import { createReadStream, createWriteStream } from "node:fs";
import fs from "node:fs/promises";
import os from "node:os";
import path from "node:path";
import type { Stats } from "node:fs";
import type { EntryType, FileEntry } from "../../shared/types";
import type { FileSystemProvider } from "./provider";

function typeOf(st: Stats): EntryType {
	if (st.isSymbolicLink()) return "symlink";
	return st.isDirectory() ? "dir" : "file";
}

/**
 * uid/gid -> names, cached per process (a listing usually has 1-3 owners).
 *
 * PORTABILITY: POSIX-only lookups (`id -nu` works on macOS and Linux; group
 * names use dscacheutil on macOS, getent elsewhere). On Windows these return
 * undefined and the Owner/Group columns show "—".
 */
const idNameCache = new Map<string, string | undefined>();

function resolveId(kind: "user" | "group", id: number): string | undefined {
	if (process.platform === "win32") return undefined;
	const cacheKey = `${kind}:${id}`;
	if (idNameCache.has(cacheKey)) return idNameCache.get(cacheKey);
	let name: string | undefined;
	try {
		const cmd =
			kind === "user"
				? ["id", "-nu", String(id)]
				: process.platform === "darwin"
					? ["dscacheutil", "-q", "group", "-a", "gid", String(id)]
					: ["getent", "group", String(id)];
		const proc = Bun.spawnSync(cmd, { stdout: "pipe", stderr: "ignore" });
		if (proc.success) {
			const out = proc.stdout.toString();
			if (kind === "user") name = out.trim() || undefined;
			else if (process.platform === "darwin") name = /^name:\s*(.+)$/m.exec(out)?.[1]?.trim();
			else name = out.split(":")[0]?.trim() || undefined;
		}
	} catch {
		// lookup tool missing — fall through to the numeric id
	}
	name ??= String(id);
	idNameCache.set(cacheKey, name);
	return name;
}

function toEntry(name: string, full: string, st: Stats): FileEntry {
	return {
		name,
		path: full,
		type: typeOf(st),
		size: st.size,
		mtime: st.mtimeMs,
		mode: st.mode & 0o7777,
		owner: resolveId("user", st.uid),
		group: resolveId("group", st.gid),
	};
}

export class LocalProvider implements FileSystemProvider {
	readonly kind = "local" as const;
	readonly fsKey = "local";

	join = (...parts: string[]) => path.join(...parts);
	dirname = (p: string) => path.dirname(p);
	basename = (p: string) => path.basename(p);
	normalize = (p: string) => path.resolve(p);

	async homeDir(): Promise<string> {
		return os.homedir();
	}

	async list(dir: string): Promise<FileEntry[]> {
		const names = await fs.readdir(dir);
		const entries: FileEntry[] = [];
		for (const name of names) {
			const full = path.join(dir, name);
			try {
				entries.push(toEntry(name, full, await fs.lstat(full)));
			} catch {
				// entry vanished or is unreadable — skip it
			}
		}
		return entries;
	}

	async stat(p: string): Promise<FileEntry> {
		return toEntry(path.basename(p), p, await fs.lstat(p));
	}

	async mkdir(p: string): Promise<void> {
		await fs.mkdir(p);
	}

	async createEmptyFile(p: string): Promise<void> {
		await fs.writeFile(p, "", { flag: "wx" });
	}

	async rename(oldPath: string, newPath: string): Promise<void> {
		await fs.rename(oldPath, newPath);
	}

	async deleteFile(p: string): Promise<void> {
		await fs.unlink(p);
	}

	async deleteEmptyDir(p: string): Promise<void> {
		await fs.rmdir(p);
	}

	async chmod(p: string, mode: number): Promise<void> {
		await fs.chmod(p, mode);
	}

	createReadStream(p: string) {
		return createReadStream(p);
	}

	createWriteStream(p: string) {
		return createWriteStream(p);
	}

	async dispose(): Promise<void> {}
}