/*
Copyright 2021 The Dapr Authors
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package storagequeues

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"net/url"
	"os"
	"os/signal"
	"strconv"
	"sync"
	"syscall"
	"time"

	"github.com/Azure/azure-storage-queue-go/azqueue"

	"github.com/dapr/components-contrib/bindings"
	contrib_metadata "github.com/dapr/components-contrib/metadata"
	"github.com/dapr/kit/logger"
)

const (
	defaultTTL = time.Minute * 10
)

type consumer struct {
	callback func(*bindings.ReadResponse) ([]byte, error)
}

// QueueHelper enables injection for testnig.
type QueueHelper interface {
	Init(accountName string, accountKey string, queueName string, decodeBase64 bool) error
	Write(data []byte, ttl *time.Duration) error
	Read(ctx context.Context, consumer *consumer) error
}

// AzureQueueHelper concrete impl of queue helper.
type AzureQueueHelper struct {
	credential   *azqueue.SharedKeyCredential
	queueURL     azqueue.QueueURL
	reqURI       string
	logger       logger.Logger
	decodeBase64 bool
}

// Init sets up this helper.
func (d *AzureQueueHelper) Init(accountName string, accountKey string, queueName string, decodeBase64 bool) error {
	credential, err := azqueue.NewSharedKeyCredential(accountName, accountKey)
	if err != nil {
		return err
	}
	d.credential = credential
	d.decodeBase64 = decodeBase64
	u, _ := url.Parse(fmt.Sprintf(d.reqURI, accountName, queueName))
	userAgent := "dapr-" + logger.DaprVersion
	pipelineOptions := azqueue.PipelineOptions{
		Telemetry: azqueue.TelemetryOptions{
			Value: userAgent,
		},
	}
	d.queueURL = azqueue.NewQueueURL(*u, azqueue.NewPipeline(credential, pipelineOptions))
	ctx := context.TODO()
	_, err = d.queueURL.Create(ctx, azqueue.Metadata{})
	if err != nil {
		return err
	}

	return nil
}

func (d *AzureQueueHelper) Write(data []byte, ttl *time.Duration) error {
	ctx := context.TODO()
	messagesURL := d.queueURL.NewMessagesURL()

	s, err := strconv.Unquote(string(data))
	if err != nil {
		s = string(data)
	}

	if ttl == nil {
		ttlToUse := defaultTTL
		ttl = &ttlToUse
	}
	_, err = messagesURL.Enqueue(ctx, s, time.Second*0, *ttl)

	return err
}

func (d *AzureQueueHelper) Read(ctx context.Context, consumer *consumer) error {
	messagesURL := d.queueURL.NewMessagesURL()
	res, err := messagesURL.Dequeue(ctx, 1, time.Second*30)
	if err != nil {
		return err
	}
	if res.NumMessages() == 0 {
		// Queue was empty so back off by 10 seconds before trying again
		time.Sleep(10 * time.Second)

		return nil
	}
	mt := res.Message(0).Text

	var data []byte

	if d.decodeBase64 {
		decoded, decodeError := base64.StdEncoding.DecodeString(mt)
		if decodeError != nil {
			return decodeError
		}
		data = decoded
	} else {
		data = []byte(mt)
	}

	_, err = consumer.callback(&bindings.ReadResponse{
		Data:     data,
		Metadata: map[string]string{},
	})
	if err != nil {
		return err
	}
	messageIDURL := messagesURL.NewMessageIDURL(res.Message(0).ID)
	pr := res.Message(0).PopReceipt
	_, err = messageIDURL.Delete(ctx, pr)
	if err != nil {
		return err
	}

	return nil
}

// NewAzureQueueHelper creates new helper.
func NewAzureQueueHelper(logger logger.Logger) QueueHelper {
	return &AzureQueueHelper{
		reqURI: "https://%s.queue.core.windows.net/%s",
		logger: logger,
	}
}

// AzureStorageQueues is an input/output binding reading from and sending events to Azure Storage queues.
type AzureStorageQueues struct {
	metadata *storageQueuesMetadata
	helper   QueueHelper

	logger logger.Logger
}

type storageQueuesMetadata struct {
	AccountKey   string `json:"storageAccessKey"`
	QueueName    string `json:"queue"`
	AccountName  string `json:"storageAccount"`
	DecodeBase64 string `json:"decodeBase64"`
	ttl          *time.Duration
}

// NewAzureStorageQueues returns a new AzureStorageQueues instance.
func NewAzureStorageQueues(logger logger.Logger) *AzureStorageQueues {
	return &AzureStorageQueues{helper: NewAzureQueueHelper(logger), logger: logger}
}

// Init parses connection properties and creates a new Storage Queue client.
func (a *AzureStorageQueues) Init(metadata bindings.Metadata) error {
	meta, err := a.parseMetadata(metadata)
	if err != nil {
		return err
	}
	a.metadata = meta

	decodeBase64 := false
	if a.metadata.DecodeBase64 == "true" {
		decodeBase64 = true
	}

	err = a.helper.Init(a.metadata.AccountName, a.metadata.AccountKey, a.metadata.QueueName, decodeBase64)
	if err != nil {
		return err
	}

	return nil
}

func (a *AzureStorageQueues) parseMetadata(metadata bindings.Metadata) (*storageQueuesMetadata, error) {
	b, err := json.Marshal(metadata.Properties)
	if err != nil {
		return nil, err
	}
	var m storageQueuesMetadata
	err = json.Unmarshal(b, &m)
	if err != nil {
		return nil, err
	}

	ttl, ok, err := contrib_metadata.TryGetTTL(metadata.Properties)
	if err != nil {
		return nil, err
	}

	if ok {
		m.ttl = &ttl
	}

	return &m, nil
}

func (a *AzureStorageQueues) Operations() []bindings.OperationKind {
	return []bindings.OperationKind{bindings.CreateOperation}
}

func (a *AzureStorageQueues) Invoke(req *bindings.InvokeRequest) (*bindings.InvokeResponse, error) {
	ttlToUse := a.metadata.ttl
	ttl, ok, err := contrib_metadata.TryGetTTL(req.Metadata)
	if err != nil {
		return nil, err
	}

	if ok {
		ttlToUse = &ttl
	}

	err = a.helper.Write(req.Data, ttlToUse)
	if err != nil {
		return nil, err
	}

	return nil, nil
}

func (a *AzureStorageQueues) Read(handler func(*bindings.ReadResponse) ([]byte, error)) error {
	c := consumer{
		callback: handler,
	}
	ctx, cancel := context.WithCancel(context.Background())
	wg := &sync.WaitGroup{}
	wg.Add(1)
	go func() {
		defer wg.Done()
		for {
			err := a.helper.Read(ctx, &c)
			if err != nil {
				a.logger.Errorf("error from c: %s", err)
			}
			if ctx.Err() != nil {
				return
			}
		}
	}()

	sigterm := make(chan os.Signal, 1)
	signal.Notify(sigterm, syscall.SIGINT, syscall.SIGTERM)
	<-sigterm
	cancel()
	wg.Wait()

	return nil
}