import { randomBytes } from "node:crypto";
import { existsSync, readFileSync, renameSync, statSync, writeFileSync } from "node:fs";
import { dirname, join } from "node:path";

export function readAdmissionBreaker(sessionId: string): string | null {
	const dataDir = process.env["PLUGIN_DATA"];
	if (typeof dataDir !== "string") return null;
	try {
		const value: unknown = JSON.parse(readFileSync(join(dataDir, "spawn-breaker", `${sessionId}.json`), "utf8"));
		return typeof value === "object" && value !== null && "reason" in value && typeof value.reason === "string"
			? value.reason
			: "capacity limit";
	} catch {
		return null;
	}
}

// These hook budget files are not plan/audit state and remain outside the log.
export function atomicWriteJson(targetPath: string, data: unknown): void {
	const tmp = join(dirname(targetPath), `.tmp-${randomBytes(6).toString("hex")}`);
	writeFileSync(tmp, JSON.stringify(data));
	renameSync(tmp, targetPath);
}
export function isNonEmptyFile(path: string): boolean {
	try {
		return existsSync(path) && statSync(path).size > 0;
	} catch (error) {
		if (error instanceof Error) return false;
		throw error;
	}
}
export function readCount(counterPath: string): number {
	try {
		const parsed: unknown = JSON.parse(readFileSync(counterPath, "utf8"));
		return typeof parsed === "object" &&
			parsed !== null &&
			"count" in parsed &&
			typeof parsed.count === "number" &&
			parsed.count >= 0
			? parsed.count
			: 0;
	} catch (error) {
		if (error instanceof Error) return 0;
		throw error;
	}
}
export function readCounts(counterPath: string): Record<string, number> {
	try {
		const parsed: unknown = JSON.parse(readFileSync(counterPath, "utf8"));
		if (typeof parsed !== "object" || parsed === null || Array.isArray(parsed)) return {};
		const counts: Record<string, number> = {};
		for (const [key, value] of Object.entries(parsed))
			if (typeof value === "number" && value >= 0) counts[key] = value;
		return counts;
	} catch (error) {
		if (error instanceof Error) return {};
		throw error;
	}
}