export const USER_ROLES = ["admin", "ap_processor", "approver", "viewer"] as const;

export type UserRole = (typeof USER_ROLES)[number];

export function isUserRole(value: string): value is UserRole {
  return (USER_ROLES as readonly string[]).includes(value);
}

export type ApiEnv = {
  nodeEnv: string;
  port: number;
  databaseDriver: "postgres" | "data-api";
  databaseUrl: string;
  awsRegion: string;
  rdsClusterArn: string;
  rdsSecretArn: string;
  rdsDatabase: string;
  cognitoIssuer: string;
  cognitoAudience: string;
  devAuthBypass: boolean;
  devAuthSub: string;
  devAuthEmail: string;
  devAuthName: string;
  devAuthRole: UserRole;
};

function required(name: string, value: string | undefined): string {
  if (!value) {
    throw new Error(`Missing required env var ${name}.`);
  }
  return value;
}

export function loadEnv(env: NodeJS.ProcessEnv = process.env): ApiEnv {
  const nodeEnv = env.NODE_ENV ?? "development";
  const databaseDriver = (env.DATABASE_DRIVER ?? "postgres") as ApiEnv["databaseDriver"];
  if (databaseDriver !== "postgres" && databaseDriver !== "data-api") {
    throw new Error(`Invalid DATABASE_DRIVER: ${databaseDriver}`);
  }

  const devAuthBypass = env.DEV_AUTH_BYPASS === "true";
  const localNodeEnvs = new Set(["development", "test"]);
  if (devAuthBypass && !localNodeEnvs.has(nodeEnv)) {
    throw new Error("DEV_AUTH_BYPASS is only allowed when NODE_ENV is development or test.");
  }

  const rawRole = env.DEV_AUTH_ROLE ?? "admin";
  if (!isUserRole(rawRole)) {
    throw new Error(`Invalid DEV_AUTH_ROLE: ${rawRole}`);
  }

  const base: ApiEnv = {
    nodeEnv,
    port: Number(env.API_PORT ?? "8787"),
    databaseDriver,
    databaseUrl: env.DATABASE_URL ?? "postgresql://seahaven:seahaven@127.0.0.1:5432/seahaven_ap",
    awsRegion: env.AWS_REGION ?? "us-east-1",
    rdsClusterArn: env.RDS_CLUSTER_ARN ?? "",
    rdsSecretArn: env.RDS_SECRET_ARN ?? "",
    rdsDatabase: env.RDS_DATABASE ?? "seahaven_ap",
    cognitoIssuer: env.COGNITO_ISSUER ?? "",
    cognitoAudience: env.COGNITO_AUDIENCE ?? "",
    devAuthBypass,
    devAuthSub: env.DEV_AUTH_SUB ?? "seed-sub-admin",
    devAuthEmail: env.DEV_AUTH_EMAIL ?? "admin@seahavenind.com",
    devAuthName: env.DEV_AUTH_NAME ?? "Dev Admin",
    devAuthRole: rawRole,
  };

  if (databaseDriver === "data-api") {
    required("RDS_CLUSTER_ARN", base.rdsClusterArn);
    required("RDS_SECRET_ARN", base.rdsSecretArn);
  }

  if (!devAuthBypass && nodeEnv !== "test") {
    required("COGNITO_ISSUER", base.cognitoIssuer);
    required("COGNITO_AUDIENCE", base.cognitoAudience);
  }

  return base;
}