"use strict";

let currentSessionID = 0;
let currentRatingID = 0;
let sessions = [];

module.exports = function () {

    // enum
    var SessionState = {
        Created: 1,
        InEvaluation: 2,
        Evaluatd: 3,
        Closed: 4
    };

    // objects
    function Session(title, speaker) {
        this.id = currentSessionID;
        this.speaker = speaker;
        this.title = title;
        this.ratings = [];
        this.currentSessionState = SessionState.Created;
        currentSessionID++;
    }
    function Rating(evaluator, ratingValue) {
        this.rateID = currentRatingID;
        this.evaluator = evaluator;
        this.ratingValue = ratingValue;
        currentRatingID++;
    }
    function _createSession(title, speaker) {
        if (sessions.filter(x => x.title === title).length > 0)
            throw "Session with the title ''" + title + "'' already exits.";

        sessions.push(new Session(title, speaker));
    }
    function _rateSession(sessionID, evaluator, ratingValue) {
        if (evaluator.Length == 0 || ratingValue < 0 || ratingValue > 10)
            throw "no valid data was passed to the function";

        let current_session = _getSession(sessionID);

        if (current_session.currentSessionState == SessionState.Closed)
            throw "You can't rate a closed session";

        current_session.ratings.push(new Rating(evaluator, ratingValue));
        current_session.currentSessionState = SessionState.Evaluatd;
    }
    function _closeSession(sessionID) {
        let current_session = _getSession(sessionID);

        if (current_session.currentSessionState == SessionState.Created)
            throw "You can't close an unevaluated session.";

        current_session.currentSessionState = SessionState.Closed;
    }
    function _deleteSession(sessionID) {
        let currentSession = _getSession(sessionID);
        let idx = sessions.indexOf(currentSession);
        let length = sessions.length - 1;

        let temporarySession = sessions[length];
        sessions[length] = currentSession;
        sessions[idx] = temporarySession;

        sessions.pop();
    }
    function _getSession(sessionID) {
        let returendSession = sessions.filter(x => x.id === sessionID)[0];

        if (returendSession == null)
            throw "Session with the ID = " + sessionID + " doesn't exist.";

        return returendSession;
    }
    function _getSessions() {
        return sessions;
    }



    return {
        CreateSession: _createSession,
        GetSession: _getSession,
        GetSessions: _getSessions,
        RateSession: _rateSession,
        CloseSession: _closeSession,
        DeleteSession: _deleteSession
    };

} ();