pierre-bot/internal/chatter/openai.go

package chatter

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"net/http"
	"reflect"

	"github.com/sashabaranov/go-openai"
	"github.com/sashabaranov/go-openai/jsonschema"
)

type OpenAIAdapter struct {
	client *openai.Client
	model  string
}

func NewOpenAIAdapter(apiKey string, model string, baseURL string) *OpenAIAdapter {
	config := openai.DefaultConfig(apiKey)

	tr := &http.Transport{
		TLSClientConfig: &tls.Config{
			InsecureSkipVerify: true, // Bypasses the "not standards compliant" error
		},
	}

	config.HTTPClient = &http.Client{Transport: tr}

	if baseURL != "" {
		config.BaseURL = baseURL
	}
	if baseURL != "" {
		config.BaseURL = baseURL
	}
	return &OpenAIAdapter{
		client: openai.NewClientWithConfig(config),
		model:  model,
	}
}

func (a *OpenAIAdapter) Generate(ctx context.Context, messages []Message) (string, error) {
	var chatMsgs []openai.ChatCompletionMessage
	for _, m := range messages {
		chatMsgs = append(chatMsgs, openai.ChatCompletionMessage{
			Role:    string(m.Role),
			Content: m.Content,
		})
	}

	resp, err := a.client.CreateChatCompletion(ctx, openai.ChatCompletionRequest{
		Model:    a.model,
		Messages: chatMsgs,
	})
	if err != nil {
		return "", err
	}
	return resp.Choices[0].Message.Content, nil
}

func (a *OpenAIAdapter) GenerateStructured(ctx context.Context, messages []Message, target any) error {
	val := reflect.ValueOf(target)
	if val.Kind() != reflect.Ptr {
		return fmt.Errorf("target must be a pointer")
	}

	elem := val.Elem()
	var schemaType reflect.Type
	isSlice := elem.Kind() == reflect.Slice

	// 1. Wrap slices in an object because OpenAI requires a root object
	if isSlice {
		schemaType = reflect.StructOf([]reflect.StructField{
			{
				Name: "Items",
				Type: elem.Type(),
				Tag:  `json:"items"`,
			},
		})
	} else {
		schemaType = elem.Type()
	}

	// 2. Build the Schema Map
	schemaObj := a.reflectTypeToSchema(schemaType)

	// 3. Convert to json.RawMessage to satisfy the json.Marshaler interface
	schemaBytes, err := json.Marshal(schemaObj)
	if err != nil {
		return fmt.Errorf("failed to marshal schema: %w", err)
	}

	var chatMsgs []openai.ChatCompletionMessage
	for _, m := range messages {
		chatMsgs = append(chatMsgs, openai.ChatCompletionMessage{
			Role:    string(m.Role),
			Content: m.Content,
		})
	}

	// 4. Send Request
	req := openai.ChatCompletionRequest{
		Model:    a.model,
		Messages: chatMsgs,
		ResponseFormat: &openai.ChatCompletionResponseFormat{
			Type: openai.ChatCompletionResponseFormatTypeJSONSchema,
			JSONSchema: &openai.ChatCompletionResponseFormatJSONSchema{
				Name:   "output_schema",
				Strict: true,
				Schema: json.RawMessage(schemaBytes),
			},
		},
	}

	resp, err := a.client.CreateChatCompletion(ctx, req)
	if err != nil {
		return err
	}

	content := resp.Choices[0].Message.Content

	// 5. Unmarshal and Unwrap if necessary
	if isSlice {
		temp := struct {
			Items json.RawMessage `json:"items"`
		}{}
		if err := json.Unmarshal([]byte(content), &temp); err != nil {
			return err
		}
		return json.Unmarshal(temp.Items, target)
	}

	return json.Unmarshal([]byte(content), target)
}

func (a *OpenAIAdapter) reflectTypeToSchema(t reflect.Type) jsonschema.Definition {
	for t.Kind() == reflect.Ptr {
		t = t.Elem()
	}

	switch t.Kind() {
	case reflect.Struct:
		def := jsonschema.Definition{
			Type:                 jsonschema.Object,
			Properties:           make(map[string]jsonschema.Definition),
			AdditionalProperties: false,
			Required:             []string{},
		}
		for i := 0; i < t.NumField(); i++ {
			field := t.Field(i)
			if !field.IsExported() {
				continue
			}
			name := field.Tag.Get("json")
			if name == "" || name == "-" {
				name = field.Name
			}
			def.Properties[name] = a.reflectTypeToSchema(field.Type)
			def.Required = append(def.Required, name)
		}
		return def

	case reflect.Slice, reflect.Array:
		items := a.reflectTypeToSchema(t.Elem())
		return jsonschema.Definition{
			Type:  jsonschema.Array,
			Items: &items,
		}

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return jsonschema.Definition{Type: jsonschema.Integer}
	case reflect.Float32, reflect.Float64:
		return jsonschema.Definition{Type: jsonschema.Number}
	case reflect.Bool:
		return jsonschema.Definition{Type: jsonschema.Boolean}
	default:
		return jsonschema.Definition{Type: jsonschema.String}
	}
}

func (a *OpenAIAdapter) GetProviderName() string {
	return "OpenAI (" + a.model + ")"
}