import { existsSync, statSync } from "fs";
import path from "path";
import isDevelopment from "./is-development";
/**
 * File path -> mtime of the version currently held in Bun's module
 * registry (dev only).
 */
const loaded_versions = new Map();
/**
 * Imports a module by its stable path.
 *
 * Dev: when the file changed since it was last imported, its registry
 * entry is evicted first so the new version is evaluated and the old one
 * can be garbage collected. A cache-busting `?t=` query would instead
 * create a new, never-evicted module record on every call.
 *
 * Prod: plain import, so each module is loaded (and kept) once.
 */
export default async function importFresh(file_path) {
    if (!isDevelopment()) {
        return import(file_path);
    }
    let mtime;
    try {
        mtime = statSync(file_path).mtimeMs;
    }
    catch { }
    if (loaded_versions.has(file_path) &&
        loaded_versions.get(file_path) !== mtime) {
        evictModule(file_path);
    }
    try {
        const mod = await import(file_path);
        loaded_versions.set(file_path, mtime);
        return mod;
    }
    catch (error) {
        // Don't keep a failed evaluation around: the next request retries.
        evictModule(file_path);
        throw error;
    }
}
/**
 * Drops a module from Bun's registry so its memory can be reclaimed and the
 * next import re-evaluates it. Only the module itself is evicted, not the
 * modules it imports.
 */
export function evictModule(file_path) {
    delete require.cache[file_path];
    loaded_versions.delete(file_path);
}
/**
 * Evicts every registry entry under `dir` whose file no longer exists. Bundle
 * outputs (entries and shared chunks) are content-hashed and esbuild deletes
 * the superseded ones on rebuild, so a missing file means no current module
 * imports it anymore.
 */
export function evictDeletedModules(dir) {
    const prefix = dir.endsWith(path.sep) ? dir : dir + path.sep;
    for (const key of Object.keys(require.cache)) {
        if (key.startsWith(prefix) && !existsSync(key)) {
            evictModule(key);
        }
    }
}