Second checkpoint

internal/storage/s3/s3.go

@@ -0,0 +1,76 @@
+// Package s3 wraps the MinIO client to provide object storage for datasets.
+package s3
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"gis/internal/config"
+
+	"github.com/minio/minio-go/v7"
+	"github.com/minio/minio-go/v7/pkg/credentials"
+)
+
+// Client stores and retrieves dataset objects in an S3-compatible bucket.
+type Client struct {
+	mc     *minio.Client
+	bucket string
+}
+
+// New constructs a Client and ensures the configured bucket exists.
+func New(ctx context.Context, cfg config.S3Config) (*Client, error) {
+	mc, err := minio.New(cfg.Endpoint, &minio.Options{
+		Creds:  credentials.NewStaticV4(cfg.AccessKey, cfg.SecretKey, ""),
+		Secure: cfg.UseSSL,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("create s3 client: %w", err)
+	}
+
+	exists, err := mc.BucketExists(ctx, cfg.Bucket)
+	if err != nil {
+		return nil, fmt.Errorf("check bucket: %w", err)
+	}
+	if !exists {
+		if err := mc.MakeBucket(ctx, cfg.Bucket, minio.MakeBucketOptions{}); err != nil {
+			return nil, fmt.Errorf("make bucket: %w", err)
+		}
+	}
+
+	return &Client{mc: mc, bucket: cfg.Bucket}, nil
+}
+
+// Put streams an object of the given size to the bucket under key.
+func (c *Client) Put(ctx context.Context, key string, r io.Reader, size int64, contentType string) error {
+	_, err := c.mc.PutObject(ctx, c.bucket, key, r, size, minio.PutObjectOptions{
+		ContentType: contentType,
+	})
+	if err != nil {
+		return fmt.Errorf("put object %q: %w", key, err)
+	}
+	return nil
+}
+
+// Get returns a reader for the object stored under key. The caller must close it.
+func (c *Client) Get(ctx context.Context, key string) (io.ReadCloser, error) {
+	obj, err := c.mc.GetObject(ctx, c.bucket, key, minio.GetObjectOptions{})
+	if err != nil {
+		return nil, fmt.Errorf("get object %q: %w", key, err)
+	}
+	return obj, nil
+}
+
+// Remove deletes the object stored under key.
+func (c *Client) Remove(ctx context.Context, key string) error {
+	if err := c.mc.RemoveObject(ctx, c.bucket, key, minio.RemoveObjectOptions{}); err != nil {
+		return fmt.Errorf("remove object %q: %w", key, err)
+	}
+	return nil
+}
+
+// Ping verifies connectivity to the object store (used by readiness checks).
+func (c *Client) Ping(ctx context.Context) error {
+	_, err := c.mc.BucketExists(ctx, c.bucket)
+	return err
+}