chat api (#991)

- update chat docs
- add messages chat endpoint
- remove deprecated context and template generate parameters from docs
- context and template are still supported for the time being and will continue to work as expected
- add partial response to chat history

server/images.go

@@ -47,37 +47,82 @@ type Model struct {
 	Options       map[string]interface{}
 }
 
-func (m *Model) Prompt(request api.GenerateRequest) (string, error) {
-	t := m.Template
-	if request.Template != "" {
-		t = request.Template
-	}
+type PromptVars struct {
+	System   string
+	Prompt   string
+	Response string
+}
 
-	tmpl, err := template.New("").Parse(t)
+func (m *Model) Prompt(p PromptVars) (string, error) {
+	var prompt strings.Builder
+	tmpl, err := template.New("").Parse(m.Template)
 	if err != nil {
 		return "", err
 	}
 
-	var vars struct {
-		First  bool
-		System string
-		Prompt string
-	}
-
-	vars.First = len(request.Context) == 0
-	vars.System = m.System
-	vars.Prompt = request.Prompt
-
-	if request.System != "" {
-		vars.System = request.System
+	if p.System == "" {
+		// use the default system prompt for this model if one is not specified
+		p.System = m.System
 	}
 
 	var sb strings.Builder
-	if err := tmpl.Execute(&sb, vars); err != nil {
+	if err := tmpl.Execute(&sb, p); err != nil {
 		return "", err
 	}
+	prompt.WriteString(sb.String())
+	prompt.WriteString(p.Response)
+	return prompt.String(), nil
+}
 
-	return sb.String(), nil
+func (m *Model) ChatPrompt(msgs []api.Message) (string, error) {
+	// build the prompt from the list of messages
+	var prompt strings.Builder
+	currentVars := PromptVars{}
+
+	writePrompt := func() error {
+		p, err := m.Prompt(currentVars)
+		if err != nil {
+			return err
+		}
+		prompt.WriteString(p)
+		currentVars = PromptVars{}
+		return nil
+	}
+
+	for _, msg := range msgs {
+		switch msg.Role {
+		case "system":
+			if currentVars.Prompt != "" || currentVars.System != "" {
+				if err := writePrompt(); err != nil {
+					return "", err
+				}
+			}
+			currentVars.System = msg.Content
+		case "user":
+			if currentVars.Prompt != "" || currentVars.System != "" {
+				if err := writePrompt(); err != nil {
+					return "", err
+				}
+			}
+			currentVars.Prompt = msg.Content
+		case "assistant":
+			currentVars.Response = msg.Content
+			if err := writePrompt(); err != nil {
+				return "", err
+			}
+		default:
+			return "", fmt.Errorf("invalid role: %s, role must be one of [system, user, assistant]", msg.Role)
+		}
+	}
+
+	// Append the last set of vars if they are non-empty
+	if currentVars.Prompt != "" || currentVars.System != "" {
+		if err := writePrompt(); err != nil {
+			return "", err
+		}
+	}
+
+	return prompt.String(), nil
 }
 
 type ManifestV2 struct {