feat: 实现 AI 规格候选匹配与审计 (#201)

admin/service/ai_specmatch_client.go

@@ -0,0 +1,109 @@
+package service
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"cmautobuy/admin/model"
+)
+
+const maxAIModelResponseBytes = 64 << 10
+
+type AIModelCandidate struct {
+	ID      string            `json:"id"`
+	Label   string            `json:"label"`
+	Options map[string]string `json:"options"`
+}
+
+type AIModelMatchRequest struct {
+	ProductTitle string             `json:"product_title"`
+	SourceSpec   string             `json:"source_spec"`
+	Candidates   []AIModelCandidate `json:"candidates"`
+}
+
+type AIModelMatchResponse struct {
+	Conclusion         string   `json:"conclusion"`
+	CandidateID        string   `json:"candidate_id"`
+	ConfidenceBPS      int      `json:"confidence_bps"`
+	Reason             string   `json:"reason"`
+	ConflictDimensions []string `json:"conflict_dimensions"`
+	MissingDimensions  []string `json:"missing_dimensions"`
+}
+
+type AIModelClient interface {
+	Match(context.Context, model.AIProviderConfig, string, AIModelMatchRequest) (AIModelMatchResponse, error)
+}
+
+type OpenAICompatibleModelClient struct{ doer AIHTTPDoer }
+
+func NewOpenAICompatibleModelClient(doer AIHTTPDoer) *OpenAICompatibleModelClient {
+	return &OpenAICompatibleModelClient{doer: doer}
+}
+
+func (c *OpenAICompatibleModelClient) Match(ctx context.Context, provider model.AIProviderConfig, secret string, input AIModelMatchRequest) (AIModelMatchResponse, error) {
+	if c == nil || c.doer == nil {
+		return AIModelMatchResponse{}, fmt.Errorf("AI 模型客户端未初始化")
+	}
+	inputJSON, err := json.Marshal(input)
+	if err != nil {
+		return AIModelMatchResponse{}, fmt.Errorf("准备 AI 规格候选失败")
+	}
+	system := `你是商品规格候选选择器。只能从 candidates 的 id 中选择，不能生成新候选。` +
+		`只返回 JSON：conclusion(match/uncertain/conflict)、candidate_id、confidence_bps(0-10000)、` +
+		`reason、conflict_dimensions、missing_dimensions。信息不足时 conclusion 必须是 uncertain。`
+	payload, err := json.Marshal(map[string]any{
+		"model":       provider.Model,
+		"messages":    []map[string]string{{"role": "system", "content": system}, {"role": "user", "content": string(inputJSON)}},
+		"temperature": 0, "max_tokens": 300,
+		"response_format": map[string]string{"type": "json_object"},
+	})
+	if err != nil {
+		return AIModelMatchResponse{}, fmt.Errorf("准备 AI 模型请求失败")
+	}
+	request, err := http.NewRequestWithContext(ctx, http.MethodPost,
+		strings.TrimRight(provider.BaseURL, "/")+"/chat/completions", bytes.NewReader(payload))
+	if err != nil {
+		return AIModelMatchResponse{}, fmt.Errorf("准备 AI 模型请求失败")
+	}
+	request.Header.Set("Authorization", "Bearer "+secret)
+	request.Header.Set("Content-Type", "application/json")
+	response, err := c.doer.Do(request)
+	if err != nil {
+		return AIModelMatchResponse{}, fmt.Errorf("AI 模型请求失败")
+	}
+	defer response.Body.Close()
+	if response.StatusCode < 200 || response.StatusCode >= 300 {
+		_, _ = io.Copy(io.Discard, io.LimitReader(response.Body, maxAIModelResponseBytes))
+		return AIModelMatchResponse{}, fmt.Errorf("AI 模型返回 HTTP %d", response.StatusCode)
+	}
+	raw, err := io.ReadAll(io.LimitReader(response.Body, maxAIModelResponseBytes+1))
+	if err != nil || len(raw) > maxAIModelResponseBytes {
+		return AIModelMatchResponse{}, fmt.Errorf("AI 模型响应无法读取或过大")
+	}
+	var outer struct {
+		Choices []struct {
+			Message struct {
+				Content string `json:"content"`
+			} `json:"message"`
+		} `json:"choices"`
+	}
+	if err := json.Unmarshal(raw, &outer); err != nil || len(outer.Choices) == 0 {
+		return AIModelMatchResponse{}, fmt.Errorf("AI 模型响应格式不正确")
+	}
+	decoder := json.NewDecoder(strings.NewReader(outer.Choices[0].Message.Content))
+	decoder.DisallowUnknownFields()
+	var result AIModelMatchResponse
+	if err := decoder.Decode(&result); err != nil {
+		return AIModelMatchResponse{}, fmt.Errorf("AI 模型结论不是有效 JSON")
+	}
+	var extra any
+	if decoder.Decode(&extra) != io.EOF {
+		return AIModelMatchResponse{}, fmt.Errorf("AI 模型结论包含多余内容")
+	}
+	return result, nil
+}