photoplaces/backend/internal/handlers/upload.go

package handlers

import (
	"encoding/json"
	"net/http"
	"time"

	"github.com/google/uuid"
	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
)

type UploadHandler struct {
	minioClient *minio.Client
	bucket      string
	endpoint    string
}

func NewUploadHandler(endpoint, accessKey, secretKey, bucket string, useSSL bool) (*UploadHandler, error) {
	client, err := minio.New(endpoint, &minio.Options{
		Creds:  credentials.NewStaticV4(accessKey, secretKey, ""),
		Secure: useSSL,
	})
	if err != nil {
		return nil, err
	}

	return &UploadHandler{
		minioClient: client,
		bucket:      bucket,
		endpoint:    endpoint,
	}, nil
}

type presignedURLRequest struct {
	ContentType string `json:"content_type"`
	MaxSizeMB   int    `json:"max_size_mb"`
}

type presignedURLResponse struct {
	UploadURL string            `json:"upload_url"`
	FileURL   string            `json:"file_url"`
	Fields    map[string]string `json:"fields"`
}

func (h *UploadHandler) PresignedURL(w http.ResponseWriter, r *http.Request) {
	var req presignedURLRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	if req.MaxSizeMB <= 0 || req.MaxSizeMB > 50 {
		req.MaxSizeMB = 10
	}

	validContentTypes := map[string]bool{
		"image/jpeg": true, "image/png": true, "image/webp": true, "image/heic": true,
	}
	if !validContentTypes[req.ContentType] {
		writeError(w, http.StatusBadRequest, "unsupported content type")
		return
	}

	fileID := uuid.New().String()
	ext := ".jpg"
	switch req.ContentType {
	case "image/png":
		ext = ".png"
	case "image/webp":
		ext = ".webp"
	case "image/heic":
		ext = ".heic"
	}
	objectName := "uploads/" + fileID + ext

	policy := minio.NewPostPolicy()
	policy.SetBucket(h.bucket)
	policy.SetKey(objectName)
	policy.SetExpires(time.Now().Add(15 * time.Minute))
	policy.SetContentType(req.ContentType)
	policy.SetContentLengthRange(1, int64(req.MaxSizeMB)*1024*1024)

	url, formData, err := h.minioClient.PresignedPostPolicy(r.Context(), policy)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to generate upload URL")
		return
	}

	fileURL := "http://" + h.endpoint + "/" + h.bucket + "/" + objectName

	writeJSON(w, http.StatusOK, presignedURLResponse{
		UploadURL: url.String(),
		FileURL:   fileURL,
		Fields:    formData,
	})
}