package mytinytodo

import (
	"fmt"
	"local/mytinytodoclient/mytinytodo/remote"
	"local/rproxy3/storage"
	"log"
	"strings"
	"sync"
	"time"

	"github.com/google/uuid"
)

const nsQueue = "delta"
const keyQueue = "queue"
const nsLists = "lists"
const keyLists = "lists"
const nsTasks = "tasks"
const keyTasks = "tasks"

type Buffer struct {
	config   *Config
	db       storage.DB
	dbLock   *sync.RWMutex
	done     chan struct{}
	interval time.Duration
}

func NewBuffer(config *Config) (*Buffer, error) {
	db := storage.NewMap()
	b := &Buffer{
		config:   config,
		db:       db,
		done:     make(chan struct{}),
		dbLock:   &sync.RWMutex{},
		interval: time.Second * 10,
	}
	go b.notDoneCallback(b.Dequeue)
	go b.notDoneCallback(b.RefreshLocal)
	return b, nil
}

func (buffer *Buffer) Close() {
	close(buffer.done)
}

func (buffer *Buffer) Enqueue(op remote.Op, listID, taskTitle string, taskTags ...string) error {
	buffer.dbLock.Lock()
	defer buffer.dbLock.Unlock()
	qop := &QueuedOp{
		Op:       op,
		List:     remote.List{ID: listID},
		Task:     remote.Task{Title: taskTitle},
		TaskTags: taskTags,
	}
	uuid, _ := uuid.NewRandom()
	key := uuid.String()

	todo := NewStringArray()
	if err := buffer.db.Get(nsQueue, keyQueue, todo); err != nil && err != storage.ErrNotFound {
		return err
	}

	sa := todo.StringArray()
	sa = append(sa, key)
	todo = NewStringArray(sa...)
	if err := buffer.db.Set(nsQueue, key, qop); err != nil {
		return err
	}
	if err := buffer.db.Set(nsQueue, keyQueue, todo); err != nil {
		return err
	}

	log.Printf("enqueued task %v as %v, %vth in line", qop, key, len(sa))
	return nil
}

func (buffer *Buffer) Dequeue() {
	client, err := remote.NewClient(buffer.config.Config)
	if err != nil {
		log.Printf("cannot create client: %v", err)
		return
	}
	if _, err := client.Lists(); err != nil {
		log.Printf("cannot client.lists: %v", err)
		return
	}

	buffer.dbLock.Lock()
	defer buffer.dbLock.Unlock()
	todo := NewStringArray()
	if err := buffer.db.Get(nsQueue, keyQueue, todo); err != nil {
		log.Printf("cannot get %v.%v: %v", nsQueue, keyQueue, err)
		return
	}

	sa := todo.StringArray()
	nsa := []string{}
	for i := range sa {
		qop := &QueuedOp{}
		if err := buffer.db.Get(nsQueue, sa[i], qop); err != nil {
			log.Printf("cannot get %v.%v: %v", nsQueue, sa[i], err)
			nsa = append(nsa, sa[i])
			continue
		}
		var err error
		switch qop.Op {
		case remote.NEW:
			err = client.NewTask(qop.List, qop.Task, strings.Join(qop.TaskTags, ","))
		case remote.CLOSE:
			err = client.CloseTask(qop.Task)
		case remote.OPEN:
			err = client.OpenTask(qop.Task)
		default:
			err = fmt.Errorf("cannot dequeue op %v", qop.Op)
		}
		if err != nil {
			log.Printf("failed op %v: %v", qop.Op, err)
			continue
		}
		if err := buffer.db.Set(nsQueue, sa[i], nil); err != nil {
			log.Printf("cannot unset %v.%v: %v", nsQueue, sa[i], err)
			nsa = append(nsa, sa[i])
			continue
		}
	}

	if err := buffer.db.Set(nsQueue, keyQueue, NewStringArray(nsa...)); err != nil {
		log.Printf("cannot update queue: %v", err)
		return
	}
}

func (buffer *Buffer) RefreshLocal() {
	client, err := remote.NewClient(buffer.config.Config)
	if err != nil {
		log.Printf("cannot create client: %v", err)
		return
	}
	lists, err := client.Lists()
	if err != nil {
		log.Printf("cannot client.lists: %v", err)
		return
	}

	buffer.dbLock.Lock()
	defer buffer.dbLock.Unlock()
	if err := buffer.db.Set(nsLists, keyLists, &lists); err != nil {
		log.Printf("cannot set lists: %v", err)
		return
	}

	for _, list := range lists {
		tasks, err := client.Tasks(list)
		if err != nil {
			log.Printf("cannot client.tasks(%v): %v", list, err)
			continue
		}
		if err := buffer.db.Set(nsTasks, list.ID, &tasks); err != nil {
			log.Printf("cannot set tasks(%v): %v", list.ID, tasks)
			continue
		}
	}
}

func (buffer *Buffer) notDoneCallback(foo func()) {
	for {
		select {
		case <-buffer.done:
			return
		case <-time.After(buffer.interval):
			foo()
		}
	}
}