s3browser-backend/internal/s3Broswer.go

package s3browser

import (
	"context"
	"fmt"
	"io"
	"log"
	"net/http"
	"path/filepath"
	"time"

	"github.com/graph-gophers/dataloader"
	"github.com/graphql-go/graphql"
	"github.com/graphql-go/handler"
	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
)

// AppConfig general config
type AppConfig struct {
	S3Endoint    string
	S3AccessKey  string
	S3SecretKey  string
	S3SSL        bool
	S3Buket      string
	CacheTTL     time.Duration
	CacheCleanup time.Duration
}

// File represents a file with its metadata
type File struct {
	ID          string `json:"id"`
	Name        string `json:"name"`
	Size        int64  `json:"size"`
	ContentType string `json:"contentType"`
	ETag        string `json:"etag"`
}

// Directory represents a directory with its metadata
type Directory struct {
	ID         string      `json:"id"`
	Name       string      `json:"name"`
	Files      []File      `json:"files"`
	Directorys []Directory `json:"directorys"`
}

var bucketName = "dev"

// initHttp setup and start the http server. Blocking
func initHttp(schema graphql.Schema, s3Client *minio.Client, loaderMap map[string]*dataloader.Loader) {
	h := handler.New(&handler.Config{
		Schema:     &schema,
		Pretty:     true,
		GraphiQL:   false,
		Playground: true,
	})

	resolveContext := context.WithValue(context.Background(), "s3Client", s3Client)
	resolveContext = context.WithValue(resolveContext, "loader", loaderMap)

	http.HandleFunc("/graphql", func(rw http.ResponseWriter, r *http.Request) {
		h.ContextHandler(resolveContext, rw, r)
	})

	http.HandleFunc("/api/file", func(rw http.ResponseWriter, r *http.Request) {
		id := r.URL.Query().Get("id")
		objInfo, err := s3Client.StatObject(context.Background(), bucketName, id, minio.GetObjectOptions{})

		if err != nil {
			rw.WriteHeader(500)
			return
		}

		reqEtag := r.Header.Get("If-None-Match")
		if reqEtag == objInfo.ETag {
			rw.WriteHeader(304)
			return
		}

		obj, err := s3Client.GetObject(context.Background(), bucketName, id, minio.GetObjectOptions{})

		if err != nil {
			rw.WriteHeader(500)
			return
		}

		rw.Header().Set("Cache-Control", "must-revalidate")
		rw.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", filepath.Base((objInfo.Key))))
		rw.Header().Set("Content-Type", objInfo.ContentType)
		rw.Header().Set("ETag", objInfo.ETag)

		io.Copy(rw, obj)
	})

	http.ListenAndServe(":8080", nil)
}

// setupS3Client connect the s3Client
func setupS3Client(config AppConfig) *minio.Client {
	minioClient, err := minio.New(config.S3Endoint, &minio.Options{
		Creds:  credentials.NewStaticV4(config.S3AccessKey, config.S3SecretKey, ""),
		Secure: config.S3SSL,
	})

	if err != nil {
		log.Fatalln(err)
	}

	exists, err := minioClient.BucketExists(context.Background(), config.S3Buket)

	if err != nil {
		log.Fatalln(err)
	}

	if !exists {
		log.Fatalf("Bucket '%s' does not exist", config.S3Buket)
	} else {
		log.Print("S3 client connected")
	}

	return minioClient
}

// Start starts the app
func Start(config AppConfig) {
	s3Client := setupS3Client(config)

	loader := createDataloader(config)

	graphqlTypes()
	schema, err := graphqlSchema()

	if err != nil {
		log.Panic(err)
	}

	initHttp(schema, s3Client, loader)
}