voice-assistant/main.go

package main

import (
	"context"
	"encoding/base64"
	"fmt"
	"log/slog"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/nats-io/nats.go"

	"git.daviestechlabs.io/daviestechlabs/handler-base/clients"
	"git.daviestechlabs.io/daviestechlabs/handler-base/config"
	"git.daviestechlabs.io/daviestechlabs/handler-base/handler"
)

func main() {
	cfg := config.Load()
	cfg.ServiceName = "voice-assistant"
	cfg.NATSQueueGroup = "voice-assistants"

	// Voice-specific settings
	ragTopK := getEnvInt("RAG_TOP_K", 10)
	ragRerankTopK := getEnvInt("RAG_RERANK_TOP_K", 5)
	ragCollection := getEnv("RAG_COLLECTION", "documents")
	sttLanguage := getEnv("STT_LANGUAGE", "") // empty = auto-detect
	ttsLanguage := getEnv("TTS_LANGUAGE", "en")
	includeTranscription := getEnvBool("INCLUDE_TRANSCRIPTION", true)
	includeSources := getEnvBool("INCLUDE_SOURCES", false)

	// Service clients
	timeout := 60 * time.Second
	stt := clients.NewSTTClient(cfg.STTURL(), timeout)
	embeddings := clients.NewEmbeddingsClient(cfg.EmbeddingsURL(), timeout, "")
	reranker := clients.NewRerankerClient(cfg.RerankerURL(), timeout)
	llm := clients.NewLLMClient(cfg.LLMURL(), timeout)
	tts := clients.NewTTSClient(cfg.TTSURL(), timeout, ttsLanguage)
	milvus := clients.NewMilvusClient(cfg.MilvusHost, cfg.MilvusPort, ragCollection)

	h := handler.New("voice.request", cfg)

	h.OnMessage(func(ctx context.Context, msg *nats.Msg, data map[string]any) (map[string]any, error) {
		requestID := strVal(data, "request_id", "unknown")
		audioB64 := strVal(data, "audio", "")
		language := strVal(data, "language", sttLanguage)
		collection := strVal(data, "collection", ragCollection)

		slog.Info("processing voice request", "request_id", requestID)

		// 1. Decode audio
		audioBytes, err := base64.StdEncoding.DecodeString(audioB64)
		if err != nil {
			return map[string]any{"request_id": requestID, "error": "Invalid audio encoding"}, nil
		}

		// 2. Transcribe audio → text
		transcription, err := stt.Transcribe(ctx, audioBytes, language)
		if err != nil {
			slog.Error("STT failed", "error", err)
			return map[string]any{"request_id": requestID, "error": "Transcription failed"}, nil
		}

		query := strings.TrimSpace(transcription.Text)
		if query == "" {
			slog.Warn("empty transcription", "request_id", requestID)
			return map[string]any{"request_id": requestID, "error": "Could not transcribe audio"}, nil
		}

		slog.Info("transcribed", "text", truncate(query, 50))

		// 3. Generate query embedding
		embedding, err := embeddings.EmbedSingle(ctx, query)
		if err != nil {
			slog.Error("embedding failed", "error", err)
			return map[string]any{"request_id": requestID, "error": "Embedding failed"}, nil
		}

		// 4. Search Milvus for context (placeholder — requires Milvus SDK)
		_ = milvus
		_ = collection
		_ = embedding
		_ = ragTopK
		var documents []map[string]any // Milvus results placeholder

		// 5. Rerank documents
		if len(documents) > 0 {
			texts := make([]string, len(documents))
			for i, d := range documents {
				if t, ok := d["text"].(string); ok {
					texts[i] = t
				}
			}
			reranked, err := reranker.Rerank(ctx, query, texts, ragRerankTopK)
			if err != nil {
				slog.Error("rerank failed", "error", err)
			} else {
				documents = make([]map[string]any, len(reranked))
				for i, r := range reranked {
					documents[i] = map[string]any{"document": r.Document, "score": r.Score}
				}
			}
		}

		// 6. Build context
		var contextParts []string
		for _, d := range documents {
			if t, ok := d["document"].(string); ok {
				contextParts = append(contextParts, t)
			}
		}
		contextText := strings.Join(contextParts, "\n\n")

		// 7. Generate LLM response
		responseText, err := llm.Generate(ctx, query, contextText, "")
		if err != nil {
			slog.Error("LLM generation failed", "error", err)
			return map[string]any{"request_id": requestID, "error": "Generation failed"}, nil
		}

		// 8. Synthesize speech
		responseAudioBytes, err := tts.Synthesize(ctx, responseText, ttsLanguage, "")
		if err != nil {
			slog.Error("TTS failed", "error", err)
			return map[string]any{"request_id": requestID, "error": "Speech synthesis failed"}, nil
		}
		responseAudioB64 := base64.StdEncoding.EncodeToString(responseAudioBytes)

		// Build response
		result := map[string]any{
			"request_id": requestID,
			"response":   responseText,
			"audio":      responseAudioB64,
		}

		if includeTranscription {
			result["transcription"] = query
		}

		if includeSources && len(documents) > 0 {
			sources := make([]map[string]any, 0, 3)
			for i, d := range documents {
				if i >= 3 {
					break
				}
				text := ""
				if t, ok := d["document"].(string); ok && len(t) > 200 {
					text = t[:200]
				} else if t, ok := d["document"].(string); ok {
					text = t
				}
				score := 0.0
				if s, ok := d["score"].(float64); ok {
					score = s
				}
				sources = append(sources, map[string]any{"text": text, "score": score})
			}
			result["sources"] = sources
		}

		// Publish to response subject
		responseSubject := fmt.Sprintf("voice.response.%s", requestID)
		_ = h.NATS.Publish(responseSubject, result)

		slog.Info("completed voice request", "request_id", requestID)
		return result, nil
	})

	if err := h.Run(); err != nil {
		slog.Error("handler failed", "error", err)
		os.Exit(1)
	}
}

// Helpers

func strVal(m map[string]any, key, fallback string) string {
	if v, ok := m[key]; ok {
		if s, ok := v.(string); ok {
			return s
		}
	}
	return fallback
}

func boolVal(m map[string]any, key string, fallback bool) bool {
	if v, ok := m[key]; ok {
		if b, ok := v.(bool); ok {
			return b
		}
	}
	return fallback
}

func getEnv(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}

func getEnvInt(key string, fallback int) int {
	if v := os.Getenv(key); v != "" {
		if i, err := strconv.Atoi(v); err == nil {
			return i
		}
	}
	return fallback
}

func getEnvBool(key string, fallback bool) bool {
	if v := os.Getenv(key); v != "" {
		return strings.EqualFold(v, "true") || v == "1"
	}
	return fallback
}

func truncate(s string, n int) string {
	if len(s) <= n {
		return s
	}
	return s[:n] + "..."
}