const mongoose = require('mongoose');
const { MeiliSearch } = require('meilisearch');
const { cleanUpPrimaryKeyValue } = require('../../lib/utils/misc');
const _ = require('lodash');
const searchEnabled = process.env.SEARCH && process.env.SEARCH.toLowerCase() === 'true';
const meiliEnabled = process.env.MEILI_HOST && process.env.MEILI_MASTER_KEY && searchEnabled;

const validateOptions = function (options) {
  const requiredKeys = ['host', 'apiKey', 'indexName'];
  requiredKeys.forEach((key) => {
    if (!options[key]) {
      throw new Error(`Missing mongoMeili Option: ${key}`);
    }
  });
};

const createMeiliMongooseModel = function ({ index, indexName, client, attributesToIndex }) {
  // console.log('attributesToIndex', attributesToIndex);
  const primaryKey = attributesToIndex[0];
  // MeiliMongooseModel is of type Mongoose.Model
  class MeiliMongooseModel {
    // Clear Meili index
    static async clearMeiliIndex() {
      await index.delete();
      // await index.deleteAllDocuments();
      await this.collection.updateMany({ _meiliIndex: true }, { $set: { _meiliIndex: false } });
    }

    static async resetIndex() {
      await this.clearMeiliIndex();
      await client.createIndex(indexName, { primaryKey });
    }
    // Clear Meili index
    // Push a mongoDB collection to Meili index
    static async syncWithMeili() {
      await this.resetIndex();
      const docs = await this.find({ _meiliIndex: { $in: [null, false] } });
      console.log('docs', docs.length);
      const objs = docs.map((doc) => doc.preprocessObjectForIndex());
      try {
        await index.addDocuments(objs);
        const ids = docs.map((doc) => doc._id);
        await this.collection.updateMany({ _id: { $in: ids } }, { $set: { _meiliIndex: true } });
      } catch (error) {
        console.log('Error adding document to Meili');
        console.error(error);
      }
    }

    // Set one or more settings of the meili index
    static async setMeiliIndexSettings(settings) {
      return await index.updateSettings(settings);
    }

    // Search the index
    static async meiliSearch(q, params, populate) {
      const data = await index.search(q, params);

      // Populate hits with content from mongodb
      if (populate) {
        // Find objects into mongodb matching `objectID` from Meili search
        const query = {};
        // query[primaryKey] = { $in: _.map(data.hits, primaryKey) };
        query[primaryKey] = _.map(data.hits, (hit) => cleanUpPrimaryKeyValue(hit[primaryKey]));
        // console.log('query', query);
        const hitsFromMongoose = await this.find(
          query,
          _.reduce(
            this.schema.obj,
            function (results, value, key) {
              return { ...results, [key]: 1 };
            },
            { _id: 1 },
          ),
        );

        // Add additional data from mongodb into Meili search hits
        const populatedHits = data.hits.map(function (hit) {
          const query = {};
          query[primaryKey] = hit[primaryKey];
          const originalHit = _.find(hitsFromMongoose, query);

          return {
            ...(originalHit ? originalHit.toJSON() : {}),
            ...hit,
          };
        });
        data.hits = populatedHits;
      }

      return data;
    }

    preprocessObjectForIndex() {
      const object = _.pick(this.toJSON(), attributesToIndex);
      // NOTE: MeiliSearch does not allow | in primary key, so we replace it with - for Bing convoIds
      // object.conversationId = object.conversationId.replace(/\|/g, '-');
      if (object.conversationId && object.conversationId.includes('|')) {
        object.conversationId = object.conversationId.replace(/\|/g, '--');
      }
      return object;
    }

    // Push new document to Meili
    async addObjectToMeili() {
      const object = this.preprocessObjectForIndex();
      try {
        // console.log('Adding document to Meili', object);
        await index.addDocuments([object]);
      } catch (error) {
        // console.log('Error adding document to Meili');
        // console.error(error);
      }

      await this.collection.updateMany({ _id: this._id }, { $set: { _meiliIndex: true } });
    }

    // Update an existing document in Meili
    async updateObjectToMeili() {
      const object = _.pick(this.toJSON(), attributesToIndex);
      await index.updateDocuments([object]);
    }

    // Delete a document from Meili
    async deleteObjectFromMeili() {
      await index.deleteDocument(this._id);
    }

    // * schema.post('save')
    postSaveHook() {
      if (this._meiliIndex) {
        this.updateObjectToMeili();
      } else {
        this.addObjectToMeili();
      }
    }

    // * schema.post('update')
    postUpdateHook() {
      if (this._meiliIndex) {
        this.updateObjectToMeili();
      }
    }

    // * schema.post('remove')
    postRemoveHook() {
      if (this._meiliIndex) {
        this.deleteObjectFromMeili();
      }
    }
  }

  return MeiliMongooseModel;
};

module.exports = function mongoMeili(schema, options) {
  // Vaidate Options for mongoMeili
  validateOptions(options);

  // Add meiliIndex to schema
  schema.add({
    _meiliIndex: {
      type: Boolean,
      required: false,
      select: false,
      default: false,
    },
  });

  const { host, apiKey, indexName, primaryKey } = options;

  // Setup MeiliSearch Client
  const client = new MeiliSearch({ host, apiKey });

  // Asynchronously create the index
  client.createIndex(indexName, { primaryKey });

  // Setup the index to search for this schema
  const index = client.index(indexName);

  const attributesToIndex = [
    ..._.reduce(
      schema.obj,
      function (results, value, key) {
        return value.meiliIndex ? [...results, key] : results;
        // }, []), '_id'];
      },
      [],
    ),
  ];

  schema.loadClass(createMeiliMongooseModel({ index, indexName, client, attributesToIndex }));

  // Register hooks
  schema.post('save', function (doc) {
    doc.postSaveHook();
  });
  schema.post('update', function (doc) {
    doc.postUpdateHook();
  });
  schema.post('remove', function (doc) {
    doc.postRemoveHook();
  });

  schema.pre('deleteMany', async function (next) {
    if (!meiliEnabled) {
      next();
    }

    try {
      if (Object.prototype.hasOwnProperty.call(schema.obj, 'messages')) {
        const convoIndex = client.index('convos');
        const deletedConvos = await mongoose.model('Conversation').find(this._conditions).lean();
        let promises = [];
        for (const convo of deletedConvos) {
          promises.push(convoIndex.deleteDocument(convo.conversationId));
        }
        await Promise.all(promises);
      }

      if (Object.prototype.hasOwnProperty.call(schema.obj, 'messageId')) {
        const messageIndex = client.index('messages');
        const deletedMessages = await mongoose.model('Message').find(this._conditions).lean();
        let promises = [];
        for (const message of deletedMessages) {
          promises.push(messageIndex.deleteDocument(message.messageId));
        }
        await Promise.all(promises);
      }
      return next();
    } catch (error) {
      if (meiliEnabled) {
        console.log(
          '[Meilisearch] There was an issue deleting conversation indexes upon deletion, next startup may be slow due to syncing',
        );
        console.error(error);
      }
      return next();
    }
  });

  schema.post('findOneAndUpdate', async function (doc) {
    if (!meiliEnabled) {
      return;
    }

    if (doc.unfinished) {
      return;
    }

    let meiliDoc;
    // Doc is a Conversation
    if (doc.messages) {
      try {
        meiliDoc = await client.index('convos').getDocument(doc.conversationId);
      } catch (error) {
        console.log('[Meilisearch] Convo not found and will index', doc.conversationId);
      }
    }

    if (meiliDoc && meiliDoc.title === doc.title) {
      return;
    }

    doc.postSaveHook();
  });
};