Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/service/openai_endpoint_url.go

@@ -0,0 +1,91 @@
+package service
+
+import (
+	"net/url"
+	"strings"
+)
+
+func buildOpenAIEndpointURL(base string, endpoint string) string {
+	normalized := strings.TrimSpace(base)
+	endpoint = "/" + strings.TrimLeft(strings.TrimSpace(endpoint), "/")
+	relative := strings.TrimPrefix(endpoint, "/v1")
+	parsed, err := url.Parse(normalized)
+	if err != nil {
+		return strings.TrimRight(normalized, "/") + endpoint
+	}
+	path := strings.TrimRight(parsed.Path, "/")
+	if !strings.HasSuffix(path, endpoint) && !strings.HasSuffix(path, relative) {
+		if openAIBaseURLHasVersionSuffix(path) {
+			path += relative
+		} else {
+			path += endpoint
+		}
+	}
+	parsed.Path = path
+	parsed.RawPath = ""
+	parsed.Fragment = ""
+	return parsed.String()
+}
+
+func buildOpenAIResponsesInputTokensURL(base string) string {
+	return buildOpenAIEndpointURL(base, "/v1/responses/input_tokens")
+}
+
+func openAIBaseURLHasVersionSuffix(raw string) bool {
+	trimmed := strings.TrimSpace(raw)
+	if trimmed == "" {
+		return false
+	}
+
+	pathValue := ""
+	if parsed, err := url.Parse(trimmed); err == nil && parsed.Scheme != "" && parsed.Host != "" {
+		pathValue = parsed.Path
+	} else if slash := strings.Index(trimmed, "/"); slash >= 0 {
+		pathValue = trimmed[slash:]
+	}
+
+	pathValue = strings.TrimRight(pathValue, "/")
+	if pathValue == "" {
+		return false
+	}
+	lastSlash := strings.LastIndex(pathValue, "/")
+	segment := pathValue
+	if lastSlash >= 0 {
+		segment = pathValue[lastSlash+1:]
+	}
+	return isOpenAIAPIVersionSegment(segment)
+}
+
+func isOpenAIAPIVersionSegment(segment string) bool {
+	s := strings.ToLower(strings.TrimSpace(segment))
+	if len(s) < 2 || s[0] != 'v' || !isASCIIDigit(s[1]) {
+		return false
+	}
+
+	i := 1
+	for i < len(s) && isASCIIDigit(s[i]) {
+		i++
+	}
+	if i == len(s) {
+		return true
+	}
+	if s[i] == '.' {
+		i++
+		if i == len(s) || !isASCIIDigit(s[i]) {
+			return false
+		}
+		for i < len(s) && isASCIIDigit(s[i]) {
+			i++
+		}
+		return i == len(s)
+	}
+
+	suffix := s[i:]
+	return strings.HasPrefix(suffix, "alpha") ||
+		strings.HasPrefix(suffix, "beta") ||
+		strings.HasPrefix(suffix, "preview")
+}
+
+func isASCIIDigit(b byte) bool {
+	return b >= '0' && b <= '9'
+}