package remotefileupload

import (
	"bytes"
	"context"
	"fmt"
	"net/url"
	"sync"
	"time"

	"github.com/fiskerinc/cloud-services/pkg/logger"
	"github.com/fiskerinc/cloud-services/pkg/utils/envtool"
	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/appendblob"
	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/bloberror"
	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/sas"

	"github.com/pkg/errors"
	"github.com/fiskerinc/cloud-services/pkg/utils/elptr"
)

// Comments on other versions I created
// Using a buffer instead of byte array, it would randomly drop one number
// was doing buffer.Write(separator), buffer.Write(x) and I would get something like 4,3,,8,1
// Using a rwmutex on map, and a mutex on []byte, read to check out the item, then write if we where assigning
// couldn't get it to work. Would drop numbers as well

// Using the sync on the inner string proves to be slightly more performant than locking the whole thing

var (
	RunBatchTimer   = true // For local testing, if you don't want to upload to azure, set to false
	ConnectToAzBlob = true // For local testing, set to false to not use credentials
	batchMaxSize    = envtool.GetEnvInt("AZURE_STORAGE_BATCH_UPLOAD_MAX_MIB", 2)
)

func NewAzureBatchUploader(azureStorageContainerName string, azureFileExtension string, messageBatchTimeSeconds int, batchSeparator string) (Uploader, error) {
	a := &AzureBatchUploader{
		accountName:   azureAccount,
		containerName: azureStorageContainerName,
		fileExtension: azureFileExtension,
	}

	var cred *azblob.SharedKeyCredential
	var err error
	if ConnectToAzBlob {
		cred, err = azblob.NewSharedKeyCredential(a.accountName, azureAccountKey)
		if err != nil {
			return a, errors.WithStack(err)
		}
	}

	containerPath := fmt.Sprintf("https://%s.blob.core.windows.net/%s/", a.accountName, a.containerName)

	a.containerPath = containerPath
	a.azureCredentials = cred

	a.separator = []byte(batchSeparator)
	a.logsToSend = &logsMapMutex{logs: map[string]*stringMutex{},
		Mutex: sync.Mutex{}}

	if RunBatchTimer {
		a.batchTicker = time.NewTicker(time.Duration(messageBatchTimeSeconds) * time.Second)
		go func() {
			for {
				select {
				case <-a.batchTicker.C:
					a.uploadNow()
				}
			}
		}()
	}

	return a, nil
}

// So the creation of logs to send
type AzureBatchUploader struct {
	accountName      string
	containerName    string
	fileExtension    string
	containerPath    string
	azureCredentials *azblob.SharedKeyCredential
	logsToSend       *logsMapMutex // A map of strings
	separator        []byte
	batchTicker      *time.Ticker
}

// Ideally we lock the map on when we have to change insert a new value, otherwise
// we rely on the string itself to lock
type logsMapMutex struct {
	logs       map[string]*stringMutex
	sync.Mutex // Not really the mutex I want, will probably swap for the sync.Map later
}

// Removing mutex, can't easily guarantee that the outside map wo't change as we are trying to modify our
// string, without the mutex just becoming repetitive
type stringMutex struct {
	Body     []byte
	logValue LogPayload
	sasToken string
}

// Instead of directly uploading, we need to delay our upload
func (a *AzureBatchUploader) Upload(block []byte, logValue LogPayload, filePath ...string) (string, error) {
	blobURL := a.azureBlobURL(a.containerPath, filePath)
	// Lock a.logs
	a.logsToSend.Mutex.Lock()
	sendMap := a.logsToSend
	defer sendMap.Unlock()
	// a.logs cant' get changed
	mstring, ok := sendMap.logs[blobURL]
	if !ok {
		var sasTokenURL string
		// If we don't have the log inside, we likely need to generate the file, and the sas token. Should implement some sort of caching for this though
		if ConnectToAzBlob {
			blobPath := a.azureBlobFilePath(filePath)
			var err error
			sasTokenURL, err = a.generateSASToken(blobPath)
			if err != nil {
				logger.Error().Str(logValue.Title, logValue.Value).Err(err).Send()
				return "", err
			}
		}

		sendMap.logs[blobURL] = &stringMutex{
			Body:     block,
			logValue: logValue,
			sasToken: sasTokenURL,
		}
	} else {
		// Tried using a buffer, but did not seem to improve performance
		mstring.Body = append(append(mstring.Body, a.separator...), block...)
	}

	// To prevent us from taking up too much memory, we will send out data early
	// This will slow down other logs coming in, so do not make this value too small
	if len(sendMap.logs[blobURL].Body) > 1024*1024*batchMaxSize {
		a.uploadBlock(blobURL, sendMap.logs[blobURL], context.Background())
		sendMap.logs[blobURL].Body = make([]byte, 0)
	}
	blobURL = blobURL + "?" + sendMap.logs[blobURL].sasToken
	return blobURL, nil
}

// Called once the batch has been expired, we actually upload. Can probably just call the azure upload service itself,
// but refactor later
func (a *AzureBatchUploader) uploadNow() {
	// Swap in new log holder
	// Acquire a lock on a.logs. Now we will wait until other writes are finished, but someone could lock behind us
	a.logsToSend.Lock()
	messageMap := a.logsToSend
	// No longer swap the whole object, just replace the map. Will create a backup for the upload time unfortunately

	// Unlocking
	defer messageMap.Unlock()
	ctx := context.Background()
	for blobURL, block := range messageMap.logs {
		a.uploadBlock(blobURL, block, ctx)
	}
	// While we still have a lock on the map, we swap it out
	messageMap.logs = make(map[string]*stringMutex)
}

func (a *AzureBatchUploader) uploadBlock(blobURL string, block *stringMutex, ctx context.Context) (err error) {
	client, err := appendblob.NewClientWithSharedKeyCredential(blobURL, a.azureCredentials, &appendblob.ClientOptions{
		ClientOptions: policy.ClientOptions{
			Retry: policy.RetryOptions{
				MaxRetries:    1,
				MaxRetryDelay: 1 * time.Minute,
			},
		},
	})
	if err != nil {
		logger.Error().Str("Message", "Failed to create new client with shared key credential").Err(err).Send()
		return
	}
	logValue := block.logValue
	logger.Debug().Str(logValue.Title, logValue.Value).Msgf("sending block of length %d to azure container: %s", len(block.Body), blobURL)

	block.Body = append(block.Body, a.separator...)
	// Instead of trying to send data to a blob, and then determining if it exists, lets just check if it exists
	_, err = client.GetProperties(ctx, nil)
	if err != nil {
		if !bloberror.HasCode(err, bloberror.BlobNotFound) {
			logger.Error().Str(logValue.Title, logValue.Value).Err(err).Send()
			return
		}
		_, err = client.Create(ctx, nil)
		if err != nil {
			logger.Error().Str(logValue.Title, logValue.Value).Err(err).Send()
			return
		}
	}

	body := block.Body
	// 2014*1024*4 == 4 MiB,
	MiB4 := 1024 * 1024 * 4
	for len(body) > 0 {
		max := MiB4
		if len(body) < max {
			max = len(body)
		}
		reader := NopCloser(bytes.NewReader(body[0:max]))
		_, err = client.AppendBlock(ctx, reader, nil)
		if err != nil {
			logger.Error().Str(logValue.Title, logValue.Value).Err(err).Msgf("Max: %d, len(body): %d", max, len(body))
			return
		}
		body = body[max:]
		logger.Debug().Str(logValue.Title, logValue.Value).Msgf("upload complete")
	}

	return
}

func (a *AzureBatchUploader) azureBlobFilePath(filepath []string) string {
	fileName := fmt.Sprintf("%s%s", "raw", a.fileExtension)
	finalPath, _ := url.JoinPath("", filepath...)
	finalPath, _ = url.JoinPath(finalPath, fileName)

	return finalPath
}

// basePath is the url to the blob storage (<account>.azurebloburl.net/<containername>)
// filepath will be added onto basepath /<your>/<file>/<path>
func (a *AzureBatchUploader) azureBlobURL(basePath string, filePath []string) string {
	fileName := fmt.Sprintf("%s%s", "raw", a.fileExtension)
	finalPath, _ := url.JoinPath(basePath, filePath...)
	finalPath, _ = url.JoinPath(finalPath, fileName)

	return finalPath
}

func (a *AzureBatchUploader) generateSASToken(blobName string) (token string, err error) {
	// blob name is something like this: 19UUA56873A044568/2023/01/11/raw.log
	sasQueryParams, err := sas.BlobSignatureValues{
		Protocol:      sas.ProtocolHTTPS,
		StartTime:     time.Now().UTC().Add(-1 * time.Hour),           // reduce an hour from current time to avoid signature issue
		ExpiryTime:    time.Now().UTC().Add(3 * 365 * 24 * time.Hour), // 3 years-ish
		Permissions:   elptr.ElPtr(sas.BlobPermissions{Read: true}).String(),
		ContainerName: a.containerName,
		BlobName:      blobName,
	}.SignWithSharedKey(a.azureCredentials)

	if err != nil {
		logger.Error().Err(err).Msg("Failed to sas.BlobSignatureValues")
		return
	}

	token = sasQueryParams.Encode()
	return
}

/* func MutexLocked(m *sync.Mutex) bool {
    state := reflect.ValueOf(m).Elem().FieldByName("state")
	const mutexLocked int64 = 1
    return state.Int()&mutexLocked == mutexLocked
} */