init: initial commit

internal/service/ai_bridge.go

@@ -0,0 +1,145 @@
+package service
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+)
+
+// AICallConfig holds the resolved configuration for a single AI API call.
+type AICallConfig struct {
+	BaseURL      string
+	APIKey       string
+	Model        string
+	MaxTokens    int
+	SystemPrompt string
+}
+
+// ── Request / Response types (OpenAI-compatible format) ──────────────────────
+
+type dsMessage struct {
+	Role    string `json:"role"`
+	Content string `json:"content"`
+}
+
+type dsRequest struct {
+	Model     string      `json:"model"`
+	Messages  []dsMessage `json:"messages"`
+	Stream    bool        `json:"stream"`
+	MaxTokens int         `json:"max_tokens,omitempty"`
+}
+
+type dsDelta struct {
+	Content string `json:"content"`
+}
+type dsChoice struct {
+	Delta        dsDelta `json:"delta"`
+	FinishReason string  `json:"finish_reason"`
+}
+type dsSSELine struct {
+	Choices []dsChoice `json:"choices"`
+}
+
+// ── Public API ────────────────────────────────────────────────────────────────
+
+// CallDeepSeekStream sends a messages list to any OpenAI-compatible endpoint
+// defined in cfg, with stream:true. Pushes each delta content chunk to streamCh.
+func CallDeepSeekStream(ctx context.Context, cfg AICallConfig, messages []dsMessage, streamCh chan<- string) error {
+	if cfg.APIKey == "" {
+		return fmt.Errorf("API key 未配置，请在设置中填写或联系管理员")
+	}
+
+	payload := dsRequest{
+		Model:     cfg.Model,
+		Messages:  messages,
+		Stream:    true,
+		MaxTokens: cfg.MaxTokens,
+	}
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("marshal request: %w", err)
+	}
+
+	client := &http.Client{Timeout: 60 * time.Second}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, cfg.BaseURL, bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("build request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Accept", "text/event-stream")
+	req.Header.Set("Authorization", "Bearer "+cfg.APIKey)
+
+	resp, err := client.Do(req)
+	if err != nil {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		return fmt.Errorf("http request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		errBody, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("upstream status %d: %s", resp.StatusCode, string(errBody))
+	}
+
+	return parseDeepSeekSSE(ctx, resp.Body, streamCh)
+}
+
+// BuildRAGMessages constructs the OpenAI-compatible messages slice.
+// If customSystemPrompt is non-empty, it replaces the built-in RAG template.
+func BuildRAGMessages(knowledgeContext, userQuery, customSystemPrompt string) []dsMessage {
+	var systemContent string
+	if customSystemPrompt != "" {
+		systemContent = customSystemPrompt
+		if knowledgeContext != "" && knowledgeContext != "(无相关本地知识)" {
+			systemContent += "\n\n以下是本地知识库中的相关内容供参考：\n---\n" + knowledgeContext + "\n---"
+		}
+	} else {
+		systemContent = fmt.Sprintf(
+			"你是一位专业的植物养护和客服顾问，擅长用温暖、自然、有亲和力的语气沟通。\n\n"+
+				"以下是来自本地知识库的相关内容，请优先参考：\n\n---\n%s\n---\n\n"+
+				"根据以上知识润色话术，直接输出内容，不加前缀或解释。",
+			knowledgeContext,
+		)
+	}
+	return []dsMessage{
+		{Role: "system", Content: systemContent},
+		{Role: "user", Content: userQuery},
+	}
+}
+
+func parseDeepSeekSSE(ctx context.Context, body io.Reader, ch chan<- string) error {
+	scanner := bufio.NewScanner(body)
+	scanner.Buffer(make([]byte, 64*1024), 64*1024)
+
+	for scanner.Scan() {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		line := scanner.Text()
+		if !strings.HasPrefix(line, "data:") {
+			continue
+		}
+		data := strings.TrimSpace(strings.TrimPrefix(line, "data:"))
+		if data == "[DONE]" {
+			break
+		}
+		var event dsSSELine
+		if err := json.Unmarshal([]byte(data), &event); err != nil {
+			continue
+		}
+		if len(event.Choices) > 0 {
+			if chunk := event.Choices[0].Delta.Content; chunk != "" {
+				ch <- chunk
+			}
+		}
+	}
+	return scanner.Err()
+}