From 08b3942d35a5c06b257909c988b56232d08bbaf3 Mon Sep 17 00:00:00 2001
From: Nikolai Papin <nikolai@weirdcat.ru>
Date: Thu, 31 Jul 2025 17:46:47 +0300
Subject: [PATCH] feat: UploadService for acquiring temporary file upload urls
 for different objects (currently avatars and general images)

---
 backend/internal/services/setup.go  |   1 +
 backend/internal/services/upload.go | 116 ++++++++++++++++++++++++++++
 2 files changed, 117 insertions(+)
 create mode 100644 backend/internal/services/upload.go

diff --git a/backend/internal/services/setup.go b/backend/internal/services/setup.go
index 58c6617..e734cfd 100644
--- a/backend/internal/services/setup.go
+++ b/backend/internal/services/setup.go
@@ -23,6 +23,7 @@ import (
 
 var Module = fx.Module("services",
     fx.Provide(
+			NewUploadService,
 			NewSmtpService,
 			NewAuthService,
 			NewProfileService,
diff --git a/backend/internal/services/upload.go b/backend/internal/services/upload.go
new file mode 100644
index 0000000..22dae44
--- /dev/null
+++ b/backend/internal/services/upload.go
@@ -0,0 +1,116 @@
+// Copyright (c) 2025 Nikolai Papin
+//
+// This file is part of Easywish
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+// the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package services
+
+import (
+	"context"
+	minioclient "easywish/internal/minioClient"
+	"easywish/internal/utils"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/minio/minio-go/v7"
+	"go.uber.org/zap"
+)
+
+type UploadService interface {
+	GetAvatarUrl() (*string, *map[string]string, error)
+	GetImageUrl() (*string, *map[string]string, error)
+}
+
+type uploadServiceImpl struct {
+	minio *minio.Client
+	log   *zap.Logger
+
+	avatarPolicy minio.PostPolicy
+	imagePolicy minio.PostPolicy
+}
+
+func NewUploadService(_minio *minio.Client, _log *zap.Logger) UploadService {
+	service := uploadServiceImpl{
+		minio: _minio,
+		log:   _log,
+	}
+
+	avatarPolicy := minio.NewPostPolicy()
+	imagePolicy := minio.NewPostPolicy()
+
+	// At the moment the parameters match for both policies but this may
+	// change with introduction of new policies
+	for _, policy := range [...]*minio.PostPolicy{avatarPolicy, imagePolicy} {
+		if err := policy.SetBucket(minioclient.Buckets["uploads"]); err != nil {
+			panic("Failed to set bucket for policy: " + err.Error())
+		}
+
+		if err := policy.SetExpires(time.Now().UTC().Add(10 * time.Minute)); err != nil {
+			panic("Failed to set expiration time for policy: " + err.Error())
+		}
+
+		if err := policy.SetContentTypeStartsWith("image/"); err != nil {
+			panic("Failed to set allowed content types for the policy: " + err.Error())
+		}
+
+		if err := policy.SetContentLengthRange(1, 512*1024); err != nil {
+			panic("Failed to set allowed content length range for the policy: " + err.Error())
+		}
+	}
+
+	service.imagePolicy = *imagePolicy
+	service.avatarPolicy = *avatarPolicy
+
+	return &service
+}
+
+func (u *uploadServiceImpl) genUrl(policy minio.PostPolicy, prefix string) (*string, *map[string]string, error) {
+
+	object := prefix + uuid.New().String()
+
+	if err := policy.SetKey(object); err != nil {
+		u.log.Error(
+			"Failed to set random key for presigned url",
+			zap.Error(err))
+		return nil, nil, err
+	}
+
+	url, formData, err := u.minio.PresignedPostPolicy(context.Background(), &policy)
+	if err != nil {
+		u.log.Error(
+			"Failed to generate presigned url",
+			zap.String("object", object),
+			zap.Error(err))
+		return nil, nil, err
+	}
+
+	convertedUrl, err := utils.LocalizeS3Url(url.String()); if err != nil {
+		u.log.Error(
+			"Failed to localize object URL to user-accessible format",
+			zap.String("url", url.String()),
+			zap.Error(err))
+		return nil, nil, err
+	}
+
+	return &convertedUrl, &formData, nil
+}
+
+func (u *uploadServiceImpl) GetAvatarUrl() (*string, *map[string]string, error) {
+	return u.genUrl(u.avatarPolicy, "avatar-")
+}
+
+func (u *uploadServiceImpl) GetImageUrl() (*string, *map[string]string, error) {
+	return u.genUrl(u.imagePolicy, "image-")
+}