/*
 * Copyright (C) 2025 TomTom Navigation B.V.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import { buildClientMetadataUrl } from "./auth/clientMetadata";

export interface AppConfig {
  port: number;
  baseUrl: string;
  baseUrlPath: string;
  allowedOrigins: string | undefined;
  logLevel: string;
  ciamTenantId: string | undefined;
  ciamDomain: string | undefined;
  workforceTenantId: string | undefined;
  authorizationServerUrl: string;
  ulsTokenEndpoint: string;
  ulsClientId: string;
  ulsResource: string;
  accountApiBaseUrl: string;
  accountApiAudience: string;
  accountApiScope: string;
  tomtomApiBaseUrl: string;
  tomtomApiKey: string | undefined;
  mcpTransportMode: string | undefined;
  testAuthorizeClientEnabled: boolean;
}

export function getAppConfig(env: NodeJS.ProcessEnv = process.env): AppConfig {
  // Both normalized slash-free at the end: they concatenate into identifiers
  // (resource, ulsClientId) that ULS compares byte-for-byte with fetch URLs.
  const baseUrl = (env.MCP_BASE_URL || `http://localhost:${env.PORT || 3000}`).replace(/\/$/, "");
  const baseUrlPath = (env.MCP_BASE_URL_PATH || "").replace(/\/$/, "");

  return {
    /** HTTP server port */
    port: Number(env.PORT) || 3000,

    /** Base URL for the MCP API */
    baseUrl,

    baseUrlPath,

    /** Comma-separated list of allowed CORS origins */
    allowedOrigins: env.ALLOWED_ORIGINS,

    /** Log level */
    logLevel: env.LOG_LEVEL || "info",

    /** CIAM tenant ID for JWT verification */
    ciamTenantId: env.CIAM_TENANT_ID,

    /** CIAM domain subdomain (e.g. "tomtomext" for tomtomext.ciamlogin.com) */
    ciamDomain: env.CIAM_DOMAIN,

    /**
     * Workforce (B2B) Entra tenant ID — optional. When set, the MCP server
     * also accepts JWTs issued by `https://login.microsoftonline.com/{id}/v2.0`,
     * in addition to the CIAM (External ID / B2C) issuer above.
     */
    workforceTenantId: env.WORKFORCE_TENANT_ID,

    /** Authorization server base URL (e.g. https://oauth.my.tomtom.com) */
    authorizationServerUrl: env.AUTHORIZATION_SERVER_URL || "https://oauth.my.tomtom.com",

    /** ULS token exchange endpoint URL */
    ulsTokenEndpoint: env.ULS_TOKEN_ENDPOINT || "https://oauth.my.tomtom.com/token",

    /**
     * ULS token exchange client_id. Per CIMD, defaults to this deployment's
     * client metadata document URL, which ULS dereferences to identify the
     * client. ULS_CLIENT_ID overrides it as an operational rollback lever.
     */
    ulsClientId: env.ULS_CLIENT_ID || buildClientMetadataUrl(baseUrl, baseUrlPath),

    /** ULS token exchange resource — the API the resolved key is for */
    ulsResource: env.ULS_RESOURCE || "https://api.tomtom.com",

    /** Base URL for account/contract API calls */
    accountApiBaseUrl: env.ACCOUNT_API_BASE_URL || "https://account.cx.tomtom.com",

    /** Audience of the token exchanged for account management API calls */
    accountApiAudience: env.ACCOUNT_API_AUDIENCE || "https://account.cx.tomtom.com",

    /** Scope requested for the account management API token */
    accountApiScope: env.ACCOUNT_API_SCOPE || "authorize",

    /** TomTom API base URL */
    tomtomApiBaseUrl: env.TOMTOM_API_BASE_URL || "https://api.tomtom.com",

    /** Static TomTom API key (used when no per-session key is provided) */
    tomtomApiKey: env.TOMTOM_API_KEY,

    /** HTTP server user-agent identity override, validated in utils/userAgent.ts */
    mcpTransportMode: env.MCP_TRANSPORT_MODE,

    /**
     * Serve the CIMD document for the test authorize client (MCP Inspector,
     * mint scripts) — see auth/testClientMetadata.ts. Dev deployments only;
     * off unless the env var is exactly "true".
     */
    testAuthorizeClientEnabled: env.TEST_AUTHORIZE_CLIENT_ENABLED === "true",
  };
}

/**
 * Central configuration singleton for the TomTom MCP server.
 * All static values and environment-derived defaults live here.
 */
export const appConfig = getAppConfig();