feat: support image upload

model/content.go

@@ -0,0 +1,93 @@
+package model
+
+import (
+	"bytes"
+	"encoding/base64"
+	"io"
+	"mime"
+	"strings"
+
+	"github.com/fumiama/imgsz"
+	"github.com/pkg/errors"
+)
+
+var (
+	ErrUnsupportedImageExtension = errors.New("unsupported image extension")
+)
+
+type ContentType string
+
+const (
+	ContentTypeText     ContentType = "text"
+	ContentTypeImageURL ContentType = "image_url"
+)
+
+type Contents []Content
+
+func (cs Contents) String() string {
+	switch len(cs) {
+	case 0:
+		return ""
+	case 1:
+		if cs[0].Type == ContentTypeText {
+			return cs[0].Text
+		}
+		fallthrough
+	default:
+		sb := strings.Builder{}
+		for _, c := range cs {
+			switch c.Type {
+			case ContentTypeText:
+				sb.WriteString("<text>")
+				sb.WriteString(c.Text)
+				sb.WriteString("</text>")
+			case ContentTypeImageURL:
+				if c.ImageURL != nil {
+					sb.WriteString("<image_url>")
+					sb.WriteString(c.ImageURL.URL)
+					sb.WriteString("</image_url>")
+				}
+			default:
+				panic("unsupported ContentType " + c.Type)
+			}
+		}
+		return sb.String()
+	}
+}
+
+type Content struct {
+	Type     ContentType      `json:"type"`
+	Text     string           `json:"text,omitempty"`
+	ImageURL *ContentImageURL `json:"image_url,omitempty"`
+}
+
+func NewContentText(txt string) Content {
+	return Content{Type: ContentTypeText, Text: txt}
+}
+
+type ContentImageURL struct {
+	URL string `json:"url"`
+}
+
+func NewContentImageURL(u string) Content {
+	return Content{Type: ContentTypeImageURL, ImageURL: &ContentImageURL{URL: u}}
+}
+
+func NewContentImageDataBase64URL(data []byte) (string, error) {
+	_, ext, err := imgsz.DecodeSize(bytes.NewReader(data))
+	if err != nil {
+		return "", err
+	}
+	typ := mime.TypeByExtension("." + ext)
+	if len(typ) == 0 {
+		return "", errors.Wrap(ErrUnsupportedImageExtension, ext)
+	}
+	sb := strings.Builder{}
+	sb.WriteString("data:")
+	sb.WriteString(typ)
+	sb.WriteString(";base64,")
+	enc := base64.NewEncoder(base64.StdEncoding, &sb)
+	_, _ = io.Copy(enc, bytes.NewReader(data))
+	_ = enc.Close()
+	return sb.String(), nil
+}