import grabOrigin from "./grab-origin";
/**
 * First line of every generated robots.txt. `bunext sitemap` only
 * overwrites an existing robots.txt that starts with it, unless robots
 * is configured explicitly.
 */
export const RobotsTxtGeneratedMarker = "# Generated by bunext";
/**
 * # Generate a robots.txt string
 */
export default function generateRobotsTxt(params) {
    const lines = [RobotsTxtGeneratedMarker, ""];
    if (params?.disallow_all) {
        lines.push("User-agent: *", "Disallow: /", "");
        return lines.join("\n");
    }
    const rules = params?.rules?.length
        ? params.rules
        : [{ user_agent: "*", allow: ["/"] }];
    for (const rule of rules) {
        const user_agents = [rule.user_agent].flat();
        for (const user_agent of user_agents) {
            lines.push(`User-agent: ${sanitizeValue(user_agent)}`);
        }
        for (const allow of rule.allow || []) {
            lines.push(`Allow: ${sanitizeValue(allow)}`);
        }
        for (const disallow of rule.disallow || []) {
            lines.push(`Disallow: ${sanitizeValue(disallow)}`);
        }
        // A group needs at least one rule; an empty Disallow allows all.
        if (!rule.allow?.length && !rule.disallow?.length) {
            lines.push("Disallow:");
        }
        if (typeof rule.crawl_delay == "number") {
            lines.push(`Crawl-delay: ${rule.crawl_delay}`);
        }
        lines.push("");
    }
    if (params?.sitemaps?.length) {
        const origin = (params.origin || grabOrigin()).replace(/\/+$/, "");
        for (const sitemap of new Set(params.sitemaps)) {
            const url = sitemap.match(/^https?:\/\//)
                ? sitemap
                : `${origin}/${sitemap.replace(/^\/+/, "")}`;
            lines.push(`Sitemap: ${sanitizeValue(url)}`);
        }
        lines.push("");
    }
    return lines.join("\n");
}
/**
 * Line breaks would let a value inject extra directives.
 */
function sanitizeValue(value) {
    return value.replace(/[\r\n]+/g, " ").trim();
}