var mongoose = require('mongoose');
var uniqueValidator = require('mongoose-unique-validator');
var slug = require('slug');

var QcmCategorySchema = new mongoose.Schema({
    num: Number,
    name: { type: String, unique: true },
    slug: { type: String, lowercase: true, unique: true },
    questions: [
        { type: mongoose.Schema.Types.ObjectId, ref: 'QcmQuestion' }
    ]
}, {timestamps: true, toJSON: {virtuals: true}});

QcmCategorySchema.plugin(uniqueValidator, { message: 'is already taken' });

QcmCategorySchema.pre('validate', function (next) {
    if (!this.slug) {
        this.slugify();
    }
    next();
});

QcmCategorySchema.methods.slugify = function () {
this.slug = slug(`${this.name}-${this.num}-`) + (Math.random() * Math.pow(36, 6) | 0).toString(36);
};

QcmCategorySchema.methods.addQuestion = function (id) {
    if (this.questions.indexOf(id) === -1) {
        this.questions.push(id);
    }
    return this.save();
};

QcmCategorySchema.methods.removeQuestion = function (id) {
    this.questions.remove(id);
    return this.save();
};

QcmCategorySchema.methods.toJSONFor = function() {
    return {
        num: this.num,
        name: this.name,
        slug: this.slug,
        questions: this.questions.map(question => question.toJSONFor())
    };
};

mongoose.model('QcmCategory', QcmCategorySchema);