export type PortRange = { start: number; end: number };

function isValidPort(port: number): boolean {
  return Number.isFinite(port) && port > 0 && port <= 65535;
}

function clampPort(port: number, fallback: number): number {
  return isValidPort(port) ? port : fallback;
}

function derivePort(base: number, offset: number, fallback: number): number {
  return clampPort(base + offset, fallback);
}

export const DEFAULT_BRIDGE_PORT = 18790;
export const DEFAULT_BROWSER_CONTROL_PORT = 18791;
export const DEFAULT_CANVAS_HOST_PORT = 18793;
export const DEFAULT_BROWSER_CDP_PORT_RANGE_START = 18800;
export const DEFAULT_BROWSER_CDP_PORT_RANGE_END = 18899;

export function deriveDefaultBridgePort(gatewayPort: number): number {
  return derivePort(gatewayPort, 1, DEFAULT_BRIDGE_PORT);
}

export function deriveDefaultBrowserControlPort(gatewayPort: number): number {
  return derivePort(gatewayPort, 2, DEFAULT_BROWSER_CONTROL_PORT);
}

export function deriveDefaultCanvasHostPort(gatewayPort: number): number {
  return derivePort(gatewayPort, 4, DEFAULT_CANVAS_HOST_PORT);
}

export function deriveDefaultBrowserCdpPortRange(
  browserControlPort: number,
): PortRange {
  const start = derivePort(
    browserControlPort,
    9,
    DEFAULT_BROWSER_CDP_PORT_RANGE_START,
  );
  const end = clampPort(
    start +
      (DEFAULT_BROWSER_CDP_PORT_RANGE_END -
        DEFAULT_BROWSER_CDP_PORT_RANGE_START),
    DEFAULT_BROWSER_CDP_PORT_RANGE_END,
  );
  if (end < start) return { start, end: start };
  return { start, end };
}