console.loggerName = 'js.watch';
console.log('Load watch module');

class Watch {

    #watchItem
    #watchObjects = new Object();

    constructor(watchItem) {

        // Fetch item if provided itemName is a string
        if (typeof watchItem === 'string' || watchItem instanceof String) {
            this.#watchItem = items[watchItem];
        } else {
            this.#watchItem = watchItem;
        }

        // Throw error if item is not existing
        if (this.#watchItem === null) {
            throw(`Item ${watchItem} not existing`);
        }
        
        console.log(`Create new Watch instance for ${this.#watchItem.name}`);
        
        // Create watch rule
        this.#createWatchRule();
    }

    add(params) {
        // Generate watchUUID
        let watchUUID = utils.randomUUID();

        // Validate config for watchObject
        if (!this.validateWatchConfig(params)) {
            console.warn(`Failed to add watch object for ${this.#watchItem.name} because no valid config was provided`);
            return;
        }

        // Set default values if no config provided
        let operator = (params['operator'] !== undefined) ? params['operator'] : '==';

        // Create watch object and return UUID
        console.log(`Add watch object for item ${this.#watchItem.name} with state ${params['targetState']} and operator ${operator} with UUID ${watchUUID}`);
        this.#watchObjects[watchUUID] = {
            targetState: params['targetState'],
            operator: operator,
            alertFunc: params['alertFunc'],
            alertDelay: (params['alertDelay'] !== undefined) ? params['alertDelay'] : 0,
            alertRepeat: (params['alertRepeat'] !== undefined) ? params['alertRepeat'] : 0,
            initialAlertFunc: (params['initialAlertFunc'] !== undefined) ? params['initialAlertFunc'] : '',
            endAlertFunc: (params['endAlertFunc'] !== undefined) ? params['endAlertFunc'] : '',
            hysteresis: (params['hysteresis'] !== undefined) ? lib.convertValue(params['hysteresis']) : '',
            alert: false
        }

        // Check if watchObject is already triggered by currentState 
        this.#checkAlertState(watchUUID);

        // return id of watchObject
        return watchUUID;
    }

    delete(watchUUID) {
        console.log(`Delete watch object for item ${this.#watchItem.name} with watchUUID ${watchUUID}`);

        // End repeatAlertTimer if existing
        if (this.#watchObjects[watchUUID].hasOwnProperty('repeatAlertTimer') && this.#watchObjects[watchUUID].repeatAlertTimer.isActive()) {
            console.log('Cancel repeatAlertTimer for ' + watchUUID);
            this.#watchObjects[watchUUID].repeatAlertTimer.cancel();
        }
        
        // End startAlertTimer if existing
        if (this.#watchObjects[watchUUID].hasOwnProperty('startAlertTimer') && this.#watchObjects[watchUUID].startAlertTimer.isActive()) {
            console.log('Cancel startAlertTimer for ' + watchUUID);
            this.#watchObjects[watchUUID].startAlertTimer.cancel();
        }

        delete this.#watchObjects[watchUUID];

        // Delete watchRule if no more watchObjects are present
        if (Object.keys(this.#watchObjects).length == 0) {
            console.debug(`Remove openHAB watch rule for item ${this.#watchItem.name}`);
            rules.removeRule(this.watchRuleID);
        }
    }

    deleteAll() {
        for (let watchUUID of Object.keys(this.#watchObjects)) {
            this.delete(watchUUID);
        }
    }

    validateWatchConfig(params) {

        if (params['targetState'] === undefined) {
            console.error('No targetState set');
            return false;
        }
        if (params['alertFunc'] === undefined) {
            console.error('No alertFunc set');
            return false;
        }

        // return true if config is valid
        return true
    }

    #applyHysteresis(currentState, targetState, hysteresis) {
        console.log(`Applying hysteresis with: ${currentState}, ${targetState}, ${hysteresis}`);
        let delta = Math.abs(targetState - currentState);
        console.log(delta);

        if (delta < hysteresis) {
            return false;
        }

        return true;
    }

    #checkAlertState(watchUUID) {
        console.debug(`Check if item is in alert state for watchObject ${watchUUID}`)

        // Convert currentState for comparison
        let currentState = lib.convertValue(this.#watchItem.state);

        // Do comparison
        if (lib.compare(currentState, this.#watchObjects[watchUUID].targetState, this.#watchObjects[watchUUID].operator)) { // Comparison successful
            console.log(`State ${currentState} is ${this.#watchObjects[watchUUID].operator} ${this.#watchObjects[watchUUID].targetState} triggered by ${watchUUID}`);
            if (this.#watchObjects[watchUUID].alert == true) { // Comparison successful and alert is already active
                this.#rescheduleAlert(watchUUID);
            } else { // Comparison successful and alert is not active
                // Start alert
                this.#startAlert(watchUUID);
            }
        } else if (this.#watchObjects[watchUUID].alert == true) { // Comparison failed but alert is active
            // Skip if currentState fails hysteresis test
            if (this.#watchObjects[watchUUID].hysteresis != '' && !this.#applyHysteresis(currentState, this.#watchObjects[watchUUID].targetState, this.#watchObjects[watchUUID].hysteresis)) {
                console.log('CurrentState is still in boundaries provided by hysteresis value');
                return;
            }
            // End alert
            this.#endAlert(watchUUID);
        }
    }

    #createWatchRule() {
        // Create openHAB rule
        console.log(`Create openHAB watch rule for item ${this.#watchItem.name}`);
        this.watchRuleID = String(utils.randomUUID());
        rules.JSRule({
            id: this.watchRuleID,
            name: 'Watch rule for ' + this.#watchItem.name,
            triggers: [triggers.ItemStateChangeTrigger(this.#watchItem.name)],
            execute: (event) => { this.#processItemEvent(event) },
        });
    }

    #endAlert(watchUUID) {
        console.log(`End alert for watchObject ${watchUUID} triggered`);
        this.#watchObjects[watchUUID].alert = false;

        // Run end alert function if existing
        if (this.#watchObjects[watchUUID].endAlertFunc != '') {
            console.log(`Run end alert function for watchObject ${watchUUID}`);
            this.#watchObjects[watchUUID].endAlertFunc();
        }

        // End repeatAlertTimer if existing
        if (this.#watchObjects[watchUUID].hasOwnProperty('repeatAlertTimer') && this.#watchObjects[watchUUID].repeatAlertTimer.isActive()) {
            console.log('Cancel repeatAlertTimer');
            this.#watchObjects[watchUUID].repeatAlertTimer.cancel();
        }
        
        // End startAlertTimer if startAlert started timer with delay
        if (this.#watchObjects[watchUUID].hasOwnProperty('startAlertTimer') && this.#watchObjects[watchUUID].startAlertTimer.isActive()) {
            console.log('Cancel startAlertTimer');
            this.#watchObjects[watchUUID].startAlertTimer.cancel();
        }
    }

    #processItemEvent(event) {
        // Skip if function is triggered without openHAB event
        if (event === undefined || event.eventType === undefined) {
            console.warn(`ProcessItemEvent for ${this.#watchItem.name} triggered without openHAB event`);
            return;
        }

        console.log(`Processing state ${this.#watchItem.state} for ${this.#watchItem.name}`);

        // Iterate through watchObjetcs // todo: rework to only fetch UUID
        for (let [watchUUID, watchObject] of Object.entries(this.#watchObjects)) {
            this.#checkAlertState(watchUUID);
        }
    }

    #rescheduleAlert(watchUUID) {
        console.log(`Subsequent alert for ${watchUUID}`);
    }

    #startAlert(watchUUID) {
        console.log(`Initial alert for watchObject ${watchUUID} triggered`);

        // Set alertFunc as inital alert function if no  initialAlertFunc is set
        let initialAlertFunc = this.#watchObjects[watchUUID].alertFunc;
        if (this.#watchObjects[watchUUID].initialAlertFunc != '') {
            initialAlertFunc = this.#watchObjects[watchUUID].initialAlertFunc;
        } 

        let alertDelay = this.#watchObjects[watchUUID].alertDelay;
        let alertRepeat = this.#watchObjects[watchUUID].alertRepeat;
        let alertDelayAbsolute = 0;

        // Set alert state
        this.#watchObjects[watchUUID].alert = true;

        // Execute initial alert function or create timer to run initial alert rule if required
        if (alertDelay == '') {
            console.log(`Run initial alert function for watchObject ${watchUUID}`);
            initialAlertFunc();
        } else {
            console.log(`Shedule initial alert function for watchObject ${watchUUID} with delay setting ${alertDelay}`);
            
            let alertDelayZDT = time.toZDT(alertDelay);
            alertDelayAbsolute = (alertDelayZDT.getMillisFromNow() / 1000);            
            
            this.#watchObjects[watchUUID].startAlertTimer = actions.ScriptExecution.createTimer('startAlert ' + watchUUID,
                                                                                                alertDelayZDT,
                                                                                                () => {
                                                                                                    console.log('Run initial alert function for watchObject ' + watchUUID);
                                                                                                    initialAlertFunc();
                                                                                                }
            );
        }

        // Create timer to run repeat alert rule if required
        if (alertRepeat != '') {
            console.log(`Shedule repeat alert function for watchObject ${watchUUID} with repeat setting ${alertRepeat}`);
            this.#watchObjects[watchUUID].repeatAlertTimer = actions.ScriptExecution.createTimer('repeatAlarm ' + watchUUID,
                                                                                                time.toZDT(alertRepeat).plusSeconds(alertDelayAbsolute),
                                                                                                () => {
                                                                                                    console.log('Run repeat alert function for watchObject ' + watchUUID);
                                                                                                    this.#watchObjects[watchUUID].alertFunc();
                                                                                                    this.#watchObjects[watchUUID].repeatAlertTimer.reschedule(time.toZDT(alertRepeat));
                                                                                                }

            );
        }
    } 
}

module.exports = {
    Watch,
};