import { chmod, mkdir, readFile, unlink, writeFile } from "node:fs/promises";
import { join } from "node:path";
import { getAgentDir } from "@earendil-works/pi-coding-agent";

export type TokenSource = "env" | "file" | "none";

const TOKEN_DIR = () => join(getAgentDir(), "ticktick");
const TOKEN_FILE = () => join(TOKEN_DIR(), "token");

export function getMcpUrl(): string {
	return process.env.TICKTICK_MCP_URL ?? "https://mcp.ticktick.com/";
}

export async function getTokenSource(): Promise<TokenSource> {
	if (process.env.TICKTICK_ACCESS_TOKEN?.trim() || process.env.TICKTICK_API_KEY?.trim()) {
		return "env";
	}
	if (await hasSavedToken()) return "file";
	return "none";
}

export async function resolveToken(): Promise<string | null> {
	const fromEnv =
		process.env.TICKTICK_ACCESS_TOKEN?.trim() || process.env.TICKTICK_API_KEY?.trim();
	if (fromEnv) return fromEnv;

	try {
		const fromFile = await readFile(TOKEN_FILE(), "utf8");
		return fromFile.trim() || null;
	} catch {
		return null;
	}
}

export async function saveToken(token: string): Promise<void> {
	const trimmed = token.trim();
	if (!trimmed) {
		throw new Error("Token cannot be empty");
	}
	await mkdir(TOKEN_DIR(), { recursive: true });
	await writeFile(TOKEN_FILE(), trimmed, { mode: 0o600 });
	await chmod(TOKEN_FILE(), 0o600);
}

export async function clearToken(): Promise<boolean> {
	try {
		await unlink(TOKEN_FILE());
		return true;
	} catch {
		return false;
	}
}

export async function hasSavedToken(): Promise<boolean> {
	try {
		const content = await readFile(TOKEN_FILE(), "utf8");
		return Boolean(content.trim());
	} catch {
		return false;
	}
}

export function getTokenFilePath(): string {
	return TOKEN_FILE();
}

export function describeTokenSource(source: TokenSource): string {
	switch (source) {
		case "env":
			return "environment variable (TICKTICK_ACCESS_TOKEN)";
		case "file":
			return `saved file (${TOKEN_FILE()})`;
		default:
			return "not configured — run /ticktick-setup or set TICKTICK_ACCESS_TOKEN";
	}
}