/**
 * gno reset - Reset GNO to fresh state
 *
 * Deletes all config, data, and cache directories.
 */

// node:fs/promises: rm and stat for recursive directory deletion (no Bun equivalent)
import { rm, stat } from "node:fs/promises";
// node:os: homedir for platform-agnostic home directory (no Bun equivalent)
import { homedir } from "node:os";
// node:path: path manipulation utilities (no Bun equivalent)
import { isAbsolute, normalize, sep } from "node:path";

import { resolveDirs } from "../../app/constants";
import { CliError } from "../errors";

interface ResetOptions {
  confirm?: boolean;
  keepConfig?: boolean;
  keepCache?: boolean;
}

interface DirResult {
  path: string;
  status: "deleted" | "missing" | "kept";
  error?: string;
}

interface ResetResult {
  results: DirResult[];
  errors: string[];
}

// Forbidden paths that should never be deleted
const FORBIDDEN_PATHS = new Set([
  "/",
  "/Users",
  "/home",
  "/var",
  "/etc",
  "/tmp",
]);

/**
 * Validate a path is safe to delete.
 * Must be absolute, under home directory, and not a system path.
 */
function assertSafePath(path: string, label: string): void {
  const normalized = normalize(path);

  // Must be absolute
  if (!isAbsolute(normalized)) {
    throw new CliError("VALIDATION", `${label} path must be absolute: ${path}`);
  }

  // Must not be a forbidden system path
  if (
    FORBIDDEN_PATHS.has(normalized) ||
    FORBIDDEN_PATHS.has(`${normalized}${sep}`)
  ) {
    throw new CliError("VALIDATION", `Refusing to delete system path: ${path}`);
  }

  // Must be under home directory (for user safety)
  const home = homedir();
  if (!normalized.startsWith(home + sep) && normalized !== home) {
    throw new CliError(
      "VALIDATION",
      `${label} path must be under home directory: ${path}`
    );
  }

  // Must not be home directory itself
  if (normalized === home || normalized === home + sep) {
    throw new CliError(
      "VALIDATION",
      `Refusing to delete home directory: ${path}`
    );
  }
}

/**
 * Reset GNO by deleting directories.
 */
export async function reset(options: ResetOptions): Promise<ResetResult> {
  if (!options.confirm) {
    throw new CliError(
      "VALIDATION",
      "Reset requires --confirm or --yes flag to prevent accidental data loss"
    );
  }

  const dirs = resolveDirs();
  const results: DirResult[] = [];
  const errors: string[] = [];

  // Validate all paths before deleting anything
  assertSafePath(dirs.data, "Data");
  if (!options.keepConfig) {
    assertSafePath(dirs.config, "Config");
  }
  if (!options.keepCache) {
    assertSafePath(dirs.cache, "Cache");
  }

  // Delete data directory (always, contains index DB)
  results.push(await rmDir(dirs.data));

  // Delete config unless --keep-config
  if (options.keepConfig) {
    results.push({ path: dirs.config, status: "kept" });
  } else {
    results.push(await rmDir(dirs.config));
  }

  // Delete cache unless --keep-cache
  if (options.keepCache) {
    results.push({ path: dirs.cache, status: "kept" });
  } else {
    results.push(await rmDir(dirs.cache));
  }

  // Collect errors
  for (const r of results) {
    if (r.error) {
      errors.push(`${r.path}: ${r.error}`);
    }
  }

  if (errors.length > 0) {
    throw new CliError("RUNTIME", `Reset failed:\n${errors.join("\n")}`);
  }

  return { results, errors };
}

async function rmDir(path: string): Promise<DirResult> {
  try {
    // Check if exists first
    await stat(path);
  } catch (e) {
    const err = e as NodeJS.ErrnoException;
    if (err.code === "ENOENT") {
      return { path, status: "missing" };
    }
    return { path, status: "missing", error: err.message };
  }

  try {
    await rm(path, { recursive: true, force: true });
    return { path, status: "deleted" };
  } catch (e) {
    const err = e as NodeJS.ErrnoException;
    return { path, status: "missing", error: err.message };
  }
}

/**
 * Format reset result for terminal output.
 */
export function formatReset(result: ResetResult): string {
  const deleted = result.results.filter((r) => r.status === "deleted");
  const missing = result.results.filter((r) => r.status === "missing");
  const kept = result.results.filter((r) => r.status === "kept");

  const lines: string[] = ["GNO reset complete.", ""];

  if (deleted.length > 0) {
    lines.push("Deleted:");
    for (const r of deleted) {
      lines.push(`  ${r.path}`);
    }
  }

  if (missing.length > 0) {
    lines.push("");
    lines.push("Already missing:");
    for (const r of missing) {
      lines.push(`  ${r.path}`);
    }
  }

  if (kept.length > 0) {
    lines.push("");
    lines.push("Kept:");
    for (const r of kept) {
      lines.push(`  ${r.path}`);
    }
  }

  return lines.join("\n");
}