export const PRODUCTION_HOST = "https://dench.com";
export const STAGING_HOST = "https://staging.dench.com";
export const LOCAL_HOST = "http://localhost:3000";
export const DEFAULT_HOST = PRODUCTION_HOST;

/**
 * Production-only fallbacks baked into the CLI binary so it does the
 * right thing even when run with no config and no env vars (e.g. in a
 * sandbox whose `buildSandboxEnvVars` map was assembled while the
 * Vercel deployment was missing one of these keys).
 *
 * If any of these is wrong, EVERY install of @dench.com/cli is broken
 * until republished — keep them in sync with whichever Convex
 * deployment + Next.js host backs `https://www.dench.com`.
 */
export const PRODUCTION_API_URL = "https://www.dench.com";
export const PRODUCTION_CONVEX_URL =
  "https://beaming-alligator-67.convex.cloud";
export const PRODUCTION_GATEWAY_URL = "https://gateway.merseoriginals.com";

export type BackendAlias = "production" | "prod" | "staging" | "local";

function optionFromArgs(args: string[], name: string) {
  const index = args.indexOf(name);
  if (index === -1) return undefined;
  return args[index + 1];
}

function hasFlag(args: string[], name: string) {
  return args.includes(name);
}

export function normalizeHost(input: string) {
  const trimmed = input.trim();
  if (/^(localhost|127\.0\.0\.1|0\.0\.0\.0|\[::1\])(?::|$)/.test(trimmed)) {
    return new URL(`http://${trimmed}`).origin;
  }
  const withProtocol = /^https?:\/\//.test(trimmed)
    ? trimmed
    : `https://${trimmed}`;
  const url = new URL(withProtocol);
  return url.origin;
}

export function isLocalHost(input: string) {
  const hostname = new URL(normalizeHost(input)).hostname;
  return (
    hostname === "localhost" ||
    hostname === "127.0.0.1" ||
    hostname === "0.0.0.0" ||
    hostname === "::1" ||
    hostname.endsWith(".localhost")
  );
}

export function apiHostForDenchHost(input: string | undefined) {
  if (!input?.trim()) return PRODUCTION_API_URL;
  const normalized = normalizeHost(input);
  // `dench.com` redirects to `www.dench.com` in production. Fetch drops the
  // Authorization header across that redirect, so CLI API calls must start on
  // the canonical API origin.
  if (normalized === PRODUCTION_HOST) return PRODUCTION_API_URL;
  return normalized;
}

/**
 * Resolve `local|staging|prod|production|<url>` -> a normalized host
 * origin. Aliases let `dench backend set <alias>` (and `--backend
 * <alias>`) accept the short forms most agents reach for first.
 * Returns `undefined` for empty input and throws on values that
 * neither match an alias nor parse as a URL.
 */
export function resolveBackendAlias(input: string): string {
  const value = input.trim();
  if (!value) {
    throw new Error(
      "Backend value is empty. Pass local, staging, prod, or a URL like https://dench.com.",
    );
  }
  const normalized = value.toLowerCase();
  if (normalized === "prod" || normalized === "production") {
    return PRODUCTION_HOST;
  }
  if (normalized === "staging" || normalized === "stage") {
    return STAGING_HOST;
  }
  if (
    normalized === "local" ||
    normalized === "localhost" ||
    normalized === "dev"
  ) {
    return LOCAL_HOST;
  }
  try {
    return normalizeHost(value);
  } catch (_error) {
    throw new Error(
      `Unrecognized backend "${value}". Use local, staging, prod, or a URL like https://dench.com.`,
    );
  }
}

export function resolveHostFromArgs(
  args: string[],
  configHost?: string,
  envHost = process.env.DENCH_HOST,
) {
  if (hasFlag(args, "--prod")) return PRODUCTION_HOST;
  if (hasFlag(args, "--staging")) return STAGING_HOST;

  const explicitBackend = optionFromArgs(args, "--backend");
  if (explicitBackend) return resolveBackendAlias(explicitBackend);

  const explicit = optionFromArgs(args, "--host") ?? envHost;
  if (explicit) return normalizeHost(explicit);
  if (configHost) return normalizeHost(configHost);
  return DEFAULT_HOST;
}