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;
const DEFAULT_BROWSER_CDP_PORT_RANGE_SPAN =
  DEFAULT_BROWSER_CDP_PORT_RANGE_END - DEFAULT_BROWSER_CDP_PORT_RANGE_START;

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 = start + DEFAULT_BROWSER_CDP_PORT_RANGE_SPAN;
  if (end <= 65535) {
    return { start, end };
  }
  return {
    start: DEFAULT_BROWSER_CDP_PORT_RANGE_START,
    end: DEFAULT_BROWSER_CDP_PORT_RANGE_END,
  };
}