| 1 | package openai |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "encoding/json" |
| 6 | "errors" |
| 7 | "fmt" |
| 8 | "io" |
| 9 | "net/http" |
| 10 | "sort" |
| 11 | "strings" |
| 12 | "time" |
| 13 | ) |
| 14 | |
| 15 | type modelFetchStatusError struct { |
| 16 | status int |
| 17 | body string |
| 18 | } |
| 19 | |
| 20 | type ModelFetchAuthMode string |
| 21 | |
| 22 | const ( |
| 23 | ModelFetchAuthAuto ModelFetchAuthMode = "" |
| 24 | ModelFetchAuthBearer ModelFetchAuthMode = "bearer" |
| 25 | ModelFetchAuthXAPIKey ModelFetchAuthMode = "x-api-key" |
| 26 | |
| 27 | // fetchModelsMaxBody caps the response body read from a model-list |
| 28 | // endpoint. Large providers like OpenRouter return ~530 KB for 338 |
| 29 | // models; 2 MiB leaves headroom while keeping memory bounded. |
| 30 | fetchModelsMaxBody = 2 << 20 // 2 MiB |
| 31 | ) |
| 32 | |
| 33 | type FetchModelsOptions struct { |
| 34 | Headers map[string]string |
| 35 | AuthMode ModelFetchAuthMode |
| 36 | } |
| 37 | |
| 38 | func (e modelFetchStatusError) Error() string { |
| 39 | return fmt.Sprintf("fetch models: status %d: %s", e.status, strings.TrimSpace(e.body)) |
| 40 | } |
| 41 | |
| 42 | // IsModelFetchEndpointMiss reports whether a model-list request reached a |
| 43 | // plausible endpoint path that the provider does not implement. |
| 44 | func IsModelFetchEndpointMiss(err error) bool { |
| 45 | var statusErr modelFetchStatusError |
| 46 | if !errors.As(err, &statusErr) { |
| 47 | return false |
| 48 | } |
| 49 | return statusErr.status == http.StatusNotFound || statusErr.status == http.StatusMethodNotAllowed |
| 50 | } |
| 51 | |
| 52 | // FetchModels calls the OpenAI-compatible GET /models endpoint and returns the |
| 53 | // available model IDs. |
| 54 | func FetchModels(ctx context.Context, baseURL, apiKey string, headers map[string]string) ([]string, error) { |
| 55 | return FetchModelsWithOptions(ctx, baseURL, apiKey, FetchModelsOptions{Headers: headers}) |
| 56 | } |
| 57 | |
| 58 | // FetchModelsWithOptions calls the OpenAI-compatible GET /models endpoint and |
| 59 | // returns the available model IDs. |
| 60 | func FetchModelsWithOptions(ctx context.Context, baseURL, apiKey string, opts FetchModelsOptions) ([]string, error) { |
| 61 | cli := &http.Client{Timeout: 10 * time.Second} |
| 62 | url := strings.TrimRight(baseURL, "/") |
| 63 | if !strings.HasSuffix(url, "/models") { |
| 64 | url += "/models" |
| 65 | } |
| 66 | |
| 67 | req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil) |
| 68 | if err != nil { |
| 69 | return nil, fmt.Errorf("fetch models: build request: %w", err) |
| 70 | } |
| 71 | applyModelFetchAPIKeyHeader(req.Header, baseURL, apiKey, opts.AuthMode) |
| 72 | req.Header.Set("Accept", "application/json") |
| 73 | applyCustomHeaders(req.Header, opts.Headers) |
| 74 | |
| 75 | resp, err := cli.Do(req) |
| 76 | if err != nil { |
| 77 | return nil, fmt.Errorf("fetch models: request failed: %w", err) |
| 78 | } |
| 79 | defer resp.Body.Close() |
| 80 | |
| 81 | body, err := io.ReadAll(io.LimitReader(resp.Body, fetchModelsMaxBody+1)) |
| 82 | if err != nil { |
| 83 | return nil, fmt.Errorf("fetch models: read response: %w", err) |
| 84 | } |
| 85 | if len(body) > fetchModelsMaxBody { |
| 86 | return nil, fmt.Errorf("fetch models: response too large (exceeds %d bytes)", fetchModelsMaxBody) |
| 87 | } |
| 88 | |
| 89 | if resp.StatusCode != http.StatusOK { |
| 90 | return nil, modelFetchStatusError{status: resp.StatusCode, body: truncateFetchBody(string(body))} |
| 91 | } |
| 92 | |
| 93 | var result struct { |
| 94 | Data []struct { |
| 95 | ID string `json:"id"` |
| 96 | } `json:"data"` |
| 97 | } |
| 98 | if err := json.Unmarshal(body, &result); err != nil { |
| 99 | return nil, fmt.Errorf("fetch models: decode response: %w", err) |
| 100 | } |
| 101 | |
| 102 | ids := make([]string, 0, len(result.Data)) |
| 103 | for _, m := range result.Data { |
| 104 | if id := normalizeModelID(baseURL, m.ID); id != "" { |
| 105 | ids = append(ids, id) |
| 106 | } |
| 107 | } |
| 108 | sort.Strings(ids) |
| 109 | return ids, nil |
| 110 | } |
| 111 | |
| 112 | func applyModelFetchAPIKeyHeader(h http.Header, baseURL, apiKey string, mode ModelFetchAuthMode) { |
| 113 | apiKey = strings.TrimSpace(apiKey) |
| 114 | if apiKey == "" { |
| 115 | return |
| 116 | } |
| 117 | switch mode { |
| 118 | case ModelFetchAuthBearer: |
| 119 | h.Set("Authorization", "Bearer "+apiKey) |
| 120 | case ModelFetchAuthXAPIKey: |
| 121 | h.Set("x-api-key", apiKey) |
| 122 | default: |
| 123 | applyAPIKeyHeader(h, baseURL, apiKey) |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | func truncateFetchBody(body string) string { |
| 128 | body = strings.TrimSpace(body) |
| 129 | const max = 512 |
| 130 | if len([]rune(body)) <= max { |
| 131 | return body |
| 132 | } |
| 133 | r := []rune(body) |
| 134 | return string(r[:max]) + "..." |
| 135 | } |
| 136 |