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

import { buildSelectors } from './selectors.js';
import { buildUpreducer } from './upreducer.js';
import { action } from './actions.js';

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

/**
 * Updux configuration object
 * @typedef {Object} Updux config
 * @property {Object} actions - Actions to be made available to the updux.
 */

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

    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),
        );

        this.#selectors = buildSelectors(
            config.selectors,
            config.splatSelectors,
            this.#subduxes,
        );
    }

    #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 selectors() {
        return this.#selectors;
    }

    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 buildUpreducer(this.#mutations, this.#subduxes);
    }

    /**
     *
     * @param {string | Function} action - Action triggering the mutation. If
     * the action is a string, it has to have been previously declared for this
     * updux, but if it's a function generator, it'll be automatically added to the
     * updux if not already present (the idea being that making a typo on a string
     * is easy, but passing a wrong function very more unlikely).
     * @param {Function} mutation - Mutating function.
     *  @return {void}
     */
    setMutation(action, mutation) {
        // TODO option strict: false to make it okay to auto-create
        // the actions as strings?
        if (action.type) {
            if (!this.#actions[action.type]) {
                this.#actions[action.type] = action;
            } else if (this.#actions[action.type] !== action) {
                throw new Error(
                    `action '${action.type}' not defined for this updux or definition is different`,
                );
            }

            action = action.type;
        }

        if (!this.#actions[action]) {
            throw new Error(`action '${action}' is not defined`);
        }

        this.#mutations[action] = mutation;
    }

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

    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;
    }
}

export const dux = (config) => new Updux(config);