export interface PromptDispatchInput {
	cwd: string;
	runId: string;
	phase: string;
	userText: string;
	now?: number;
	holdMs?: number;
}

export interface PromptDispatchDecision {
	admitted: boolean;
	key: string;
	fingerprint: string;
	reason?: string;
}

const DEFAULT_HOLD_MS = 3000;
const recentDispatches = new Map<string, { fingerprint: string; admittedAt: number }>();

export function admitPromptDispatch(input: PromptDispatchInput): PromptDispatchDecision {
	const now = input.now ?? Date.now();
	const holdMs = input.holdMs ?? DEFAULT_HOLD_MS;
	pruneExpiredDispatches(now, holdMs);

	const key = dispatchKey(input);
	const fingerprint = stableHash([input.cwd, input.runId, input.phase, normalizeText(input.userText)].join("\n"));
	const previous = recentDispatches.get(key);
	if (previous?.fingerprint === fingerprint && now - previous.admittedAt <= holdMs) {
		return {
			admitted: false,
			key,
			fingerprint,
			reason: `重复内部 workflow prompt 已在 ${now - previous.admittedAt}ms 内登记，拒绝再次注入。`,
		};
	}

	recentDispatches.set(key, { fingerprint, admittedAt: now });
	return { admitted: true, key, fingerprint };
}

export function resetPromptDispatchGateForTests(): void {
	recentDispatches.clear();
}

function dispatchKey(input: Pick<PromptDispatchInput, "cwd" | "runId" | "phase">): string {
	return [normalizePath(input.cwd), input.runId.trim(), input.phase.trim()].join("::");
}

function pruneExpiredDispatches(now: number, holdMs: number): void {
	for (const [key, value] of recentDispatches) {
		if (now - value.admittedAt > holdMs) recentDispatches.delete(key);
	}
}

function normalizePath(path: string): string {
	return path.trim().replace(/\\/g, "/").toLowerCase();
}

function normalizeText(text: string): string {
	return text.trim().replace(/\s+/g, " ");
}

function stableHash(text: string): string {
	let hash = 2166136261;
	for (let index = 0; index < text.length; index++) {
		hash ^= text.charCodeAt(index);
		hash = Math.imul(hash, 16777619);
	}
	return (hash >>> 0).toString(16).padStart(8, "0");
}