type EnvValue = string | undefined;

function readEnv(
  key:
    | "VITE_BACKEND_BASE_URL"
    | "VITE_LANGGRAPH_BASE_URL"
    | "VITE_CANVAS_LANGGRAPH_BASE_URL"
    | "VITE_NOTE_API_BASE_URL"
    | "VITE_NOTEBOOK_API_BASE_URL"
    | "VITE_STATIC_WEBSITE_ONLY"
    | "VITE_GITHUB_OAUTH_TOKEN",
): EnvValue {
  const value = import.meta.env[key];
  return typeof value === "string" && value.trim() ? value : undefined;
}

export const env = {
  NEXT_PUBLIC_BACKEND_BASE_URL: readEnv("VITE_BACKEND_BASE_URL"),
  NEXT_PUBLIC_LANGGRAPH_BASE_URL: readEnv("VITE_LANGGRAPH_BASE_URL"),
  // Canvas page uses its own LangGraph base URL so it can be independently
  // routed (e.g. a separate canvas-agent server). Falls back to the main URL.
  NEXT_PUBLIC_CANVAS_LANGGRAPH_BASE_URL: readEnv("VITE_CANVAS_LANGGRAPH_BASE_URL"),
  NEXT_PUBLIC_NOTE_API_BASE_URL: readEnv("VITE_NOTE_API_BASE_URL"),
  NEXT_PUBLIC_NOTEBOOK_API_BASE_URL: readEnv("VITE_NOTEBOOK_API_BASE_URL"),
  NEXT_PUBLIC_STATIC_WEBSITE_ONLY: readEnv("VITE_STATIC_WEBSITE_ONLY"),
  GITHUB_OAUTH_TOKEN: readEnv("VITE_GITHUB_OAUTH_TOKEN"),
};