/**
 * sh-mcp-ops configuration — read entirely from the environment.
 *
 * Nothing is hardcoded (build-plan §7, design.md §2): client ids, issuer, JWKS
 * URL, table names, scope prefix all arrive via env. `SH_MCP_ENV` selects local
 * (dev clients + LocalAuthProvider) vs aws (real stub clients + Cognito).
 */

import { cognitoIssuer, cognitoJwks, type CognitoAuthConfig } from '@sh-mcp/shared';

export type Env = 'local' | 'aws';

export interface OpsConfig {
  env: Env;
  port: number;
  audience: string;
  /** Cognito config — only required/used in `aws` mode. */
  cognito?: CognitoAuthConfig;
  // Real-client settings (aws mode only; unused locally).
  googleMapsApiKey?: string;
  reminderTargetArn?: string;
  schedulerRoleArn?: string;
}

const AUDIENCE = 'sh-mcp-ops';
const SCOPE_PREFIX = 'sh-mcp-ops';

function readEnv(name: string): string | undefined {
  const v = process.env[name];
  return v !== undefined && v.length > 0 ? v : undefined;
}

/** Parse and validate the process environment into an {@link OpsConfig}. */
export function loadOpsConfig(): OpsConfig {
  // Fail CLOSED: SH_MCP_ENV must be set explicitly. An unset value must NEVER
  // silently select local mode (which wires LocalAuthProvider + static dev
  // bearer tokens). A misconfigured deploy should refuse to start, not run dev
  // auth on a finance/ops service.
  const rawEnv = readEnv('SH_MCP_ENV');
  if (rawEnv !== 'local' && rawEnv !== 'aws') {
    throw new Error(
      `SH_MCP_ENV must be explicitly set to "local" or "aws" ` +
        `(got ${rawEnv === undefined ? 'unset' : `"${rawEnv}"`}); refusing to start.`,
    );
  }
  const env = rawEnv;
  const port = Number(readEnv('PORT') ?? '8081');

  const base: OpsConfig = { env, port, audience: AUDIENCE };

  if (env === 'aws') {
    const region = readEnv('AWS_REGION') ?? 'us-east-1';
    const userPoolId = required('COGNITO_USER_POOL_ID');
    const allowedClientIds = required('COGNITO_ALLOWED_CLIENT_IDS')
      .split(',')
      .map((s) => s.trim())
      .filter(Boolean);
    base.cognito = {
      issuer: cognitoIssuer(region, userPoolId),
      audience: AUDIENCE,
      allowedClientIds,
      scopePrefix: SCOPE_PREFIX,
      jwks: cognitoJwks(region, userPoolId),
    };
    base.googleMapsApiKey = readEnv('GOOGLE_MAPS_API_KEY');
    base.reminderTargetArn = readEnv('REMINDER_TARGET_ARN');
    base.schedulerRoleArn = readEnv('SCHEDULER_ROLE_ARN');
  }

  return base;
}

function required(name: string): string {
  const v = readEnv(name);
  if (!v) throw new Error(`Missing required env var ${name} for SH_MCP_ENV=aws.`);
  return v;
}