import { buildIcon, getIcon, iconLoaded, loadIcon, type IconifyIcon } from 'iconify-icon';
import { loading } from './components.util';
import { deepEquals } from './general.util';

export type RedrawableHTML = HTMLElement & { update?: (recursive: boolean) => void }
export type Node = HTMLElement & { update?: (recursive: boolean) => void } | SVGElement | Text | undefined;
export type NodeChildren = Array<Reactive<Node>> | undefined;

export type Class = Reactive<string | Array<Class> | Record<string, boolean> | undefined>;
type Listener<K extends keyof HTMLElementEventMap> = | ((this: RedrawableHTML, ev: HTMLElementEventMap[K]) => any) | {
    options?: boolean | AddEventListenerOptions;
    listener: (this: RedrawableHTML, ev: HTMLElementEventMap[K]) => any;
} | undefined;

export type Reactive<T> = T | (() => T);
export interface DOMList<T> extends Array<T>{
    render(redraw?: boolean): void;
};

export interface NodeProperties
{
    attributes?: Record<string, Reactive<string | undefined | boolean | number>>;
    text?: Reactive<string | number | Text>;
    class?: Class;
    style?: Reactive<Record<string, string | undefined | boolean | number> | string>;
    listeners?: {
        [K in keyof HTMLElementEventMap]?: Listener<K>
    };
}

let defered = false, _deferSet = new Set<() => void>();
const _defer = (fn: () => void) => {
    if(!defered)
    {
        defered = true;
        queueMicrotask(() => {
            _deferSet.forEach(e => e());
            _deferSet.clear();
            defered = false;
        });
    }

    _deferSet.add(fn);
}
let reactiveEffect: (() => void) | null = null;
const _reactiveCache = new WeakMap();
// Store a Weak map of all the tracked object.
// For each object, we have a map of its properties, allowing us to effectively listen to absolutely everything on the object
// For a given property, we have a set of "effect" (function called on value update)
const _tracker = new WeakMap<{}, Map<string | symbol, Set<() => void>>>();
function trigger<T extends {}>(target: T, key: string | symbol)
{
    const dependencies = _tracker.get(target)
    if(!dependencies) return;

    const set = dependencies.get(key);
    set?.forEach(e => e());
}
function track<T extends {}>(target: T, key: string | symbol)
{
    if(!reactiveEffect) return;

    let dependencies = _tracker.get(target);
    if(!dependencies)
    {
        dependencies = new Map();
        _tracker.set(target, dependencies);
    }

    let set = dependencies.get(key);
    if(!set)
    {
        set = new Set();
        dependencies.set(key, set);
    }

    set.add(reactiveEffect);
}
export function reactive<T extends {}>(obj: T): T
{
    if(_reactiveCache.has(obj))
        return _reactiveCache.get(obj)!;

    const proxy = new Proxy<T>(obj, {
        get: (target, key, receiver) => {
            track(target, key);
            const value = Reflect.get(target, key, receiver);

            if(value && typeof value === 'object')
                return reactive(value);

            return value;
        },
        set: (target, key, value, receiver) => {
            const old = Reflect.get(target, key, receiver);
            const result = Reflect.set(target, key, value, receiver);

            if(old !== value)
                _defer(() => trigger(target, key));
            
            return result;
        },
    });

    _reactiveCache.set(obj, proxy);
    return proxy;
}
function requireReactive<T>(reactiveProperty: Reactive<T>, effect: (processed: T) => void)
{
    if(typeof reactiveProperty !== 'function')
        return effect(reactiveProperty);
    else
    {
        // Function wrapping to keep the context safe and secured.
        // Also useful to retrigger the tracking system if the reactive property provides new properties (via conditions for example)
        const secureEffect = () => effect((reactiveProperty as () => T)());
        const secureContext = () => {
            reactiveEffect = secureContext;
            try {
                secureEffect();
            } finally {
                reactiveEffect = null;
            }
        };

        secureContext();
    }
}

export const cancelPropagation = (e: Event) => e.stopImmediatePropagation();
export function dom<T extends keyof HTMLElementTagNameMap>(tag: T, properties?: NodeProperties, children?: NodeChildren): HTMLElementTagNameMap[T] & { update?: (recursive: boolean) => void };
export function dom<T extends keyof HTMLElementTagNameMap, U extends any>(tag: T, properties?: NodeProperties, children?: { render: (data: U) => Node, list?: Array<U>, redraw?: boolean }): HTMLElementTagNameMap[T] & { array?: DOMList<U>, update?: (recursive: boolean) => void };
export function dom<T extends keyof HTMLElementTagNameMap, U extends any>(tag: T, properties?: NodeProperties, children?: NodeChildren | { render: (data: U) => Node, list?: Array<U>, redraw?: boolean }): HTMLElementTagNameMap[T] & { array?: DOMList<U>, update?: (recursive: boolean) => void }
{
    const element = document.createElement(tag) as HTMLElementTagNameMap[T] & { array?: DOMList<U>, update: (recursive: boolean) => void };
    let setup = true, updating = false;

    const _cache = new Map<U, Node>();

    const update = (recursive: boolean) => {
        updating = true;
        
        if(children !== undefined && (setup || recursive))
        {
            if(Array.isArray(children))
            {
                for(const c of children)
                {
                    const child = typeof c === 'function' ? c() : c;
                    if(child !== undefined)
                    {
                        element.appendChild(child);
                        recursive && 'update' in child && _defer(() => child.update!(true));
                    }
                }
            }
            else if(children.list !== undefined)
            {
                if(setup)
                {
                    children.list.forEach(e => _cache.set(e, children.render(e)));

                    const _push = children.list.push;
                    children.list.push = (...items: U[]) => { 
                        items.forEach(e => {
                            if(!_cache.has(e))
                            {
                                const dom = children.render(e);
                                _cache.set(e, dom);
                                dom && element.appendChild(dom);
                            }
                            else
                            {
                                const dom = _cache.get(e);
                                dom && element.appendChild(dom);
                            }
                        });
                        if(children.redraw) _defer(() => update(false));
                        return _push.bind(children.list)(...items);
                    };
                    const _splice = children.list.splice;
                    children.list.splice = (start: number, deleteCount: number, ...items: U[]) => {
                        const list = _splice.bind(children.list)(start, deleteCount, ...items);
                        list.forEach(e => { if(!children.list!.find(_e => _e === e)) _cache.delete(e); });
                        element.array!.render();
                        return list;
                    };
                }
                else if(recursive)
                    _cache.forEach((v, k) => v && 'update' in v && v.update!(true));
                
                element.array = children.list as DOMList<U>;
                element.array.render = (redraw?: boolean) => {
                    element.replaceChildren(...children.list?.map(e => _cache.get(e)).filter(e => !!e) ?? []);
                    if((redraw !== undefined || children.redraw !== undefined) && !updating) _defer(() => update(redraw ?? children.redraw!));
                }

                element.array.render();
            }
        }

        if(properties?.attributes)
        {
            for(const [k, v] of Object.entries(properties.attributes))
            {
                if(!setup && typeof v !== 'function') continue;

                const value = typeof v === 'function' ? v() : v;
                if(typeof value === 'string' || typeof value === 'number') element.setAttribute(k, value.toString(10));
                else if(typeof value === 'boolean') element.toggleAttribute(k, value);
            }
        }

        if(properties?.text && (setup || typeof properties.text === 'function'))
        {
            requireReactive(properties.text, (text) => {
                if(typeof text === 'string')
                    element.textContent = text;
                else if(typeof text === 'number')
                    element.textContent = text.toString();
                else
                    element.appendChild(text as Text);
            })
        }

        if(properties?.listeners && setup)
        {
            for(let [k, v] of Object.entries(properties.listeners)) 
            {
                const key = k as keyof HTMLElementEventMap, value = v as Listener<typeof key>;
                if(typeof value === 'function') 
                    element.addEventListener(key, value.bind(element));
                else if(value)
                    element.addEventListener(key, value.listener.bind(element), value.options);
            }
        }

        styling(element, properties ?? {});
        updating = false;
    };

    update(false);
    setup = false;
    element.update = update;

    return element;
}
export function div(cls?: Class, children?: NodeChildren): HTMLElementTagNameMap['div'] & { update?: (recursive: boolean) => void }
export function div<U extends any>(cls?: Class, children?: { render: (data: U) => Node, list?: Array<U>, redraw?: boolean }): HTMLElementTagNameMap['div'] & { array: DOMList<U>, update?: (recursive: boolean) => void }
export function div<U extends any>(cls?: Class, children?: NodeChildren | { render: (data: U) => Node, list?: Array<U>, redraw?: boolean }): HTMLElementTagNameMap['div'] & { array?: DOMList<U>, update?: (recursive: boolean) => void }
{
    //@ts-expect-error
    return dom("div", { class: cls }, children);
}
export function span(cls?: Class, text?: Reactive<string | number | Text>): HTMLElementTagNameMap['span'] & { update?: (recursive: boolean) => void }
{
    return dom("span", { class: cls, text: text });
}
export function svg<K extends keyof SVGElementTagNameMap>(tag: K, properties?: NodeProperties, children?: SVGElement[]): SVGElementTagNameMap[K]
{
    const element = document.createElementNS("http://www.w3.org/2000/svg", tag);

    if(children && children.length > 0)
        for(const c of children) if(c !== undefined) element.appendChild(c);

    if(properties?.attributes)
        for(const [k, v] of Object.entries(properties.attributes))
            if(typeof v === 'string') element.setAttribute(k, v);
            else if(typeof v === 'boolean') element.toggleAttribute(k, v);

    if(properties?.text && typeof properties.text === 'string')
        element.textContent = properties.text;

    styling(element, properties ?? {});

    return element;
}
export function text(data: Reactive<string | number>): Text
{
    const text = document.createTextNode('');
    requireReactive(data, (txt) => text.textContent = txt.toString());
    return text;
}
export function styling(element: SVGElement | RedrawableHTML, properties: { 
    class?: Class;
    style?: Reactive<Record<string, string | undefined | boolean | number> | string>; 
}): SVGElement | RedrawableHTML
{
    if(properties?.class)
    {
        element.setAttribute('class', mergeClasses(properties.class));
    }

    if(properties?.style)
    {
        if(typeof properties.style === 'string')
        {
            element.setAttribute('style', properties.style);
        }
        else
            for(const [k, v] of Object.entries(properties.style)) if(v !== undefined && v !== false) element.attributeStyleMap.set(k, v);
    }

    return element;
}

export interface IconProperties
{
    mode?: 'svg' | 'style' | 'bg' | 'mask';
    inline?: boolean;
    width?: string | number;
    height?: string | number;
    hFlip?: boolean;
    vFlip?: boolean;
    rotate?: number;
    style?: Reactive<Record<string, string | undefined> | string>;
    class?: Class;
}
const iconLoadingRegistry: Map<string, Promise<Required<IconifyIcon>> | null | undefined> = new Map();
export function icon(name: string, properties?: IconProperties)
{
    const element = dom('div', { class: properties?.class, style: properties?.style });
    const build = (icon: IconifyIcon | null | undefined) => {
        if(!icon) return element.replaceChildren();
        const built = buildIcon(icon, properties);
        const dom = svg('svg', { attributes: built.attributes });
        dom.innerHTML = built.body;
        element.replaceChildren(dom);
    }
    if(!iconLoaded(name))
    {
        element.appendChild(loading('small'));
        if(!iconLoadingRegistry.has(name)) iconLoadingRegistry.set(name, loadIcon(name));
        iconLoadingRegistry.get(name)?.then(build);
    }
    else build(getIcon(name));
    
    return element;
}

export function mergeClasses(cls: Class): string
{
    const classes = typeof cls === 'function' ? cls() : cls;
    if(typeof classes === 'string')
    {
        return classes.trim();
    }
    else if(Array.isArray(classes))
    {
        return classes.map(e => mergeClasses(e)).join(' ');
    }
    else if(classes)
    {
        return Object.entries(classes).filter(e => e[1]).map(e => e[0].trim()).join(' ');
    }
    else
    {
        return '';
    }
}