feat: embedding router

internal/embeddings/embeddings.go

@@ -0,0 +1,102 @@
+package embeddings
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+)
+
+type Embedder interface {
+	Embed(ctx context.Context, input string) ([]float32, error)
+	Dimensions() int
+}
+
+type OpenAIEmbedder struct {
+	apiKey  string
+	baseURL string
+	model   string
+	dims    int
+	http    *http.Client
+}
+
+type openAIEmbeddingRequest struct {
+	Input string `json:"input"`
+	Model string `json:"model"`
+}
+
+type openAIEmbeddingResponse struct {
+	Data []struct {
+		Embedding []float32 `json:"embedding"`
+	} `json:"data"`
+}
+
+func NewOpenAIEmbedder(apiKey, baseURL, model string, dims int, timeout time.Duration) *OpenAIEmbedder {
+	if baseURL == "" {
+		baseURL = "https://api.openai.com"
+	}
+	if model == "" {
+		model = "text-embedding-3-small"
+	}
+	if dims <= 0 {
+		dims = 1536
+	}
+	if timeout <= 0 {
+		timeout = 10 * time.Second
+	}
+	return &OpenAIEmbedder{
+		apiKey:  apiKey,
+		baseURL: strings.TrimRight(baseURL, "/"),
+		model:   model,
+		dims:    dims,
+		http: &http.Client{
+			Timeout: timeout,
+		},
+	}
+}
+
+func (e *OpenAIEmbedder) Dimensions() int {
+	return e.dims
+}
+
+func (e *OpenAIEmbedder) Embed(ctx context.Context, input string) ([]float32, error) {
+	payload, err := json.Marshal(openAIEmbeddingRequest{
+		Input: input,
+		Model: e.model,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, e.baseURL+"/v1/embeddings", bytes.NewReader(payload))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	if e.apiKey != "" {
+		req.Header.Set("Authorization", "Bearer "+e.apiKey)
+	}
+
+	resp, err := e.http.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		body, _ := io.ReadAll(resp.Body)
+		return nil, fmt.Errorf("openai embeddings error: %s", strings.TrimSpace(string(body)))
+	}
+
+	var parsed openAIEmbeddingResponse
+	if err := json.NewDecoder(resp.Body).Decode(&parsed); err != nil {
+		return nil, err
+	}
+	if len(parsed.Data) == 0 {
+		return nil, fmt.Errorf("openai embeddings empty response")
+	}
+	return parsed.Data[0].Embedding, nil
+}