argument
    .addMatcher<FulfilledAction>(
      (action) => action.type.endsWith("/fulfilled"),
      (state, action) => {
        state[action.meta.requestId] = "fulfilled";
      }
    );
});
```
   */
  addMatcher<A>(
    matcher: TypeGuard<A> | ((action: any) => boolean),
    reducer: CaseReducer<State, A extends Action ? A : A & Action>,
  ): Omit<ActionReducerMapBuilder<State>, 'addCase' | 'addAsyncThunk'>

  /**
   * Adds a "default case" reducer that is executed if no case reducer and no matcher
   * reducer was executed for this action.
   * @param reducer - The fallback "default case" reducer function.
   *
   * @example
```ts
import { createReducer } from '@reduxjs/toolkit'
const initialState = { otherActions: 0 }
const reducer = createReducer(initialState, builder => {
  builder
    // .addCase(...)
    // .addMatcher(...)
    .addDefaultCase((state, action) => {
      state.otherActions++
    })
})
```
   */
  addDefaultCase(reducer: CaseReducer<State, Action>): {}
}

export function executeReducerBuilderCallback<S>(
  builderCallback: (builder: ActionReducerMapBuilder<S>) => void,
): [
  CaseReducers<S, any>,
  ActionMatcherDescriptionCollection<S>,
  CaseReducer<S, Action> | undefined,
] {
  const actionsMap: CaseReducers<S, any> = {}
  const actionMatchers: ActionMatcherDescriptionCollection<S> = []
  let defaultCaseReducer: CaseReducer<S, Action> | undefined
  const builder = {
    addCase(
      typeOrActionCreator: string | TypedActionCreator<any>,
      reducer: CaseReducer<S>,
    ) {
      if (process.env.NODE_ENV !== 'production') {
        /*
         to keep the definition by the user in line with actual behavior,
         we enforce `addCase` to always be called before calling `addMatcher`
         as matching cases take precedence over matchers
         */
        if (actionMatchers.length > 0) {
          throw new Error(
            '`builder.addCase` should only be called before calling `builder.addMatcher`',
          )
        }
        if (defaultCaseReducer) {
          throw new Error(
            '`builder.addCase` should only be called before calling `builder.addDefaultCase`',
          )
        }
      }
      const type =
        typeof typeOrActionCreator === 'string'
          ? typeOrActionCreator
          : typeOrActionCreator.type
      if (!type) {
        throw new Error(
          '`builder.addCase` cannot be called with an empty action type',
        )
      }
      if (type in actionsMap) {
        throw new Error(
          '`builder.addCase` cannot be called with two reducers for the same action type ' +
            `'${type}'`,
        )
      }
      actionsMap[type] = reducer
      return builder
    },
    addAsyncThunk<
      Returned,
      ThunkArg,
      ThunkApiConfig extends AsyncThunkConfig = {},
    >(
      asyncThunk: AsyncThunk<Returned, ThunkArg, ThunkApiConfig>,
      reducers: AsyncThunkReducers<S, ThunkArg, Returned, ThunkApiConfig>,
    ) {
      if (process.env.NODE_ENV !== 'production') {
        // since this uses both action cases and matchers, we can't enforce the order in runtime other than checking for default case
        if (defaultCaseReducer) {
          throw new Error(
            '`builder.addAsyncThunk` should only be called before calling `builder.addDefaultCase`',
          )
        }
      }
      if (reducers.pending)
        actionsMap[asyncThunk.pending.type] = reducers.pending
      if (reducers.rejected)
        actionsMap[asyncThunk.rejected.type] = reducers.rejected
      if (reducers.fulfilled)
        actionsMap[asyncThunk.fulfilled.type] = reducers.fulfilled
      if (reducers.settled)
        actionMatchers.push({
          matcher: asyncThunk.settled,
          reducer: reducers.settled,
        })
      return builder
    },
    addMatcher<A>(
      matcher: TypeGuard<A>,
      reducer: CaseReducer<S, A extends Action ? A : A & Action>,
    ) {
      if (process.env.NODE_ENV !== 'production') {
        if (defaultCaseReducer) {
          throw new Error(
            '`builder.addMatcher` should only be called before calling `builder.addDefaultCase`',
          )
        }
      }
      actionMatchers.push({ matcher, reducer })
      return builder
    },
    addDefaultCase(reducer: CaseReducer<S, Action>) {
      if (process.env.NODE_ENV !== 'production') {
        if (defaultCaseReducer) {
          throw new Error('`builder.addDefaultCase` can only be called once')
        }
      }
      defaultCaseReducer = reducer
      return builder
    },
  }
  builderCallback(builder)
  return [actionsMap, actionMatchers, defaultCaseReducer]
}