// Terminal focus state signal — non-React access to DECSET 1004 focus events.
export type TerminalFocusState = 'focused' | 'blurred' | 'unknown'

let focusState: TerminalFocusState = 'unknown'
const resolvers: Set<() => void> = new Set()
const subscribers: Set<() => void> = new Set()

export function setTerminalFocused(v: boolean): void {
	focusState = v ? 'focused' : 'blurred'
	for (const cb of subscribers) {
		cb()
	}
	if (!v) {
		for (const resolve of resolvers) {
			resolve()
		}
		resolvers.clear()
	}
}

export function getTerminalFocused(): boolean {
	return focusState !== 'blurred'
}

export function getTerminalFocusState(): TerminalFocusState {
	return focusState
}

// For useSyncExternalStore
export function subscribeTerminalFocus(cb: () => void): () => void {
	subscribers.add(cb)
	return () => {
		subscribers.delete(cb)
	}
}

export function resetTerminalFocusState(): void {
	focusState = 'unknown'
	for (const cb of subscribers) {
		cb()
	}
}