import { ClickEvent } from '../events/click-event.js'
import type { EventHandlerProps } from '../events/event-handlers.js'
import type { DOMElement } from './dom.js'
import { nodeCache } from './node-cache.js'

/**
 * Find the deepest DOM element whose rendered rect contains (col, row).
 */
export function hitTest(node: DOMElement, col: number, row: number): DOMElement | null {
	const rect = nodeCache.get(node)
	if (!rect) return null
	if (col < rect.x || col >= rect.x + rect.width || row < rect.y || row >= rect.y + rect.height) {
		return null
	}
	for (let i = node.childNodes.length - 1; i >= 0; i--) {
		const child = node.childNodes[i]!
		if (child.nodeName === '#text') continue
		const hit = hitTest(child, col, row)
		if (hit) return hit
	}
	return node
}

/**
 * Hit-test the root at (col, row) and bubble a ClickEvent from the deepest
 * containing node up through parentNode.
 */
export function dispatchClick(
	root: DOMElement,
	col: number,
	row: number,
	cellIsBlank = false,
): boolean {
	let target: DOMElement | undefined = hitTest(root, col, row) ?? undefined
	if (!target) return false

	if (root.focusManager) {
		let focusTarget: DOMElement | undefined = target
		while (focusTarget) {
			if (typeof focusTarget.attributes['tabIndex'] === 'number') {
				root.focusManager.handleClickFocus(focusTarget)
				break
			}
			focusTarget = focusTarget.parentNode
		}
	}
	const event = new ClickEvent(col, row, cellIsBlank)
	let handled = false
	while (target) {
		const handler = target._eventHandlers?.onClick as ((event: ClickEvent) => void) | undefined
		if (handler) {
			handled = true
			const rect = nodeCache.get(target)
			if (rect) {
				event.localCol = col - rect.x
				event.localRow = row - rect.y
			}
			handler(event)
			if (event.didStopImmediatePropagation()) return true
		}
		target = target.parentNode
	}
	return handled
}

/**
 * Fire onMouseEnter/onMouseLeave as the pointer moves.
 */
export function dispatchHover(
	root: DOMElement,
	col: number,
	row: number,
	hovered: Set<DOMElement>,
): void {
	const next = new Set<DOMElement>()
	let node: DOMElement | undefined = hitTest(root, col, row) ?? undefined
	while (node) {
		const h = node._eventHandlers as EventHandlerProps | undefined
		if (h?.onMouseEnter || h?.onMouseLeave) next.add(node)
		node = node.parentNode
	}
	for (const old of hovered) {
		if (!next.has(old)) {
			hovered.delete(old)
			if (old.parentNode) {
				;(old._eventHandlers as EventHandlerProps | undefined)?.onMouseLeave?.()
			}
		}
	}
	for (const n of next) {
		if (!hovered.has(n)) {
			hovered.add(n)
			;(n._eventHandlers as EventHandlerProps | undefined)?.onMouseEnter?.()
		}
	}
}