/**
 * Canonical ~/.pi/agent/* path helpers and JSON file I/O.
 *
 * Both pi-credential-vault and pi-multicodex read and write files under
 * the agent directory. This module provides a single, permission-aware
 * set of helpers so path construction and file I/O are not duplicated.
 */
import { existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
import { mkdir, readFile, stat, writeFile } from "node:fs/promises";
import { dirname, join } from "node:path";
import { getAgentDir } from "@mariozechner/pi-coding-agent";

// ---------------------------------------------------------------------------
// Path helpers
// ---------------------------------------------------------------------------

/**
 * Resolve a path relative to the agent directory (~/.pi/agent/).
 *
 * When called with no arguments, returns the agent directory itself.
 */
export function getAgentPath(...segments: string[]): string {
	return join(getAgentDir(), ...segments);
}

/**
 * Get the canonical path to the shared settings file.
 *
 * Returns `~/.pi/agent/settings.json`.
 */
export function getAgentSettingsPath(): string {
	return getAgentPath("settings.json");
}

/**
 * Get the canonical path to the native auth credentials file.
 *
 * Returns `~/.pi/agent/auth.json`.
 */
export function getAgentAuthPath(): string {
	return getAgentPath("auth.json");
}

// ---------------------------------------------------------------------------
// Directory helpers
// ---------------------------------------------------------------------------

/**
 * Ensure the parent directory of a file path exists.
 *
 * Creates intermediate directories as needed with mode 0o755.
 * No-op if the directory already exists.
 */
export function ensureParentDir(filePath: string): void {
	const dir = dirname(filePath);
	if (!existsSync(dir)) {
		mkdirSync(dir, { recursive: true, mode: 0o755 });
	}
}

/**
 * Async variant of ensureParentDir.
 */
export async function ensureParentDirAsync(filePath: string): Promise<void> {
	const dir = dirname(filePath);
	try {
		await stat(dir);
	} catch {
		await mkdir(dir, { recursive: true, mode: 0o755 });
	}
}

// ---------------------------------------------------------------------------
// JSON file I/O (sync)
// ---------------------------------------------------------------------------

/**
 * Read a JSON file and return its contents as a plain object.
 *
 * Returns an empty object if the file does not exist, is not valid JSON,
 * or does not contain a JSON object at the top level.
 */
export function readJsonObjectFile(filePath: string): Record<string, unknown> {
	try {
		if (!existsSync(filePath)) {
			return {};
		}
		const raw = readFileSync(filePath, "utf-8");
		const parsed: unknown = JSON.parse(raw);
		if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) {
			return {};
		}
		return parsed as Record<string, unknown>;
	} catch {
		return {};
	}
}

/**
 * Write a plain object to a JSON file.
 *
 * Creates parent directories if they do not exist.
 * Uses 2-space indentation for human readability.
 */
export function writeJsonObjectFile(
	filePath: string,
	data: Record<string, unknown>,
): void {
	ensureParentDir(filePath);
	writeFileSync(filePath, JSON.stringify(data, null, 2), "utf-8");
}

// ---------------------------------------------------------------------------
// JSON file I/O (async)
// ---------------------------------------------------------------------------

/**
 * Async variant of readJsonObjectFile.
 */
export async function readJsonObjectFileAsync(
	filePath: string,
): Promise<Record<string, unknown>> {
	try {
		const stats = await stat(filePath).catch(() => undefined);
		if (!stats) {
			return {};
		}
		const raw = await readFile(filePath, "utf-8");
		const parsed: unknown = JSON.parse(raw);
		if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) {
			return {};
		}
		return parsed as Record<string, unknown>;
	} catch {
		return {};
	}
}

/**
 * Async variant of writeJsonObjectFile.
 */
export async function writeJsonObjectFileAsync(
	filePath: string,
	data: Record<string, unknown>,
): Promise<void> {
	await ensureParentDirAsync(filePath);
	await writeFile(filePath, JSON.stringify(data, null, 2), "utf-8");
}