import path from "path";
import AppNames from "./grab-app-names";
/**
 * Env var holding the dist directory. The CLI sets it from `--dist-dir` or
 * `dist_dir` in bunext.config.ts before any other module loads: most
 * modules read the directory names once, at import time. Child processes
 * (dev/start servers) inherit it.
 */
export const DistDirEnvName = "BUNEXT_DIST_DIR";
const ReservedDirs = ["src", "public", "node_modules"];
/**
 * # Resolve the dist directory
 * Returns the absolute path of the build artifact directory. `dist_dir` is
 * relative to the project root (or absolute) and must sit inside it: the
 * dev watcher only watches the project root, and checks it is alive through
 * a probe file in the dist directory. Its relative path is also the URL
 * path of the client bundles, so it is limited to URL-safe characters.
 */
export function resolveDistDir({ dist_dir, root_dir }) {
    const resolved = path.resolve(root_dir, dist_dir?.trim() || AppNames.defaultDistDir);
    if (!isInsideDir(resolved, root_dir)) {
        throw new Error(`Invalid dist directory \`${dist_dir}\`: it must be a directory ` +
            `inside the project root (${root_dir}).`);
    }
    const url_path = path
        .relative(root_dir, resolved)
        .split(path.sep)
        .join("/");
    if (!/^[\w.\-\/]+$/.test(url_path)) {
        throw new Error(`Invalid dist directory \`${dist_dir}\`: use only letters, ` +
            `digits, \`.\`, \`_\`, \`-\` and \`/\`.`);
    }
    for (const reserved of ReservedDirs) {
        const reserved_dir = path.join(root_dir, reserved);
        if (resolved === reserved_dir || isInsideDir(resolved, reserved_dir)) {
            throw new Error(`Invalid dist directory \`${dist_dir}\`: it can't be ` +
                `\`${reserved}/\` or inside it.`);
        }
    }
    return resolved;
}
/**
 * Whether `target` is strictly inside `dir` (not `dir` itself)
 */
function isInsideDir(target, dir) {
    const relative = path.relative(dir, target);
    return (Boolean(relative) &&
        relative !== ".." &&
        !relative.startsWith(`..${path.sep}`) &&
        !path.isAbsolute(relative));
}