Add image uploads

client.go

@@ -13,6 +13,7 @@ type Client struct {
 	BaseUrl  string
 	ApiUrl   string
 	ApiKey   string
+	MediaUrl string
 }
 
 func NewClient(options ...func(*Client)) *Client {
@@ -28,6 +29,9 @@ func NewClient(options ...func(*Client)) *Client {
 	if c.ApiKey == "" {
 		c.ApiKey = os.Getenv("SN_API_KEY")
 	}
+	if c.MediaUrl == "" {
+		c.MediaUrl = "https://m.stacker.news"
+	}
 	c.ApiUrl = fmt.Sprintf("%s/api/graphql", c.BaseUrl)
 
 	return c
@@ -45,6 +49,12 @@ func WithBaseUrl(baseUrl string) func(*Client) {
 	}
 }
 
+func WithMediaUrl(mediaUrl string) func(*Client) {
+	return func(c *Client) {
+		c.MediaUrl = mediaUrl
+	}
+}
+
 type GqlBody struct {
 	Query     string                 `json:"query"`
 	Variables map[string]interface{} `json:"variables,omitempty"`

upload.go

@@ -0,0 +1,127 @@
+package sn
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"image"
+	"image/png"
+	"io"
+	"mime/multipart"
+	"net/http"
+)
+
+type GetSignedPOST struct {
+	Url    string            `json:"url"`
+	Fields map[string]string `json:"fields"`
+}
+
+type GetSignedPOSTResponse struct {
+	Errors []GqlError `json:"errors"`
+	Data   struct {
+		GetSignedPOST GetSignedPOST `json:"getSignedPOST"`
+	} `json:"data"`
+}
+
+func (c *Client) UploadImage(img *image.RGBA) (string, error) {
+	var (
+		b      = img.Bounds()
+		width  = b.Max.X
+		height = b.Max.Y
+		size   = width * height
+		type_  = "image/png"
+	)
+
+	// get signed URL for S3 upload
+	body := GqlBody{
+		Query: `
+		mutation getSignedPOST($type: String!, $size: Int!, $width: Int!, $height: Int!, $avatar: Boolean) {
+			getSignedPOST(type: $type, size: $size, width: $width, height: $height, avatar: $avatar) {
+				url
+				fields
+			}
+		}`,
+		Variables: map[string]interface{}{
+			"type":   type_,
+			"size":   size,
+			"width":  width,
+			"height": height,
+			"avatar": false,
+		},
+	}
+
+	resp, err := c.callApi(body)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	var respBody GetSignedPOSTResponse
+	err = json.NewDecoder(resp.Body).Decode(&respBody)
+	if err != nil {
+		err = fmt.Errorf("error decoding getSignedPOST: %w", err)
+		return "", err
+	}
+
+	err = c.checkForErrors(respBody.Errors)
+	if err != nil {
+		return "", err
+	}
+
+	s3Url := respBody.Data.GetSignedPOST.Url
+	fields := respBody.Data.GetSignedPOST.Fields
+
+	// create multipart form
+	var (
+		buf bytes.Buffer
+		w   = multipart.NewWriter(&buf)
+		fw  io.Writer
+	)
+
+	for k, v := range fields {
+		if fw, err = w.CreateFormField(k); err != nil {
+			return "", err
+		}
+		fw.Write([]byte(v))
+	}
+
+	for k, v := range map[string]string{
+		"Content-type":  type_,
+		"Cache-Control": "max-age=31536000",
+		"acl":           "public-read",
+	} {
+		if fw, err = w.CreateFormField(k); err != nil {
+			return "", err
+		}
+		fw.Write([]byte(v))
+	}
+
+	if fw, err = w.CreateFormFile("file", "image.png"); err != nil {
+		return "", err
+	}
+	if err = png.Encode(fw, img); err != nil {
+		return "", err
+	}
+
+	if err = w.Close(); err != nil {
+		return "", err
+	}
+
+	// upload to S3
+	var req *http.Request
+	if req, err = http.NewRequest("POST", s3Url, &buf); err != nil {
+		return "", err
+	}
+	req.Header.Set("Content-Type", w.FormDataContentType())
+
+	client := http.DefaultClient
+	if resp, err = client.Do(req); err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	imgId := respBody.Data.GetSignedPOST.Fields["key"]
+	imgUrl := fmt.Sprintf("%s/%s", c.MediaUrl, imgId)
+
+	return imgUrl, nil
+}