MIME type detection

mimetype module seems to work nicely and we can avoid a system dependency

Closes #4

go.mod

@@ -9,6 +9,7 @@ require (
 
 require (
 	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.4 // indirect
 	github.com/go-ini/ini v1.67.0 // indirect
 	github.com/goccy/go-json v0.10.3 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect

go.sum

@@ -7,6 +7,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/gabriel-vasile/mimetype v1.4.4 h1:QjV6pZ7/XZ7ryI2KuyeEDE8wnh7fHP9YnQy+R0LnH8I=
+github.com/gabriel-vasile/mimetype v1.4.4/go.mod h1:JwLei5XPtWdGiMFB5Pjle1oEeoSeEuJfJE+TtfvdB/s=
 github.com/go-chi/chi/v5 v5.0.12 h1:9euLV5sTrTNTRUU9POmDUvfxyj6LAABLUcEWO+JJb4s=
 github.com/go-chi/chi/v5 v5.0.12/go.mod h1:DslCQbL2OYiznFReuXYUmQ2hGd1aDpCnlMNITLSKoi8=
 github.com/go-ini/ini v1.67.0 h1:z6ZrTEZqSWOTyH2FlglNbNgARyHG8oLW9gMELqKr06A=

server/files.go

@@ -12,6 +12,7 @@ import (
 	"strings"
 
 	"github.com/danielgtaylor/huma/v2"
+	"github.com/gabriel-vasile/mimetype"
 	"github.com/google/uuid"
 )
 
@@ -42,7 +43,15 @@ func Upload(ctx context.Context, input *UploadInput) (*UploadOutput, error) {
 		return nil, err
 	}
 
-	err = UploadToS3(ctx, fd, file_id.String(), file.Filename, file.Size)
+	det_buf := make([]byte, 1024)
+	n, err := fd.Read(det_buf)
+	if err != nil {
+		return nil, err
+	}
+	mime := mimetype.Detect(det_buf[:n])
+	fd.Seek(0, 0)
+
+	err = UploadToS3(ctx, fd, file_id.String(), file.Filename, file.Size, mime.String())
 	if err != nil {
 		return nil, err
 	}
@@ -120,10 +129,18 @@ func Download(ctx context.Context, input *DownloadInput) (*huma.StreamResponse,
 
 			stat, err := obj.Stat()
 			filename := stat.UserMetadata["Filename"]
+			content_type := stat.UserMetadata["Type"]
+
+			main_type, _, _ := strings.Cut(content_type, "/")
 
 			ctx.SetHeader("Accept-Range", "bytes")
 			ctx.SetHeader("Content-Length", fmt.Sprintf("%d", stat.Size))
-			ctx.SetHeader("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
+			if main_type == "text" {
+				ctx.SetHeader("Content-Disposition", fmt.Sprintf("inline; filename=%s", filename))
+			} else {
+				ctx.SetHeader("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
+			}
+			ctx.SetHeader("Content-Type", content_type)
 
 			var start int64
 			var end int64

server/producer_test.go

@@ -12,6 +12,7 @@ import (
 	"testing"
 
 	"github.com/danielgtaylor/huma/v2/humatest"
+	"github.com/gabriel-vasile/mimetype"
 )
 
 func getTestAPI(t *testing.T) humatest.TestAPI {
@@ -60,7 +61,8 @@ func uploadData(t *testing.T, api humatest.TestAPI, data []byte, filename string
 func TestUploadDownload(t *testing.T) {
 	api := getTestAPI(t)
 
-	test_data := []byte{1, 2, 3, 4, 5, 6, 7, 8, 9}
+	test_data := []byte("hello world")
+	mime := mimetype.Detect(test_data)
 	filename := "test_file"
 	upload_data := uploadData(t, api, test_data, filename)
 
@@ -83,6 +85,15 @@ func TestUploadDownload(t *testing.T) {
 
 	res := resp.Result()
 	content_disposition_header := res.Header["Content-Disposition"][0]
+	content_type := res.Header["Content-Type"][0]
+
+	if content_type == "" {
+		t.Fatal("Content-Type header is not set")
+	}
+
+	if content_type != mime.String() {
+		t.Fatalf("Content-Type header is not the detected file type: %s != %s", content_type, mime.String())
+	}
 
 	matched, _ := regexp.MatchString(
 		fmt.Sprintf("filename=%s", regexp.QuoteMeta(filename)),

server/s3.go

@@ -19,7 +19,7 @@ func getS3Client() (*minio.Client, error) {
 	return client, err
 }
 
-func UploadToS3(ctx context.Context, file io.Reader, file_id string, filename string, filesize int64) error {
+func UploadToS3(ctx context.Context, file io.Reader, file_id string, filename string, filesize int64, content_type string) error {
 	client, err := getS3Client()
 	if err != nil {
 		return err
@@ -31,7 +31,10 @@ func UploadToS3(ctx context.Context, file io.Reader, file_id string, filename st
 		file,
 		filesize,
 		minio.PutObjectOptions{
-			UserMetadata: map[string]string{"Filename": filename},
+			UserMetadata: map[string]string{
+				"Filename": filename,
+				"Type":     content_type,
+			},
 		},
 	)
 	getLogger().Printf("upload info: %+v\n", info)