import { CdkMenuTrigger } from '@angular/cdk/menu';
import { computed, Directive, effect, forwardRef, inject, input } from '@angular/core';
import {
	createMenuPosition,
	MENU_SIDE,
	type MenuAlign,
	type MenuSide,
} from '@spartan-ng/brain/core';
import { injectHlmDropdownMenuConfig } from './hlm-dropdown-menu-token';

@Directive({
	selector: '[hlmDropdownMenuTrigger]',
	providers: [{ provide: MENU_SIDE, useExisting: forwardRef(() => HlmDropdownMenuTrigger) }],
	hostDirectives: [
		{
			directive: CdkMenuTrigger,
			inputs: [
				'cdkMenuTriggerFor: hlmDropdownMenuTrigger',
				'cdkMenuTriggerData: hlmDropdownMenuTriggerData',
			],
			outputs: ['cdkMenuOpened: hlmDropdownMenuOpened', 'cdkMenuClosed: hlmDropdownMenuClosed'],
		},
	],
	host: { 'data-slot': 'dropdown-menu-trigger' },
})
export class HlmDropdownMenuTrigger {
	private readonly _cdkTrigger = inject(CdkMenuTrigger, { host: true });
	private readonly _config = injectHlmDropdownMenuConfig();

	public readonly align = input<MenuAlign>(this._config.align);
	public readonly side = input<MenuSide>(this._config.side);

	private readonly _menuPosition = computed(() => createMenuPosition(this.align(), this.side()));

	constructor() {
		// CDK sets transform-origin on the menu content from the resolved position; the content reads it to
		// animate from the anchored corner and to derive its data-side. Cast tolerates @angular/cdk < 21.2
		// (we still support >=21.0), where the property is absent and the assignment is a harmless no-op.
		(this._cdkTrigger as { transformOriginSelector?: string }).transformOriginSelector =
			'[data-slot="dropdown-menu"]';

		effect(() => {
			this._cdkTrigger.menuPosition = this._menuPosition();
		});
	}
}