//
//  Database.swift
//  SocialFriends
//
//  Created by Jógvan Olsen on 3/7/16.
//  Copyright © 2016 Jógvan Olsen. All rights reserved.
//

import UIKit
import CloudKit

class Database: NSObject {

    var db:CKDatabase

    override init(){
        db = CKContainer.defaultContainer().publicCloudDatabase
    }

    /* Posts functions */
    func getFeed(user:User, comletionHander ch: (posts:[Post]) -> Void){
        let startLoadingFeed = {
            var allPosts:[Post] = []
            var userCount = 0

            let userFeedLoaded:([Post])->Void = {
                posts in
                userCount--
                allPosts += posts

                if userCount == 0{
                    ch(posts: allPosts)
                }
            }

            self.loadFeed(user.record, completionHandler: userFeedLoaded)
            for friend in user.friends!{
                userCount++
                self.loadFeed(friend.record, completionHandler: userFeedLoaded)
            }

        }


        // Load friends first if not loaded.
        if user.friends == nil{
            loadFriends(user, completionHandler: startLoadingFeed)
        } else {
            startLoadingFeed()
        }
    }

    func loadFeed(userRecord: CKRecord, completionHandler ch: (posts: [Post]) -> Void){
        let predicate = NSPredicate(format: "user == %@", CKReference(record: userRecord, action: .DeleteSelf))
        let query = CKQuery(recordType: "post", predicate: predicate)

        db.performQuery(query, inZoneWithID: nil){
            records, error in

            if error == nil{
                var posts:[Post] = []

                var c = records!.count*2
                for record in records!{
                    let user = record.objectForKey("user") as! CKReference
                    let content = record.objectForKey("content") as! String
                    let time = record.objectForKey("time") as! NSDate

                    self.loadUser(user){
                        user in

                        let post = Post(recordName: record, user: user!, content: content, time: time)
                        posts.append(post)

                        let f = {
                            c--
                            if c == 0{
                                ch(posts: posts)
                            }
                        }

                        self.loadPostComments(post, completionHandler: f)
                        self.loadPostLikes(post, completionHandler: f)
                    }
                }
            }
        }
    }

    func loadPostComments(post: Post, completionHandler ch: () -> Void){
        post.comments = []
        let predicate = NSPredicate(format: "post == %@", CKReference(record: post.recordName, action: .DeleteSelf))
        let query = CKQuery(recordType: "comment", predicate: predicate)

        db.performQuery(query, inZoneWithID: nil){
            records, error in
            if error == nil{
                var c = records!.count
                if c == 0 {
                    ch()
                }
                for record in records!{
                    let userReference = record.objectForKey("user") as! CKReference
                    let content = record.objectForKey("content") as! String
                    let time = record.objectForKey("time") as! NSDate

                    self.loadUser(userReference){
                        user in
                        let comment = Comment(recordName: record, user: user!, post: post, content: content, time: time)
                        self.loadCommentLikes(comment){
                            post.comments!.append(comment)
                            c--
                            if c == 0{
                                ch()
                            }
                        }
                    }
                }
            }
        }
    }

    func loadCommentLikes(comment:Comment, completionHandler ch: () -> Void){
        comment.likes = []
        let predicate = NSPredicate(format: "comment == %@", CKReference(record: comment.recordName, action: .DeleteSelf))
        let query = CKQuery(recordType: "like_comment", predicate: predicate)

        db.performQuery(query, inZoneWithID: nil){
            records, error in

            if error == nil{
                var c = records!.count
                if c == 0 {
                    ch()
                }
                for record in records!{
                    self.loadUser(record.objectForKey("user") as! CKReference){
                        user in
                        comment.likes!.append(user!)
                        c--
                        if c == 0{
                            ch()
                        }
                    }
                }
            }
        }
    }

    func loadPostLikes(post:Post, completionHandler ch: () -> Void){
        post.likes = []
        let predicate = NSPredicate(format: "post == %@", CKReference(record: post.recordName, action: .DeleteSelf))
        let query = CKQuery(recordType: "like_post", predicate: predicate)

        db.performQuery(query, inZoneWithID: nil){
            records, error in
            if error == nil{
                var c = records!.count
                if c == 0 {
                    ch()
                }
                for record in records!{
                    self.loadUser(record.objectForKey("user") as! CKReference){
                        user in
                        post.likes!.append(user!)
                        c--
                        if c == 0{
                            ch()
                        }
                    }
                }
            }
        }
    }

    /* *** User functions *** */
    func login(username:String, password: String, completionHandler ch: (User? -> Void)){
        let predicate = NSPredicate(format: "username == %@ AND password == %@", username, password)
        let query = CKQuery(recordType: "user", predicate: predicate)


        db.performQuery(query, inZoneWithID: nil){
            records, error in

            if error == nil {
                if records?.count > 0{
                    // Logged in successfully
                    let username = records?[0].objectForKey("username") as! String
                    let fullname = records?[0].objectForKey("fullname") as! String
                    let gender = records?[0].objectForKey("gender") as! String
                    let about = records?[0].objectForKey("about") as! String

                    ch(User(record: records![0], username: username, fullname: fullname, gender: gender, about: about))
                    return
                }
            }else{
                // TODO: This error (also?) happends when user is not connected to iCloud
                print("Error: \(error)")
            }
            ch(nil)
        }
    }


    func usernameExists(username:String, completionHandler ch: (exists: Bool) -> Void){
        let predicate = NSPredicate(format: "username == %@", username)
        let query = CKQuery(recordType: "user", predicate: predicate)

        db.performQuery(query, inZoneWithID: nil){
            (records, error) -> Void in

            ch(exists: error == nil && records?.count > 0)
        }
    }


    func register(username:String, password:String, fullname:String, gender:String, completionHandler ch: (user:User) -> Void){
        let record = CKRecord(recordType: "user")

        record.setObject(username, forKey: "username")
        record.setObject(password, forKey: "password")
        record.setObject(fullname, forKey: "fullname")
        record.setObject(gender, forKey: "gender")
        record.setObject("", forKey: "about")
        record.setObject(NSDate(), forKey: "last_action")

        db.saveRecord(record){
            r, error -> Void in
            let user = User(record: r!, username: username, fullname: fullname, gender: gender, about: "")
            ch(user: user)
        }
    }

    func loadFriends(user: User, completionHandler ch: () -> Void){
        user.friends = []

        let predicate1 = NSPredicate(format: "user_one == %@", user.record)
        let predicate2 = NSPredicate(format: "user_two == %@", user.record)
        let query1 = CKQuery(recordType: "friends", predicate: predicate1)
        let query2 = CKQuery(recordType: "friends", predicate: predicate2)

        var friendsCount = 0
        var both = false
        let f:(User)->Void = {
            friend in
            friendsCount--
            user.friends?.append(friend)

            if friendsCount == 0 && both {
                ch()
            }
        }


        db.performQuery(query1, inZoneWithID: nil){
            (records, error) -> Void in

            friendsCount += records!.count

            for record in records!{
                self.loadUser(record.objectForKey("user_two") as! CKReference){
                    friend in
                    f(friend!)
                }
            }
            both = true
        }



        db.performQuery(query2, inZoneWithID: nil){
            (records, error) -> Void in

            friendsCount += records!.count

            for record in records!{
                self.loadUser(record.objectForKey("user_one") as! CKReference){
                    friend in
                    f(friend!)
                }
            }

            both = true
        }


    }

    func loadUser(userReference:CKReference, completionHandler ch: (user:User?) -> Void){
        db.fetchRecordWithID(userReference.recordID){
            record, error in
            let username = record?.objectForKey("username") as! String
            let fullname = record?.objectForKey("fullname") as! String
            let gender = record?.objectForKey("gender") as! String
            let about = record?.objectForKey("about") as! String

            ch(user: User(record: record!, username: username, fullname: fullname, gender: gender, about: about))
        }
    }
}