import { prisma } from "./db";

// ── Platform limits ────────────────────────────────────────────────────────────

/** Max change requests an agent may create per rolling hour. */
export const MAX_REQUESTS_PER_HOUR = 15;

/** Max agents a single human account may own. */
export const MAX_AGENTS_PER_USER = 5;

/** Pending-request cap bounds (human-configurable per agent). */
export const MIN_PENDING_LIMIT = 1;
export const MAX_PENDING_LIMIT = 10;
export const DEFAULT_PENDING_LIMIT = 5;

/** Request expiry bounds, in seconds. */
export const DEFAULT_EXPIRY_SECONDS = 30 * 60; // 30 minutes
export const MIN_EXPIRY_SECONDS = 60; // 1 minute
export const MAX_EXPIRY_SECONDS = 12 * 60 * 60; // 12 hours

/** Auto-delete retention bounds, in days. */
export const MIN_AUTO_DELETE_DAYS = 7;
export const DEFAULT_AUTO_DELETE_DAYS = 30;

// ── Pure clamps ────────────────────────────────────────────────────────────────

export function clampPendingLimit(value: number): number {
	if (!Number.isFinite(value)) return DEFAULT_PENDING_LIMIT;
	return Math.min(MAX_PENDING_LIMIT, Math.max(MIN_PENDING_LIMIT, Math.trunc(value)));
}

export function clampExpirySeconds(value: number | undefined | null): number {
	if (value === undefined || value === null || !Number.isFinite(value)) {
		return DEFAULT_EXPIRY_SECONDS;
	}
	return Math.min(MAX_EXPIRY_SECONDS, Math.max(MIN_EXPIRY_SECONDS, Math.trunc(value)));
}

export function clampAutoDeleteDays(value: number): number {
	if (!Number.isFinite(value)) return DEFAULT_AUTO_DELETE_DAYS;
	return Math.max(MIN_AUTO_DELETE_DAYS, Math.trunc(value));
}

// ── Limit checks (DB-backed) ────────────────────────────────────────────────────

export type LimitResult = { allowed: true } | { allowed: false; reason: string };

/** An agent may create at most MAX_REQUESTS_PER_HOUR requests per rolling hour. */
export async function checkAgentHourlyLimit(agentId: number): Promise<LimitResult> {
	const oneHourAgo = new Date(Date.now() - 60 * 60 * 1000);
	const count = await prisma.changeRequest.count({
		where: { agentId, createdAt: { gte: oneHourAgo } },
	});
	if (count >= MAX_REQUESTS_PER_HOUR) {
		return {
			allowed: false,
			reason: `Rate limit reached: an agent may create at most ${MAX_REQUESTS_PER_HOUR} requests per hour`,
		};
	}
	return { allowed: true };
}

/** An agent may have at most `maxPendingRequests` requests in PENDING state. */
export async function checkAgentPendingLimit(
	agentId: number,
	maxPendingRequests: number,
): Promise<LimitResult> {
	const count = await prisma.changeRequest.count({
		where: { agentId, state: "PENDING" },
	});
	if (count >= maxPendingRequests) {
		return {
			allowed: false,
			reason: `Pending limit reached: this agent may have at most ${maxPendingRequests} pending requests at a time`,
		};
	}
	return { allowed: true };
}

/** A human may own at most MAX_AGENTS_PER_USER agents. */
export async function checkAgentCountLimit(userId: number): Promise<LimitResult> {
	const count = await prisma.agent.count({ where: { ownerId: userId } });
	if (count >= MAX_AGENTS_PER_USER) {
		return {
			allowed: false,
			reason: `Agent limit reached: a human may own at most ${MAX_AGENTS_PER_USER} agents`,
		};
	}
	return { allowed: true };
}