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: {
      async 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');

        // `this.appActor` is set at the very END of the mixin's started(). During boot,
        // this action is already routable (the api gateway is up before the services
        // finish starting) and `@activitypods/app`'s own `awaitCreateComplete` polls the
        // actor over HTTP through this very route — waiting on an action that waits on the
        // boot it blocks. Read the actor straight from the triplestore in that window.
        let actor = this.appActor;
        if (!actor) {
          try {
            actor = await ctx.call('ldp.resource.get', {
              resourceUri: urlJoin(CONFIG.HOME_URL, 'as/actor/app'),
              accept: 'application/ld+json',
              webId: 'system'
            });
          } catch (e) {
            actor = undefined;
          }
        }

        if (isOidcClientIdDocument) {
          // The client_id must equal the fetched URI exactly. Both `/app` and `/as/actor/app`
          // serve this document (the configured client_id is the actor uri; `/app` remains
          // a valid alias), so echo the request path rather than hardcoding one.
          // `req.url` is rewritten to the alias remainder by moleculer-web; the raw path
          // survives in `originalUrl`.
          const requestPath = String((req && (req.originalUrl || req.url)) || '/as/actor/app').split('?')[0];
          return {
            '@context': ['https://www.w3.org/ns/solid/oidc-context.jsonld'],
            client_id: urlJoin(CONFIG.HOME_URL, requestPath),
            redirect_uris: [urlJoin(CONFIG.FRONT_URL, 'login')],
            client_name: CONFIG.APP_NAME,
            client_uri: CONFIG.FRONT_URL
          };
        }

        return actor;
      }
    }
  },
  async started() {
    // Heal the actor ↔ access-need-group link. `@activitypods/app` attaches the group to the
    // actor in an after.post hook of the group's creation, but the hook races the actor's own
    // creation on a cold start (both run inside the broker's parallel started() phase): the
    // group then exists while the actor never gets `interop:hasAccessNeedGroup`, and both the
    // pod frontend (consent screen) and the pod backend (requirements discovery) read the
    // needs from that link — an empty consent registers the app with zero grants and the
    // register flow loops. Idempotent: only patches when the link is missing.
    const actorUri = urlJoin(CONFIG.HOME_URL, 'as/actor/app');
    const actor = await this.broker.call('ldp.resource.get', {
      resourceUri: actorUri,
      accept: 'application/ld+json',
      webId: 'system'
    });
    const link = actor && actor['interop:hasAccessNeedGroup'];
    const hasLink = Array.isArray(link) ? link.length > 0 : Boolean(link);
    if (!hasLink) {
      const groups = await this.broker.call('access-needs-groups.list', {
        filters: {
          'http://www.w3.org/ns/solid/interop#accessNecessity': 'http://www.w3.org/ns/solid/interop#AccessRequired'
        },
        accept: 'application/ld+json'
      });
      const group = groups && groups['ldp:contains'] && groups['ldp:contains'][0];
      if (group) {
        await this.broker.call('actors.attachAccessNeedGroup', {
          accessNeedGroupUri: group.id || group['@id']
        });
        this.logger.info(`Healed the actor's interop:hasAccessNeedGroup link to ${group.id || group['@id']}`);
      }
    }
  }
};