class HomeworkSession extends HomeworkElement {

    constructor() {
        super()
        this.addEventListener('texts-loaded', this.updateTexts.bind(this))
    }
    
    connectedCallback() {
        let top = new HomeworkLayout()
        this.append(top)
        console.log("Session added to DOM")
    }

    static get observedAttributes () { 
		return [ 'language' ] 
	}

    attributeChangedCallback(name, oldValue, newValue) {
        if(name == 'language') {
            if(oldValue === null) {
                console.log("Language initiated to " + newValue)
            } else {
                console.log("Language changed to " + newValue + " from " + oldValue)
            }
            this.changeLanguage(newValue)
        } else {
            console.log("Unknown property", name)
        }
    }

    get language() {
        let languageCode = this.getAttribute("language")
        return languageCode
    }

    set language(languageCode) {
        this.setAttribute("language", languageCode)
    }

    async changeLanguage(languageCode) {
        let languageFile = "/resources/" + languageCode + ".json"
        let response = await fetch(languageFile)
        HomeworkSession.texts = await response.json()
        this.dispatchEvent(new CustomEvent('texts-loaded', { bubbles: true }))
    }

    updateTexts() {
        HomeworkElement.updateTexts(this)
    }

/*

    homeworkTypeChanged(event) {
        let homeworkType = event.target.value
        console.log("Changed homework type to " + homeworkType )
        let pages = this.querySelectorAll('.page')
        pages.forEach((page) => {
            page.classList.remove('active')
        })
        let page = null
        switch(homeworkType) {
            case 'math':
                page = this.querySelector('homework-page-math')
                page.classList.add('active')
                break
            case 'englishVocabulary':
                page = this.querySelector('homework-page-english-vocabulary')
                page.classList.add('active')
                break
            default:
                console.warn("Unknown type " + homeworkType)
                break
        }
    }
        */
}
HomeworkSession.texts = { }
customElements.define('homework-session', HomeworkSession)