import logger from './util/logger';
import data from './util/data';
import * as settings from './util/settings';
import utils from './util/utils';
import fs from 'fs';
import objectAssignDeep from 'object-assign-deep';

const saveInterval = 1000 * 60 * 5; // 5 minutes

const dontCacheProperties = [
    'action', 'action_.*', 'button', 'button_left', 'button_right', 'click', 'forgotten', 'keyerror',
    'step_size', 'transition_time', 'group_list', 'group_capacity', 'no_occupancy_since',
    'step_mode', 'transition_time', 'duration', 'elapsed', 'from_side', 'to_side',
];

class State {
    private state: {[s: string | number]: KeyValue} = {};
    private file = data.joinPath('state.json');
    private timer: NodeJS.Timeout = null;

    constructor(private readonly eventBus: EventBus, private readonly zigbee: Zigbee) {
        this.eventBus = eventBus;
        this.zigbee = zigbee;
    }

    start(): void {
        this.load();

        // Save the state on every interval
        this.timer = setInterval(() => this.save(), saveInterval);
    }

    stop(): void {
        // Remove any invalid states (ie when the device has left the network) when the system is stopped
        Object.keys(this.state)
            .filter((k) => typeof k === 'string' && !this.zigbee.resolveEntity(k)) // string key = ieeeAddr
            .forEach((k) => delete this.state[k]);

        clearTimeout(this.timer);
        this.save();
    }

    private load(): void {
        if (fs.existsSync(this.file)) {
            try {
                this.state = JSON.parse(fs.readFileSync(this.file, 'utf8'));
                logger.debug(`Loaded state from file ${this.file}`);
            } catch (e) {
                logger.debug(`Failed to load state from file ${this.file} (corrupt file?)`);
            }
        } else {
            logger.debug(`Can't load state from file ${this.file} (doesn't exist)`);
        }
    }

    private save(): void {
        if (settings.get().advanced.cache_state_persistent) {
            logger.debug(`Saving state to file ${this.file}`);
            const json = JSON.stringify(this.state, null, 4);
            try {
                fs.writeFileSync(this.file, json, 'utf8');
            } catch (e) {
                logger.error(`Failed to write state to '${this.file}' (${e.message})`);
            }
        } else {
            logger.debug(`Not saving state`);
        }
    }

    exists(entity: Device | Group): boolean {
        return this.state.hasOwnProperty(entity.ID);
    }

    get(entity: Group | Device): KeyValue {
        return this.state[entity.ID] || {};
    }

    set(entity: Group | Device, update: KeyValue, reason: string=null): KeyValue {
        const fromState = this.state[entity.ID] || {};
        const toState = objectAssignDeep({}, fromState, update);
        const newCache = {...toState};
        const entityDontCacheProperties = entity.options.filtered_cache || [];

        utils.filterProperties(dontCacheProperties.concat(entityDontCacheProperties), newCache);

        this.state[entity.ID] = newCache;
        this.eventBus.emitStateChange({entity, from: fromState, to: toState, reason, update});
        return toState;
    }

    remove(ID: string | number): void {
        delete this.state[ID];
    }
}

export default State;