import { Constructor } from "@implab/core-amd/interfaces";
import { HtmlRendition } from "./tsx/HtmlRendition";
import { WidgetRendition } from "./tsx/WidgetRendition";
import { isElementNode, isWidget, isWidgetConstructor, Rendition } from "./tsx/traits";
import { FunctionRendition } from "./tsx/FunctionRendition";
import Stateful = require("dojo/Stateful");
import _WidgetBase = require("dijit/_WidgetBase");
import { DjxWidgetBase } from "./tsx/DjxWidgetBase";
import { WatchRendition } from "./tsx/WatchRendition";
import { Observable, observe, Subscribable } from "./observable";
import djAttr = require("dojo/dom-attr");
import djClass = require("dojo/dom-class");

export function createElement<T extends Constructor | string | ((props: any) => Element)>(elementType: T, ...args: any[]): Rendition {
    if (typeof elementType === "string") {
        const ctx = new HtmlRendition(elementType);
        if (args)
            args.forEach(x => ctx.visitNext(x));

        return ctx;
    } else if (isWidgetConstructor(elementType)) {
        const ctx = new WidgetRendition(elementType);
        if (args)
            args.forEach(x => ctx.visitNext(x));

        return ctx;
    } else if (typeof elementType === "function") {
        const ctx = new FunctionRendition(elementType as (props: any) => Element);
        if (args)
            args.forEach(x => ctx.visitNext(x));

        return ctx;
    } else {
        throw new Error(`The element type '${elementType}' is unsupported`);
    }
}

export interface EventDetails<T = any> {
    detail: T;
}

export interface EventSelector {
    selectorTarget: HTMLElement;
    target: HTMLElement;
}

export type DojoMouseEvent<T = any> = MouseEvent & EventSelector & EventDetails<T>;

type StatefulProps<T> = T extends Stateful<infer A> ? A :
    T extends _WidgetBase ? T : never;


/**
 * Observers the property and calls render callback each change.
 *
 * @param target The target object which property will be observed.
 * @param prop The name of the property.
 * @param render The callback which will be called every time the value is changed
 * @returns Rendition which is created instantly
 */
export function watch<W extends _WidgetBase, K extends keyof W>(
    target: W,
    prop: K,
    render: (model: W[K]) => any
): Rendition;
/**
 * Observers the property and calls render callback each change.
 *
 * @param target The target object which property will be observed.
 * @param prop The name of the property.
 * @param render The callback which will be called every time the value is changed
 * @returns Rendition which is created instantly
 */
export function watch<T extends Stateful, K extends keyof StatefulProps<T>>(
    target: T,
    prop: K,
    render: (model: StatefulProps<T>[K]) => any
): Rendition;
export function watch<V>(subj: Subscribable<V>, render: (model: V) => unknown): Rendition;
export function watch(
    ...args: [Stateful, string, (model: unknown) => unknown] |
        [Subscribable<unknown>, (model: unknown) => unknown]
) {
    if (args.length === 3) {
        const [target, prop, render] = args;
        return new WatchRendition(
            render,
            observe(({next}) => {
                const h = target.watch<any>(
                    prop,
                    (_prop, oldValue, newValue) => oldValue !== newValue && next(newValue)
                );
                next(target.get(prop));
                return () => h.remove();
            })
        );
    } else {
        const [subj, render] = args;
        return new WatchRendition(render, subj);
    }
}

export const prop: {
    <T extends Stateful, K extends string & keyof StatefulProps<T>>(target: T, name: K): Observable<StatefulProps<T>[K]>;
    <T extends _WidgetBase, K extends keyof T>(target: T, name: K): Observable<T[K]>;
} = (target: Stateful, name: string) => {
    return observe(({next}) => {
        const h = target.watch(
            name,
            (_prop, oldValue, newValue) => oldValue !== newValue && next(newValue)
        );
        next(target.get(name));
        return () => h.remove();
    })
};

export const attach = <W extends DjxWidgetBase, K extends keyof W>(target: W, name: K) => (v: W[K]) => target.set(name, v);

export const bind = <K extends string, T>(attr: K, subj: Subscribable<T>) => {
    let h = { unsubscribe() { } };

    return <E extends (HTMLElement & { [p in K]: T }) | { set(name: K, value: T): void; }>(el: E | undefined) => {
        if (el) {
            if (isElementNode(el)) {
                h = subj.subscribe({
                    next: value => djAttr.set(el, attr, value)
                });
            } else {
                h = subj.subscribe({
                    next: value => el.set(attr, value)
                });
            }
        } else {
            h.unsubscribe();
        }
    }
};

export const toggleClass = (className: string, subj: Subscribable<boolean>) => {
    let h = { unsubscribe() { } };
    return (elOrWidget: HTMLElement | _WidgetBase | undefined) => {
        const el = isWidget(elOrWidget) ? elOrWidget.domNode : elOrWidget;
        if (el) {
            h = subj.subscribe({
                next: v => djClass.toggle(el, className, v)
            });
        } else {
            h.unsubscribe();
        }
    }
}

export const all = <T, A extends JSX.Ref<T>[]>(...cbs: A): JSX.Ref<T> => (arg: T | undefined) => cbs.forEach(cb => cb(arg));

/** Decorates the method which will be registered as the handle for the specified event.
 * This decorator can be applied to DjxWidgetBase subclass methods.
 *
 * ```
 *  @on("click")
 *  _onClick(eventObj: MouseEvent) {
 *      // ...
 *  }
 * ```
 */
export const on = <E extends string>(...eventNames: E[]) =>
    <K extends string,
        T extends DjxWidgetBase<any, { [p in E]: EV }>,
        EV extends Event
    >(
        target: T,
        key: K,
        _descriptor: TypedPropertyDescriptor<(eventObj: EV) => void> | TypedPropertyDescriptor<() => void>
    ): any => {
        const handlers = eventNames.map(eventName => ({ eventName, handlerMethod: key }));
        target._eventHandlers = target._eventHandlers ? target._eventHandlers.concat(handlers) : handlers;
    };