const smForm = document.createElement('template');
smForm.innerHTML = `
            <style>
            *{
                padding: 0;
                margin: 0;
                box-sizing: border-box;
            }
            :host{
                display: grid;
                width: 100%;
            }
            form{
                display: inherit;
                gap: var(--gap, 1.5rem);
                width: 100%;
            }
            </style>
            <form part="form" onsubmit="return false">
                <slot></slot>
            </form>
        `;

customElements.define('sm-form', class extends HTMLElement {
	constructor() {
		super();
		this.attachShadow({
			mode: 'open'
		}).append(smForm.content.cloneNode(true));

		this.form = this.shadowRoot.querySelector('form');
		this.invalidFieldsCount;
		this.skipSubmit = false;
		this.isFormValid = undefined;
		this.supportedElements = 'input, sm-input, sm-textarea, sm-checkbox, tags-input, file-input, sm-switch, sm-radio';
		this._requiredElements = []
		this.debounce = this.debounce.bind(this);
		this._checkValidity = this._checkValidity.bind(this);
		this.handleKeydown = this.handleKeydown.bind(this);
		this.reset = this.reset.bind(this);
		this.elementsChanged = this.elementsChanged.bind(this);
	}
	static get observedAttributes() {
		return ['skip-submit'];
	}
	get validity() {
		return this.isFormValid;
	}
	debounce(callback, wait) {
		let timeoutId = null;
		return (...args) => {
			window.clearTimeout(timeoutId);
			timeoutId = window.setTimeout(() => {
				callback.apply(null, args);
			}, wait);
		};
	}
	_checkValidity() {
		if (!this.submitButton || this._requiredElements.length === 0) return;
		this.invalidFieldsCount = 0
		this._requiredElements.forEach(([elem, isWC]) => {
			if (!elem.disabled && isWC && !elem.isValid || !isWC && !elem.checkValidity())
				this.invalidFieldsCount++;
		});
		if (this.isFormValid === (this.invalidFieldsCount === 0)) return;
		this.isFormValid = this.invalidFieldsCount === 0;
		this.dispatchEvent(new CustomEvent(this.isFormValid ? 'valid' : 'invalid', {
			bubbles: true,
			composed: true,
		}));
		if (!this.skipSubmit)
			this.submitButton.disabled = !this.isFormValid;
	}
	handleKeydown(e) {
		if (e.key === 'Enter' && e.target.tagName.includes('INPUT')) {
			if (this.invalidFieldsCount === 0) {
				if (this.submitButton) {
					this.submitButton.click();
				}
				this.dispatchEvent(new CustomEvent('submit', {
					bubbles: true,
					composed: true,
				}));
			} else {
				for (const [elem, isWC] of this._requiredElements) {
					const invalid = isWC ? !elem.isValid : !elem.checkValidity();
					if (invalid) {
						(elem?.shadowRoot?.lastElementChild || elem).animate([
							{ transform: 'translateX(-1rem)' },
							{ transform: 'translateX(1rem)' },
							{ transform: 'translateX(-0.5rem)' },
							{ transform: 'translateX(0.5rem)' },
							{ transform: 'translateX(0)' },
						], {
							duration: 300,
							easing: 'ease'
						});
						if (isWC) elem.focusIn();
						else elem.focus();
						break;
					}
				}
			}
		}
	}
	reset() {
		this.formElements.forEach(([elem, isWC]) => {
			if (isWC) elem.reset();
			else elem.value = '';
		});
	}
	elementsChanged() {
		this.formElements = [...this.querySelectorAll(this.supportedElements)].map(elem => {
			return [elem, elem.tagName.includes('-')];
		});
		this._requiredElements = this.formElements.filter(([elem]) => elem.hasAttribute('required'));
		this.submitButton = this.querySelector('[variant="primary"], [type="submit"]');
		this.resetButton = this.querySelector('[type="reset"]');
		if (this.resetButton) {
			this.resetButton.addEventListener('click', this.reset);
		}
		this._checkValidity();
	}
	connectedCallback() {
		const updateFormDecedents = this.debounce(this.elementsChanged, 100);
		this.addEventListener('input', this.debounce(this._checkValidity, 100));
		this.addEventListener('keydown', this.debounce(this.handleKeydown, 100));
		this.shadowRoot.querySelector('slot').addEventListener('slotchange', updateFormDecedents);
		this.mutationObserver = new MutationObserver(mutations => {
			mutations.forEach(mutation => {
				if (
					mutation.type === 'childList' &&
					[...mutation.addedNodes].some(node => node.nodeType === 1 && node.querySelector(this.supportedElements)) ||
					[...mutation.removedNodes].some(node => node.nodeType === 1 && node.querySelector(this.supportedElements))
				) {
					updateFormDecedents();
				}
			});
		});
		this.mutationObserver.observe(this, { childList: true, subtree: true });
	}
	attributeChangedCallback(name, oldValue, newValue) {
		if (name === 'skip-submit') {
			this.skipSubmit = newValue !== null;
		}
	}

	disconnectedCallback() {
		this.removeEventListener('input', this.debounce(this._checkValidity, 100));
		this.removeEventListener('keydown', this.debounce(this.handleKeydown, 100));
		this.mutationObserver.disconnect();
	}
});