package module

import (
	"context"
	"io"
	"mime/multipart"

	"forge.cadoles.com/arcad/edge/pkg/app"
	"forge.cadoles.com/arcad/edge/pkg/bus"
	"forge.cadoles.com/arcad/edge/pkg/storage"
	"github.com/dop251/goja"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

const (
	DefaultBlobBucket string = "default"
)

type BlobModule struct {
	server *app.Server
	bus    bus.Bus
	store  storage.BlobStore
}

func (m *BlobModule) Name() string {
	return "blob"
}

func (m *BlobModule) Export(export *goja.Object) {
}

func (m *BlobModule) handleMessages() {
	ctx := context.Background()

	go func() {
		err := m.bus.Reply(ctx, MessageNamespaceUploadRequest, func(msg bus.Message) (bus.Message, error) {
			uploadRequest, ok := msg.(*MessageUploadRequest)
			if !ok {
				return nil, errors.Wrapf(bus.ErrUnexpectedMessage, "expected message upload request, got '%T'", msg)
			}

			res, err := m.handleUploadRequest(uploadRequest)
			if err != nil {
				logger.Error(ctx, "could not handle upload request", logger.E(errors.WithStack(err)))

				return nil, errors.WithStack(err)
			}

			logger.Debug(ctx, "upload request response", logger.F("response", res))

			return res, nil
		})
		if err != nil {
			panic(errors.WithStack(err))
		}
	}()

	err := m.bus.Reply(ctx, MessageNamespaceDownloadRequest, func(msg bus.Message) (bus.Message, error) {
		downloadRequest, ok := msg.(*MessageDownloadRequest)
		if !ok {
			return nil, errors.Wrapf(bus.ErrUnexpectedMessage, "expected message download request, got '%T'", msg)
		}

		res, err := m.handleDownloadRequest(downloadRequest)
		if err != nil {
			logger.Error(ctx, "could not handle download request", logger.E(errors.WithStack(err)))

			return nil, errors.WithStack(err)
		}

		return res, nil
	})
	if err != nil {
		panic(errors.WithStack(err))
	}
}

func (m *BlobModule) handleUploadRequest(req *MessageUploadRequest) (*MessageUploadResponse, error) {
	blobID := storage.NewBlobID()
	res := NewMessageUploadResponse(req.RequestID)

	ctx := logger.With(req.Context, logger.F("blobID", blobID))

	blobInfo := map[string]interface{}{
		"size":        req.FileHeader.Size,
		"filename":    req.FileHeader.Filename,
		"contentType": req.FileHeader.Header.Get("Content-Type"),
	}

	rawResult, err := m.server.ExecFuncByName(ctx, "onBlobUpload", ctx, blobID, blobInfo, req.Metadata)
	if err != nil {
		if errors.Is(err, app.ErrFuncDoesNotExist) {
			res.Allow = false

			return res, nil
		}

		return nil, errors.WithStack(err)
	}

	result, ok := rawResult.Export().(map[string]interface{})
	if !ok {
		return nil, errors.Errorf(
			"unexpected onBlobUpload result: expected 'map[string]interface{}', got '%T'",
			rawResult.Export(),
		)
	}

	var allow bool

	rawAllow, exists := result["allow"]
	if !exists {
		allow = false
	} else {
		allow, ok = rawAllow.(bool)
		if !ok {
			return nil, errors.Errorf("invalid 'allow' result property: got type '%T', expected type '%T'", rawAllow, false)
		}
	}

	res.Allow = allow

	if res.Allow {
		bucket := DefaultBlobBucket

		rawBucket, exists := result["bucket"]
		if exists {
			bucket, ok = rawBucket.(string)
			if !ok {
				return nil, errors.Errorf("invalid 'bucket' result property: got type '%T', expected type '%T'", bucket, "")
			}
		}

		if err := m.saveBlob(ctx, bucket, blobID, *req.FileHeader); err != nil {
			return nil, errors.WithStack(err)
		}

		res.Bucket = bucket
		res.BlobID = blobID
	}

	return res, nil
}

func (m *BlobModule) saveBlob(ctx context.Context, bucketName string, blobID storage.BlobID, fileHeader multipart.FileHeader) error {
	file, err := fileHeader.Open()
	if err != nil {
		return errors.WithStack(err)
	}

	defer func() {
		if err := file.Close(); err != nil {
			logger.Error(ctx, "could not close file", logger.E(errors.WithStack(err)))
		}
	}()

	bucket, err := m.store.OpenBucket(ctx, bucketName)
	if err != nil {
		return errors.WithStack(err)
	}

	defer func() {
		if err := bucket.Close(); err != nil {
			logger.Error(ctx, "could not close bucket", logger.E(errors.WithStack(err)))
		}
	}()

	writer, err := bucket.NewWriter(ctx, blobID)
	if err != nil {
		return errors.WithStack(err)
	}

	defer func() {
		if err := file.Close(); err != nil {
			logger.Error(ctx, "could not close file", logger.E(errors.WithStack(err)))
		}
	}()

	defer func() {
		if err := writer.Close(); err != nil {
			logger.Error(ctx, "could not close writer", logger.E(errors.WithStack(err)))
		}
	}()

	if _, err := io.Copy(writer, file); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func (m *BlobModule) handleDownloadRequest(req *MessageDownloadRequest) (*MessageDownloadResponse, error) {
	res := NewMessageDownloadResponse(req.RequestID)

	rawResult, err := m.server.ExecFuncByName(req.Context, "onBlobDownload", req.Context, req.Bucket, req.BlobID)
	if err != nil {
		if errors.Is(err, app.ErrFuncDoesNotExist) {
			res.Allow = false

			return res, nil
		}

		return nil, errors.WithStack(err)
	}

	result, ok := rawResult.Export().(map[string]interface{})
	if !ok {
		return nil, errors.Errorf(
			"unexpected onBlobDownload result: expected 'map[string]interface{}', got '%T'",
			rawResult.Export(),
		)
	}

	var allow bool

	rawAllow, exists := result["allow"]
	if !exists {
		allow = false
	} else {
		allow, ok = rawAllow.(bool)
		if !ok {
			return nil, errors.Errorf("invalid 'allow' result property: got type '%T', expected type '%T'", rawAllow, false)
		}
	}

	res.Allow = allow

	reader, info, err := m.openBlob(req.Context, req.Bucket, req.BlobID)
	if err != nil && !errors.Is(err, storage.ErrBlobNotFound) {
		return nil, errors.WithStack(err)
	}

	if reader != nil {
		res.Blob = reader
	}

	if info != nil {
		res.BlobInfo = info
	}

	return res, nil
}

func (m *BlobModule) openBlob(ctx context.Context, bucketName string, blobID storage.BlobID) (io.ReadSeekCloser, storage.BlobInfo, error) {
	bucket, err := m.store.OpenBucket(ctx, bucketName)
	if err != nil {
		return nil, nil, errors.WithStack(err)
	}

	defer func() {
		if err := bucket.Close(); err != nil {
			logger.Error(ctx, "could not close bucket", logger.E(errors.WithStack(err)), logger.F("bucket", bucket))
		}
	}()

	info, err := bucket.Get(ctx, blobID)
	if err != nil {
		return nil, nil, errors.WithStack(err)
	}

	reader, err := bucket.NewReader(ctx, blobID)
	if err != nil {
		return nil, nil, errors.WithStack(err)
	}

	return reader, info, nil
}

func BlobModuleFactory(bus bus.Bus, store storage.BlobStore) app.ServerModuleFactory {
	return func(server *app.Server) app.ServerModule {
		mod := &BlobModule{
			store:  store,
			bus:    bus,
			server: server,
		}

		go mod.handleMessages()

		return mod
	}
}