Controller

public class TourPlanningController {

    //selectList indexes for swap
    Integer oldIndex {get; set;}
    Integer newIndex {get; set;}

    public PageReference onOrderSelect() {
            //oldIndex = this.options[this.selectedIndex];
            system.debug('Order status: '+Order);
            return null;
    }
    public PageReference onOrderChange() {
            //newIndex = this.options[this.selectedIndex];
            //reOrder(oldIndex, newIndex);
            return null;
    }

    //Preview block display flag
    public Boolean rendPreview {
        get {
            if (rendPreview == NULL) {
                rendPreview = false;
            }
            return rendPreview;
        }
        set;
    }

    //Properties implementation
    public Time startTime {
        get {
            if (startTime == NULL) {
                startTime = Time.newInstance(9, 0, 0, 0);
            }
            return startTime;
        }
        set;
    }
    public Time endTime {
        get {
            if (endTime == NULL) {
                endTime = Time.newInstance(18, 0, 0, 0);
            }
            return endTime;
        }
        set;
    }
    public Integer duration {
        get {
            if (duration == NULL) {
                duration = 15;
            }
            return duration;
        }
        set;
    }
    public Integer pause {
        get {
            if (pause == NULL) {
                pause = 30;
            }
            return pause;
        }
        set;
    }

    public List<Integer> Order {
        //REWRITE THIS METHOD!
        get {
            Integer sC = selectedContacts.size();
            if ((order == NULL) || (order.size()<sC)) {
                //Generate initial order
                order = new List<Integer>();
                for (Integer i=0; i<sC; i++) {
                    order.add(i);
                    system.debug('Added order record: '+order[i]);
                }
            }

            system.debug('Generated order: '+order);
            return Order;
        }
        set {
            for (Integer i=0; i<tableRows.size(); i++) {
                this.order[i]=tableRows[i].visitOrder;
                system.debug('Copied order record: '+order[i]);
            }
            system.debug('Updated order: '+order);
        }
    }
    public List<SelectOption> getOrderOptions() {
        List<SelectOption> options = new List<SelectOption>();
        Integer sC = selectedContacts.size();
        for (Integer i=0; i<sC; i++) {
            String str = String.valueOf(Order[i]);
            SelectOption option = new SelectOption(str, str);
            options.add(option);
        }
        return options;
    }

    public List<String> selectedContacts {get; set;}  //holds the values of the selected contacts
    // Generates Customers list
    public List<SelectOption> getTargetedContacts() {
        List<SelectOption> options = new List<SelectOption>();

        // Find all the targeted contacts
        List<Contact> targetedContacts = Database.query('SELECT Id, Name ' +
                                                        'FROM Contact ' +
                                                        'WHERE Is_Target__c = true'
        );

        // Sort them by name
        targetedContacts.sort();

        // Create the Select Options.
        if (targetedContacts.size() > 0) {
            for (Integer i=0; i<targetedContacts.size(); i++) {
                //create new selectOption
                SelectOption option = new SelectOption(targetedContacts[i].Id, targetedContacts[i].Name);

                //add the option to options
                options.add(option);
            }
        } else {
            options.add(new SelectOption('', 'Targeted customers are absent'));
        }

        return options;
    }

    //visits for preview
    public List<Visit__c> Visits {
        get {
            visits = new List<Visit__c>();

            //calculate visitsNumber
            Integer visitsNumber = selectedContacts.size();

            //prepere data for the visits generation
            DateTime startDateTime = System.today(); //initialization startDateTime for a visit generation
            startDateTime = startDateTime.addHours(startTime.hour()); //add hours to startDateTime
            startDateTime = startDateTime.addMinutes(startTime.minute()); //add minutes to startDateTime
            DateTime edgeDateTime = System.today(); //for a visit number limit detection
            edgeDateTime = edgeDateTime.addHours(endTime.hour());
            edgeDateTime = edgeDateTime.addMinutes(endTime.minute());
            Integer curDuration = 0; //for the total duration counting in the loop

            //visits list generation
            for (Integer i=0; i<visitsNumber; i++) {
                //generate startDateTime__c and endDateTime__c
                //calculate values for the loop each iteration
                startDateTime = startDateTime.addMinutes(curDuration);
                //system.debug('Start DateTime in '+i+' FOR loop: '+startDateTime);
                curDuration += duration;
                DateTime endDateTime = startDateTime.addMinutes(duration);
                //system.debug('End DateTime: '+endDateTime);

                if (endDateTime > edgeDateTime) {
                    //proceed to preview generation (ignore the rest of the visits)
                    system.debug('The visit end time ('+endDateTime+') is greater than work hours: '+edgeDateTime);
                    return visits;
                }

                if (i<visitsNumber-1) {
                    curDuration += pause;
                }

                Visit__c visit = new Visit__c(Representative__c=UserInfo.getUserId(), Customer__c=selectedContacts[i], StartDateTime__c=startDateTime, EndDateTime__c=endDateTime);
                system.debug('Single visit for '+i+' iteration: '+visit);
                visits.add(visit);
            }
            system.debug('Generated visits: '+visits);
            return visits;
        }
        set;
    }

    //Visits preview combined record
    public List<cTableRow> tableRows {
        get {
            tableRows = new List<cTableRow>();
            Integer rowsNumber = selectedContacts.size();
            for (Integer i=0; i<rowsNumber; i++) {
                tableRows.add(new cTableRow(visits[i],
                                            order[i]));
            }
            return tableRows;
        }
        set { //HOW TO INVOKE THIS METHOD?
            system.debug('Table rows status: '+tableRows);

            //setOrder();
        } /*{
            system.debug('Selected index: '+newIndex+'. Index to replace: '+oldIndex);
            Id tmpId = visits[oldIndex].Customer__c;
            visits[oldIndex].Customer__c = visits[newIndex].Customer__c;
            visits[newIndex].Customer__c = tmpId;
            rendPreview = true;
            system.debug('Reordered table: '+tableRows);
        }*/
    }
    //OR THIS METHOD?
    public void setTableRows(List<cTableRow> tableRows) {
        system.debug('Table rows before renew: '+tableRows);
        for (Integer i=0; i<tableRows.size(); i++) {
            this.tableRows[i].visitOrder = tableRows[i].visitOrder;
        }
        system.debug('Table rows after renew: '+tableRows);
    }
    public class cTableRow {
        //fields of the record
        public Id customerId { get; set; }
        public String customerName { get; set; }
        private DateTime visitStartDatetime { get; set; }
        private DateTime visitEndDatetime { get; set; }
        public Time visitStartTime { get; set; }
        public Time visitEndTime { get; set; }
        public Integer visitOrder { get; set; }

        public cTableRow(Visit__c v, Integer o) {
            customerId = v.Customer__c;
            List<Contact> contNames = [SELECT Name FROM Contact WHERE id=:customerId];
            customerName = contNames[0].Name;
            visitStartDatetime = v.startDateTime__c;
            visitEndDatetime = v.endDateTime__c;
            visitStartTime = visitStartDatetime.time();
            visitEndTime = visitEndDatetime.time();
            visitOrder = o;
        }
    }
    public void reOrder(Integer newIndex, Integer oldIndex) {
        system.debug('Selected index: '+newIndex+'. Index to replace: '+oldIndex);
        Id tmpId = visits[oldIndex].Customer__c;
        visits[oldIndex].Customer__c = visits[newIndex].Customer__c;
        visits[newIndex].Customer__c = tmpId;
        rendPreview = true;
        system.debug('Reordered table: '+tableRows);
    }

    //Render id="preview"
    public PageReference calculate() {
        //initiate Order
        if (order == NULL) {
            order = new List<Integer>();
        } else {
            order.clear();
        }

        //validate parameters

        //rerender "preview"
        rendPreview = true;

        return null;
    }

    public PageReference save() {
        //check order list for collisions
        for (Integer i=0; i<order.size(); i++) {
            Integer etalon = Order[i];
            for (Integer j=0; j<order.size(); j++) {
                if ((etalon==Order[j]) && (j!=i)) {
                    //show validation error

                    return null;
                }
            }
        }

        //prepare visits list (sort by order)
        for (Integer j=0; j<order.size(); j++) {
            if ((Order[j]!=j) && (Order[j]>j)) {
                newIndex = Order[j];
                oldIndex = j;
                //swap visits (customers)
                for (Integer i=0; i<visits.size(); i++) {
                    Id tmpId = visits[oldIndex].Customer__c;
                    visits[oldIndex].Customer__c = visits[newIndex].Customer__c;
                    visits[newIndex].Customer__c = tmpId;
                }
            }
        }

        if (visits != null) {
            //insert visits;
            return null;
        } else {
            //show error message and
            return null;
        }
    }

}