'use strict';

/**
 * Module dependencies
 */

// Core
const path = require('path');

// Public node modules.
const _ = require('lodash');
const bookshelf = require('bookshelf');
const pluralize = require('pluralize');

// Local helpers.
const utils = require('./utils/');

// Strapi helpers for models.
const utilsModels = require('strapi-utils').models;

/**
 * Bookshelf hook
 */

module.exports = function (strapi) {
  const hook = {

    /**
     * Default options
     */

    defaults: {
      defaultConnection: 'default',
      host: 'localhost'
    },

    /**
     * Initialize the hook
     */

    initialize: cb => {
      let globalName;

      // Make sure the Knex hook is present since Knex needs it.
      if (!strapi.hooks.knex) {
        strapi.log.error('Impossible to load the ORM without the query builder!');
        strapi.log.error('You need to install the Strapi query builder with `$ npm install strapi-knex --save`.');
        strapi.stop(1);
      }

      // Only run this logic after the Knex has finished to load.
      strapi.after('hook:knex:loaded', () => {
        // Initialize collections
        _.set(strapi, 'bookshelf.collections', {});

        // Return callback if there is no model
        if (_.isEmpty(strapi.models)) {
          return cb();
        }

        const connections = _.pickBy(strapi.config.connections, {connector: 'strapi-bookshelf'});

        const done = _.after(_.size(connections), () => {
          cb();
        });

        _.forEach(connections, (connection, connectionName) => {
          // Apply defaults
          _.defaults(connection.settings, strapi.hooks.bookshelf.defaults);

          // Create Bookshelf instance for this connection.
          const ORM = new bookshelf(strapi.connections[connectionName]);

          try {
            // Require `config/functions/bookshelf.js` file to customize connection.
            require(path.resolve(strapi.config.appPath, 'config', 'functions', 'bookshelf.js'))(ORM, strapi.connections[connectionName]);
          } catch (err) {
            // This is not an error if the file is not found.
          }

          // Load plugins
          if (_.get(connection, 'options.plugins') !== false) {
            ORM.plugin('visibility');
            ORM.plugin('pagination');
          }

          // Select models concerned by this connection
          const models = _.pickBy(strapi.models, {connection: connectionName});

          // Return callback if there is no model
          if (_.isEmpty(models)) {
            cb();
            
            // Break the loop.
            return false;
          }

          const loadedHook = _.after(_.size(models), () => {
            done();
          });

          // Parse every registered model.
          _.forEach(models, (definition, model) => {
            globalName = _.upperFirst(_.camelCase(definition.globalId));

            // Make sure the model has a table name.
            // If not, use the model name.
            if (_.isEmpty(definition.tableName)) {
              definition.tableName = model;
            }

            if (!_.isEmpty(definition.collectionName)) {
              return cb('Attribute `collectionName` should be `tableName` in ' + globalName + ' model');
            }

            // Add some informations about ORM & client connection
            definition.orm = 'bookshelf';
            definition.client = _.get(connection.settings, 'client');

            // Register the final model for Bookshelf.
            const loadedModel = {
              tableName: definition.tableName,
              hasTimestamps: _.get(definition, 'options.timestamps') === true,
              idAttribute: _.get(definition, 'options.idAttribute') || 'id'
            };

            // Initialize the global variable with the
            // capitalized model name.
            global[globalName] = {};

            // Call this callback function after we are done parsing
            // all attributes for relationships-- see below.
            const done = _.after(_.size(definition.attributes), () => {
              try {
                // Initialize lifecycle callbacks.
                loadedModel.initialize = () => {
                  const self = this;
                  const lifecycle = {
                    creating: 'beforeCreate',
                    created: 'afterCreate',
                    destroying: 'beforeDestroy',
                    destroyed: 'afterDestroy',
                    updating: 'beforeUpdate',
                    updated: 'afterUpdate',
                    fetching: 'beforeFetch',
                    fetched: 'afterFetch',
                    saving: 'beforeSave',
                    saved: 'afterSave'
                  };

                  _.forEach(lifecycle, (fn, key) => {
                    if (_.isFunction(strapi.models[model.toLowerCase()][fn])) {
                      self.on(key, strapi.models[model.toLowerCase()][fn]);
                    }
                  });
                };

                loadedModel.hidden = _.keys(_.keyBy(_.filter(definition.attributes, (value, key) => {
                  if (value.hasOwnProperty('columnName') && !_.isEmpty(value.columnName) && value.columnName !== key) {
                    return true;
                  }
                }), 'columnName'));

                global[globalName] = ORM.Model.extend(loadedModel);
                global[pluralize(globalName)] = ORM.Collection.extend({
                  model: global[globalName]
                });

                // Push model to strapi global variables.
                strapi.bookshelf.collections[globalName.toLowerCase()] = global[globalName];

                // Push attributes to be aware of model schema.
                strapi.bookshelf.collections[globalName.toLowerCase()]._attributes = definition.attributes;

                loadedHook();
              } catch (err) {
                strapi.log.error('Impossible to register the `' + model + '` model.');
                strapi.log.error(err);
                strapi.stop();
              }
            });

            if (_.isEmpty(definition.attributes)) {
              done();
            }

            // Add every relationships to the loaded model for Bookshelf.
            // Basic attributes don't need this-- only relations.
            _.forEach(definition.attributes, (details, name) => {
              const verbose = _.get(utilsModels.getNature(details, name), 'verbose') || '';

              // Build associations key
              if (!_.isEmpty(verbose)) {
                utilsModels.defineAssociations(globalName, definition, details, name);
              }

              switch (verbose) {
                case 'hasOne': {
                  const FK = _.findKey(strapi.models[details.model].attributes, details => {
                    if (details.hasOwnProperty('model') && details.model === model && details.hasOwnProperty('via') && details.via === name) {
                      return details;
                    }
                  });

                  const globalId = _.get(strapi.models, `${details.model.toLowerCase()}.globalId`);

                  loadedModel[name] = function () {
                    return this.hasOne(global[globalId], _.get(strapi.models[details.model].attributes, `${FK}.columnName`) || FK);
                  };
                  break;
                }
                case 'hasMany': {
                  const globalId = _.get(strapi.models, `${details.collection.toLowerCase()}.globalId`);
                  const FKTarget = _.get(strapi.models[globalId.toLowerCase()].attributes, `${details.via}.columnName`) || details.via;

                  loadedModel[name] = function () {
                    return this.hasMany(global[globalId], FKTarget);
                  };
                  break;
                }
                case 'belongsTo': {
                  const globalId = _.get(strapi.models, `${details.model.toLowerCase()}.globalId`);

                  loadedModel[name] = function () {
                    return this.belongsTo(global[globalId], _.get(details, 'columnName') || name);
                  };
                  break;
                }
                case 'belongsToMany': {
                  const tableName = _.get(details, 'tableName') || _.map(_.sortBy([strapi.models[details.collection].attributes[details.via], details], 'collection'), table => {
                    return _.snakeCase(pluralize.plural(table.collection) + ' ' + pluralize.plural(table.via));
                  }).join('__');

                  const relationship = _.clone(strapi.models[details.collection].attributes[details.via]);

                  // Force singular foreign key
                  relationship.attribute = pluralize.singular(relationship.collection);
                  details.attribute = pluralize.singular(details.collection);

                  // Define PK column
                  details.column = utils.getPK(model, strapi.models);
                  relationship.column = utils.getPK(details.collection, strapi.models);

                  // Sometimes the many-to-many relationships
                  // is on the same keys on the same models (ex: `friends` key in model `User`)
                  if (details.attribute + '_' + details.column === relationship.attribute + '_' + relationship.column) {
                    relationship.attribute = pluralize.singular(details.via);
                  }

                  loadedModel[name] = function () {
                    return this.belongsToMany(global[_.upperFirst(details.collection)], tableName, relationship.attribute + '_' + relationship.column, details.attribute + '_' + details.column);
                  };
                  break;
                }
                default: {
                  break;
                }
              }

              done();
            });
          });
        });
      });
    }
  };

  return hook;
};