const A = (...args) => {
    const classname = args[0].constructor.name;

    if (classname === 'String') {
        const c = document.querySelectorAll(args[0]);
        return new A._Collection(c);
    }
    if (classname === 'NodeList') {
        return new A._Collection(args[0]);
    }
    // TODO: lol this is such a hack
    if (classname.startsWith('HTML')) {
        return new A._Collection([args[0]]);
    }
    if (classname === 'Function') {
        return A.on('DOMContentLoaded', args[0]);
    }

    throw new Error(`Function "A" does not accept first argument of type ${typeof args[0]}`);
};

A.on = (event, handler) => {
    document.addEventListener(event, handler);
};

// --- Collection class ---

A._Collection = class {
    constructor(list) {
        this._list = list;
        this.reactors = [];
    }
};

A._Collection.prototype._forCollection = function (f) {
    for (let i = 0; i < this._list.length; i++) {
        f(this._list[i], i);
    }
    return this;
};

A._Collection.prototype.html = function (html) {
    return this._forCollection((el, _) => {
        el.innerHTML = html;
    });
};

A._Collection.prototype.load = async function (url) {
    const res = await fetch(url);
    if (!res.ok) {
        console.error(`load(${url}) failed with code ${res.status}`);
        return;
    }
    const html = await res.text();

    return this._forCollection((el, _) => {
        el.innerHTML = html;
    });
};

A._Collection.prototype.on = function (event, handler) {
    return this._forCollection((el, _) => {
        el.addEventListener(event, handler);
    });
};

A._Collection.prototype.each = function (handler) {
    return this._forCollection((el, i) => {
        handler(el, i);
    });
};

A._Collection.prototype.hide = function () {
    return this._forCollection((el, _) => {
        el.style.display = 'none';
    });
};

A._Collection.prototype.show = function () {
    return this._forCollection((el, _) => {
        el.style.display = 'inline';
    });
};

A._Collection.prototype.remove = function () {
    return this._forCollection((el, _) => {
        el.parentNode.removeChild(el);
    });
};

A._Collection.prototype.css = function (...args) {
    if (typeof args[0] === 'string' && typeof args[1] === 'string') {
        return this._forCollection((el, _) => {
            el.style[args[0]] = args[1];
        });
    } else if (typeof args[0] === 'object') {
        return this._forCollection((el, _) => {
            for (const [prop, value] of Object.entries(args[0])) {
                el.style[prop] = value;
            }
        });
    } else {
        throw new Error(`Method "css" does not accept first argument of type ${typeof handler}`);
    }
};

A._Collection.prototype.createReactor = function (values, watchData=undefined, elementIndex=undefined) {
    const el = this._list[elementIndex];

    const reactor = new A._Reactor(values, el, watchData);
    this.reactors.push(reactor);
    return reactor;
};

// --- Reactor class ---

A._Reactor = class {
    constructor(values, element=undefined, watchData=undefined) {
        this.values = values;
        this._data = {};
        this.element = element;
        
        if (watchData) {
            this.watch(watchData);
        }
    }
};

A._Reactor.prototype.watch = function (value) {
    if (typeof value === 'object') {
        // Format of config object { valueThatChanged: 'propertytoupdate' }
        if (!this.element) {
            throw new Error(`Method "watch" requires that "element" argument must exist in its class when being passed an object as an argument`);
        }

        for (const [i, v] of Object.entries(value)) {
            Object.defineProperty(this.values, i, { 
                set: (x) => {
                    this._data[value] = x;

                    if (typeof v === 'function') {
                        v(x);
                    } else if (typeof v === 'string') {
                        if (v.startsWith('!')) {
                            // Property

                            this.element[v.substring(1)] = x;
                            return;
                        }
                        if (v.startsWith('.')) {
                            // Attribute
                            
                            this.element.setAttribute(v.substring(1), x);
                            return;
                        }
                    }

                    // TODO: Don't blindly trust that the property exists.
                    this.element.setAttribute(v, x);
                }
            });
        }
    } else {
        throw new Error(`Method "watch" does not accept value argument of type ${typeof value}`);
    }
};