import { existsSync, readFileSync, statSync } from "node:fs";
import { getWebSearchConfigPath } from "../config/path.ts";

export type WebAccessConfig = Record<string, unknown> & {
	provider?: unknown;
	searchProvider?: unknown;
	maxInlineContentChars?: unknown;
	webSearch?: { enabled?: unknown };
	tools?: {
		webSearch?: { enabled?: unknown };
		webFetch?: { enabled?: unknown };
		fetchContent?: { enabled?: unknown };
	};
};

const CONFIG_PATH = getWebSearchConfigPath();
let cache: { signature: string; config: WebAccessConfig } | undefined;

export function getConfig(): WebAccessConfig {
	if (!existsSync(CONFIG_PATH)) return {};
	const stat = statSync(CONFIG_PATH);
	const signature = `${stat.mtimeMs}:${stat.size}`;
	if (cache?.signature === signature) return cache.config;
	let parsed: unknown;
	try {
		parsed = JSON.parse(readFileSync(CONFIG_PATH, "utf8"));
	} catch (error) {
		const message = error instanceof Error ? error.message : "";
		const position = message.match(/at position \d+(?: \(line \d+ column \d+\))?/i)?.[0];
		throw new Error(`Failed to parse ${CONFIG_PATH}: not valid JSON${position ? `, ${position}` : ""}`);
	}
	if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) {
		throw new Error(`Invalid config in ${CONFIG_PATH}: expected a JSON object`);
	}
	const config = parsed as WebAccessConfig;
	cache = { signature, config };
	return config;
}

export function clearConfigCache(): void {
	cache = undefined;
}

export function getConfigOrEmpty(): WebAccessConfig {
	try {
		return getConfig();
	} catch {
		return {};
	}
}

export function isToolEnabled(config: WebAccessConfig, tool: "webSearch" | "webFetch"): boolean {
	if (tool === "webSearch") {
		const override = config.tools?.webSearch?.enabled;
		if (typeof override === "boolean") return override;
		return config.webSearch?.enabled !== false;
	}
	const override = config.tools?.webFetch?.enabled ?? config.tools?.fetchContent?.enabled;
	return override !== false;
}

const DEFAULT_MAX_INLINE_CONTENT_CHARS = 30_000;
const MAX_INLINE_CONTENT_CHARS = 200_000;

export function getMaxInlineContentChars(): number {
	const value = getConfigOrEmpty().maxInlineContentChars;
	if (typeof value !== "number" || !Number.isInteger(value) || value <= 0) return DEFAULT_MAX_INLINE_CONTENT_CHARS;
	return Math.min(value, MAX_INLINE_CONTENT_CHARS);
}