go-llm/anthropic.go

package go_llm

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"log/slog"
	"net/http"

	anth "github.com/liushuangls/go-anthropic/v2"
)

type anthropic struct {
	key   string
	model string
}

var _ LLM = anthropic{}

func (a anthropic) ModelVersion(modelVersion string) (ChatCompletion, error) {
	a.model = modelVersion

	// TODO: model verification?
	return a, nil
}

func deferClose(c io.Closer) {
	err := c.Close()
	if err != nil {
		slog.Error("error closing", "error", err)
	}
}

func (a anthropic) requestToAnthropicRequest(req Request) anth.MessagesRequest {
	res := anth.MessagesRequest{
		Model:     anth.Model(a.model),
		MaxTokens: 1000,
	}

	msgs := []anth.Message{}

	// we gotta convert messages into anthropic messages, however
	// anthropic does not have a "system" message type, so we need to
	// append it to the res.System field instead

	for _, msg := range req.Messages {
		if msg.Role == RoleSystem {
			if len(res.System) > 0 {
				res.System += "\n"
			}
			res.System += msg.Text
		} else {
			role := anth.RoleUser

			if msg.Role == RoleAssistant {
				role = anth.RoleAssistant
			}

			m := anth.Message{
				Role:    role,
				Content: []anth.MessageContent{},
			}

			if msg.Text != "" {
				m.Content = append(m.Content, anth.MessageContent{
					Type: anth.MessagesContentTypeText,
					Text: &msg.Text,
				})
			}

			for _, img := range msg.Images {
				// anthropic doesn't allow the assistant to send images, so we need to say it's from the user
				if m.Role == anth.RoleAssistant {
					m.Role = anth.RoleUser
				}

				if img.Base64 != "" {
					m.Content = append(m.Content, anth.NewImageMessageContent(
						anth.NewMessageContentSource(
							anth.MessagesContentSourceTypeBase64,
							img.ContentType,
							img.Base64,
						)))
				} else if img.Url != "" {

					// download the image
					cl, err := http.NewRequest(http.MethodGet, img.Url, nil)
					if err != nil {
						log.Println("failed to create request", err)
						continue
					}

					resp, err := http.DefaultClient.Do(cl)
					if err != nil {
						log.Println("failed to download image", err)
						continue
					}

					defer deferClose(resp.Body)

					img.ContentType = resp.Header.Get("Content-Type")

					// read the image
					b, err := io.ReadAll(resp.Body)
					if err != nil {
						log.Println("failed to read image", err)
						continue
					}

					// base64 encode the image
					img.Base64 = string(b)

					m.Content = append(m.Content, anth.NewImageMessageContent(
						anth.NewMessageContentSource(
							anth.MessagesContentSourceTypeBase64,
							img.ContentType,
							img.Base64,
						)))
				}
			}

			// if this has the same role as the previous message, we can append it to the previous message
			// as anthropic expects alternating assistant and user roles

			if len(msgs) > 0 && msgs[len(msgs)-1].Role == role {
				m2 := &msgs[len(msgs)-1]

				m2.Content = append(m2.Content, m.Content...)
			} else {
				msgs = append(msgs, m)
			}
		}
	}

	if req.Toolbox != nil {
		for _, tool := range req.Toolbox.funcs {
			res.Tools = append(res.Tools, anth.ToolDefinition{
				Name:        tool.Name,
				Description: tool.Description,
				InputSchema: tool.Parameters,
			})
		}
	}

	res.Messages = msgs

	if req.Temperature != nil {
		res.Temperature = req.Temperature
	}

	log.Println("llm request to anthropic request", res)

	return res
}

func (a anthropic) responseToLLMResponse(in anth.MessagesResponse) Response {
	res := Response{}

	for _, msg := range in.Content {
		choice := ResponseChoice{}

		switch msg.Type {
		case anth.MessagesContentTypeText:
			if msg.Text != nil {
				choice.Content = *msg.Text
			}

		case anth.MessagesContentTypeToolUse:
			if msg.MessageContentToolUse != nil {
				b, e := json.Marshal(msg.MessageContentToolUse.Input)
				if e != nil {
					log.Println("failed to marshal input", e)
				} else {
					choice.Calls = append(choice.Calls, ToolCall{
						ID: msg.MessageContentToolUse.ID,
						FunctionCall: FunctionCall{
							Name:      msg.MessageContentToolUse.Name,
							Arguments: string(b),
						},
					})
				}
			}
		}

		res.Choices = append(res.Choices, choice)
	}

	log.Println("anthropic response to llm response", res)

	return res
}

func (a anthropic) ChatComplete(ctx context.Context, req Request) (Response, error) {
	cl := anth.NewClient(a.key)

	res, err := cl.CreateMessages(ctx, a.requestToAnthropicRequest(req))

	if err != nil {
		return Response{}, fmt.Errorf("failed to chat complete: %w", err)
	}

	return a.responseToLLMResponse(res), nil
}