import R from 'remeda';
import { createStore as reduxCreateStore } from 'redux';

import { action } from './actions.js';

function isActionGen(action) {
    return typeof action === 'function' && action.type;
}

export class Updux {
    #localInitial = {};
    #subduxes = {};
    #actions;
    #mutations = {};
    #config = {};

    constructor(config = {}) {
        this.#config = config;
        this.#localInitial = config.initial ?? {};
        this.#subduxes = config.subduxes ?? {};

        this.#actions = R.mapValues(config.actions ?? {}, (arg, name) =>
            isActionGen(arg) ? arg : action(name, arg),
        );
        Object.entries(this.#subduxes).forEach(([slice, sub]) =>
            this.#addSubduxActions(slice, sub),
        );
    }

    #addSubduxActions(_slice, subdux) {
        if (!subdux.actions) return;
        // TODO action 'blah' defined multiple times: <where>
        Object.entries(subdux.actions).forEach(([action, gen]) => {
            if (this.#actions[action]) {
                if (this.#actions[action] === gen) return;
                throw new Error(`action '${action}' already defined`);
            }

            this.#actions[action] = gen;
        });
    }

    get actions() {
        return this.#actions;
    }

    get initial() {
        if (Object.keys(this.#subduxes).length === 0) return this.#localInitial;

        return Object.assign(
            {},
            this.#localInitial,
            R.mapValues(this.#subduxes, ({ initial }) => initial),
        );
    }

    get reducer() {
        return (state, action) => this.upreducer(action)(state);
    }

    get upreducer() {
        return (action) => (state) => {
            const mutation = this.#mutations[action.type];

            if (mutation) {
                state = mutation(action.payload, action)(state);
            }

            return state;
        };
    }

    setMutation(action, mutation) {
        this.#mutations[action.type] = mutation;
    }

    createStore(initial = undefined, enhancerGenerator = undefined) {
        // const enhancer = (enhancerGenerator ?? applyMiddleware)(
        //     this.middleware
        // );

        const store = reduxCreateStore(
            this.reducer,
            initial ?? this.initial,
            //enhancer
        );

        store.actions = this.actions;

//        store.selectors = this.selectors;

        // store.getState = R.merge(
        //     store.getState,
        //     R.mapValues(this.selectors, (selector) => {
        //         return (...args) => {
        //             let result = selector(store.getState());

        //             if (typeof result === 'function') return result(...args);

        //             return result;
        //         };
        //     })
        // );

        for (const action in this.actions) {
            store.dispatch[action] = (...args) => {
                return store.dispatch(this.actions[action](...(args)));
            };
        }

        //this.subscribeAll(store);

        return store;
    }

}