feat: impl. multi-model / attachments, images

common/attachment.go

@@ -0,0 +1,130 @@
+package common
+
+import (
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"github.com/gabriel-vasile/mimetype"
+	"io/ioutil"
+	"net/http"
+)
+
+type Attachment struct {
+	Type    *string `json:"type,omitempty"`
+	Path    *string `json:"path,omitempty"`
+	URL     *string `json:"url,omitempty"`
+	Content []byte  `json:"content,omitempty"`
+	ID      *string `json:"id,omitempty"`
+}
+
+func (a *Attachment) GetId() (ret string, err error) {
+	if a.ID == nil {
+		var hash string
+		if a.Content != nil {
+			hash = fmt.Sprintf("%x", sha256.Sum256(a.Content))
+		} else if a.Path != nil {
+			var content []byte
+			if content, err = ioutil.ReadFile(*a.Path); err != nil {
+				return
+			}
+			hash = fmt.Sprintf("%x", sha256.Sum256(content))
+		} else if a.URL != nil {
+			data := map[string]string{"url": *a.URL}
+			var jsonData []byte
+			if jsonData, err = json.Marshal(data); err != nil {
+				return
+			}
+			hash = fmt.Sprintf("%x", sha256.Sum256(jsonData))
+		}
+		a.ID = &hash
+	}
+	ret = *a.ID
+	return
+}
+
+func (a *Attachment) ResolveType() (ret string, err error) {
+	if a.Type != nil {
+		ret = *a.Type
+		return
+	}
+	if a.Path != nil {
+		var mime *mimetype.MIME
+		if mime, err = mimetype.DetectFile(*a.Path); err != nil {
+			return
+		}
+		ret = mime.String()
+		return
+	}
+	if a.URL != nil {
+		var resp *http.Response
+		if resp, err = http.Head(*a.URL); err != nil {
+			return
+		}
+		defer resp.Body.Close()
+		ret = resp.Header.Get("Content-Type")
+		return
+	}
+	if a.Content != nil {
+		ret = mimetype.Detect(a.Content).String()
+		return
+	}
+	err = fmt.Errorf("attachment has no type and no content to derive it from")
+	return
+}
+
+func (a *Attachment) ContentBytes() (ret []byte, err error) {
+	if a.Content != nil {
+		ret = a.Content
+		return
+	}
+	if a.Path != nil {
+		if ret, err = ioutil.ReadFile(*a.Path); err != nil {
+			return
+		}
+		return
+	}
+	if a.URL != nil {
+		var resp *http.Response
+		if resp, err = http.Get(*a.URL); err != nil {
+			return
+		}
+		defer resp.Body.Close()
+		if ret, err = ioutil.ReadAll(resp.Body); err != nil {
+			return
+		}
+		return
+	}
+	err = fmt.Errorf("no content available")
+	return
+}
+
+func (a *Attachment) Base64Content() (ret string, err error) {
+	var content []byte
+	if content, err = a.ContentBytes(); err != nil {
+		return
+	}
+	ret = base64.StdEncoding.EncodeToString(content)
+	return
+}
+
+func FromRow(row map[string]interface{}) (ret *Attachment, err error) {
+	attachment := &Attachment{}
+	if id, ok := row["id"].(string); ok {
+		attachment.ID = &id
+	}
+	if typ, ok := row["type"].(string); ok {
+		attachment.Type = &typ
+	}
+	if path, ok := row["path"].(string); ok {
+		attachment.Path = &path
+	}
+	if url, ok := row["url"].(string); ok {
+		attachment.URL = &url
+	}
+	if content, ok := row["content"].([]byte); ok {
+		attachment.Content = content
+	}
+	ret = attachment
+	return
+}