const DEFAULTS = {
    threshold: 2,
    maximumItems: 5,
    highlightTyped: true,
    highlightClass: 'text-primary',
    label: 'label',
    value: 'value',
    showValue: false,
    showValueBeforeLabel: false,
};

class Autocomplete {
    constructor(field, options) {
        this.field = field;
        this.options = Object.assign({}, DEFAULTS, options);
        this.dropdown = null;

        field.parentNode.classList.add('dropdown');
        field.setAttribute('data-bs-toggle', 'dropdown');
        field.classList.add('dropdown-toggle');

        const dropdown = ce(`<div class="dropdown-menu"></div>`);
        if (this.options.dropdownClass)
            dropdown.classList.add(this.options.dropdownClass);

        insertAfter(dropdown, field);

        this.dropdown = new bootstrap.Dropdown(field, this.options.dropdownOptions);

        field.addEventListener('click', (e) => {
            if (this.createItems() === 0) {
                e.stopPropagation();
                this.dropdown.hide();
            }
        });

        field.addEventListener('input', () => {
            if (this.options.onInput)
                this.options.onInput(this.field.value);
            this.renderIfNeeded();
        });

        field.addEventListener('keydown', (e) => {
            if (e.keyCode === 27) {
                this.dropdown.hide();
                return;
            }
            if (e.keyCode === 40) {
                this.dropdown._menu.children[0]?.focus();
                return;
            }
        });
    }

    setData(data) {
        this.options.data = data;
        this.renderIfNeeded();
    }

    renderIfNeeded() {
        if (this.createItems() > 0)
            this.dropdown.show();
        else
            this.field.click();
    }

    createItem(lookup, item) {
        let label;
        if (this.options.highlightTyped) {
            const idx = removeDiacritics(item.label)
                .toLowerCase()
                .indexOf(removeDiacritics(lookup).toLowerCase());
            const className = Array.isArray(this.options.highlightClass) ? this.options.highlightClass.join(' ')
                : (typeof this.options.highlightClass == 'string' ? this.options.highlightClass : '');
            label = item.label.substring(0, idx)
                + `<span class="${className}">${item.label.substring(idx, idx + lookup.length)}</span>`
                + item.label.substring(idx + lookup.length, item.label.length);
        } else {
            label = item.label;
        }

        if (this.options.showValue) {
            if (this.options.showValueBeforeLabel) {
                label = `${item.value} ${label}`;
            } else {
                label += ` ${item.value}`;
            }
        }

        return ce(`<button type="button" class="dropdown-item" data-label="${item.label}" data-value="${item.value}">${label}</button>`);
    }

    createItems() {
        const lookup = this.field.value;
        if (lookup.length < this.options.threshold) {
            this.dropdown.hide();
            return 0;
        }

        const items = this.field.nextSibling;
        items.innerHTML = '';

        const keys = Object.keys(this.options.data);

        let count = 0;
        for (let i = 0; i < keys.length; i++) {
            const key = keys[i];
            const entry = this.options.data[key];
            const item = {
                label: this.options.label ? entry[this.options.label] : key,
                value: this.options.value ? entry[this.options.value] : entry
            };

            if (removeDiacritics(item.label).toLowerCase().indexOf(removeDiacritics(lookup).toLowerCase()) >= 0) {
                items.appendChild(this.createItem(lookup, item));
                if (this.options.maximumItems > 0 && ++count >= this.options.maximumItems)
                    break;
            }
        }

        this.field.nextSibling.querySelectorAll('.dropdown-item').forEach((item) => {
            item.addEventListener('click', (e) => {
                let dataLabel = e.target.getAttribute('data-label');
                let dataValue = e.target.getAttribute('data-value');

                this.field.value = dataLabel;

                if (this.options.onSelectItem) {
                    this.options.onSelectItem({
                        value: dataValue,
                        label: dataLabel
                    });
                }

                this.dropdown.hide();
            })
        });

        return items.childNodes.length;
    }
}

/**
 * @param html
 * @returns {Node}
 */
function ce(html) {
    let div = document.createElement('div');
    div.innerHTML = html;
    return div.firstChild;
}

/**
 * @param elem
 * @param refElem
 * @returns {*}
 */
function insertAfter(elem, refElem) {
    return refElem.parentNode.insertBefore(elem, refElem.nextSibling);
}

/**
 * @param {String} str
 * @returns {String}
 */
function removeDiacritics(str) {
    return str
        .normalize('NFD')
        .replace(/[\u0300-\u036f]/g, '');
}