import { access } from "node:fs/promises";
import { join } from "node:path";
import { pathToFileURL } from "node:url";
import type { ExportConfig } from "./types.ts";

const CONFIG_FILENAMES = ["sitebase.config.ts", "sitebase.config.js"];

/**
 * Find config file in directory (auto-discovery)
 */
export async function findConfigFile(dir: string): Promise<string | null> {
	for (const filename of CONFIG_FILENAMES) {
		const configPath = join(dir, filename);
		try {
			await access(configPath);
			return configPath;
		} catch {
			// File doesn't exist, try next
		}
	}
	return null;
}

/**
 * Load export config from a JS/TS file
 */
export async function loadExportConfig(
	configPath: string,
): Promise<ExportConfig> {
	const configUrl = pathToFileURL(configPath).href;
	const configModule = await import(configUrl);
	const config = configModule.default as ExportConfig;

	// Validate required fields
	if (!config.publicationUri) {
		throw new Error("Config missing required field: publicationUri");
	}
	if (
		!config.exports ||
		!Array.isArray(config.exports) ||
		config.exports.length === 0
	) {
		throw new Error(
			"Config missing required field: exports (must be non-empty array)",
		);
	}

	// Validate each export target
	for (const [i, target] of config.exports.entries()) {
		if (!target.outputDir) {
			throw new Error(`Export target ${i} missing required field: outputDir`);
		}
		if (!target.filename || typeof target.filename !== "function") {
			throw new Error(
				`Export target ${i} missing required field: filename (must be a function)`,
			);
		}
	}

	return config;
}