package gcssink

import (
	"context"
	"fmt"
	"os"
	"strings"

	"cloud.google.com/go/storage"
	"github.com/seaweedfs/seaweedfs/weed/replication/repl_util"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/option"

	"github.com/seaweedfs/seaweedfs/weed/filer"
	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
	"github.com/seaweedfs/seaweedfs/weed/replication/sink"
	"github.com/seaweedfs/seaweedfs/weed/replication/source"
	"github.com/seaweedfs/seaweedfs/weed/util"
)

type GcsSink struct {
	client        *storage.Client
	bucket        string
	dir           string
	filerSource   *source.FilerSource
	isIncremental bool
}

func init() {
	sink.Sinks = append(sink.Sinks, &GcsSink{})
}

func (g *GcsSink) GetName() string {
	return "google_cloud_storage"
}

func (g *GcsSink) GetSinkToDirectory() string {
	return g.dir
}

func (g *GcsSink) IsIncremental() bool {
	return g.isIncremental
}

func (g *GcsSink) Initialize(configuration util.Configuration, prefix string) error {
	g.isIncremental = configuration.GetBool(prefix + "is_incremental")
	return g.initialize(
		configuration.GetString(prefix+"google_application_credentials"),
		configuration.GetString(prefix+"bucket"),
		configuration.GetString(prefix+"directory"),
	)
}

func (g *GcsSink) SetSourceFiler(s *source.FilerSource) {
	g.filerSource = s
}

func (g *GcsSink) initialize(google_application_credentials, bucketName, dir string) error {
	g.bucket = bucketName
	g.dir = dir

	// Creates a client.
	var clientOpts []option.ClientOption
	if google_application_credentials != "" {
		var data []byte
		var err error
		if strings.HasPrefix(google_application_credentials, "{") {
			data = []byte(google_application_credentials)
		} else {
			googleCredentialsPath := util.ResolvePath(google_application_credentials)
			data, err = os.ReadFile(googleCredentialsPath)
			if err != nil {
				return fmt.Errorf("failed to read credentials file %s: %v", googleCredentialsPath, err)
			}
		}
		creds, err := google.CredentialsFromJSON(context.Background(), data, storage.ScopeFullControl)
		if err != nil {
			return fmt.Errorf("failed to parse credentials: %v", err)
		}
		httpClient := oauth2.NewClient(context.Background(), creds.TokenSource)
		clientOpts = append(clientOpts, option.WithHTTPClient(httpClient), option.WithoutAuthentication())
	}
	client, err := storage.NewClient(context.Background(), clientOpts...)
	if err != nil {
		return fmt.Errorf("failed to create client with credentials \"%s\" env \"%s\": %v",
			google_application_credentials, os.Getenv("GOOGLE_APPLICATION_CREDENTIALS"), err)
	}

	g.client = client

	return nil
}

func (g *GcsSink) DeleteEntry(key string, isDirectory, deleteIncludeChunks bool, signatures []int32) error {

	if isDirectory {
		key = key + "/"
	}

	if err := g.client.Bucket(g.bucket).Object(key).Delete(context.Background()); err != nil {
		return fmt.Errorf("gcs delete %s/%s: %v", g.bucket, key, err)
	}

	return nil

}

func (g *GcsSink) CreateEntry(key string, entry *filer_pb.Entry, signatures []int32) error {

	if entry.IsDirectory {
		return nil
	}

	totalSize := filer.FileSize(entry)
	chunkViews := filer.ViewFromChunks(context.Background(), g.filerSource.LookupFileId, entry.GetChunks(), 0, int64(totalSize))

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	wc := g.client.Bucket(g.bucket).Object(key).NewWriter(ctx)

	writeFunc := func(data []byte) error {
		_, writeErr := wc.Write(data)
		return writeErr
	}

	var writeErr error
	if len(entry.Content) > 0 {
		content, decErr := repl_util.MaybeDecryptContent(entry.Content, entry)
		if decErr != nil {
			writeErr = fmt.Errorf("decrypt inline SSE content: %w", decErr)
		} else {
			writeErr = writeFunc(content)
		}
	} else {
		writeErr = repl_util.CopyFromChunkViews(chunkViews, g.filerSource, writeFunc, entry)
	}

	if writeErr != nil {
		// Cancel the context to abort the GCS upload without touching
		// any existing object at this key.
		cancel()
		wc.Close()
		return writeErr
	}

	return wc.Close()

}

func (g *GcsSink) UpdateEntry(key string, oldEntry *filer_pb.Entry, newParentPath string, newEntry *filer_pb.Entry, deleteIncludeChunks bool, signatures []int32) (foundExistingEntry bool, err error) {
	return true, g.CreateEntry(key, newEntry, signatures)
}
