Add image handling for Gemini requests with URL download and base64 support

google.go

@@ -2,8 +2,11 @@ package go_llm
 
 import (
 	"context"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"io"
+	"net/http"
 
 	"github.com/google/generative-ai-go/genai"
 	"google.golang.org/api/option"
@@ -54,6 +57,57 @@ func (g google) requestToChatHistory(in Request, model *genai.GenerativeModel) (
 			content.Role = "user"
 		}
 
+		for _, img := range c.Images {
+			if img.Url != "" {
+				// gemini does not support URLs, so we need to download the image and convert it to a blob
+
+				// Download the image from the URL
+				resp, err := http.Get(img.Url)
+				if err != nil {
+					panic(fmt.Sprintf("error downloading image: %v", err))
+				}
+				defer resp.Body.Close()
+
+				// Check the Content-Length to ensure it's not over 20MB
+				if resp.ContentLength > 20*1024*1024 {
+					panic(fmt.Sprintf("image size exceeds 20MB: %d bytes", resp.ContentLength))
+				}
+
+				// Read the content into a byte slice
+				data, err := io.ReadAll(resp.Body)
+				if err != nil {
+					panic(fmt.Sprintf("error reading image data: %v", err))
+				}
+
+				// Ensure the MIME type is appropriate
+				mimeType := http.DetectContentType(data)
+				switch mimeType {
+				case "image/jpeg", "image/png", "image/gif":
+					// MIME type is valid
+				default:
+					panic(fmt.Sprintf("unsupported image MIME type: %s", mimeType))
+				}
+
+				// Create a genai.Blob using the validated image data
+				content.Parts = append(content.Parts, genai.Blob{
+					MIMEType: mimeType,
+					Data:     data,
+				})
+
+			} else {
+				// convert base64 to blob
+				b, e := base64.StdEncoding.DecodeString(img.Base64)
+				if e != nil {
+					panic(fmt.Sprintf("error decoding base64: %v", e))
+				}
+
+				content.Parts = append(content.Parts, genai.Blob{
+					MIMEType: img.ContentType,
+					Data:     b,
+				})
+			}
+		}
+
 		// if this is the last message, we want to add to history, we want it to be the parts
 		if i == len(in.Messages)-1 {
 			return &res, cs, content.Parts