import * as fs from "node:fs";
import * as path from "node:path";
import { DEFAULT_FILE_SYSTEM_RETRY_DELAYS_MS, runFileSystemOperationWithRetry, waitForFileSystemRetry } from "./file-system-retry.ts";

type AtomicJsonFs = Pick<typeof fs, "mkdirSync" | "writeFileSync" | "renameSync" | "rmSync">;

type AtomicJsonWriterOptions = {
	fs?: AtomicJsonFs;
	now?: () => number;
	pid?: number;
	random?: () => number;
	mode?: number;
	retryRenameErrors?: boolean;
	retryDirectoryErrors?: boolean;
	retryDelaysMs?: readonly number[];
	wait?: (delayMs: number) => void;
};

function renameWithRetry(
	fsImpl: AtomicJsonFs,
	sourcePath: string,
	targetPath: string,
	retryDelaysMs: readonly number[],
	wait: (delayMs: number) => void,
): void {
	runFileSystemOperationWithRetry(() => {
		fsImpl.renameSync(sourcePath, targetPath);
	}, { retryDelaysMs, wait });
}

export function createAtomicJsonWriter(options: AtomicJsonWriterOptions = {}): (filePath: string, payload: object) => void {
	const fsImpl = options.fs ?? fs;
	const now = options.now ?? Date.now;
	const pid = options.pid ?? process.pid;
	const random = options.random ?? Math.random;
	const mode = options.mode;
	const retryRenameErrors = options.retryRenameErrors ?? process.platform === "win32";
	const retryDirectoryErrors = options.retryDirectoryErrors ?? retryRenameErrors;
	const retryDelaysMs = options.retryDelaysMs ?? DEFAULT_FILE_SYSTEM_RETRY_DELAYS_MS;
	const renameRetryDelaysMs = retryRenameErrors ? retryDelaysMs : [];
	const directoryRetryDelaysMs = retryDirectoryErrors ? retryDelaysMs : [];
	const wait = options.wait ?? waitForFileSystemRetry;
	return (filePath: string, payload: object): void => {
		runFileSystemOperationWithRetry(() => {
			fsImpl.mkdirSync(path.dirname(filePath), { recursive: true });
		}, { retryDelaysMs: directoryRetryDelaysMs, wait });
		const tempPath = path.join(
			path.dirname(filePath),
			`.${path.basename(filePath)}.${pid}.${now()}.${random().toString(36).slice(2)}.tmp`,
		);
		try {
			fsImpl.writeFileSync(tempPath, JSON.stringify(payload, null, 2), mode === undefined ? "utf-8" : { encoding: "utf-8", mode });
			renameWithRetry(fsImpl, tempPath, filePath, renameRetryDelaysMs, wait);
		} finally {
			fsImpl.rmSync(tempPath, { force: true });
		}
	};
}

export const writeAtomicJson = createAtomicJsonWriter();
export const writePrivateAtomicJson = createAtomicJsonWriter({ mode: 0o600 });