'use strict';

const Toposort = require('toposort-class');
const _ = require('lodash');

class ModelManager {
  constructor(sequelize) {
    this.models = [];
    this.sequelize = sequelize;
  }

  addModel(model) {
    this.models.push(model);
    this.sequelize.models[model.name] = model;

    return model;
  }

  removeModel(modelToRemove) {
    this.models = this.models.filter(model => model.name !== modelToRemove.name);

    delete this.sequelize.models[modelToRemove.name];
  }

  getModel(against, options) {
    options = _.defaults(options || {}, {
      attribute: 'name'
    });

    return this.models.find(model => model[options.attribute] === against);
  }

  get all() {
    return this.models;
  }

  /**
   * Iterate over Models in an order suitable for e.g. creating tables.
   * Will take foreign key constraints into account so that dependencies are visited before dependents.
   *
   * @param {Function} iterator method to execute on each model
   * @param {object} [options] iterator options
   * @private
   */
  forEachModel(iterator, options) {
    const models = {};
    const sorter = new Toposort();
    let sorted;
    let dep;

    options = _.defaults(options || {}, {
      reverse: true
    });

    for (const model of this.models) {
      let deps = [];
      let tableName = model.getTableName();

      if (_.isObject(tableName)) {
        tableName = `${tableName.schema}.${tableName.tableName}`;
      }

      models[tableName] = model;

      for (const attrName in model.rawAttributes) {
        if (Object.prototype.hasOwnProperty.call(model.rawAttributes, attrName)) {
          const attribute = model.rawAttributes[attrName];

          if (attribute.references) {
            dep = attribute.references.model;

            if (_.isObject(dep)) {
              dep = `${dep.schema}.${dep.tableName}`;
            }

            deps.push(dep);
          }
        }
      }

      deps = deps.filter(dep => tableName !== dep);

      sorter.add(tableName, deps);
    }

    sorted = sorter.sort();
    if (options.reverse) {
      sorted = sorted.reverse();
    }
    for (const name of sorted) {
      iterator(models[name], name);
    }
  }
}

module.exports = ModelManager;
module.exports.ModelManager = ModelManager;
module.exports.default = ModelManager;