nip96: http file storage

nip96/nip96.go

@@ -0,0 +1,127 @@
+package nip96
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"mime/multipart"
+	"net/http"
+	"strconv"
+
+	"github.com/nbd-wtf/go-nostr"
+)
+
+// Upload uploads a file to the provided req.Host.
+func Upload(ctx context.Context, req UploadRequest) (*UploadResponse, error) {
+	if err := req.Validate(); err != nil {
+		return nil, err
+	}
+
+	client := http.DefaultClient
+	if req.HTTPClient != nil {
+		client = req.HTTPClient
+	}
+
+	var requestBody bytes.Buffer
+	writer := multipart.NewWriter(&requestBody)
+	{
+		// Add the file
+		fileWriter, err := writer.CreateFormFile("file", req.Filename)
+		if err != nil {
+			return nil, fmt.Errorf("multipartWriter.CreateFormFile: %w", err)
+		}
+		if _, err := io.Copy(fileWriter, req.File); err != nil {
+			return nil, fmt.Errorf("io.Copy: %w", err)
+		}
+
+		// Add the other fields
+		writer.WriteField("caption", req.Caption)
+		writer.WriteField("alt", req.Alt)
+		writer.WriteField("media_type", req.MediaType)
+		writer.WriteField("content_type", req.ContentType)
+		writer.WriteField("no_transform", fmt.Sprintf("%t", req.NoTransform))
+		if req.Expiration == 0 {
+			writer.WriteField("expiration", "")
+		} else {
+			writer.WriteField("expiration", strconv.FormatInt(int64(req.Expiration), 10))
+		}
+
+		if err := writer.Close(); err != nil {
+			return nil, fmt.Errorf("multipartWriter.Close: %w", err)
+		}
+	}
+
+	uploadReq, err := http.NewRequest("POST", req.Host, &requestBody)
+	if err != nil {
+		return nil, fmt.Errorf("http.NewRequest: %w", err)
+	}
+	uploadReq.Header.Set("Content-Type", writer.FormDataContentType())
+
+	if req.SK != "" {
+		auth, err := generateAuthHeader(req.SK, req.Host)
+		if err != nil {
+			return nil, fmt.Errorf("generateAuthHeader: %w", err)
+		}
+		uploadReq.Header.Set("Authorization", auth)
+	}
+
+	resp, err := client.Do(uploadReq)
+	if err != nil {
+		return nil, fmt.Errorf("httpclient.Do: %w", err)
+	}
+	defer resp.Body.Close()
+
+	switch resp.StatusCode {
+	case http.StatusRequestEntityTooLarge:
+		return nil, fmt.Errorf("File is too large")
+
+	case http.StatusBadRequest:
+		return nil, fmt.Errorf("Bad request")
+
+	case http.StatusForbidden:
+		return nil, fmt.Errorf("Unauthorized")
+
+	case http.StatusPaymentRequired:
+		return nil, fmt.Errorf("Payment required")
+
+	case http.StatusOK, http.StatusCreated, http.StatusAccepted:
+		var uploadResp UploadResponse
+		if err := json.NewDecoder(resp.Body).Decode(&uploadResp); err != nil {
+			return nil, fmt.Errorf("Error decoding JSON: %w", err)
+		}
+		return &uploadResp, nil
+
+	default:
+		return nil, fmt.Errorf("Unexpected error %v", resp.Status)
+	}
+}
+
+func generateAuthHeader(sk, host string) (string, error) {
+	pk, err := nostr.GetPublicKey(sk)
+	if err != nil {
+		return "", fmt.Errorf("nostr.GetPublicKey: %w", err)
+	}
+
+	event := nostr.Event{
+		Kind:      27235,
+		PubKey:    pk,
+		CreatedAt: nostr.Now(),
+		Tags: nostr.Tags{
+			nostr.Tag{"u", host},
+			nostr.Tag{"method", "POST"},
+		},
+	}
+	event.Sign(sk)
+
+	b, err := json.Marshal(event)
+	if err != nil {
+		return "", fmt.Errorf("json.Marshal: %w", err)
+	}
+
+	payload := base64.StdEncoding.EncodeToString(b)
+
+	return fmt.Sprintf("Nostr %s", payload), nil
+}