/**
 * Utility helpers. Mirrors `apps/infrastructure/src/utils.rs`.
 */
import { randomUUID } from "node:crypto";
import * as fs from "node:fs";
import * as path from "node:path";

/** Atomically write JSON `data` to `path`, with optional mode and parent fsync. */
export function writeJsonAtomic(filePath: string, data: unknown, mode?: number): void {
  const tmp = `${filePath}.tmp.${randomUUID()}`;
  const parent = path.dirname(filePath);
  try {
    fs.mkdirSync(parent, { recursive: true });
    const bytes = JSON.stringify(data, null, 2);
    const fd = fs.openSync(tmp, "w");
    try {
      fs.writeFileSync(fd, bytes);
      fs.fsyncSync(fd);
    } finally {
      fs.closeSync(fd);
    }
    if (mode !== undefined) fs.chmodSync(tmp, mode);
    fs.renameSync(tmp, filePath);
    try {
      const dirFd = fs.openSync(parent, "r");
      try {
        fs.fsyncSync(dirFd);
      } finally {
        fs.closeSync(dirFd);
      }
    } catch {
      /* best-effort */
    }
  } catch (e) {
    try {
      fs.unlinkSync(tmp);
    } catch {
      /* orphan cleanup */
    }
    throw e;
  }
}

/** Convert a string into a filesystem-safe slug, or null if empty/too long. */
export function slugify(s: string): string | null {
  let slug = s.toLowerCase().replace(/[^a-z0-9]/g, "-");
  slug = slug.split("-").filter((seg) => seg !== "").join("-");
  if (slug === "" || slug.length > 80) return null;
  return slug;
}

/** Write `text` to the terminal clipboard via OSC-52 escape sequence. */
export function writeOsc52(text: string, out: { write: (s: string) => unknown } = process.stdout): void {
  const encoded = Buffer.from(text, "utf8").toString("base64");
  out.write(`\x1b]52;c;${encoded}\x1b\\`);
}

/** Truncate a string to at most `maxChars` characters (UTF-8 safe). */
export function truncateChars(s: string, maxChars: number): string {
  if ([...s].length <= maxChars) return s;
  return [...s].slice(0, maxChars).join("");
}

/** Build a string directory tree of `root`, respecting .gitignore semantics loosely. */
export function buildWorkspaceTree(root: string, maxFiles: number): string {
  const lines: string[] = [];
  let count = 0;
  const walk = (dir: string, depth: number, ignore: Set<string>) => {
    if (count >= maxFiles) {
      lines.push("... (truncated)");
      return;
    }
    let entries: fs.Dirent[] = [];
    try {
      entries = fs.readdirSync(dir, { withFileTypes: true }).sort((a, b) => (a.isDirectory() === b.isDirectory() ? a.name.localeCompare(b.name) : a.isDirectory() ? -1 : 1));
    } catch {
      return;
    }
    for (const entry of entries) {
      if (count >= maxFiles) {
        lines.push("... (truncated)");
        return;
      }
      if (entry.name === ".git" || ignore.has(entry.name)) continue;
      const indent = "  ".repeat(Math.max(depth - 1, 0));
      if (entry.isDirectory()) {
        lines.push(`${indent}${entry.name}/`);
        count++;
        const subIgnore = new Set(ignore);
        // Honor .gitignore briefly
        try {
          const gi = fs.readFileSync(path.join(dir, entry.name, ".gitignore"), "utf8");
          for (const l of gi.split("\n")) {
            const t = l.trim().replace(/\/$/, "");
            if (t && !t.startsWith("#")) subIgnore.add(t);
          }
        } catch {
          /* keep default ignore set */
        }
        walk(path.join(dir, entry.name), depth + 1, subIgnore);
      } else {
        lines.push(`${indent}${entry.name}`);
        count++;
      }
    }
  };
  lines.push(".");
  walk(root, 1, new Set(["node_modules", "target"]));
  return lines.join("\n").trimEnd();
}

/** Run a shell command and return trimmed stdout (best-effort). */
export function runCommand(cmd: string, cwd?: string, args?: string[]): string {
  try {
    const res = Bun.spawnSync({ cmd: args ? [cmd, ...args] : [cmd], cwd, stdout: "pipe", stderr: "pipe" });
    return res.stdout.toString().trim();
  } catch {
    return "";
  }
}