import {Core} from './Core';
import {Schema} from './Schema';
import {Model} from './Model';
import {ModelCache} from './ModelCache';
import * as ModelOptions from './ModelOptions';

import Skmatc = require('skmatc');
import _ = require('lodash');
import MongoDB = require('mongodb');
import Bluebird = require('bluebird');

/**
 * Provides a number of methods which are used to handle events that occur within
 * the Iridium workflow - such as what happens when a document is received from
 * the database, or how to handle the creation of new documents and saving of instances.
 *
 * Mostly this is for cache support, wrapping and hook triggering.
 * @internal
 */
export class ModelHandlers<TDocument extends { _id?: any }, TInstance> {
    constructor(public model: Model<TDocument, TInstance>) {

    }

    documentReceived<TResult>(conditions: any,
        result: TDocument,
        wrapper: (document: TDocument, isNew?: boolean, isPartial?: boolean) => TResult,
        options: ModelOptions.QueryOptions = {}): Bluebird<TResult> {
        _.defaults(options, {
            cache: true,
            partial: false
        });

        return Bluebird.resolve(result).then((target: any) => {
            return <Bluebird<TResult>>Bluebird.resolve().then(() => {

                // Cache the document if caching is enabled
                if (this.model.core.cache && options.cache && !options.fields) {
                    this.model.cache.set(target); // Does not block execution pipeline - fire and forget
                }

                // Trigger the received hook
                if (this.model.hooks.onRetrieved) this.model.hooks.onRetrieved(target);

                // Wrap the document and trigger the ready hook
                let wrapped: TResult = wrapper(target, false, !!options.fields);

                if (this.model.hooks.onReady && wrapped instanceof this.model.Instance) this.model.hooks.onReady(<TInstance><any>wrapped);
                return wrapped;
            });
        });
    }

    creatingDocuments(documents: TDocument[]): Bluebird<any[]> {
        return Bluebird.all(documents.map((document: any) => {
            return Bluebird.resolve().then(() => {
                if (this.model.hooks.onCreating) this.model.hooks.onCreating(document);
                document = this.model.helpers.convertToDB(document);
                let validation: Skmatc.Result = this.model.helpers.validate(document);
                if (validation.failed) return Bluebird.reject(validation.error);

                return document;
            });
        }));
    }

    savingDocument(instance: TInstance, changes: any): Bluebird<TInstance> {
        return Bluebird.resolve().then(() => {
            if (this.model.hooks.onSaving) this.model.hooks.onSaving(instance, changes);
            return instance;
        });
    }
}