package main

// Queue for pending authentication requests

import (
	"crypto/rand"
	"math/big"
	"sync"
	"time"
)

type AuthenticationMap struct {
	requestMap      map[string]*AuthRequest
	app             *App
	requestMapMutex *sync.RWMutex
}

// Returns empty string when no request by that id is present
func (q *AuthenticationMap) GetRequestByID(ID string) *AuthRequest {
	q.requestMapMutex.RLock()

	req, ok := q.requestMap[ID]

	q.requestMapMutex.RUnlock()

	if !ok {
		return nil
	}

	return req
}

func GenerateUniqueID() (string, error) {
	length := 64

	const letters = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-"
	ret := make([]byte, length)
	for i := 0; i < length; i++ {
		num, err := rand.Int(rand.Reader, big.NewInt(int64(len(letters))))
		if err != nil {
			return "", err
		}
		ret[i] = letters[num.Int64()]
	}
	return string(ret), nil
}

func (q *AuthenticationMap) QueueRequest(r *AuthRequest) error {
	var ID string
	var err error
	for {
		ID, err = GenerateUniqueID()
		if err != nil {
			return err
		}

		q.requestMapMutex.Lock()
		if _, exists := q.requestMap[ID]; exists {
			q.requestMapMutex.Unlock()
			continue
		}
		q.requestMapMutex.Unlock()
		break
	}

	err = r.SetId(ID)
	if err != nil {
		return err
	}

	r.Queued = time.Now()

	q.requestMapMutex.Lock()
	q.requestMap[ID] = r
	q.requestMapMutex.Unlock()

	(*q.app.Logger).Info("Queued request by id: ", ID)

	return nil
}

func (q *AuthenticationMap) Init() {
	q.requestMap = make(map[string]*AuthRequest)
	q.requestMapMutex = &sync.RWMutex{}
	q.startRequestMapCleaner()
}

func (q *AuthenticationMap) startRequestMapCleaner() {
	go func() {
		for _ = range time.Tick(10 * time.Minute) {
			q.requestMapMutex.Lock()

			for key, req := range q.requestMap {
				// If the request has been queued for more than 30
				// minutes, it's time to delete it.
				if req.Queued.Add(30 * time.Minute).Before(time.Now()) {
					(*q.app.Logger).Info("Deleting inactive request with id: ", req.ID)

					req.Cancel()
					delete(q.requestMap, key)
				}

			}

			q.requestMapMutex.Unlock()
		}
	}()
}

func (q *AuthenticationMap) Delete(ID string) {
	q.requestMapMutex.Lock()
	delete(q.requestMap, ID)
	q.requestMapMutex.Unlock()
}