'use strict';

/**
 * Module dependencies
 */

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

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

/**
 * Add an entry to a specific parent entry
 */

module.exports = function destroy(_ctx) {
  const deferred = Promise.defer();

  // Ensure a model and alias can be deduced from the request.
  const Model = actionUtil.parseModel(_ctx);
  const relation = _ctx.params.relation;
  if (!relation) {
    _ctx.status = 500;
    return deferred.reject({
      message: 'Missing required route option, `_ctx.params.relation`.'
    });
  }

  // The primary key of the parent record.
  const parentPk = _ctx.params.parentId;

  // Find the alias key.
  const associationAttr = _.findWhere(strapi.orm.collections[_ctx.model].associations, {alias: relation});

  // Init the child model.
  const ChildModel = strapi.orm.collections[associationAttr.collection];
  const childPkAttr = ChildModel.primaryKey;

  _ctx.options = _ctx.options || {};

  // The child record to associate is defined by either...
  // a primary key or an object of values.
  let child;
  const supposedChildPk = actionUtil.parsePk(_ctx);
  if (supposedChildPk) {
    child = {};
    child[childPkAttr] = supposedChildPk;
  } else {
    _ctx.options.values = _ctx.options.values || {};
    _ctx.options.values.blacklist = _ctx.options.values.blacklist || ['limit', 'skip', 'sort', 'id', 'parentId'];
    child = actionUtil.parseValues(_ctx);
  }

  if (!child) {
    _ctx.status = 400;
    deferred.reject({
      message: 'You must specify the record to add (either the primary key of an existing record to link, or a new object without a primary key which will be used to create a record then link it.)'
    });
  }

  async.auto({

    // Look up the parent record.
    parent: function (cb) {
      Model.findOne(parentPk).exec(function foundParent(err, parentRecord) {
        if (err) {
          return cb(err);
        }
        if (!parentRecord) {
          return cb({status: 404});
        }
        if (!parentRecord[relation]) {
          return cb({status: 404});
        }
        cb(null, parentRecord);
      });
    },

    // If a primary key was specified in the `child` object we parsed
    // from the request, look it up to make sure it exists. Send back its primary key value.
    // This is here because, although you can do this with `.save()`, you can't actually
    // get ahold of the created child record data, unless you create it first.
    actualChildPkValue: ['parent', function (cb) {

      // Below, we use the primary key attribute to pull out the primary key value
      // (which might not have existed until now, if the .add() resulted in a `create()`).
      // If the primary key was specified for the child record, we should try to find
      // it before we create it.
      // Otherwise, it must be referring to a new thing, so create it.
      if (child[childPkAttr]) {
        ChildModel.findOne(child[childPkAttr]).exec(function foundChild(err, childRecord) {
          if (err) {
            return cb(err);
          }

          // Didn't find it? Then try creating it.
          if (!childRecord) {
            return createChild();
          }

          // Otherwise use the one we found.
          return cb(null, childRecord[childPkAttr]);
        });
      } else {
        return createChild();
      }

      // Create a new instance and send out any required pub/sub messages.
      function createChild() {
        ChildModel.create(child).exec(function createdNewChild(err, newChildRecord) {
          if (err) {
            return cb(err);
          }

          return cb(null, newChildRecord[childPkAttr]);
        });
      }
    }],

    // Add the child record to the parent's collection.
    add: ['parent', 'actualChildPkValue', function (cb, asyncData) {

      // `collection` is the parent record's collection we
      // want to add the child to.
      try {
        const collection = asyncData.parent[relation];
        collection.add(asyncData.actualChildPkValue);
        return cb();
      } catch (err) {
        if (err) {
          return cb(err);
        }

        return cb();
      }
    }]
  },

  // Save the parent record.
  function readyToSave(err, asyncData) {
    if (err) {
      _ctx.status = 400;
      deferred.reject(err);
    }

    asyncData.parent.save(function saved(err) {

      // Ignore `insert` errors for duplicate adds
      // (but keep in mind, we should not `publishAdd` if this is the case...)
      const isDuplicateInsertError = (err && typeof err === 'object' && err.length && err[0] && err[0].type === 'insert');
      if (err && !isDuplicateInsertError) {
        deferred.reject(err);
      }

      // Finally, look up the parent record again and populate the relevant collection.
      let query = Model.findOne(parentPk);

      query = actionUtil.populateEach(query, _ctx, Model);
      query.populate(relation);

      query.exec(function (err, matchingRecord) {
        if (err) {
          return deferred.reject(err);
        }
        if (!matchingRecord) {
          return deferred.reject({
            message: 'Matching record not found.'
          });
        }
        if (!matchingRecord[relation]) {
          return deferred.reject({
            message: '`matchingRecord[relation]` not found.'
          });
        }

        return deferred.resolve(matchingRecord);
      });
    });
  });

  return deferred.promise;
};