import { readFileSync } from "node:fs";
import { homedir } from "node:os";
import { join } from "node:path";

export const SEARCH_API_KEY_NAMES = ["TAVILY_API_KEY", "EXA_API_KEY", "KEENABLE_API_KEY"] as const;

type SearchApiKeyName = (typeof SEARCH_API_KEY_NAMES)[number];
type SearchEnvironment = Record<string, string | undefined>;

const SAFE_VALUE = /^[A-Za-z0-9._-]+$/;

export function getSearchConfigPath(env: SearchEnvironment = process.env): string {
	if (env.MY_PI_SEARCH_CONFIG?.trim()) {
		return env.MY_PI_SEARCH_CONFIG.trim();
	}
	const configHome = env.XDG_CONFIG_HOME?.trim() || join(env.HOME?.trim() || homedir(), ".config");
	return join(configHome, "my-pi", "search.env");
}

export function parseSearchConfig(text: string): Partial<Record<SearchApiKeyName, string>> {
	const parsed: Partial<Record<SearchApiKeyName, string>> = {};
	for (const rawLine of text.split(/\r?\n/u)) {
		const line = rawLine.trim().replace(/^export[ \t]+/u, "");
		if (!line || line.startsWith("#")) continue;
		const separator = line.indexOf("=");
		if (separator < 1) continue;
		const name = line.slice(0, separator).trim() as SearchApiKeyName;
		const value = line.slice(separator + 1).trim();
		if (!SEARCH_API_KEY_NAMES.includes(name) || !SAFE_VALUE.test(value)) continue;
		parsed[name] = value;
	}
	return parsed;
}

/** Load package-managed search credentials without overriding explicit process environment values. */
export function loadSearchConfigEnv(
	env: SearchEnvironment = process.env,
	configPath = getSearchConfigPath(env),
): Partial<Record<SearchApiKeyName, string>> {
	let parsed: Partial<Record<SearchApiKeyName, string>> = {};
	try {
		parsed = parseSearchConfig(readFileSync(configPath, "utf8"));
	} catch {
		// Missing or unreadable config is equivalent to an empty package-managed config.
	}
	const effective: Partial<Record<SearchApiKeyName, string>> = {};
	for (const name of SEARCH_API_KEY_NAMES) {
		if (!env[name]?.trim() && parsed[name]) env[name] = parsed[name];
		if (env[name]?.trim()) effective[name] = env[name]?.trim();
	}
	return effective;
}

/** Load search API keys before provider extensions initialize. */
export default function searchConfigExtension(): void {
	loadSearchConfigEnv();
}