const urlJoin = require('url-join');
const { AppService } = require('@activitypods/app');
const CONFIG = require('../config/config');

// `GET /app` has two personalities, discriminated by the request's `JsonLdContext` header.
//
// 1. Solid-OIDC Client ID Document. The pod provider's OIDC adapter (RedisAdapter.find)
//    resolves an unknown `client_id` that starts with `http` by fetching it, sending
//    `Accept: application/ld+json` and `JsonLdContext: https://www.w3.org/ns/solid/oidc-context.jsonld`.
//    The pod provider runs the login with `client_id = <HOME_URL>/app`, so this same URL must,
//    for that fetch, return a document whose `@context` literally includes the Solid-OIDC
//    context, whose `client_id` equals the fetched URI exactly, and which carries `redirect_uris`.
//    Anything else fails `invalid_client_metadata / client_id is mandatory property`.
//
// 2. SAI app description (the actor). The pod provider's auth-agent fetches this URL
//    WITHOUT the `JsonLdContext` header (`ldp.remote.getNetwork`) to install/describe the app,
//    and expects the app actor document served today (`type: [Application, interop:Application]`).
//
// The `JsonLdContext` header is the only discriminator: same path, two representations.
module.exports = {
  mixins: [AppService],
  settings: {
    baseUrl: CONFIG.HOME_URL,
    app: {
      name: CONFIG.APP_NAME,
      description: CONFIG.APP_DESCRIPTION,
      thumbnail: urlJoin(CONFIG.FRONT_URL, 'logo.svg'),
      frontUrl: CONFIG.FRONT_URL,
      supportedLocales: CONFIG.APP_LANG
    },
    oidc: {
      clientUri: CONFIG.FRONT_URL,
      redirectUris: urlJoin(CONFIG.FRONT_URL, 'login'),
      postLogoutRedirectUris: urlJoin(CONFIG.FRONT_URL, 'login?logout=true'),
      tosUri: null
    },
    accessNeeds: {
      required: [
        {
          shapeTreeUri: urlJoin(CONFIG.SHAPE_REPOSITORY_URL, 'shapetrees/as/Event'),
          accessMode: ['acl:Read', 'acl:Write', 'acl:Control'],
          preferredScope: 'interop:AllFromRegistry'
        },
        {
          shapeTreeUri: urlJoin(CONFIG.SHAPE_REPOSITORY_URL, 'shapetrees/as/Profile'),
          accessMode: ['acl:Read', 'acl:Write'],
          preferredScope: 'interop:AllFromRegistry'
        },
        {
          shapeTreeUri: urlJoin(CONFIG.SHAPE_REPOSITORY_URL, 'shapetrees/vcard/Group'),
          accessMode: 'acl:Read',
          preferredScope: 'interop:AllFromRegistry'
        },
        'apods:ReadInbox',
        'apods:ReadOutbox',
        'apods:PostOutbox',
        'apods:QuerySparqlEndpoint',
        'apods:CreateWacGroup',
        'apods:CreateCollection',
        'apods:UpdateWebId'
      ],
      optional: []
    },
    queueServiceUrl: CONFIG.QUEUE_SERVICE_URL
  },
  actions: {
    // Overrides the mixin's `get` (which returns `this.appActor` for every request) to
    // answer the Solid-OIDC Client ID Document fetch as well. `this.appActor` is set by the
    // mixin's `started()`, i.e. long before any request is served.
    get: {
      handler(ctx) {
        // moleculer-web exposes the raw request only when the route alias sets
        // passReqResToParams (see services/core/core.service.js). Internal calls
        // (ctx.call('app.get')) have no `$req`, so they always get the actor.
        const req = ctx.params && ctx.params.$req;
        const headers = (req && req.headers) || {};
        const jsonLdContextKey = Object.keys(headers).find(key => key.toLowerCase() === 'jsonldcontext');
        const isOidcClientIdDocument =
          jsonLdContextKey !== undefined && String(headers[jsonLdContextKey]).includes('solid/oidc-context.jsonld');

        if (isOidcClientIdDocument) {
          return {
            '@context': ['https://www.w3.org/ns/solid/oidc-context.jsonld'],
            client_id: urlJoin(CONFIG.HOME_URL, 'app'),
            redirect_uris: [urlJoin(CONFIG.FRONT_URL, 'login')],
            client_name: CONFIG.APP_NAME,
            client_uri: CONFIG.FRONT_URL
          };
        }

        return this.appActor;
      }
    }
  }
};